NuttX Release Notes
===================

This file contains are the release notes for the NuttX (and apps) packages
for every release.  The text is just as was written at the time of release
(with perhaps some corrected typos).  Over the course of time, NuttX has
used several different repositories:  CVS, two SVN repositories, and
currently a GIT repository.  Therefore, revision information specific to an
older repository may not be meaningful today.

To make it easier to track there older versions in the current GIT
repository, a GIT lightweight tag has been applied for each release.  The
tag name is the release name (for example, the release 6.27 has tag name
"nuttx-6.27").

NuttX-0.1.0
-----------

This is the initial.  This initial includes the complete NuttX RTOS
with support for the Linux user mode simulation and the TI TMS320C5471
(Arm7) processor.  Partial support for the 87C52 is included.

This release has been verified on both the Linux user-mode and C5471
platforms using the test program under examples/ostest.  Test results
for the C5471 can be found in arch/c5471/doc/test-results.txt.

This tarball contains a complete CVS snapshot from March 9,2007.

NuttX-0.1.1
-----------

This is the second release of NuttX.  This release includes the following.
See the ChangeLog for more detailed description of the changes.

(1) General OS bugfixes (see the ChangeLog for details),
(2) bugfixes for the TI TMS320C5471 (Arm7) platform (see
    the ChangeLog)
(3) Complete support for the 87C52. (However, the 87C52
    release is not stable enough for general usage).
(4) Added the beginning of a shell call NuttShell (nsh)

This release has been verified on the Linux user-mode platform, the
Spectrum Digital TMS320C5471 EVM, and the PJRC 87C52 development board
using the test program under examples/ostest.

STATUS: The development status remains as ALPHA until further testing
is performed.

This tarball contains a complete CVS snapshot from March 14, 2007.

NuttX-0.1.2
-----------

This is the third release of NuttX.  This release is
primarily a bugfix release with minimal new features.  See
the ChangeLog for a more detailed description of the
changes.

(1) Several important OS and ARM7 bugfixes,
(2) opendir(), closedir(), readdir(), etc. added
(3) Added C5471 watchdog timer.
(4) Created a shareable, serial driver.
(5) Added 'ls' command to NuttShell (nsh)
(6) Added a test of the round robin scheduler

This release has been verified on the Linux user-mode
platform, the  Spectrum Digital TMS320C5471 EVM using the
test program under examples/ostest.

This tarball contains a CVS snapshot from March 19, 2007.

NuttX-0.2.1
-----------

This is the fourth release of NuttX.  This release adds adds
support for a new platform, restructures many header files,
and adds a few new features:

(1) Support for Neuros OSD / DM320
(2) Restructuring of header files for better POSIX compliance
(3) Added kill()
(4) Added POSIX timers
(5) bugfixes and documentation updates

This release has been verified on the Linux user-mode
platform, the  Spectrum Digital TMS320C5471 EVM, and the
Neuros OSD  using the test program under examples/ostest.  Because
of the stability of these tests, the project status
has been upgraded to 'beta.'

This tarball contains a complete CVS snapshot from March 22, 2007.

NuttX-0.2.2
------------

This is the fifth release of NuttX.  There is no major new
functionality in this release.  This release adds support
for new pthread barrier APIs, changes the directory
structure, to better handle different board configurations
using the same processor architecture, and corrects a few
defects.

See the ChangeLog for a complete list of changes.

This release has been verified on the Linux user-mode
platform and the Neuros OSD using the test program under
examples/ostest.  There are no known, critical defects but
the project development status remains at 'beta' status
pending further test and evaluation.

This tarball contains a complete CVS snapshot from
March 26, 2007.

NuttX-0.2.3
------------

This is the sixth release of NuttX.  This release is
primarily a bugfix release.  Numerous problems were fixed
as detailed in the change log.  New functionality includes
support for timed message queues.

See the ChangeLog for a complete list of changes.

This release has been verified on the Linux user-mode
platform and the Neuros OSD using the test program under
examples/ostest. The results of the testing is available in
the source tree under configs/ntosd-dm320/doc/test-results.
There are no known, critical defects but the project
development status remains at 'beta' status pending further
test and evaluation.

This tarball contains a complete CVS snapshot from March 29,
2007.

NuttX-0.2.4
------------

This is the 7th release of NuttX.  This release is only to roll out
build changes to better support different SoC's that use the same
processor architecture.  In particular, the two existing ARM architectures,
c5471 and DM320 were combined into a single ARM directory.  This was done
in preparation for an LPC2148 port that is currently in progress.  There
is NO new functionality or significant bugfixes in this release.

See the ChangeLog for a complete list of changes.

This release has been verified on the Linux user-mode platform
and the Neuros OSD using the test program under examples/ostest.
The results of the testing is available in the source tree under
configs/ntosd-dm320/doc/test-results and under configs/sim/doc/test-results.
There are no known, critical defects but the project development status
remains at 'beta' status pending further test and evaluation.

This tarball contains a complete CVS snapshot from April 28, 2007.

NuttX-0.2.5
------------

This is the 8th release of NuttX.  This release includes:

(1) Several bug fixes
(2) Initial support for FAT filesystems.  Testing has not
    been exhaustive and some functionality is missing
   (mkdir, stat, unlink chmod, and rename functionality is
    not yet implemented).
(3) Support for the NXP lpc2148 processor is included but
    is untested as of this writing.  The current
    implementation includes only support for serial console
    and timer interrupt.

See the ChangeLog for a complete list of changes.

This release has been verified only on the Linux user-mode
platform.

This tarball contains a complete CVS snapshot from May 19,
2007.

NuttX-0.2.6
-----------

This is the 9th release of NuttX.  This is primarily a
bugfix release to correct a number of problems introduced
with the 0.2.5 release. This release does include some FAT
filesystem extensions including unlink(), mkdir(), rmdir(),
rename(), opendir(), closedir(), readdir(), seekdir(),
telldir(), rewindir().  There are some pending FAT changes
that did not make it into this release including stat(),
truncate(), and long file names.

See the ChangeLog for a complete list of changes.

This release has been verified only on the Linux user-mode platform.

This tarball contains a complete CVS snapshot from May 26, 2007.

NuttX-0.2.7
-----------

This is the 10th release of NuttX.  This is primarily a bugfix
release to correct a number of problems reported to me (thanks
Didier!). This release does include the final changes complete the
FAT filesystem logic including stat(), statfs(), and non-standard
APIs to manage FAT attributes.  At present, FAT long file names and
file truncate() are still not supported.

See the ChangeLog for a complete list of changes.

This release has been verified only on the Linux user-mode platform.

This tarball contains a complete CVS snapshot from June 9, 2007.

NuttX-0.2.8
-----------

This is the 11th release of NuttX.  This release:
(1) corrects important bugs in opendir() and realloc()
(2) adds support for environment variables
(3) adds several new C library interfaces
(4) extends several example programs

See the ChangeLog for a complete list of changes.

This release has been verified only on the Linux user-mode platform.

This tarball contains a complete CVS snapshot from July 2, 2007.

NuttX-0.3.0
-----------

This is the 12th release of NuttX.  This release includes the initial
integration of a network subsystem and the uIP TCP/IP stack into NuttX
(see http://www.sics.se/~adam/uip/index.php/Main_Page).  Also included
is a device driver for the Davicom DM90x0 Ethernet controller.

This integration is very preliminary.  Only a small portion of the
network functionality has been integrated and there are a number of
open issues (see the TODO file).  The network subsystem is pre-alpha
at this point in time.  I expect that it will stabilize and mature
over the next few releases.

The baseline functionality of NuttX continues to mature and remains at
post-beta (as long as the network is not used).

See the ChangeLog for a complete list of changes.

This release has been verified only on the Neuros OSD (DM320 ARM9)
platform using the DM90x0 driver.

This tarball contains a complete CVS snapshot from November 6, 2007.

NuttX-0.3.1
-----------

This is the 13th release of NuttX and the second release containing
the integration of a network subsystem and the uIP TCP/IP, UDP, and
ICMP stacks into NuttX (see http://www.sics.se/~adam/uip/index.php/Main_Page).

Many network-related problems have been fixed and the implementation
has matured significantly.  However, the level of network reliability
is probably still at the pre-alpha or early level.  It is sufficiently
complete that you may begin to perform some network integration and
is expected to achieve beta level of reliability over the next few
releases.

The baseline functionality of NuttX continues to mature and remains at
post-beta (as long as the network is not used).

See the ChangeLog for a complete list of changes.

This release has been verified only on the Neuros OSD (DM320 ARM9)
platform using the DM90x0 driver.

This tarball contains a complete CVS snapshot from November 19, 2007.

NuttX-0.3.2
-----------

This is the 14th release of NuttX and the 3rd release containing
the integration of a network subsystem and the uIP TCP/IP, UDP, and
ICMP stacks into NuttX (see http://www.sics.se/~adam/uip/index.php/Main_Page).

Many network-related problems have been fixed and the implementation
has matured significantly.  This release consists of:

o TCP-related bug-fixes
o TCP performance improvements
o Initial UDP integration
o Initial uIP micro webserver integration

See the ChangeLog for a complete list of changes.

The level of network reliability is at alpha level is expected to
achieve beta level of reliability over the next few releases.

The baseline functionality of NuttX continues to mature and remains at
post-beta.

This release has been verified only on the Neuros OSD (DM320 ARM9)
platform using the DM90x0 driver.

This tarball contains a complete CVS snapshot from November 23, 2007.

NuttX-0.3.3
-----------

This is the 15th release of NuttX and the 4th release containing
the integration of a network subsystem and the uIP TCP/IP, UDP, and
ICMP stacks into NuttX (see http://www.sics.se/~adam/uip/index.php/Main_Page).

Many network-related problems have been fixed and the implementation
has matured significantly.  This release consists of:

o TCP-related bug-fixes for disconnecting sockets
o Correction of some TCP read-ahead logic
o TCP performance improvements
o Misc. additions and cleanup (See the ChangeLog for a complete list of
  changes).

The level of network reliability is at an early beta release level.  The
baseline functionality of NuttX continues to mature and remains at
post-beta. Open network-related issues include only:

o Some minor unimplemented BSD socket functionality,
o Thread safety issues: the same socket cannot be used concurrently on
  different threads.
o Pending design changes necessary to support multiple network interfaces.
o IPv6 support is incomplete.

This release has been verified only on the Neuros OSD (DM320 ARM9)
platform using the DM90x0 driver. Any feedback for improving the network
reliability/performance would be greatly appreciated.

This tarball contains a complete CVS snapshot from November 28, 2007.

NuttX-0.3.4
-----------

This is the 16th release of NuttX and the 5th release containing
the integration of a network subsystem and the uIP TCP/IP, UDP, and
ICMP stacks into NuttX (see http://www.sics.se/~adam/uip/index.php/Main_Page).

This release is primarily a bug-fix release.  New features include
only:

o TELNET front-end to NSH,
o DHCPC server functionality, and
o C5471 Ethernet driver.

Numerous network related problems were fixed related to DHCPC, UDP
input processing, UDP broadcast, send timeouts, and bad compilation when
uIP is compiled at high levels of optimization.

The level of network reliability is at a strong beta release level.  The
baseline functionality of NuttX continues to mature and remains at
post-beta or production level.

Parts of this release were verified only on the Neuros OSD (DM320 ARM9)
platform using the DM90x0 Ethernet driver and other parts on the Spectrum
Digital C5471 EVM using the C5471 Ethernet driver. Any feedback about bugs
or suggestions for improving the network reliability/performance would be
greatly appreciated.

This tarball contains a complete CVS snapshot from December 10, 2007.

NuttX-0.3.5
-----------

This is the 17th release of NuttX this release is primarily a bug-fix
release and intended to synchronize with the current CVS contents.  See
the ChangeLog for a detailed list of changes and fixes.

This release were verified only on the Spectrum Digital C5471 EVM using
the C5471 Ethernet driver. Any feedback about bugs or suggestions for
improvement would be greatly appreciated.

This tarball contains a complete CVS snapshot from December 18, 2007.

NuttX-0.3.6
-----------

This is the 18th release of NuttX.  This release contains on a few
changes.  The primary purpose of this release is to synchronize with
the release of the pascal-0.1.0 add-on package.

This release of NuttX includes the following changes:

* Fixes for use with SDCC compiler
* Added a simulated z80 target (arch/z80)
* Fix deadlock errors when using stdio but with no buffering
* Add support for the add-on Pascal P-Code interpreter (pcode/)
  (see the pascal-0.1.0 package)

This release were verified only on the simulated Z80 and host
simulation targets.  As usual, any feedback about bugs or suggestions
for improvement would be greatly appreciated.

This tarball contains a complete CVS snapshot from January 6, 2007.

====

There was an error in the initial 0.3.6 release that prevented
a successful build unless the Pascal add-on was present.  The
tarball was patched to include the fix.  Make sure that you download
the nuttx-0.3.6.1.tar.gz version to avoid this problem.

NuttX-0.3.7
-----------

This is the 19th release of NuttX.  This release includes the
preliminary port of NuttX to the ZiLOG z16f 16-bit microcontroller.
This port was verified using the ZiLOG z16f2800100zcog Development
and the ZiLOG ZDS-II toolchain. See http://www.zilog.com for
further information.

I emphasize that this is a preliminary release of the z16f port and
is only alpha or, perhaps, pre-alpha quality as of this writing.
There are a list of known issues in the TODO file in the root of
the NuttX directory.  The overall quality of NuttX (excluding the
z16f port) continues to improve beyond the late beta level.

The z16f port required numerous changes to NuttX to handle:

* NEAR and FAR addressing, and
* Use of a Windows native toolchain in a Cygwin build environment.

In addition to the z16f port, at least one very critical bug was
found and corrected in NuttX:  The thread-specific errno value of one
task was being randomly trashed when a different thread exited.

This release were verified on the ZiLOG z16f2800100zcog, Neuros OSD
(ARM9), and the simulation platforms.  As usual, any feedback about bugs
or suggestions for improvement would be greatly appreciated.

This tarball contains a complete CVS snapshot from January 31, 2008.

NuttX-0.3.8
-----------

This is the 20th release of NuttX.  This is a minor bugfix release.
It corrects a few minor problems, adds a few minor features, and
continues the integration of the ZiLOG Z18F and of the Pascal P-Code
add-on.  This release is synchronized with the release of Pascal-0.1.2.

This tarball contains a complete CVS snapshot from February 10, 2008.

NuttX-0.3.9
-----------

This is the 21st release of NuttX.  This is a minor future enhancement
release.  This release includes support for the ZiLOG Z8Encore! micro-
controller.  Also included is the initial framework for support for
the Z80, XTRS platform (http://www.tim-mann.org/xtrs.html).

This released has been verified only on the ZiLOG ZDS-II Z8Encore!
chip simulation.

This tarball contains a complete CVS snapshot from March 9, 2008.

NuttX-0.3.10
------------

This is the 22nd release of NuttX.  This is an important bug fix
release.  This release incorporates fixes to correct critical list
handling errors in task shutdown logic: One in timer deletion logic
(timer_delete.c) and one in stream logic (lib_init.c).  This release
also includes support to ZiLOG EZ80Acclaim microcontroller (EZ80F91
chip) and configurations for the ZiLOG z8f64200100kit (Z8F6423) and
ez80f0910200kitg (EZ80F091) development kit.

NuttX-0.3.11
------------

This is the 23rd release of NuttX.  This is another important bugfix
release.  This releases fixes several bugs:

* Two POSIX timer bugs: a memory leak as well a fatal sequencing error.
* Several FAT filesystem errors.
* A deadlock that can occur in opendir()

A few new features were also added:

* Support for recursive mutexes
* Added a RAM disk block driver
* The host simulator no longer uses direct Linux system calls and
  now also works on Cygwin.
* The OS test was strengthen and now runs as an endurance test

These changes were verified only on the Host simulator under Cygwin.
Please report any errors to me.

This tarball contains a complete CVS snapshot from June 1, 2008.

NuttX-0.3.12
------------

This is the 24th release of NuttX.  This release includes some minor
bugfixes as well as a few new features.  Bugs fixed include:

* Corrected an error in recursive mutex implementation.
* task_create() was only dup()ing the first three file descriptors.
* Fixed driver open reference counting errors in dup(), dup2(), and exit().
* Fixed error handling logic in fflush().

New features were also added:

* Pipes and pipe() API
* FIFOs and mkfifo() API
* mkfatfs() API can be used to format FAT file systems.

These changes were verified only on the Host simulator under Cygwin.
Please report any errors to me.

This tarball contains a complete CVS snapshot from August 10, 2008.

NuttX-0.3.13
------------

This is the 25th release of NuttX.  This release includes some
important bugfixes as well as a few new features.  Bugs fixed
include:

* Fixed problems with Cygwin-based console input.  NSH now works
  with the Cygwin simulator.
* sched_get_priority_max/min returned error on SCHED_RR
* Corrected detection of End-of-File in fgets()
* Fixed an error in opendir() that could cause an assertion to fail
  inappropriately.
* Corrected an error in the FAT that caused files opened for writing
  with O_APPEND to fail.
* Fix error in getopt() when called with argc==1
* Fix error in stat() when used on the root directory
* Fixed a critical bug that effects the way that environment variables
  are shared among pthreads.
* uIP port now supports multi-threaded, concurrent socket access.
  So, for example, one thread can be reading from a socket while
  another is writing to the socket.

New features were also added:

* New OS APIs: chdir() and getcwd()
* The NuttX shell (NSH) has been extended in many ways.
  - New commands: mkfatfs, mkfifo, sleep, usleep, nice, sh, cd, and pwd
  - New memory inspection commands and heap usage commands
  - New capabilities:
    - Execution of commands in background
    - Execution of simple scripts
    - Redirection of command output
    - Last command status ($?)
  - Now supports if-then[-else]-fi construct
  - Other features as noted in the ChangeLog.

These changes were verified only on the Host simulator under Cygwin
and under Linux and also on the Neuros OSD (ARM9).  Please report
any errors to me.

This tarball contains a complete CVS snapshot from September 1, 2008.

nutt-0.3.14
-----------

This is the 26th release of NuttX.  This release includes some
important bugfixes as well as a few new features.  Critical bugs
fixed include:

FAT FS:
  * Fixed several critical bugs with regard to fat reading and
    writing and FAT12 accesses.  Basically the FAT FS only worked
    with my tiny test files and test cases.  A lot of stronger FAT
    tested is still needed!
  * Fixed another FAT bug in implementation of FAT lseek();
    this prohibited correct random access to large files.

Network:
  * Corrected a critical bug that may prevent recvfrom from receiving
    packets from most remote UDP port numbers.
  * Corrected an error in multi-threaded socket handling in send() and
    sendto().  Outgoing data could overwrite incoming data.
  * Corrected IP checksum calculation in ICMP and UDP message send logic.
  * Corrected an error in send() timeout logic.

New features were also added:

Network:
  * Added support for application access to ICMP protocol stacks
  * Added ping request logic (net/uip).
  * Added basic TFTP client logic (netutils/tftpc).

NuttShell (NSH):
  * New commands: 'test', '[', 'ping', 'mkrd', 'xd', and TFTP 'get' and 'put'
    See the new NuttShell User Guide for additional information.

Other less critical bugs were also fixed and other less important
features were were added.  See the ChangeLog for details.

These changes were verified only on the Neuros OSD (ARM9).  Please
report any errors to me.

This tarball contains a complete CVS snapshot from September 8, 2008.

nutt-0.3.15
-----------

This is the 27th release of NuttX.  This release includes some new features:

* Adds support for the ROMFS filesystem
* ROMFS supports mmap() to provide eXecute In Place (XIP) capability
* NuttShell (NSH) can be configured to use ROMFS to provide a tiny read-only
  filesystem with a startup script in /etc.
* Completed the basic port of the NXP LPC2148 on the mcu123.com board.
  The basic port includes successful booting, timer interrupts,
  serial console, successfully passing the examples/ostest, and a
  NuttShell (NSH) configuration.

These changes were verified only on the mcu123.com NXP LPC2148
board.  Please report any errors to me.

This tarball contains a complete CVS snapshot from September 20, 2008.

nutt-0.3.16
-----------

This is the 28th release of NuttX.  This release includes the first
support for USB in NuttX.  A set of USB APIs were added to support
USB device controller drivers and bindings to USB device class
drivers.  The form of the interface was inspired by the Linux Gadget APIs.

At present USB device controller drivers are included for:
  * The NXP LPC214x.  This driver has been verified and is an early alpha
    stage in quality.
  * TI DM320.  Coding for this driver is complete but it is completely
    untested as of this release.

A controller-independent class driver is also included for:
  * USB serial class device driver (emulates the Prolific PL2303
    serial-to-USB adapter).  This driver has only been verified with
    the Linux host PL2303 driver.

Other new features include:
  * Add an option to set aside a separate stack for interrupt
    handling (ARM only).  This is useful when memory is constrained,
    there are multiple tasks, and the interrupt stack requirement
    is high (as when USB is enabled).

A few bugs were also fixed:
  * Fixed the frequency of system timer interrupts in the NXP LPC214x port
    (off by 20x in nuttx-0.3.15)
  * Fixed serial driver bugs related to (1) open counts and (2) recognizing
    O_NONBLOCK on read.
  * Fixed an error in read(); it was not setting the errno on errors returned
    from the driver.

These changes were verified only on the mcu123.com NXP LPC2148 board
using with a Linux host.  Please report any errors to me.

This tarball contains a complete CVS snapshot from October 10, 2008.

UPDATE
------
This release does not build for the ARM target when USB is disabled.
Here is the fix:

Index: arch/arm/src/common/up_internal.h
===================================================================
RCS file: /cvsroot/nuttx/nuttx/arch/arm/src/common/up_internal.h,v
retrieving revision 1.13
diff -u -r1.13 up_internal.h
--- arch/arm/src/common/up_internal.h   6 Oct 2008 16:20:52 -0000       1.13
+++ arch/arm/src/common/up_internal.h   13 Oct 2008 20:48:21 -0000
@@ -200,7 +200,8 @@
 extern void up_usbinitialize(void);
 extern void up_usbuninitialize(void);
 #else
-# define up_netinitialize()
+# define up_usbinitialize()
+# define up_usbuninitialize()
 #endif

 #endif /* __ASSEMBLY__ */

NuttX-0.3.17
------------

This is the 29th release of NuttX.  This release includes the
additional support for USB in NuttX.  The following new features
were added:

* Added support for SPI-based MMC/SD cards (with an SPI driver
  for the NXP LPC214x).
* Added USB storage class device side driver (BBB)
* Added an example that demonstrates the USB storage class by
  exporting the SPI based MMC/SD card on the NXP LPC214x.

This is an early alpha release of these drivers.  At present they
only work with debug features enabled so there are probably some
race conditions that occur only with debug features disabled.
(Anyone out there with a USB analyzer?  I would love to know what
is happening.)

Several important bugs were also fixed in the FAT file system, USB
serial driver and NXP LPC214x USB controller driver. (See the ChangeLog
for details.)

These changes were verified only on the mcu123.com NXP LPC2148 board
using a Linux development environment.  USB testing was performed
using both a Linux host and a WinXP host.  Please report any errors
to me.

This tarball contains a complete CVS snapshot from October 28, 2008.

NuttX-0.3.18
------------

This is the 30th release of NuttX.  This release includes two
partially completed ports, several new features, and a couple of
important bug fixes.  The two partially completed ports are:

  * The STMicro STR71x processor and configuration for the Olimex
    STR-P711 board.
  * The Hitachi SH-1 using the SH1_LCEVB1 (SH-1/US7032EVB1) board

Progress on these ports is stalled (as detailed in the ChangeLog).

The new features focus primarily on management of block devices and
extensions of the NuttShell (NSH).  These include:

  * A loop device that converts a file into a block device.
  * A block to character (BCH) driver that  allow access a block device as
    if it were character device.
  * Added strcasecmp() and strncasecmp() libc functions.
  * Added the 'dd' and 'losetup' commands to NSH. These commands
    (along with mkfatfs and mount), give good management of filesystems
    on the target.

Several bugs were fixed, the most important of which are:

  * Fixed a race condition workaround delay in LPC214X SPI logic.
    This was also the cause of some bad MMC/SD performance on that
    platform.

  * Fixed a recently introduced FAT file system problem: It would
    mount a (invalid) FAT file system even if the medium is not formatted!

  * Corrected two other important errors in the FAT lseek() implementation:
    1 - The sectors-per-cluster value was being reset to "1".
    2 - Important lseek logic was omitted when the seek position was zero.

The FAT filesystem has had many bugs fixed in it and, I think, is
now maturing and becoming stable.

These changes were verified only on the mcu123.com NXP LPC2148
board, the Hitachi SH1_LCEVB1 board, and the Linux simulator, all
using a Linux development environment.  Please report any errors
to me.

This tarball contains a complete CVS snapshot from November 16, 2008.

NuttX-0.3.19
------------

This is the 31st release of NuttX.  This release includes the
following new feature:

  * Add poll() and select() APIs that may be used to monitor for
    data availability on character devices or TCP/IP sockets.
  * Implemented support TCP/IP connection backlog.  This allows
    select() to wake-up on new connections to a listener socket.
  * Added definition of a framebuffer driver and implement framebuffer
    drivers for the simulated platform and the TI DM320 (untested
    as of the initial check-in).
  * Partially developed a graphics framework based on the framebuffer
    drivers, however, this will not be ready for use for a few more
    releases.  Currently this includes only a few color conversion
    routines and some rasterizing functions.  A tiny windowing system
    is under development but not ready for check-in yet.
  * Added support for fixed precision math.
  * Added support for outgoing multicast packets.

Several bugs were fixed, the most important of which are:

  * Fixed an important bug in the TCP/IP buffering logic.  When
    TCP/IP read-ahead is enabled and not recv() is in-place when a
    TCP/IP packet is received, the packet is placed into a read-ahead
    buffer.  However, the old contents of the read-ahead buffer
    were not being cleared and old data would contaminate the newly
    received buffer.

  * Changed the behavior of the serial driver read.  It now returns
    data as it is available rather than waiting for the full requested
    read size.  This makes functions like fgetc() work much more
    smoothly.

These changes were verified only on the Neuros OSD (ARM9) using a
Linux development environment. Please report any errors to me.

This tarball contains a complete CVS snapshot from November 26, 2008.

NuttX-0.4.0
-----------

This is the 32nd release of NuttX.  This release adds graphics
support and a tiny windowing subsystem.  That new graphics subsystem
is documented at http://nuttx.sourceforge.net/NXGraphicsSubsystem.html.
No other substantial changes were made.

These changes were verified only on the NuttX simulation platform
with X11 windows simulating a device framebuffer. Please report any
errors to me.

The version number was bumped up to 0.4.0 in part to reflect the
new graphics subsystem, but also to recognize the NuttX is approaching
complete functionality.  In the 0.3.x versions, network support was
added, Pascal P-code runtime support was added, FAT and ROMFS
filesystems were added, MMC/SD and USB device support were added.
There were also numerous extensions to the NuttShell, NuttX APIs,
and architecture ports.

This tarball contains a complete CVS snapshot from December 6, 2008.

NuttX-0.4.1
-----------

This is the 33rd release of NuttX.  This is a minor bugfix release.
The primary reason for this release is to correct numerous build
errors that have accumulated for the ZiLOG ZDS-II based targets.
All ZDS-II targets now build correctly (but have not been re-tested).
In addition to platform-specific build failures, this release also
adds the following features which were not tested as of the time
of the release:

  * Board support for the ZiLog ez80Acclaim! ez80f910200zco Development Kit
  * ZiLOG eZ80F91 EMAC driver

These changes were verified only on the NuttX simulation platform.
Please report any errors to me.

This tarball contains a complete CVS snapshot from February 6, 2009.

NuttX-0.4.2
-----------

This is the 34th release of NuttX.  This release adds no new OS
features but does include support for two new architectures:

  * ez80Acclaim!  Basic support has been integrated and verified
    for the ez80f910200zcog-d board (eZ80F91-based).  That basic
    support includes timer interrupts and serial console.  Ongoing
    work includes an EMAC driver that should be integrated for the
    next release nuttx-0.4.2.  eZ80Acclaim! support has been in the
    code base for some time, but has only just been integrated due
    to toolchain issues.

  * Renesas M16C/20.  Support for the Renesas SKP16C20 board has
    been included in the NuttX source tree.  However, as the
    eZ80Acclaim!, testing and integration of that port is stalled
    due to toolchain issues.

These changes were verified only on the ZiLOG eZ80910200zcog-d
board. Please report any errors to me.

This tarball contains a complete CVS snapshot from February 28, 2009.

NuttX-0.4.3
-----------

This is the 35th release of NuttX.  This release one important new
OS feature and corrects and extends the eZ80 port:

  * Priority Inheritance.  The basic NuttX waiting logic was extended
    to support priority inheritance. See the NuttX User Manual for
    further information:
    http://nuttx.apache.org/docs/latest/reference/user/05_counting_semaphore.html.

  * ez80Acclaim! Corrected several critical, show-stopping bugs on that
    platform including:
    - Errors in the serial driver interrupts.
    - An error in the eZ80 table.
  * eZ80Acclaim!: Completed integration of the eZ80F91 EMAC driver.

These changes were verified only on the ZiLOG eZ80910200zcog-d board
and on Cygwin-based simulation platform in various configurations.
Please report any errors to me.

This tarball contains a complete CVS snapshot from March 13, 2009.

NuttX-0.4.4
-----------

This is the 36th release of NuttX.  This release focuses on bugfixes
and extending and verifying certain networking features.

  * Important bugs were fixed in NSH, UDP checksum calculation, UDP
    bind() behavior for port==0, the eZ80Acclaim! EMAC driver, Z80
    interrupt handling, and in the C libraries.

  * Testing was extended to further verify the tiny webserver,
    DHCPD, wget(), and sendmail.

See the Changelog for a detailed description of these changes.

These changes were verified only on the ZiLOG eZ80910200zcog-d board
using the ZDS-II toolchain in Cygwin-based environment. Please
report any errors to me.

This tarball contains a complete CVS snapshot from March 29, 2009.

NuttX-0.4.5
-----------

This is the 37th release of NuttX.  This release focuses on a few new features.

  * The basic port for the Freescale ARM920T i.MX1 processor on the
    Freescale MX1ADS board.  Coding is complete for this port, but
    it is has not yet fully integrated
  * Extended I2C and SPI interface definitions
  * Add basic support for C++ applications.  Very simple C++
    applications can now be built against NuttX without any external
    libraries.  At present, only the most primitive C++ programs
    are supported, but it is hoped that this support will be extended
    in future releases.

See the Changelog for a detailed description of these changes.

This tarball contains a complete CVS snapshot from April 19, 2009.

NuttX-0.4.6
-----------

This is the 38th release of NuttX.  The release features support
for the Micromint Eagle-100 development board.  This board is based
around, the Luminary LM3S6918 MCU.  This is the first ARM Cortex-M3
architecture supported by NuttX. This initial, basic port includes
timer and serial console with configurations to execute the NuttX
OS test and to run the NuttShell (NSH). Work is still underway on
this port and current plans are to have I2C, SSI, MMC/SD, and
Ethernet driver in the 0.4.7 release.

Additional work was done on the MXADS i.MX1 port, however, that
work has been set aside until I complete work on the Eagle-100 (I
also need to come up with a 3V power supply).

Other changes in this release include: Extensions to the SPI interface
definition in order to handle 9-bit interfaces to displays.  Several
bugs were fixed (see the ChangeLog for a complete list of changes).

This tarball contains a complete CVS snapshot from May 19, 2009.

NuttX-0.4.7
-----------

This is the 39th release of NuttX.  This release focuses on cleaning
up and extending the Eagle100/LM3S6918 port released in nuttx-0.4.6
and on improved MMC/SD support.  New features include:

  * Improved reliably and additional drivers for the Eagle-100 board
    (LM3S6918 ARM Cortex-M3).  Additional drivers include Ethernet,
    SSI, and support for the on-board LEDs and microSD cards.

  * The SPI-based MMC/SD driver was extended to support SDHC Version
    2.xx cards.

In addition, this release includes several important bugfixes for
the LM3S6918, the LPC2148, the SPI-based MMC/SD driver, and to
FAT32.  See the ChangeLog for details of these bugfixes.

This tarball contains a complete CVS snapshot from May 29, 2009.

NuttX-0.4.8
-----------

This is the 40th release of NuttX.  This release adds:

  * Support for the Olimex STRP711 board.  That board is based on
    the STMicro STR711 MCU (ARM7TDMI). Integration is complete on
    the basic port (boot logic, system time, serial console). Two
    configurations have been verified: (1) The board boots and
    passes the OS test with console output visible on UART0, and
    the NuttShell (NSH) is fully functional with interrupt driven
    serial console.  An SPI driver is available but untested (because
    the Olimex card slot appears to accept only MMC cards; I have
    only SD cards).  Additional needed: USB and driver, MMC
    integration.

  * Support for the CodeSourcery and devkitARM Windows-native GNU
    toolchains.  Makefiles have been modified for the LM3S6918,
    LPC2148, and STR711 to support these toolchains under Cygwin.

This tarball contains a complete CVS snapshot from June 13, 2009.

NuttX-0.4.9
-----------

This is the 41st release of NuttX.  This release adds:

  * Support for a new binary format call NXFLAT that can be used to
    execute separately linked programs in place in a file system.
    See https://nuttx.apache.org/docs/latest/components/nxflat.html.

  * Several important bugs were files related to networking and ROMFS.
    See the ChangeLog for a complete list.

This tarball contains a complete CVS snapshot from June 26, 2009.

NuttX-0.4.10
-----------

This is the 42nd release of NuttX.  This released focused on the
port of Jeff Poskanzer's THTTPD HTTP server (see
http://acme.com/software/thttpd/).  As of the 0.4.10 release, that
port is still not fully complete and functional.  However, numerous
related bug-fixes and functional additions for THTTPD were added:

  * Several new standard C-library functions (fileno, strstr,
    strpbrk, fcntl).
  * Improved and extended timing APIs (mktime, gmtime, gmtime_r,
    gettimeofday, localtime, localtime_r, and strftime)
  * Networking enhancements: recvfrom() and accept() now work with
    non-blocking sockets.
  * NXFLAT extensions (exec)
  * Pattern matching logic.
  * And miscellaneous bug fixes (see the ChangeLog for details).

This tarball contains a complete CVS snapshot from August 8, 2009.

NuttX-0.4.11
------------

This is the 43rd release of NuttX. This release of NuttX incorporates
the verified port of Jeff Poskanzer's THTTPD HTTP server (see
http://acme.com/software/thttpd/).  Many of the key features of
THTTPD have been tested on the Micromint Eagle-100 development board
(Cortex-M3).  These tests verify:

  * Serving of files from any file system
  * Execution of CGI executable.  This release supports execution
    of NXFLAT executables on a ROMFS file system
    (https://nuttx.apache.org/docs/latest/components/nxflat.html)

A standard CGI interface is used:  Information is pasted to the CGI
program via POST commands and via environment variables.  CGI socket
I/O is redirected to stdin and stdout so that the CGI program only
need to printf() to send its content back to the HTTP client.

Another value to this THTTPD integration effort has been that THTTPD
has provided a very good test bed for finding NuttX networking bugs.
Several very critical networking bugs have been fixed with this
0.4.11 release (see the ChangeLog for details).  Networking throughput
has also been greatly improved.  Anyone using NuttX networking
should consider upgrading to this release.

This tarball contains a complete CVS snapshot from September 16, 2009

NuttX-0.4.12
------------

This is the 44th release of NuttX.  This release adds basic support
for the STMicro STM32, Cortex-M3 MCU.  The specific port is to the
STMicro STM3210E-EVAL development board based around the STM32F103ZET6
MCU.  Some highlights of this port:

  * This basic port includes boot-up logic, interrupt driven serial
    console, and system timer interrupts.
  * Includes a basic STMicro RIDE7 project that can be used to
    perform basic STM32 board bring-up (due to RIDE7 size limitations,
    it cannot be used for the full NuttX bring-up).
  * Working, Tested Configurations: the NuttX OS test and the
    NuttShell (NSH) example.

This basic STM32 port will be extended in the 0.4.13 NuttX release.
Functionality needed for complete STM32 support includes:  USB
device driver, LCD driver and NX bringup on the development board's
display and MicroSD support.  An SPI driver and a DMA support was
included in this 0.4.12 release, but is not yet tested.

This tarball contains a complete CVS snapshot from October 17, 2009

NuttX-0.4.13
------------

This is the 45th release of NuttX.  The release extends the support
for the STMicro STM32 microcontroller.  Minimal support for the
STM3210E-EVAL development board based around the STM32F103ZET6 MCU
was released in NuttX-0.4.12.  This release adds:

  * A simple interface definition to support some FLASH, EEPROM,
    NVRAM, etc. devices.
  * Verified SPI operation using driver for SPI based FLASH parts
    M25P64 and M25P128.
  * Improved Cortex-M3 context switching.  This should improve
    context switching performance be 2x in certain cases.
  * Added a USB device-side driver for the STM32.  This is an early
    release of a very complex driver; some bugs are expected.
  * The USB driver has been verified against the USB serial device
    class driver.  There is at least one known outstanding issue
    (see the full bug description in the TODO list).

This release also corrects some important bugs in the early STM32 release:

  * Fixed several errors the prevented operation of NuttX on an
    STM32 development board using USART2 as the serial console.
  * Fixed and optimization-dependent race condition in the clock
    initialization.
  * Fixed a critical bug in the interrupt control logic that could
    cause interrupt operations to failed used for interrupts in a
    certain range.

This tarball contains a complete CVS snapshot from November 4, 2009

NuttX-4.14
----------

This is the 46th release of NuttX.  The release extends the support
for the STMicro STM32 microcontroller.  Minimal support for the
STM3210E-EVAL development board based around the STM32F103ZET6 MCU
was released in NuttX-0.4.12 and extended in NuttX-0.4.13 to include
initial USB support.  This completes the STM32F103ZET6 and adds:

New Generic RTOS Features:

  * Added generic support that can be included in any block driver
    to provide read-ahead buffering and write buffering for improved
    driver performance.
  * Added a generic worker thread that can used to defer processing
    from an interrupt to a task.
  * Defined a generic SD/SDIO interface can can be bound to a MMC/SD
    or SDIO driver to provide SDIO support.
  * Implemented a an SDIO-based MMC/SD driver using this new SDIO
    interface.

New STM32 Features:

  * Add support to configure an STM32 input GPIO to generate an
    EXTI interrupt.
  * Added support for buttons on the STM3210E-EVAL board.
  * Implemented an STM32 version of the common the SDIO interface.
  * Added a configuration to exercise the STM32 with the USB mass
    storage device class example.

This release also corrects some important bugs in the early STM32 release:

  * Correct error handling in the mount() logic.
  * Fixed several STM32 DMA-related issues. Integrated and debugged
    STM32 DMA functionality that was added in 0.4.12.
  * Fixed several bugs in the STM32 USB device-side driver.

NOTE:  This version, 4.14, is equivalent to what would have been
called 0.4.14 to follow 0.4.13.  The zero has been eliminated from
the front of the version number to avoid confusion about the state
of development:  Some have interpreted the leading zero to mean
that the code is in some way unstable.  That was not the intent.
Beginning in January 2010, I will switch to the 2010.nn versioning
as many others have done to avoid such confusion.

This tarball contains a complete CVS snapshot from December 2, 2009

NuttX-5.0
---------

This is 47th release of NuttX and the successor to nuttx-4.14.  This
major revision number has been incremented to indicate that an
incompatibility with previous nuttx releases has been introduced.
This version adopts standard fixed width integer names as specified
by the ANSI C99 standard.  The core logic of NuttX is older than
that standard and did not conform to it.

If you have applications running on NuttX-4.14, those applications
should continue to build and execute without problem on NuttX-5.0.
However, if you have device drivers or other OS-internal logic, you
will probably have to make some minor changes to your code to use
this version.  Below is a summary of those changes:

  * If you include sys/types.h to get the non-standard, fixed width
    integer types (uint32, uint16, ubyte, etc.), that is no longer
    necessary.
  * Instead, you will need to include stdint.h where the new fixed
    width integer types are defined (uint32_t, uint16_t, uint8_t, etc).
  * You will have to change all occurrences of the following types:

    uint32 -> uint32_t
    uint16 -> uint16_t
    ubyte  -> uint8_t
    uint8  -> uint8_t
    sint32 -> int32_t
    sint16 -> int16_t
    sint8  -> int8_t

 * In addition, the non-standard type 'boolean' must replaced with
   the standard type 'bool'.  The type definition for 'bool' is in
   stdbool.h

This change in typing caused small changes to many, many files.  It
was verified that all configurations in the release still build
correctly (other than the SDCC-based configurations).  Regression
testing was performed on a few configurations, but it is possible
that minor build issues still exist. (If you encounter any, please
let me know and I will help you to fix them.)

In the course of the regression testing, several important bugs
unrelated to the type changes were found and corrected.

  * Fixed an important error in the RX FIFO handling logic of the
    LM3S6918 Ethernet driver.
  * Corrected the handling of TCP sequence numbers in the TCP stack.
  * And other less important bugs as detailed in the ChangeLog.

The primary focus of this release was standards compatibility, but
a few new features were added including a (1) Flash Translation
Layer (FTL) that will support filesystems on a FLASH device and (2)
partial ports for the STM32F107VC and HCS12 C9S12NE64 MCUs.  Those
ports are very incomplete as of this writing.

This tarball contains a complete CVS snapshot from December 21, 2009

NuttX-5.1
---------

This is the 48th release of NuttX.  This release adds support for
two new MCU architectures in various states of development:

* AT91SAM3U (http://www.atmel.com/products/at91/sam3landing.asp?family_id=605)

  This release adds support for the SAM3U-EK development board with
  the AT91SAM3U4E MCU
  (http://www.atmel.com/dyn/products/product_card_mcu.asp?part_id=4562).
  As with most NuttX architecture releases, the release will be
  rolled out in two parts:  A basic port and an extended port.

  NuttX-5.1 includes the basic port for the SAM3U-EK board.  This
  release passes the NuttX OS test and is proven to have a valid
  OS implementation.  It supports the basic boot-up, serial console
  and timer interrupts.  A configuration to support the NuttShell
  is also included.

  The extended port will also include support for SDIO-based SD
  cards and USB device (and possible LCD support).  These extensions
  may or may not happen by the NuttX 5.2 release as my plate is
  kind of full now.

* LPC3131 (http://ics.nxp.com/products/lpc3000/lpc313x.lpc314x.lpc315x/)

  This release also adds the complete implementation of the basic
  port for the NXP LPC3131 MCU on the Embedded Artists EA3131 board
  (http://www.embeddedartists.com/products/kits/lpc3131_kit.php).
  That port, unfortunately has stalled due to tools issues.  Those
  tool issues have been resolved and I am confident that the verified
  basic port will be available in NuttX-5.2.

  The extended release will follow and should include SDIO-based
  SD card support and device USB.

A few additional features and bugfixes of a minor nature were also
incorporated as detailed in the ChangeLog.

NuttX-5.2
---------

This is the 49th release of NuttX.  This release completes the
verification of the basic port for the NXP LPC3131 MCU on the
Embedded Artists EA3131 board
(http://www.embeddedartists.com/products/kits/lpc3131_kit.php).
This basic port includes basic boot-up, serial console, and timer
interrupts.  This port has been verified on the using the NuttX OS
test and includes a working implementation of the NuttShell (NSH).

An extended release will follow and should include SDIO-based SD
card support and device USB.

NuttX-5.3
---------

This is the 50th release of NuttX.  This release support for one new
architecture:

  * A basic port for the NXP LPC2378 MCU on the Olimex-LPC2378
    development board was contributed by Rommel Marcelo.

And extensions to two existing architectures:

  * David Hewson contributed a dual-speed (full/high) USB device-side
    driver for the NXP LPC3131 on the Embedded Artists EA3131
    development board.

  * A DMA driver and a high speed MCI driver for the Atmel AT91SAM3U
    are included (but not fully tested in this release).

Two important bugfix was also included:

  * An important fix to the USB mass storage driver was contributed
    by David Hewson.
  * A serious error in the AT91SAM3U PIO handling was fixed.

NuttX-5.4
---------

This is the 51st release of NuttX.  This release includes one new,
important extension to th NX graphics system (See
https://nuttx.apache.org/docs/latest/components/nxgraphics/index.html).

NX was develop a couple years back on hardware that supported only
framebuffer devices, that is, video hardware with video memory
directly converts the memory content to video.  However, most MCUs
that NuttX focuses on do not support such video memory; rather,
that typically only support LCDs via parallel or serial interfaces.

This release of NuttX extends NX so that now renders directly to
the LCD device via its serial or parallel interface.  No in-memory
copy of the screen memory need be maintained so this solution should
also work in MCUs with very limited SRAM.

This initial release of this feature includes the verified NX
extensions plus a driver for the HX8347, 16-bit parallel LCD.  This
LCD supports 16-bit RGB (5:6:5).

NuttX-5.5
---------

This is the 52nd release of NuttX.  This release includes one new
port, some new drivers and some important bugfixes:

  * NuttX was ported to the Luminary/TI LM3S6965 Ethernet Evaluation
    Kit.  At present, that port includes an OS test configuration
    and a NuttShell (NSH) configuration with Telnet support.

    MMC/SD and Networking support are provided but not thoroughly
    verified in this release: Current development efforts are focused
    on porting the NuttX window system (NX) to work with the
    Evaluation Kits OLED display.

  * A NuttX Ethernet driver for the Microchip ENC28J60 SPI Ethernet
    chip is available in the source tree (but has not yet been fully
    verified because I haven't properly connected it to hardware
    yet).

  * The Olimex STR-P711 NuttX port was extended to support the
    ENC28J60 and some new networking configurations were added.
    The ENC28J60 has not been tested on the STR-P711, however,
    because of hardware issues (I don't think the USB powered board
    provides enough power for the ENC28J60 and I don't have the
    right wall wart yet).

    Along the way, external interrupt support (XTI) was added to
    the STMicro STR-P711 port and some important bugs were fixed
    in the STR-P711 SPI driver.

  * Added (optional) floating point support for printf().
    (Contributed by Yolande Cates.)

  * Corrected an important UDP reference counting error.  It was
    not a serious error, but it trigger an assertion was IS a serious
    error.

NuttX-5.6
---------

This is the 53rd release of NuttX.  This release includes one several
new drivers for existing NuttX ports:

  * This port adds support for the RiT displays P14201 4-bpp,
    greyscale OLED.  4-bpp greyscale support was integrated into
    the NX graphics sub-system and verified using the TI/Luminary
    LP3S6965 Ethernet Evaluation Kit.

  * The M25Px driver was extended for the M24P1 FLASH part (see NOTE).

  * An I2C driver and (basic) SPI driver were added for the NXP
    LPC313x port.  The I2C interface definition was extended to
    efficiently handle multiple I2C transfers.
    (Contributed by David Hewson.)

As well as a few, important USB-related bugfixes (See the ChangeLog
for details).

This release also includes the beginnings of a port for the NXP
LPC1768 MCU.  However, it is too early for that port to be useful
(stay tuned for a future announce of the availability of the LPC1768
port).

NuttX-5.7
---------

This is the 54th release of NuttX.  This release adds basic support
for one new ARM Cortex-M3 architecture:

  * Added support for NXP LPC1768 MCU as provided on the Nucleus
    2G board from 2G Engineering (http://www.2g-eng.com).
  * Some initial files for the LPC17xx family were released in NuttX
    5.6, but the first functional release for the NXP LPC1768/Nucleus2G
    occurred with NuttX 5.7.
  * That initial basic release included timer interrupts and a
    serial console and was verified using the NuttX OS test.
  * That release includes a verified NuttShell (NSH) configuration
    (see the https://nuttx.apache.org/docs/latest/components/nsh/index.html).
  * Also included are unverified SPI and USB device drivers.

Further efforts include:
  (1) development of a DMA support library
  (2) SPI-based MMC/SD support
  (3) verification of the USB driver

Watch for announcement of the completed LPC1768 port expected in
NuttX-5.8.

NuttX-5.8
---------

This is the 55th release of NuttX.  This includes several important
bugfixes:

  * Corrects some interrupt vectoring for the TI/Stellarix LM3S
    port
  * Correct initialization logic for NXP LPC17xxx NuttX ports:
    Power was not being provided to the GPIO module!
  * Corrected (but did not verify) implementation of the optional
    interrupt stack feature (all Cortex M3 architectures).
  * Correct a HardFault in the LPC17xx SSP driver.

Additional minor fixes are also included as detailed in the ChangeLog.

Several new features have been fully developed and included in this
release, but full verification of most of these new features has
been blocked for a variety of issues:

  * Added microSD support for the NuttShell (NSH) configuration in
    the Nucleus2G LPC1768 port.  For reasons that have not yet been
    determined, I have not successfully accessed the microSD card
    as of this writing.
  * Two USB configurations were also added for the Nucleus2G board:
    One to support the USB serial device and one for the USB mass
    storage device.  Some testing of the USB driver was performed,
    but full verification is stalled for an OTG style USB cable.
  * LEDs now work correctly on the Nucleus2G LPC1768 board.
  * The NuttX/uIP networking subsystem now supports IGMPv2 client.
    IGMP (Internet Group Multicast Protocol) network "appliances"
    to join into multicast groups.  Outbound traffic to enter and
    leave multicast groups has been verified, but full verification
    will require a switch capable of multicast.  Issues associated
    with the receipt of multicast packets are likely.

NuttX-5.9
---------

This is the 56th release of NuttX.  This release is difficult to
categorize; NuttX-5.9 was really released because there were too
many changes accumulating in CVS -- a few important, some unfinished
implementations, and a couple of important bugfixes.

  * By far biggest change in this release is the complete implementation
    of on-demand paging support.  This feature will allow you to
    execute large programs on a mass storage device (such as SPI
    FLASH) in a small RAM.  All of the core on-demand paging logic
    was completed
    (see https://nuttx.apache.org/docs/latest/components/paging.html)
    and support was implemented for the ARM-9 family.  A test
    configuration is in place for the NXP LPC3131.  It has been
    verified that this new logic does not interfere with normal
    fixed-page ARM9 operation, but otherwise this new on-demand
    paging feature is untested.
  * Add support for the CodeSourcery toolchain to the Olimex-lpc2378
    port and for the Neuros OSD port.
  * The Neuros OSD port has been updated to work with the production
    v1.0 OSD (previously it only worked with the development board).
  * And some miscellaneous feature enhancements as detailed in the
    ChangeLog.

This includes several important bugfixes:

  * NXP LPC17xx - Fixed a critical bug in the GPIO configuration
    logic: When attempting to set no pull-up or pull-down (floating),
    it would, instead, select pull-down.

  * TI/Luminary LM3Sxxxx - Fixed:
    (1) A logic error in an address table lookup.
    (2) GPIO port encoding the limited support to only 8 GPIO ports.

  * Corrected the lease time in the DHCPC implementation:  It was
    not in host byte order.

  * And several other less important bugs as documented in the
    ChangeLog: Warnings, cornercase compilation problems, etc.

NuttX-5.10
----------

This is the 57th release of NuttX.  This release includes a combination
of some new features as well as several bugfixes.  New features
include:

  * TI/Luminary Stellaris LM3S9B96:
    Header file changes contributed by Tiago Maluta.
  * TI/Luminary Stellaris LM3S8962:
    Header file changes and support for the Stellaris LM3S8962
    Ethernet+CAN Evaluation Board contributed by Larry Arnold.
  * On-Demand Paging Support:
    The basic logic for the On-Demand Paging feature is complete,
    implemented for the NXP LPC3131, and partially tested.  See
    https://nuttx.apache.org/docs/latest/components/paging.html.
    Some additional test infrastructure will be needed in order to complete
    the verification.  See configs/ea3131/README.txt for details.
  * Two Pass Build Support:
    The make system now supports a two pass build where a relocatable,
    partially linked object is created on the first pass and that
    object is linked with the NuttX libraries to produce the final
    executable on the second pass.  This two pass build is currently
    only used to support the On-Demand paging feature:  The first
    pass link forces critical logic into the locked text region;
    the second pass builds the NuttX executable more-or-less as
    normal.
  * CONFIG_APP_DIR:
    Generalized the way in which applications are built and linked
    with NuttX.  The new configuration CONFIG_APP_DIR replaces
    CONFIG_EXAMPLE.  CONFIG_EXAMPLE used to identify the sub-directory
    within the NuttX examples/ directory that held the example
    application to be built.  That made it awkward to configure to
    build an application that resides outside of the NuttX examples/
    directory.  CONFIG_APP_DIR is more general; it can be used to
    refer to any directory containing the application to be built.

    For people who have their own configurations and/or Makefiles,
    you will need to make a couple of changes:

      - Replace all occurrences of CONFIG_EXAMPLE=foobar with
    CONFIG_APP_DIR=examples/foobar in all of the configuration
    files.
      - Replace any occurrences of examples/$(CONFIG_EXAMPLE) with
    $(CONFIG_APP_DIR)
      - Replace any occurrences of lib$(CONFIG_EXAMPLE)$(LIBEXT)
        with libapp$(LIBEXT) in your Makefiles.
      - Check any other occurrences of CONFIG_EXAMPLE.

  * Several bugfixes are included as well as code changes to eliminate
    some warnings.  See the ChangeLog for details.

NuttX-5.11
----------

This is the 58th release of NuttX.  This is a bugfix release.

  * One very important bug fixes a race condition that can occur
    using semaphores that can be awakened by signals.  Under this
    particular race condition, a task could hang waiting for a
    semaphore.
  * Corrections to lm3s8962 port contributed by Larry Arnold.  That
    port is purported to work correctly with these changes in place.

Plus less critical bugfixes as detailed in the ChangeLog.  New features
include:

  * A new configuration to support the mbed.org LPC1768 board.
    (Contributed by Dave Marples.)
  * A driver for the Atmel AT45DB161D 4Mbit SPI FLASH part

NuttX-5.12
----------

This is the 59th release of NuttX.  This is a critical bugfix release.

  * Fixed an important error in the signal trampoline logic.
    Essentially, interrupts are re-enabled while the signal handler
    executes, but the logic to re-disable the interrupts before
    returning from the signal handler trampoline was missing.  Under
    certain circumstances, this can cause stack corruption.  This
    was discovered by David Hewson on an ARM9 platform, but since
    the code has been leveraged, the bug has been propagated from
    ARM to Cortex-M3, AVR32, M16C, SH1, ZNEO, eZ80, Z8, and Z80 --
    almost every architecture. The correction has been incorporated
    for all architectures but only verified on a few.

Other notable changes in NuttX-5.12:

  * A complete port for the AVR32 (AT32UC3B0256) is incorporated
    in the source tree.  Testing of this port is underway now.  This
    release was made before verifying this port in order to get the
    important bugfix in place.

  * Other miscellaneous bugfix and enhancements as noted in the
    ChangeLog.

NuttX-5.13
----------

This is the 60th release of NuttX.  Headlines for this release
include:

  * AVR32, www.mcuzone.com AVR32DEV1

    The port for the www.mcuzone.com AVRDEV1 board based on the
    Atmel AT32UC3B0256 MCU was (almost) fully integrated. The port
    now successfully passes the NuttX OS test (examples/ostest).
    A NuttShell (NSH) configuration is in place (see the NSH User
    Guide at https://nuttx.apache.org/docs/latest/components/nsh/index.html).
    Testing of that NSH configuration, however, has been postponed
    (because it got bumped by the Olimex LPC1766-STK port -- see below)

    Current Status: I think I have a hardware problem with my serial
    port setup. There is a good chance that the NSH port is complete
    and functional, but I am not yet able to demonstrate that. At
    present, I get nothing coming in the serial RXD line (probably
    because the pins are configured wrong or I have the MAX232
    connected wrong).

    A complete port will include drivers for additional AVR32 UC3
    devices -- like SPI and USB --- and will be available in a
    later release, time permitting.

  * LPC1766, Olimex LPC1766-STK

    Support for the Olimex-LPC1766 is newly added to NuttX and is
    still undergoing development, test, and integration. Verified
    configurations for the NuttX OS test and for the NuttShell (NSH,
    see the NSH User Guide at
    https://nuttx.apache.org/docs/latest/components/nsh/index.html .
    Additional USB configurations are in the release as well, but
    they have not yet been verified.  Goals for NuttX-5.14 include:
    (1) An Ethernet driver, (2) Verified USB support, and (3) SD
    card support.

  * Additional changes and bugfixes as detailed in the ChangeLog.

NuttX-5.14
----------

The 61st release of NuttX, NuttX-5.14, was made on November 27,
2010.  This release includes multiple, important bugfixes as well
as a new driver for the NXP LPC1766.

This release corresponds with SVN release number: r3137

Important bugfixes include:

  * Cortex-M3 Hard Fault.  Fixed a hard fault problem that can occur
    if certain types of interrupts are pending at the time another
    interrupt returns. This problem has only been observed on the
    LPC1766 (returning from a SYSTICK interrupt with a pending
    Ethernet interrupt).  However, it is assumed that all Cortex-M3
    ports could have this as a latent bug.

  * TCP/IP Sequence Number Bug.  Corrected errors some important
    logic in the way that sequence numbers are managed when send()
    sends out packets before a previous packet has been acknowledged.
    Some of that send() logic was incompatible with logic in the
    uIP layer.  Errors seen include: (1) The final final packet in
    a sequence of packets might be too large!  In the THTTPD example,
    this might leave some garbage at the bottom of the display. Or
    (2) send() might hang with outstanding, unacknowledged data
    (and with no re-transmission requests).  This was due to
    differences in sequence number handling in send() and in
    uip_tcpinput.c; uip_tcpinput.c thought (incorrectly) that all
    of the bytes were acknowledged; send.c knew that they were not.

  * One-Shot POSIX Timer Bug. Fixed an error in set-up of a one-shot
    POSIX timer.  It was using the repetitive timer value (which
    is zero in the one-shot case), always resulting in a 10Ms timer!
    Found and fixed by Wilton Tong.

Additional support has been included for the Olimex-LPC1766.  Support
for that board was added to NuttX 5.13.  This release extends that
support with an Ethernet driver.  Verified configurations are now
available for the NuttX OS test, for the NuttShell (NSH, see
https://nuttx.apache.org/docs/latest/components/nsh/index.html),
for the NuttX network test, and for the THTTPD webserver.
(Additional USB configurations are in the release as well, but those
have not yet been verified.  Goals for NuttX-5.15 (and beyond) include:
(1) Verified USB support, (2) SD card support, and (3) LCD support.

NuttX-5.15
----------

The 62nd release of NuttX, NuttX-5.15, was made on December 12,
2010.  This release includes several bugfixes as well as feature
enhancements, primarily for the Olimex LPC1766-STK board.

Important bugfixes included:

  * Additional fixes needed with the TCP sequence number problem
    "fixed" in NuttX-5.14.
  * In the send() logic, now checks if the destination IP address
    is in the ARP table before sending the packet; an ARP request
    will go out instead.  This improves behavior, for example, on
    the first on the first GET request from a browser
  * All USB class drivers need to call DEV_CONNECT() when they are
    ready to be enumerated.  That is, (1) initially when bound to
    the USB driver, and (2) after a USB reset.
  * The SPI_SETBITS macro was calling the SPI setmode method.
  * And several other bug fixes of lower importance (see the
    ChangeLog for details).

And feature enhancements:

  * The LPC176x Ethernet driver was using all of AHB SRAM Bank0 for
    Ethernet packet buffers (16K).  An option was added to limit
    the amount of SRAM used for packet buffering and to re-use any
    extra Bank0 memory for heap.

  * Enabled networking and SD/MMC card support in the Olimex
    LPC1766-STK NuttShell (NSH) configuration.

  * The LPC176x USB driver is now fully fully functional.
  * Added an optional cmddata() method to the SPI interface.  Some
    devices require an additional out-of-band bit to specify if the
    next word sent to the device is a command or data. The cmddata
    method provides selection of command or data.

  * A driver for the Nokia 6100 LCD (with either the Phillips PCF8833
    LCD controller and for the Epson S1D15G10 LCD controller) and
    an NX graphics configuration for the Olimex LPC1766-STK have
    been added.  However, neither the LCD driver nor the NX
    configuration have been verified as of the this release.

NuttX-5.16
----------

The 63rd release of NuttX, Version 5.16, was made on January 10,
2010 and is available for download from the SourceForge website.
This release includes initial support for USB host in NuttX. The
USB host infrastructure is new to NuttX. This initial USB host release
is probably only beta quality; it is expected the some bugs remain
in the logic and that the functionality requires extension.

Below is a summary of the NuttX USB host implementation as extracted
from the NuttX Porting Guide:

  6.3.9 USB Host-Side Drivers
  * include/nuttx/usb/usbhost.h. All structures and APIs needed to
    work with USB host-side drivers are provided in this header
    file.
  * struct usbhost_driver_s. Each USB host controller driver must
    implement an instance of struct usbhost_driver_s. This structure
    is defined in include/nuttx/usb/usbhost.h.  Examples:
    arch/arm/src/lpc17xx/lpc17_usbhost.c.
  * struct usbhost_class_s. Each USB host class driver must implement
    an instance of struct usbhost_class_s. This structure is also
    defined in include/nuttx/usb/usbhost.h.  Examples:
    drivers/usbhost/usbhost_storage.c
  * USB Host Class Driver Registry. The NuttX USB host infrastructure
    includes a registry. During its initialization, each USB host
    class driver must call the interface, usbhost_registerclass()
    in order add its interface to the registry. Later, when a USB
    device is connected, the USB host controller will look up the
    USB host class driver that is needed to support the connected
    device in this registry.  Examples: drivers/usbhost/usbhost_registry.c,
    drivers/usbhost/usbhost_registerclass.c, and
    drivers/usbhost/usbhost_findclass.c,
  * Detection and Enumeration of Connected Devices. Each USB host
    device controller supports two methods that are used to detect
    and enumeration newly connected devices (and also detect
    disconnected devices):
    + int (*wait)(FAR struct usbhost_driver_s *drvr, bool connected);
      Wait for a device to be connected or disconnected.
    + int (*enumerate)(FAR struct usbhost_driver_s *drvr);
      Enumerate the connected device. As part of this enumeration
      process, the driver will (1) get the device's configuration
      descriptor, (2) extract the class ID info from the configuration
      descriptor, (3) call usbhost_findclass() to find the class
      that supports this device, (4) call the create() method on
      the struct usbhost_registry_s interface to get a class instance,
      and finally (5) call the connect() method of the struct
      usbhost_class_s interface. After that, the class is in charge
      of the sequence of operations.
  * Binding USB Host-Side Drivers. USB host-side controller drivers
    are not normally directly accessed by user code, but are usually
    bound to another, higher level USB host class driver. The class
    driver exports the standard NuttX device interface so that the
    connected USB device can be accessed just as with other, similar,
    on-board devices. For example, the USB host mass storage class
    driver (drivers/usbhost/usbhost_storage.c) will register a
    standard, NuttX block driver interface (like /dev/sda) that can
    be used to mount a file system just as with any other other
    block driver instance. In general, the binding sequence is:

    1. Each USB host class driver includes an initialization entry
       point that is called from the application at initialization
       time.  This driver calls usbhost_registerclass() during this
       initialization in order to makes itself available in the
       event that the device that it supports is connected.  Examples:
       The function usbhost_storageinit() in the file
       drivers/usbhost/usbhost_storage.c
    2. Each application must include a waiter thread thread that
       (1) calls the USB host controller driver's wait() to detect
       the connection of a device, and then (2) call the USB host
       controller driver's enumerate method to bind the registered
       USB host class driver to the USB host controller driver.
       Examples: The function nsh_waiter() in the file
       configs/nucleus2g/src/up_nsh.c and the function nsh_waiter()
       in the file configs/olimex-lpc1766stk/src/up_nsh.c.
    3. As part of its operation during the binding operation, the
       USB host class driver will register an instances of a standard
       NuttX driver under the /dev directory. To repeat the above
       example, the USB host mass storage class driver
       (drivers/usbhost/usbhost_storage.c) will register a standard,
       NuttX block driver interface (like /dev/sda) that can be
       used to mount a file system just as with any other other
       block driver instance.  Examples: See the call to
       register_blockdriver() in the function usbhost_initvolume()
       in the file drivers/usbhost/usbhost_storage.c.

NuttX-5.17
----------

The 64th release of NuttX, Version 5.17, was made on January 19,
2011 and is available for download from the SourceForge website.
This release follows close on the heels of the 5.16 release and
extends the USB host capabilities first introduced in that version.

  * The LPC17xx USB host controller driver was extended to (1) add
    support for low-speed devices, (2) handle multiple concurrent
    transfers on different endpoints (still only one TD per endpoint),
    and (3) handle periodic interrupt endpoint types.

  * Add a USB host HID keyboard class driver.  Now you can connect
    a standard USB keyboard to NuttX and receive keyboard input for
    an application.

And other changes as detailed in the ChangeLog.

NuttX-5.18
----------

The 65th release of NuttX, Version 5.18, was made on February 27,
2011 and is available for download from the SourceForge website.
This is first release from the new NuttX SVN repository.  This
release is made primarily to keep the release tarball in synchronization
with SVN.  Many smaller changes have been made as identified in the
ChangeLog.  Headlines include:

  * Incorporate several important uIP patches -- including the well
    known patch to handle missing SYNACK.
  * The Freescale mc8s12ne64 port is code complete but testing has
    not yet begun due to toolchain issues.  Added support for the
    Future Electronics Group NE64 Badge board.
  * Added support for a new STM32 board, the ISOTEL NetClamps VSN
    V1.2 ready2go sensor network platform.  This board is based on
    a STM32F103RET6 and includes some interesting power saving/clock
    control extensions.
  * USB host support expanded to handle vendor specific USB devices.
  * Incorporated the LUFA HID parser.
  * Various bugfix as detailed in the ChangeLog

NuttX-5.19
----------

The 66th release of NuttX, Version 5.19, was made on March 12, 2011
and is available for download from the SourceForge website.  This
release includes several new features in various states of integration
and maturity:

  * 486SX QEMU port.  This port supports the Intel 486SX architecture
    using the QEMU simulator.  Initial functionality is in place a
    partially tested.  There are still some outstanding issues with
    timer interrupts.
  * Platform specific application support.  A new apps/ directory
    appears in this port.  This apps/ directory provides a mechanism
    for applications using NuttX to have a highly customized
    initialization process. It supports a set of end-user applications
    than can be executed (1) standalone so you can have a fully
    customized application startup, or (2) on top of NSH.  Think
    of it this way:  In a buckled-up embedded application, your
    end-user programs will probably have their own dedicated start-up
    logic.  But, during development, you might want to have you
    applications available and executable from the NSH command line.
    This apps/ add-on (and NSH hooks) was contributed by Uros to
    accomplish just that.
  * NSH was also extended to support application specific ROMFS
    /etc/init.d/rcS start-up scripts.  This feature, as well, as
    all of the above-mentioned apps/ directory support was contributed
    by Uros Platise
  * Additional NSH improvements and bug fixes.  See the Changelog
    for details.
  * This release also provides a new SLIP network driver.  This
    driver should support point-to-point network communications to
    a host using TCP/IP or UDP.  This driver is code complete, but
    not tested in this release.
  * New RAMTRON FRAM driver (contributed by Uros Platise)
  * New generic 16550 UART driver.
  * Cortex-M3 Power improvements: Waits for Interrupt (WFI) in idle
    loop for reduced power consumption (LPC17xx and STM32 only -
    contributed by Uros Platise))
  * New waitpid() system interface.
  * Additional bugfixes: pipes, stdint.h, STM32 SDIO and SPI drivers

NuttX-6.0
---------

The 67th release of NuttX, Version 6.0, was made on March 21, 2011
and is available for download from the SourceForge website.  The
version number of this release was bumped from 5.19 to 6.0.  A
change in the major revision number is used to reflect an incompatibility
with previous versions.  In this release, the NuttX core OS
functionality has been separated from NuttX application-related
functionality.  These are provided as separate tarballs:

  * nuttx-6.0.tar.gz, and
  * apps-6.0.tar.gz

The purpose of this separation is both to better organize and
modularize the NuttX source tree, but also to provide better support
for incorporation of end-user applications with NuttX.

The incompatibility results from the changes to the board configuration
logic needed to supported the separable application.  The major
changes to the configuration include:

  * CONFIG_APPS_DIR - This should not be set.  The default is
    ../apps.  This should only be set if you have a custom,
    product-specific application directory in some different location.

  * appconfig - Each board configuration now requires a new file
    called 'appconfig.'  As its name suggests, this file provides
    new configuration information needed by the logic in ../apps.

In addition to this major reorganization in the directory structure,
this release also includes some important extensions to existing
features and some important bugfixes.  These include:

  * The SLIP driver was been well debugged and significantly
    re-designed.  Now you can have an Ethernet connection to you
    board even if you have no Ethernet hardware.  How cool is that?

  * The QEMU i486 port is now functional.  It has also been reported
    to work on the Bifferboard (see http://bifferos.bizhat.com/).

  * And extensions to the uIP driver interface, and

  * Bug fixes to fopen() and STM32 GPIO configuration

Please see the ChangeLog for details.

NuttX-6.1
---------

The 68th release of NuttX, Version 6.1, was made on April 10, 2011
and is available for download from the SourceForge website.  The
6.0 release introduced a detach-able application environment to
build applications outside of the NuttX source tree.  The primary
purpose of this release is to correct numerous build problems
introduced by that architectural change:

  * In many newer environments, NuttX produced strange Makefile
    errors but built correctly in older environments.  A fix provided
    by Rafael Noronha was incorporated and is reported to fix those
    build problems.
  * The apps/ directory build system would not handle Windows-native
    toolchains due to obscure path formatting issues.
  * And other problems as detailed in the Changelog.

Many additional changes were made in the 6.1 release for another
major architectural change:  NuttX will now build as a separately
linked microkernel.  In this build option the RTOS builds as a
kernel, applications build separately and interface with kernel via
system calls.  Applications run in user mode and kernel logic users
in kernel-mode.  This provides a secure environment for NuttX.  This
feature is fully coded in NuttX-6.1, but has not been tested due
to higher priority tasks that have arisen.

Related to this change, support for the Cortex-M3 memory protection
unit (MPU) has been integrated with the NuttX kernel build to provide
an even higher level of security.

NOTE: This kernel build is an option; the default build configuration
is still the standard, flat, unsecured RTOS as in previous releases.

Additional new features in this release:

  * Support for LPC17xx GPIO interrupts (with much support from
    Decio Renno).
  * Basic timer support for STM32 (Contributed by Uros Platise)
  * A binfs file system.  This is a tiny pseudo file system that
    lets named applications to be viewed and accessed in NSH under
    the /bin directory.
  * An I2C-based driver for the LIS331DL MEMS motion sensor.
    (Contributed by Uros Platise.)
  * A configuration for the Embedded Artists LPCXpresso LPC1768 board.
  * The user_initialize() interface has been removed.

And several bugfix associated with SD drivers, opendir(), signed
8-bit types (int8_t), and USB serial device.  See the ChangeLog for
details.

NuttX-6.2
---------

The 69th release of NuttX, Version 6.2, was made on May 6, 2011 and
is available for download from the SourceForge website.  The 6.2
release includes several new features:

  * NXFFS: The obvious new feature is NXFFS, the NuttX wear-leveling
    FLASH file system.   This new file system is intended to be
    small for the MCU usage and has some limitations.  No formal
    documentation of NXFFS yet exists.  See the fs/nxffs/README.txt
    file for details (see
    http://svn.code.sf.net/p/nuttx/code/trunk/nuttx/fs/nxffs/README.txt?view=log)
  * Support for NXP LPCXpresso LPC1768 board on the Embedded
    Artists base board.  The Code Red toolchain is supported under
    either Linux or Windows.   Verified configurations include
    dhcpd, nsh, nx, ostest, thttpd, and usbstorage.
  * Support for the Univision UG-9664HSWAG01 OLED with Solomon
    Systech SD1305 LCD controller.
  * A new RAM MTD driver with FLASH simulation capability.
  * A version.h file is now automatically generated so that C code
      can now be version aware.

In addition to these new feature, several important bugfixes are
included in this release correcting problems with dup2(), LPC17xx
GPIO interrupts, LPC17xx UART2/3, the FAT file system, build issues,
and strrch().  See the ChangeLog for more details.

NuttX-6.3
---------

The 70th release of NuttX follows only a nines days after the release
of version 6.2.  It was released on May 15, 2011.  This special
back-to-back release was made so that the current released version
of NuttX will correspond to the initial release from the RGMP
project.

This release adds architecture support and build configuration for
RGMP.  RGMP is a project for running GPOS and RTOS simultaneously
on multi-processor platforms. See
http://rgmp.sourceforge.net/wiki/index.php/Main_Page for further
information about RGMP.

This release also includes support for STM32 FLASH, build improvements,
and initial, incomplete support for the MicroChip PIC32MX MCU.  Bug
fixes are included for some build problems, USB host class driver
error handling, NX graphics color mapping, and problems with C
standard I/O buffer flushing.  See the ChangeLog for further details.

NuttX-6.4
---------

The 71st release of NuttX, Version 6.4, was made on June 5, 2011
and is available for download from the SourceForge website.  The
6.4 release includes several new features:

  * A new, full-featured FTP client.  This client may be used as a library
    for automated FTP or via an FTP client shell.  The FTP shell
    supports the following commands: cd, chmod, get, help, idle,
    login, ls, quit, mkdir, noop, put, pwd, rename, rhelp, rm,
    rmdir, size, time, and up.  A configuration is available for
    the NXP LPC17xx to demonstrate this functionality.
  * A functional C1101 wireless driver (contributed by Uros Platise)
  * A PCI-based E1000 Ethernet driver (contributed by Yu Qiang)
  * New C library functions: inet_addr() (contributed by Yu Qiang),
    strndup(), asprintf()
  * Reduced memory allocation overhead for MCUs with small heaps (<64K).
  * fdopen() now works with socket descriptors allowing standard
    buffered C functions to be used for network communications.
  * The NSH ifconfig command can now be used to set or change the
    IP address (contributed by Yu Qiang)

This release also includes some completed but untested functionality.

  * The MicroChip PIC32MX port is now code complete and ready to
    begin testing.  Unfortunately, testing will be delayed due to
    tool issues.
  * Support for the NXP LPC315x MCUs.

Additional miscellaneous enhancements and bug fixes to task_delete(),
recvfrom(), and other changes as noted in the ChangeLog.

NuttX-6.5
---------

The 72nd release of NuttX, Version 6.5, was made on June 21, 2011
and is available for download from the SourceForge website.  The
6.5 release is all about support for the Atmel 8-bit AVR family.
I have been interested in the AVR family for some time but because
of the severe SRAM constraints and because of the availability of
many tiny schedulers for the AVR, it has not been "on the radar
screen."  However, I have recently become interested because of
interest expressed by members of the forum and because of the
availability of newer, larger capacity AVR parts (that I don't have
yet).

This release corresponds with SVN release number: r3730

This release includes support for the following AVR boards.  As
with any initial support for new architectures, there are some
incomplete areas and a few caveats that need to be stated.  Here
they are, ordered from the least to the most complete:

  * SoC Robotics Amber Web Server (ATMega128).

    This port of NuttX to the Amber Web Server from SoC Robotics
    (http://www.soc-robotics.com/index.htm).  Is only partially in
    place.  The Amber Web Server is based on an Atmel ATMega128
    (128K FLASH but only 4K of SRAM).

    STATUS: Work on this port has stalled due to toolchain issues.  It
    is complete, but untested.

  * Micropendous 3 AT9USB647

    This port of NuttX to the Opendous Micropendous 3 board. The
    Micropendous3 may be populated with an AT90USB646, 647, 1286,
    or 1287.  See http://code.google.com/p/opendous/. I have only
    the AT90USB647 version for testing.  This version has very
    limited memory resources: 64K of FLASH and 4K of SRAM.

    STATUS: The basic port was released in NuttX-6.5.  This basic
    port consists only of a "Hello, World!!" example that demonstrates
    initialization of the OS, creation of a simple task, and serial
    console output.  The tiny SRAM limits what you can do with the
    AT90USB647 (see issues below).

  * PJRC Teensy++ 2.0 AT9USB1286

    This is a port of NuttX to the PJRC Teensy++ 2.0 board.  This
    board was developed by PJRC (http://pjrc.com/teensy/). The
    Teensy++ 2.0 is based on an Atmel AT90USB1286 MCU with 128K
    of FLASH and 8K of SRAM; a little more room to move than the
    AT90USB647.

    STATUS:  The basic port was released in NuttX-6.5.  This basic
    port consists of a "Hello, World!!" example and also slightly
    simplified NuttShell (NSH) configuration (see the NSH User Guide
    at https://nuttx.apache.org/docs/latest/components/nsh/index.html).

    An SPI driver and a USB device driver exist for the AT90USB as
    well as a USB mass storage configuration.  However, this
    configuration is not fully debugged as of the NuttX-6.5 release.

AVR-specific issues.  The basic AVR port is solid and biggest issue
for using AVR is its tiny SRAM memory and its Harvard architecture.
Because of the Harvard architecture, constant data that resides to
flash is inaccessible using "normal" memory reads and writes (only
SRAM data can be accessed "normally").  Special AVR instructions
are available for accessing data in FLASH, but these have not been
integrated into the normal, general purpose OS.

Most NuttX test applications are console-oriented with lots of
strings used for printf and debug output.  These strings are all
stored in SRAM now due to these data accessing issues and even the
smallest console-oriented applications can quickly fill a 4-8K
memory.  So, in order for the AVR port to be useful, one of two
things would need to be done:

1. Don't use console applications that required lots of strings.
   The basic AVR port is solid and your typical deeply embedded
   application should work fine.

2. Create a special version of printf that knows how to access
   strings that reside in FLASH (or EEPROM).

NuttX-6.6
---------

The 73rd release of NuttX, Version 6.6, was made on July 11, 2011
and is available for download from the SourceForge website.  The
6.6 release adds several smaller features but is mostly a bugfix
release.

Bugfixes include

  * Fixed several NX Graphics bugs: Rendering fonts at >8 bits-per-pixel,
    graphics move logic, and display artifacts that appear when a
    window is closed.
  * Corrections to the USB host mass storage class driver
  * STM32 bugfixes: serial driver, GPIO interrupt handling
  * LPC17xx: Changes for a success compilation with no console.
  * Corrections to the Teensy AT90USB SD driver
  * Changes for a clean compilation under the ZDS-II toolchain.

Minor features:

  * Add logic to extract printf strings from FLASH (but there are
    still printf issues for that target)
  * Added a configuration for the Sure Electronics PIC32MX board.
    However, higher priority tasks have stopped work on that
    configuration.
  * Added several new configurations for the STMicro STM3210E-EVAL
    board.
  * Added support for the STM3210E-EVAL board: (1) LCD in either
    landscape or portrait mode, and (2) interrupting buttons.
  * Added a configuration option to use different serial ports for
    debug and for the NSH serial console (there are some issues
    with CR-LF expansion and character echo if NSH is not run on
    the console).
  * Standardized the button press and button interrupt interfaces
    so that they are common across all boards.
  * Added a new graphics example that focuses on placing text on
    the background while pop-up windows occur.  Text should continue
    to update normally with or without the popup windows present.
  * Added ARM stack checking logic.

See the ChangeLog for a detailed description of these changes.

NuttX-6.7
---------

The 74th release of NuttX, Version 6.7, was made on August 2, 2011
and is available for download from the SourceForge website.  Note
that release consists of two tarballs:  nuttx-6.7.tar.gz and
apps-6.7.tar.gz.  Both may be needed (see the top-level nuttx/README.txt
file for build information).  Changes in this release are summarized
below:

  * New OS APIs: Add the standard sem_timedwait() interface.
  * FAT File System:  Adds (optional) support for VFAT long file
    names.
  * USB:  Now the mass storage device can be connected when needed
    and disconnected when not needed (or re-connected as a different
    kind of device).
  * Touchscreen Support:  Defined a new NuttX touchscreen interface.
    Added a driver for the TI TSC2007 touchscreen controller chip.
  * NX Fonts:  Add support for multiple fonts; developed a tool to
    convert open source fonts into NuttX format; Converted and
    installed nine new, high quality fontsets.
  * NX Graphics: Add new NX APIs to support drawing of wide lines
    in any orientation.  Added new low level routines to set
    individual pixel more efficiently.
  * Build system:  Added a export target that will bundle up all
    of the NuttX libraries, header files, and the startup object
    into an exportable tarball.
  * LPC17xx: A CAN driver was contributed by Li Zhuoyi (Lzyy).
  * STM32: New NX-related configurations to exercise text and
    graphic image displays.
  * C Library:  Added a fixed precision atan2() math function.
  * Bugfixes:  Serial RX overrun error, FAT upper/lower NT 8.3 name
    handling fixed.  FAT directory allocation and initialization
    bug.  STM32 SDIO DMA race condition bug.  eZ80 UART1 serial
    driver errors (Paul Osmialowski)

NuttX-6.8
---------

The 75th release of NuttX, Version 6.8, was made on August 19, 2011
and is available for download from the SourceForge website.  Note
that release consists of two tarballs:  nuttx-6.8.tar.gz and
apps-6.8.tar.gz.  Both may be needed (see the top-level nuttx/README.txt
file for build information).  Changes in this release are summarized
below:

  * NuttX has been ported to run on the Freescale Cortex-M4 "Kinetis"
    boards.  Two board ports are available for (1) the Kinetis
    KwikStik-K40 and (2) the Kinetis TWR-K60N512 tower.
  * Support for RGMP 0.3.  This version of RGMP now runs on the
    OMAP4430 (arm) pandaboard
  * LPC17xx CAN driver extended to support both CAN1 and CAN2
    (submitted by Li Zhuoy (Lzzy))
  * Fixed several critical bugs related to signal handling
    initialization and for signals the wake up tasks that are waiting
    to send or receive message queues.Both are important.  (submitted
    by hkwilton).
  * drivers/can.c:  Fixed a semaphore overflow problem in the CAN
    driver (reported by Li Zhouy (Lzzy)).
  * Added a new ADC driver infrastructure and TI ADS1255 driver
    both developed and submitted by Li Zhouy (Lzzy)).

See the Changelog for additional changes included in this release.

NuttX-6.9
---------

The 76th release of NuttX, Version 6.9, was made on September 11, 2011
and is available for download from the SourceForge website.  Note
that release consists of two tarballs:  nuttx-6.9.tar.gz and
apps-6.9.tar.gz.  Both may be needed (see the top-level nuttx/README.txt
file for build information).

This release includes a few new features and several important bug fixes.
The new features (some still incomplete) include:

  * Analog Support/ NXP LPC17xx: New DAC sub-system including ADC and DAC
    drivers for the LPC17xx.  Extensions to the ADS1255 driver.
    (Contributed by Li Zhuoyi (Lzyy))

  * Power Management:  Added a new NuttX power management sub-system for
    controlling and coordinating reduced power states.  At present, only
    verified in a simulation environment.

  * I2C Test Tool:  A new application was added that can be used to
    verify and debug I2C interfaces from the NuttShell (NSH) command
    line.

  * NuttShell (NSH):  In addition to the I2C test tool, a date command
    is now supported (if CONFIG_RTC is defined) that can be used to
    read and set the RTC.

  * NXP LPC17xx: I2C and DAC driver for the NXP LPC17xx family submitted by Li Zhuoyi
   (Lzyy)

  * Kinetis Cortex-M4:  Added a SDHC driver for the Kinetis parts.
    Complete debug of the Kinetis SDHC driver was not completed, however,
    do to some higher priority tasks that forced me to stop work.

  * Other new drivers: Driver for I2C-based at24cxx EEPROM submitted by
    Li Zhuoyi (Lzyy); Driver for the LM-75 temperature sensor.  Support
    for the LM-75 temperature sensor integrated into the SM3210E-EVAL
    development board.

  * NuttX Graphics (NX):  Added new NX interfaces for drawing circles,
    both circle outlines and filled circles.

  * FLASH: Added a function that accepts the path to a block driver and
    then erases the underlying FLASH memory

  * Build System:  The Make export logic now also tries to track down all
    architecture-specific header files and include these in the NuttX
    export bundle as well.  Various changes and modifications so that
    NuttX wil build on FreeBSD using the ASH shell (submitted by Kurt Lidl).

Bugfixes, order roughly on decreasing criticality include:

  * STM32 I2C Driver:  Add resets, timeout, and other fixes to work
    reliably with the I2C tool.  Corrected a major error introduced in
    NuttX 6.8.

  * BCH Driver.  Several important bugs (noted by Li Zhuoyi (Lzyy))
    were fixed.

  * C Library:  Fixed errors in gmtime() and gmtime_r() that could lead to
    errors in date calculations.

  * Timing:  Correct an error in the tv_nsec calculation that happens
    only config CONFIG_RTC is enabled

  * Build System: Use of -print-libgcc-file-name to get path to
    libgcc.a might select the wrong libgcc.a if a multilib toolchain
    is used

NuttX-6.10
----------

The 77th release of NuttX, Version 6.10, was made on October 6, 2011
and is available for download from the SourceForge website.  Note
that release consists of two tarballs:  nuttx-6.10.tar.gz and
apps-6.10.tar.gz.  Both may be needed (see the top-level nuttx/README.txt
file for build information).

This release corresponds with SVN release number: r4028

This release includes a few new features and several important bug fixes.
The new features (some still incomplete) include:

  * CDC ACM serial class device-side driver

  * RTC:  Now supports hi-res and lo-res hardware RTC.  The lo-res RTC
    runs at 1Hz.

  * STM32 I2C driver.  Now supports faster, polled mode of operation.
    Added an I2C trace capability.

  * ADS7843E touchscreen driver.  As used on the SAM3U-EK development
    board.

  * AT91SAM3U SPI driver.  To support the ADS7843E toucscreen

  * X11 Support on simulation target.  Build errors in the X11 windows
    for the simulated target have been correct.  Added support for a
    simulated touchscreen on the X11 window (based on mouse inputs).

  * System Timer. Added support for a 64-bit system timer.

  * TIFF Support. Added a TIFF library (currently used for storing
    LCD screen shots).

  * LCD Support.  Added a test to verify that we read and write correct
    to LCD GRAM memory.

  * I2C tool. Extended to support to include a verify command and
    repetitions and auto-address increment for most commands.

  * USB terminal example.  Line oriented serial bridge connects a host
    USB serial terminal to a host UART serial terminal.

  * Build System.  apps/ Makefile will now include external directories
    in the application build.

Bugfixes, order roughly on decreasing criticality include:

  * Message Queues.  Correct errors in mq_timedsend() and
    mq_timedreceive().

  * FAT. Writes that cross sector boundaries, stray write into the FAT,
    and a FAT long file name issue

  * NXFFS.  Added a missed error check.  Files cannot be opened for
    writing if they are already opened for reading.

  * Library: fopen() for append modse was not appending.

  * STM32 I2C driver.  Correct another conflict between concurrent FSMC
    and I2C1 accesses.  Fixed some bad error detection logic.

  * STM32 SDHC driver.  Interrupts were being left disabled.

NuttX-6.11
----------

The 78th release of NuttX, Version 6.11, was made on November 12, 2011
and is available for download from the SourceForge website.  Note
that release consists of two tarballs:  nuttx-6.11.tar.gz and
apps-6.11.tar.gz.  Both may be needed (see the top-level nuttx/README.txt
file for build information).

This release corresponds with SVN release number: r4090

This release is a maintenance release that includes a few new features
and some important bugfixes.  New features include:

    * NX Graphics:  New interfaces to read from graphics memory
    * Drivers:  AT24 FLASH driver will now supports clustering of blocks
      to achieve a larger, more usable block size for NXFFS.
    * STM32: LCD color corrections
    * PIC32: Board configuration for the Microchip PIC32 Ethernet Starter kit
      (not yet verified), new GPIO support library, button and LED support
      for the Sure Electronics PIC32MX board.  A lot of progress has been
      made on the PIC32 NuttX port, but it is still not ready for prime time.
    * NXP LPC3152: Board configuration for the Embedded Artists EA3152.

Bugfixes, order roughly on decreasing criticality include:

    * NXFFS: Corrected critical bugs in initialization, some full FLASH handling,
      and errors in certain cases where the FLASH is repacked.
    * ARM EABI: Fix stack alignment required for passing floating point values.
    * Build system: Fix build issues when g++ is used as the compiler.
    * NX Graphics: Bitmap error handling, correct RGB color conversion macros,
      Error when the background window is released.
    * STM32: RTC build fixes, LCD color corrections
    * Simulation target: build fixes
    * C Library: fclose() return value.

See the change log for more detailed information.

NuttX-6.12
----------

The 79th release of NuttX, Version 6.12, was made on December 6, 2011
and is available for download from the SourceForge website.  Note
that release consists of two tarballs:  nuttx-6.12.tar.gz and
apps-6.12.tar.gz.  Both may be needed (see the top-level nuttx/README.txt
file for build information).

This release corresponds with SVN release number: r4141

New features in this release include:

    * STM32. Basic support added for the STM32 F4 family.  Board support
      verified for the STMicro STM3250G-EVAL board.
    * FAT.  Enhanced partition handling.
    * SDIO-Based SD Card support.  Add support for large (>4Gb) devices
    * Graphics.  Added four new small sans serif fonts.
    * Drivers. Fix a banding problem with the R61580 LCD.

Bugfixes, order roughly on decreasing criticality include:

    * FAT. Fix errors in how the first entries in the root directory are
      added.  Fix errors in FAT date/time handling.
    * Signals.  Fix bug in certain sig_timedwait() error handling.
    * Drivers. Fix cloned errors in poll() handling in several drivers.
    * Message Queues.  errno was not being set correctly by mq_notify().
    * C Library. wchar_t is a built-in type for C++

NuttX-6.13
----------

The 80th release of NuttX, Version 6.13, was made on December 26, 2011
and is available for download from the SourceForge website.  Note
that release consists of two tarballs:  nuttx-6.13.tar.gz and
apps-6.13.tar.gz.  Both may be needed (see the top-level nuttx/README.txt
file for build information).

This release corresponds with SVN release number: r4231

New features in this release include:

    * Drivers. New standard interface for PWM drivers and common
      "upper half" PWM driver.  Updated the MP25x driver to support
      the Macronix MX25 chips (submitted by Mohammad Elwakeel).
    * STM32 F1/F4.  Added an Ethernet driver, ADC drivers, DAC driver,
      PWM driver, CAN driver, F4 RTC driver, F4 DMA support,
      logic for saving/restoring F4 FPU registers in context switches.
    * STM32 Boards.  Added STM3240G-EVAL DHPCD and nettest configuration.
      Support for a new STM32 board, the HY-Mini STM32v board, was
      contributed by Laurent Latil
    * PIC32.  The port to the Microchip PIC32MX is finally functional and
      reliable.  The NuttX PIC32 port has verified configurations for
      the OS test and the NuttShell (NSH) both exist.
    * Tests:  New re-usable tests (in apps/examples) for PWM, ADC, and
      CAN loopback.  Several existing tests can now be built as NSH built-in
      applications (dhcpd, nettest, and all of the new tests).

Bugfixes, order roughly on decreasing criticality include:

    * STM32:  Correct handling of data overrun conditions.  Existing logic
      would hang with infinite interrupts when a data overrun occurred.
    * DHCPD.  Fix several problems using host order address where network
      addresses expected (and vice versa).

And several others.  See the ChangeLog for more details.

NuttX-6.14
----------

The 81st release of NuttX, Version 6.14, was made on January 15, 2012,
and is available for download from the SourceForge website.  Note
that release consists of two tarballs:  nuttx-6.14.tar.gz and
apps-6.14.tar.gz.  Both may be needed (see the top-level nuttx/README.txt
file for build information).

This release corresponds with SVN release number: r4301

New features in this release include:

    * Drivers. The upper-half PWM driver will now support a pulse count (as
      would be needed to control a stepper motor).

    * STM32.  The CAN driver has been verified in loopback mode.  ADC driver
      support for the STM32 F4.  Add support for UART4-5 and USART6
      (Contributed by Mike Smith).  The PWM driver now supports a pulse
      count for TIM1 and TIM8.  Timer driver now supports the F4's 32-bit
      timers (Contributed by Mikhail Bychek)

    * STM32F4Discovery.  Support for the STM32F4-Discovery board contributed
      by Mike Smith.

    * STM3240G-EVAL.  Add support for user control of LEDs.

    * LPC17xx.  Add support for loopback mode to CAN driver.  CAN TX done
      perations are now interrupt driver.  Now supports configurable CAN bit
      rate.

    * LPC1766-STK. Add support for on-board buttons. Add support for user
      control of LEDs.

    * LM3S.  Add support for the LM3S6432S2E on the TI RDK-S2E (Contributed
      by Mike Smith)

    * PIC32MX.  USB device-side driver (needs further testing).  A partial
      Ethernet driver is also in place.

    * Library. Support added for fixed floating point fieldwidths in output
      formatting (Contributed by Mikhail Bychek)

    * Build.  New targets apps_clean and apps_distclean to simplify working
      with application directories.

Bugfixes include:

    * Drivers.  Fixed a buffer-full test in the upper-half CAN driver.

    * STM32.  GPIO initialize logic (submitted by Mike Smith).  Fix the
      debug logic that dumps the GPIO configuration.

    * LPC17xxx.  Correct an integer overflow in GPIO interrupt setup
      (prevented pins > 15 from being used as interrupt sources).  Correct
      a value used in GPIO interrupt number range test.

    * FAT.  Now returns the correct error value when it is unable to
      recognize the file system.

    * Build.  macOS build fixes (submitted by Mike Smith)

And several others.  See the ChangeLog for more details.

NuttX-6.15
----------

The 82nd release of NuttX, Version 6.15, was made on February 12, 2012,
and is available for download from the SourceForge website.  Note
that release consists of two tarballs:  nuttx-6.15.tar.gz and
apps-6.15.tar.gz.  Both may be needed (see the top-level nuttx/README.txt
file for build information).

This release corresponds with SVN release number: r4387

New features and extended functionality:

    * General Drivers:  Add support for (29-bit) extended CAN IDs.  Add an
      infrastructure to support battery drivers.   Add a driver for MAX17040x
      battery "fuel gauge".  Add support for Composite USB drivers (in
      particular for a CDC/ACM with MSC USB composite driver).

      Added a new RAM logging driver.  This will allow debug output into
      a RAM buffer associated with a character driver at /dev/ramlog.
      Added the new command 'dmesg' to NSH that can be used to dump the
      current contents of the log.  This is useful for systems that do not
      have the usual serial console (for example, if you only have a
      Telnet console with NSH).

    * Networking:  Add a lower level, primitive socket interface.  Telnet
      driver:

      A New Telnet daemon was created.  It wraps a Telnet session within a
      character driver that can serve as a "controlling terminal."  The
      Telnet session will then be inherited by tasks created from the
      Telnet session and the stdin/stdout from the created task will
      still go through the same Telnet connection.

    * STM32 Drivers.  PWM driver pulse count was limited to 128; now is
      (essentially) unlimited.  Add support for (29-bit) extended CAN IDs.
      Add support for I2C3.  The SDIO driver is (mostly) verified on the
      STM32 F4 platforms.

    * LPC17xx Drivers.  Extended the CAN driver so that the TSEG1 and TSEG2
      bit times can be set via the NuttX configuration.  Add support for
      (29-bit) extended CAN IDs.

    * PIC32 Drivers. The PIC32 Ethernet driver is code complete (but still
      untested).

    * FTPD.  Add a new FTP server daemon.  This is based loosely on
      the hwport_ftpd library provided by Jaehyuk Cho.

    * Library:  Add support for on_exit().  Implemented tcsetattr() and
      tcgetattr().  Moved the old, too-smart fgets() to a new application
      library function called readline().  Dumbed down the original fgets().
      Add strcasestr(), avsprintf(), inet_ntop(), and inet_pton().
      Add support to enable or disable debug output.

    * Build system: Support for building a 32-bit simulation executable on
      a 64-bit Linux machine.  Correct a dependency issue in the arch/*/src/board
      directory.

Bugfixes:

    * System:  Correct PTHREAD_MUTEX_INITIALIZER

    * FAT: Fix an error in the FAT statfs() reported by David Sidrane.

    * STM32: Fix clock frequencies for APB2 timers.  Correct AFIO register
      offset.

    * PIC32.  Correct GPIOs used for LEDs on the Sure PIC32MX board.

    * NSH.  Wait for a USB connection if a USB serial class is used to
      interface with the host.

Additional bugfixes, name changes, and other differences as detailed in the
ChangeLog.

NuttX-6.16
----------

The 83rd release of NuttX, Version 6.16, was made on March 10, 2012,
and is available for download from the SourceForge website.  Note
that release consists of two tarballs:  nuttx-6.16.tar.gz and
apps-6.16.tar.gz.  Both may be needed (see the top-level nuttx/README.txt
file for build information).

This release corresponds with SVN release number: r4475

New features and extended functionality:

    * ARMv7M Support:  Includes new, streamlined Cortex-M exception
      handling provided by Mike Smith.  Context switching support for the
      Cortex-M4 FPU registers is now provided (in both "lazy" and "non-lazy"
      modes)

    * General Drivers: Added a generic "upper half" Quadrature Encoder driver.
      The USB CDC/ACM serial driver can now be dynamically connected or
      disconnected from the host (programmatically or using NSH commands).

    * STM32 Drivers: Added a "lower half" Quadrature Encoder driver.
      Verified the STM32 F4 DMA driver; Added F4 DMA support to the existing
      STM32 SDIO driver.

    * STM32 Board Support.  Added support for the STM32 F2 family and
      for the STM3220G-EVAL board (contributed by Gary Teravskis).
      Support is now included for C++ static constructors (verified using
      the Atollic toolchain). Added support for the SRAM available on the
      STM3240G-EVAL board.

    * PIC32 Drivers.  PIC32MX USB (device) driver is now functional.
      The PIC32MX Ethernet driver not yet fully verified (and an
      unverified SPI driver is also available).

    * Networking.  Added a lower-level, thread-independent socket layer.
      Parts of this layer were created in 6.15 to support the FTPD
      controlling terminal; this support has been extended in order
      to support an NFS file system (not yet released).

    * NuttShell (NSH).  NSH will now support a USB serial connection for
      the console (such as CDC/ACM).  This is useful in environments
      where there is no physical serial port on the board.

    * Build System.  Reorgnaization of networking header files.

Critical Bugfixes.  The following bug fixes are considered critical:

    * Networking:  Fixed a "leak" in the TCP/IP read-ahead buffering logic.
      Corrected an error in TCP/IP sequence numbering/ACK logic which
      occurred when read-ahead buffering memory is exhausted.

    * STM32 Drivers: Fixed an buffer sizing error in the STM32 Ethernet
      driver.

Additional Bugfixes:  Other important bug fixes are listed below. See
the ChangeLog of a complete, detailed list of bug fixes.

    * Networking: Corrected recv()/recvfrom() return value.  Added logic to
      monitor for loss of connection after a new connection has been
      established via accept() (Contributed by Max Nekludov).  Add
      logic to select() to correctly handle POLLHUP (Contributed by Max
      Nekludov)

Additional bugfixes, name changes, and other differences as detailed in the
ChangeLog.

NuttX-6.17
----------

The 84th release of NuttX, Version 6.17, was made on April 14, 2012,
and is available for download from the SourceForge website.  Note
that release consists of two tarballs:  nuttx-6.17.tar.gz and
apps-6.17.tar.gz.  Both may be needed (see the top-level nuttx/README.txt
file for build information).

This release corresponds with SVN release number: r4607

New features and extended functionality:

    * Networking:  Additional low-level, thread-independent socket
      interfaces (for NFS client support).

    * RTC:  Added a new interface call clock_synchronize().  This function
      will reload the system time from an RTC and is required when the
      system re-awakens from certain deep-sleep modes.

    * Graphics:  Add NxConsole.  This is a character device driver that
      wraps an NX window and can be re-directed for stdout.  This allows,
      for example, a pop-up graphics window that contains a NuttShell (NSH)
      session.  A test of NxConsole is available at apps/examples/nxconsole.

    * Watchdog Drivers:  Added an interface definition an "upper half"
      driver to support watchdog timers.

    * Calypso:  Support for TI Calypso-based cellphones (as supported by
      the Osmocom-BB project) was contributed by members of the Osmocom-BB
      team.  This includes configurations for the Compal e88 and e99 phones.

    * USB Device Interface:  Needed to extend the USB device interface
      because there was no mechanism for passing endpoint OUT data that
      may need to accompany a setup request.

    * STM32 drivers:  Added some power management controls for entering
      reduced power consumption states.  An OTG FS driver was completed
      and partially verified (this driver seems to be functional but since
      it has been test so lightly, it might better be listed in the
      next section "Work in progress").

    * PIC32 drivers: The PIC32 Ethernet driver is now stable.  The PIC32
      USB device controller driver is now functional (but not yet stable).

    * PIC32 boards: Added support for the Sure DB-DP11212 PIC32 General
      Purpose Demo Board.  There is now a PIC32 Starter Kit that
      provides NSH only through a Telnet connection.

    * Build System:  Some header files were moved into include/nuttx.
      The goal is to move any non-standard header files to include/nuttx
      or include/arch.  Moved include/math.h to include/nuttx/math.h;
      this file is now only instantiated as the 'system' math.h if
      CONFIG_ARCH_MATH_H=y is defined.

    * Tools:  Added tools/cmpconfig.c, a tool for comparing two
      configuration files.

Work in progress.  This release includes some partially completed
work that is still not ready for prime time.

    * NFS Client:  Work is progressing on support for an NFS client
      file system.    This is a port of the BSD NFS client file system
      that is being done by Jose Pablo Rojas V.

    * Automated Configuration:  Automated configuration based on the
      kconfig-frontends tool is being incorporated into the build
      system.  The configuration is still not complete enough for
      general use in this release.

    * STM32 Drivers:  Added files that will (eventually) hold an STM32
      OTG FS host driver.  This is still a work in progress.

Bugfixes:

    * Networking:  Corrected a deadlock that only occurred when
      executing the NSH 'ifconfig' command over Telnet.

    * File system:  Fix incorrect return errno value from read() when
      the file is opened write-only.

    * Graphics:   Fix several compilation errors that have crept into the
      multi-user NX server because of lack of use.

    * STM32:  In order to use CAN2, both CAN1 and CAN2 clocking must be
      enabled. Fixed a troublesome bug in the STM32 F4 I2C driver that
      resulting in timeouts.

    * LPC17xx: Fixes for errors the crept in the LPC17xx DAC logic
      Contributed by Lzyy).

    * Build System:  Reordered the link command line to account for new
      versions of libgcc.a that require symbols from the application
      (abort()).

NuttX-6.18
----------

The 85th release of NuttX, Version 6.18, was made on May 19, 2012,
and is available for download from the SourceForge website.  Note
that release consists of two tarballs:  nuttx-6.18.tar.gz and
apps-6.18.tar.gz.  Both may be needed (see the top-level nuttx/README.txt
file for build information).

The majority of changes in this release are focused on supporting the
synchronized release of NxWM, the NuttX tiny window manager.  That
window manager is released as part of the NxWidgets package, but depends
upon many of the changes in this NuttX release.

This release corresponds with SVN release number: r4751

New features and extended functionality:

    * Drivers.  Added a watchdog timer driver infrastructure.  Add general
      support for STMicro STMPE811 I/O Expander/touchscreen device.

    * STM32. Add support for the STM32 IWDG and WWDG watchodog timers.  DMA
      now supports circular buffer mode; serial driver now uses circular
      DMA to improve Rx performance (Contributed by Mike Smith).

    * STM3240G-EVAL Board.  Add support for the LCD and for the STMPE811
      I/O Expander as a touchscreen controller.

    * PIC32 Boards.  Board support for the Mikroelektronika PIC32MX7
      Multimedia Board (MMB) and for the Sparkfun UBW32 PIC32 board.

    * NX. Framed windows are now draw in three colors instead of just two.
      Numerous other extensions needed to support NxWM (see the ChangeLog
      for details).

    * Library. Add prctl() command that can be used to setting and getting
      the names of threads.  This (plus several other improvements and bug
      fixes) are part of a larger effort to improve task monitoring
      capabilities.

Work in progress.  This release includes some partially completed
work that is still not ready for prime time.

    * NFS Client. Work is progressing on support for an NFS client
      file system.   This is a port of the BSD NFS client file system
      that is being done by Jose Pablo Rojas V.

    * Automated Configuration. Automated configuration based on the
      kconfig-frontends tool is being incorporated into the build
      system.  The configuration is still not complete enough for
      general use in this release.

    * STM32 Drivers. Added files that will (eventually) hold an STM32
      OTG FS host driver.  This is still a work in progress.

Bugfixes (see the change log for details) :

    * sched_setscheduler() return value (Contributed by Richard Cochran).

    * stdio. Ignore CONFIG_STDIO_LINEBUFFER if the file was opened in binary mode.

    * fopen(). Correct an error in parsing open mode string.

    * serial driver. Improved performance be reducing the amount of time
      that Rx interrupts are disabled.

    * recvfrom(). Fix a compilation problem.

    * CDC/ACM device driver. Fix an infinite loop that occurs when the serial
      device is unregistered.

    * STM32 OTG FS device driver. Numerous fixes and the driver is partially
      functional but there are still some issues that become apparent when
      debug output is disabled.

    * fcntl(). Always returned zero on success; however, some fcntl commands
      need to return non-zero values on success.

    * graphics:  Many multi-use mode fixes added to support NxWM (see the
      ChangeLog for details).  Auto-raise is temporarily disabled in multi-
      user mode because it causes some problems with NxWM.

    * on_exit():  Fix compilation errors if CONFIG_SCHED_ONEXIT is enabled.

NuttX-6.19
----------

The 86th release of NuttX, Version 6.19, was made on June 15, 2012,
and is available for download from the SourceForge website.  Note
that release consists of two tarballs:  nuttx-6.19.tar.gz and
apps-6.19.tar.gz.  Both may be needed (see the top-level nuttx/README.txt
file for build information).

This release corresponds with SVN release number: r4847

This release features new support for a Network File System (NFS) client.
This feature allows a tiny, embedded MCU to mount a remote file system
exported by an NFS server and then to access the file system as it would
any local file system.  Then the tiny MCU can effectively have terabytes
of storage!

This might be useful for data collection, for MCU configuration information,
for software updates, for providing modular, loadable code modes, controlling
a "farm" of MCUs, ... there are many possibilities and opportunities for
innovation!

The NuttShell (NSH) now supports the following command:

  nfsmount <server-address> <mount-point> <remote-path>

That command will mount the remote NFS server directory <remote-path> at
<mount-point> on the target machine.  <server-address> is the IP address of
the remote server.

The NFS development was the graduation project of Jose Pablo Rojas V. who
is a student at the Instituto Tecnológico de Costa Rica (ITCR, or TEC).
A lot of effort went into understanding what a tiny, embedded NFS client should
do and getting the target resource usage to a bare minimum.  Only around a
kilobyte or so of memory is required to run the NFS client (and most of that
for I/O buffers).  Jose Pablo has spent several months living with NFS and
should be congratulated.

Additional new features and extended functionality:

    * Drivers:  SSD1289 LCD driver, MIO283QT2 LCD driver

    * LM3S: Additional register definition header files (contributed by Max
      Neklyudov).

    * STM32 Boards:  The STM32F4Discovery will now support an SSD1289 LCD,
      The STM3220G-EVAL board support is now equivalent to the STM3240G-EVAL
      board support.

    * PIC32 Boards: The Mikroelektronika PIC32MX7 MMB board port is now
      functional, very complete, and stable.

    * Graphics:  The NxConsole will now take keyboard input from the NX graphics
      subsystem.  This means that if there are multiple NxConsole windows, only
      the top instance that has focus will receive the keyboard input.

    * apps/:  Add the capability to use an arbitrary USB device as the console
      (not necessarily /dev/console).  Additional enhancements for USB consoles.
      Added the 'mv' command.

Work in progress.  This release includes some partially completed
work that is still not ready for prime time.

    * Automated Configuration. Automated configuration based on the
      kconfig-frontends tool is being incorporated into the build
      system.  The configuration is still not complete enough for
      general use in this release.

    * STM32 Drivers. Added files that will (eventually) hold an STM32
      OTG FS host driver.  This is still a work in progress.

Bugfixes (see the change log for details) :

    * General:  sleep() and usleep() return values, sig_timedwait() errno setting
      on timeout.
    * Drivers: STMPE811 touchscreen driver, USB PLC2303, USB CDC/ACM
    * STM32: Several USB device controller driver fixes, F4 interrupt priorities
      (contributed by Mike Smith).
    * Graphics: Keyboard input, fill trapezoid bug

As well as other, less critical bugs (see the ChangeLog for details)

NuttX-6.20
----------

The 87th release of NuttX, Version 6.20, was made on July 12, 2012,
and is available for download from the SourceForge website.  Note
that release consists of two tarballs:  nuttx-6.20.tar.gz and
apps-6.20.tar.gz.  Both may be needed (see the top-level nuttx/README.txt
file for build information).

This release corresponds with SVN release number: r4937

Additional new features and extended functionality:

    * Power Management:  An evolving power management example is being
      created by Diego Sanchez.  This effort currently involves on the
      STM32 F1 but clearly demonstrates the NuttX power management
      system which will automatically drive the system to lower power
      usage states due to lack of use.

    * Drivers:  Added a driver for the SST 25 SPI-based FLASH parts.

    * PIC32:  Added support for the PIC32MX1 and PIC32MX2 families.
      Added support for the microchipOpen and Pinguino toolchains.

    * NXP LPC43XX: Added support for the entire LPC43xx family

    * PIC32 boards:  Added support for the DTX1-4000L "Mirtoo" module
      from http://www.dimitech.com/ (PIC32MX2).

    * NXP LPC43XX Boards: Added support for NGX LPC4330-Xplorer board.

    * NXP LPC17XX Boards: Added support for Micromint Lincoln60 board
      (LPC1769).

    * LM3S Boards:  Add a configuration to support the TI/Stellaris
      EKK-LM3S3B96 development board.  Contributed by Jose Pablo Rojas V.

    * Library:  NuttX now supports platform-specific stdarg.h header
      files.

Work in progress.  This release includes some partially completed
work that is still not ready for prime time.

    * Automated Configuration. Automated configuration based on the
      kconfig-frontends tool is being incorporated into the build
      system.  The configuration is still not complete enough for
      general use in this release.

    * STM32 Drivers. Added files that will (eventually) hold an STM32
      OTG FS host driver.  This is still a work in progress.

Bugfixes (see the change log for details) :

    * PIC32: GPIO output configuration (critical bug)
    * STM32: Typos in pin mapping files.
    * LM3S:  Fixed an optimization related but that caused slow start-up
      times if optimization was disabled.
    * Library:  Fixed signed extension but in all limit.h files
      (reported by Lorenz Meier).  inet_ntoa compilation failure
      on Z80.

As well as other, less critical bugs (see the ChangeLog for details)

NuttX-6.21
----------

The 88th release of NuttX, Version 6.21, was made on August 25, 2012,
and is available for download from the SourceForge website.  Note
that release consists of two tarballs:  nuttx-6.21.tar.gz and
apps-6.21.tar.gz.  Both may be needed (see the top-level nuttx/README.txt
file for build information).

This release corresponds with SVN release number: r5052

Additional new features and extended functionality:

    * Core: Add support for multiple registered atexit() functions.  Syslog
      extended:  Now any character driver may be used for the debug logging
      device.  Mountpoint traversal logic.
    * Drivers: Added support for the TI PGA112-7 amplifier/multiplexor.
    * LPC43xx:  Added clock ramp-up logic to run at 204 MHz
    * LPC43xx Drivers:  SPIFI block driver, RS-485 support, Minimal termios
      support.  Framework for USB0 device controller driver.
    * LPC17xx Drivers:  Minimal termios support
    * STM32: Support for STM32 F1 "Value Line" (contributed by Mike Smith).
      Add support for STM32 F107 "Connectivity Line" (contributed by Max
      Holtzberg).
      Clock restart logic needed for recovery from low power modes.
    * STM32 Drivers:  RTC alarm support.  Usable for wakeup from sleep mode,
      Minimal serial termios support.  USB OTG FS host driver (alpha).
    * STM32 Boards: Add power management hooks for the STM32F4Discovery,
      Add support for the Olimex STM32-P107 (contributed by Max Holtzberg).
    * PIC32:  Add support for the Pinguino MIPS toolchain.
    * PIC32 Drivers:  GPIO driver now supports F1 analog regiaters (ANSEL).
    * PIC32 Boards: Add support for the PGA117 on the Mirtoo module.
    * Calypso:  Add support for the SSD1783 LCD on the Compal E99.
    * Library:  cfsetispeed(), cfsetospeed(), tcflush(), memchr(), and
      memccpy().
    * Applications:  Port of freemodbus-v1.5.0. Add support for testing
      devices with multiple ADC, PWM, and QE devices.
      NSH: NSH 'mount' command (with no arguments) will now show mounted
      volumes.  Add new NSH 'df' command.  Extended 'help' support. NSH
      now catches the return value from spawned applications (provided
      by Mike Smith).
    * Build System: mkconfig will not define CONFIG_DRAM_END.  A lot of
      progress has been made on the automated NuttX configuration logic
      (Thanks go to Richard Cochran).
    * Documentation: Document ways to customize the behavior of NSH.

Bugfixes (see the change log for details) :

    * Serial drivers (all): Fix ioctl return value. Common "upper half"
      serial driver will now return with EINTR if a serial wait is
      interrupted by a signal.
    * FAT: Fix statfs() file name length.
    * LPC43xx: Clock configuration.
    * STM32: Pinmap fixes, SPI driver re-initialization
    * STM32 Boards: Correct and lower SDIO frequency for F2 and f4 boards.
    * AVR: C++ build issues.
    * PM: Fix a place where interrupts were not be re-enabled.
    * Applications: NSH application start-up race conditions.
    * Library: Fieldwidth and justification for %s format.  Fixed several
      issues with presenting floating point numbers.  NULL definition
      for C++

As well as other, less critical bugs (see the ChangeLog for details)

NuttX-6.22
----------

The 89th release of NuttX, Version 6.22, was made on September 29, 2012,
and is available for download from the SourceForge website.  Note
that release consists of two tarballs:  nuttx-6.22.tar.gz and
apps-6.22.tar.gz.  Both may be needed (see the top-level nuttx/README.txt
file for build information).

This release corresponds with SVN release number: r5206

Note that all SVN information has been stripped from the tarballs.  If you
need the SVN configuration, you should check out directly from SVN.  Revision
r5206 should equivalent to release 6.22 of NuttX 6.22:

    svn checkout -r5206 svn://svn.code.sf.net/p/nuttx/code/trunk nuttx-code

Or

    svn checkout -r5206 http://svn.code.sf.net/p/nuttx/code/trunk nuttx-code

Additional new features and extended functionality:

    * RTOS: Application entry point is no longer user_start, but can be
      configured using CONFIG_USER_ENTRYPOINT.  NuttX now supports two work
      queues:  A lower priority work queue (for extended processing) and a
      higher priority work queue (for quick, high priority operations).

    * Memory Management: Added a new granule-based allocated that can be
      used to manage, aligned and quantized DMA memory.

    * File System: Add hooks to allocate I/O memory with and external
      allocated (need if required by DMA).

    * Networking: ENC28J60 driver is (finally) verified.

    * Drivers: Add hooks USB device drivers to allocate I/O memory with and
      external allocated (need if required by DMA).  Driver for the Windbond
      SPI FLASH family (W25x16, W25x32, W25x64, and others).  ADS7843E driver
      extended for TSC2046 and XPT2046 and verified.

    * ARMv7-M: Added logic to reset the MCU using the NVIC.

    * STM32: Add support for STM32F103VET6.

    * STM32 Drivers: Add logic to re-initialize UARTs a second time to
      enable DMA (Mike Smith).  I2C driver error recovery (Mike Smith).

    * STM32 boards: Support for USB host added add to several configurations
      (or at least explained in README files).  Support for the Shenzhou
      STM32F107 board (see www.armjishu.com).  Support for M3 Wildfire
      STM32F103 board (v2 and v3).

    * Build System:  Kconfig string de-quoting logic.  Remove comments from
      defconfig files (Kate).  Add tool to create NuttX-style symbol tables.
      Numerous changes to configuration logic as needed for the new mconf-based
      configuration (much of this from Richard Cochran).  Refactor common
      Make.defs logic into tools/Config.mk (Richard Cochran).

    * Library: Configurable terse output from strerror(). Added perror() (Kate).
      Add %n format to sscanf() (Kate).

    * Applications: Numerous changes and extensions to the old uIP web server
      (from Kate and Max Holtzberg, see the ChangeLog for specific extensions).
      UDP network discovery utility (Max Holtzberg).  Embeddable Lightweight
      XML-RPC Server (http://www.drdobbs.com/web-development/an-embeddable-lightweight-xml-rpc-server/184405364, Max Holtzberg).

Bugfixes (see the change log for details).  Some of these are very important
(marked *critical*):

    * RTOS: Fixes to priority inheritance logic (*critical*).  waitpid()
      critical section.  Assertion in work_cancel() (Mike Smith).  mmap() (Kate).

    * FAT File System: Improper Boolean expression caused un-necessary writes
      and performance issues (*critical*, Ronen Vainish).

    * Networking: Remove an un-necessary delay from recvfrom().  This greatly
      improves network performance (*critical*, Max Holtzberg).

    * Graphics: NX parameter checking errors.

    * Drivers: Fix double release of memory in SDIO-based, MMC/SD driver
      (Ronen Vainish).

    * LPC17xx:  Ethernet driver fixes needed for certain PHYs (Kate).

    * AVR: Fix build error (Richard Cochran).

    * STM32: USB OTG FS host driver NAKing an retries.  Power management
      compilation errors (Diego Sanchez).  Missing SPI3 remap logic.

    * STM32 Drivers: Fix for Ethernet errata for STM32F107 (*critical*).
      Ethernet buffer alignment check.  Add "kludge" to Ethernet driver to
      handle DM9161 PHY which (at least on the Shenzhou board), sometimes
      does not come up correctly.

    * Applications: THTTPD (Kate).  NSH ping when IP address is on a different
      network (Darcy Gong).

    * Library: fread(), fflush(), fdopen(): Fix error handling logic (Ronen
      Vainish). Fix some field-width handling issues in sscanf()

As well as other, less critical bugs (see the ChangeLog for details)

NuttX-6.23
----------

The 90th release of NuttX, Version 6.23, was made on November 5, 2012,
and is available for download from the SourceForge website.  Note
that release consists of two tarballs:  nuttx-6.23.tar.gz and
apps-6.23.tar.gz.  Both may be needed (see the top-level nuttx/README.txt
file for build information).

This release corresponds with SVN release number: r5313

Note that all SVN information has been stripped from the tarballs.  If you
need the SVN configuration, you should check out directly from SVN.  Revision
r5313 should equivalent to release 6.23 of NuttX 6.23:

    svn checkout -r5313 svn://svn.code.sf.net/p/nuttx/code/trunk nuttx-code

Or

    svn checkout -r5313 http://svn.code.sf.net/p/nuttx/code/trunk nuttx-code

Additional new features and extended functionality:

    * RTOS:  If both atexit() and on_exit() are enabled, use on_exit() to
      implement atexit().  Updates for RGMP 4.0.

    * Binfmt:  Add support for loading and executing ELF binary modules from
      a file system.

    * Drivers:  Maxim MAX11802 touchscreen controller (Petteri Aimonen)

    * STM32 Driver:  Implementation of /dev/random using the STM32 Random Number
      Generator (RNG).

    * STM32 Boards:  ADC support for the Shenzhou IV board.  Relay support for
      the Shenzhou IV board.

    * C Library:  Support is now included for the add-on uClibc++ C++
      standard library support.  This includes support for iostreams, strings,
      STL, RTTI, exceptions -- the complete C++ environment.  (uClibc++ is
      provided as a separate add-on package due to licensing issues).

      Optimized generic and ARM-specific memcpy() function.  Optimized
      memset() function.

      Add support for ferror(), feof(), and clearerror().   Add support for
      __cxa_atexit().

      Math Library:  Port of the math library from Rhombus OS by Nick Johnson
      (Darcy Gong).

    * Applications: New NSH commands:  ifup, ifdown, urlencode, urldecode,
      base64enc, bas64dec, md5 (Darcy Gong).  Add support for NSH telnet login
      (Darcy Gong).  Enancements to NSH ping command to support pinging hosts
      with very long round-trip times.  Extensions to the ifconfig command
      Darcy Gong),

      Many extensions to the webclient/wget and DNS resolver logic from Darcy
      Gong.  JSON, Base64, URL encoding, and MD5 libraries contributed by Darcy
      Gong.

      New examples: ELF loader, JSON, wgetjson, cxxtest, relays.

Bugfixes (see the change log for details).  Some of these are very important
(marked *critical*):

    * Drivers: W25 SPI FLASH

    * STM32 Drivers: ADC reset

    * Graphics: Missing implementation of the blocked method (*critical*,
      Petteri Aimonen).

    * C Library: Floating point numbers in printf and related formatting functions
     (Mike Smith), cf[get|set]speed() (Mike Smith)

As well as other, less critical bugs (see the ChangeLog for details)

NuttX-6.24
----------

The 91st release of NuttX, Version 6.24, was made on December 20, 2012,
and is available for download from the SourceForge website.  Note
that release consists of two tarballs:  nuttx-6.24.tar.gz and
apps-6.24.tar.gz.  Both may be needed (see the top-level nuttx/README.txt
file for build information).

This release corresponds with SVN release number: r5447

Note that all SVN information has been stripped from the tarballs.  If you
need the SVN configuration information, you should check out directly from
SVN.  Revision r5447 should equivalent to release 6.24 of NuttX 6.24:

    svn checkout -r5447 svn://svn.code.sf.net/p/nuttx/code/trunk nuttx-code

Or (HTTP):

    svn checkout -r5447 http://svn.code.sf.net/p/nuttx/code/trunk nuttx-code

Additional new features and extended functionality:

  * RTOS:

    - Implemented the POSIX pause() function (still has some compiance
      issues).
    - Tasking logic is extended to support the notion of address
      environments.  An address environment is the key notion underlying
      "process" vs. tasks.  If tasks are created with address environments
      (by binfmt), the OS will propagate that environment to child threads
      and will destroy the address environment when the "process" exists.
    - If support for the PATH variable is enabled, the OS start up logic
      will create an initial environment containing the default PATH
      setting (CONFIG_PATH_INITIAL).  This initial PATH will then be
      inherited by all tasks.

  * Binfmt

    - The NuttX binary loaders have been updated to support the PATH
      environment variable.  Now, if the PATH is properly defined, programs
      can be executed from mass storage using only the file name.  This
      feature is added to support more standard behavior (eventually, NSH
      will support execution of programs in file systems by just entering
      the file name, perhaps in 6.25?).
    - The NXFLAT and ELF binary loaders have been extended to create
      address environments for any new tasks executed from the file system.
      This feature requires that the architecture support a memory management
      unit (MMU) and the address environment interfaces declared in
      include/nuttx/arch.h (currently, this is only supported by the z180).

    * Drivers: LCD driver for the Univision UG-2864AMBAG01 OLED

    * STM32: Support for STM32F100 high density chips contributed by Freddie
      Chopin.

    * STM32 Drivers:  Added optional RS-485 direction bit control (from
      Freddie Chopin).

    * STM32 Boards:

      - Support for generic STM32F100RC board contributed by Freddie Chopin.
      - stm32f4discovery/nxlines: STM32F4Discovery support for the
        UG-2864AMBAG01 OLED.
      - stm32f4discovery/winbuild:  A version of the NuttX OS test
        configured to build natively on Windows.
      - stm32f4discovery/elf: Now uses the PATH variable to find ELF
        executables.
      - configs/cloudctrl: Added for Darcy Gong's CloudController board

    * PIC32 Boards: Update the Mirtool configuration for Release 2 of the
      Mirtoo module.

    * Calypso: Add Calypso keypad driver.  From Denis Cariki.

    * ZiLOG:

      - Add support for the z180 chip family and, specifically, for
        the P112 retro hardware (see http://p112.feedle.net/).
      - All ZiLOG configurations updated to use the current ZDS-II
        and/or SDCC toolchains.

    * Graphics:

      - Add a semaphore handshake so that operations on buffers from
        the NXMU client will be blocked until the NX server operates on the
        buffer data (from Petteri Aimonen).
      - nxtk_subwindowmove() and nxtk_getwindow(): Improvements to clipping
        logic from Petteri Aimonen.

    * C Library: lib/ sub-directory renamed libc/ (there is a new lib/ sub-
      directory that is used to hold all archives).

    * C++: Exception stubs from Petteri Aimonen.

    * Applications:

      - Add NSH hexdump command to dump the contents of a file (or character
        device) to the console (contributed by Petteri Aimonen).
      - Extend the NSH ifconfig command plus various DHCPC improvements
        (from Darcy Gong).

    * apps/examples:

      - ostest: Replace large tables with algorithmic prime number
        generation.  This allows the roundrobin test to run on platforms
        with minimal SRAM (Freddie Chopin).
      - keypadtest:  A new keypad test example contributed by Denis Carikli.
      - elf and nxflat:  If CONFIG_BINFMT_EXEPATH is defined, these examples
        will now use a relative path to the program and expect the binfmt/
        logic to find the absolute path to the program using the PATH
        variable.

    * Build system:

      - New top-level Makefiles: Makefile.unix and Makefile.win (along with
        numerous changes to other make-related files).  This adds basic
        support for building NuttX natively under Windows from a CMD.exe
        window (rather than in a POSIX-like environment). This build: (1)
        Uses all Windows style paths, (2) Uses primarily Windows batch
        commands from cmd.exe, with (3) a few extensions from GNUWin32.

        This capability should still be considered a work in progress
        because: (1) it has not been verfied on all targets and tools,
        and (2) still lacks some of the creature-comforts of the more
        mature environments (like a function configure.sh script and
        'make menuconfig' support).

      - Example Windows native builds for STM32F4Discovery, eZ80, z16f, z8,
        Z80, and Z180.
      - Several configurations have been converted to work the kconfig-
        frontends mconf configuration tool: stm32f4discovery/nxlines, and
        all eZ80, z16f, z8, Z80, and Z180 configurations.
      - Architectures now include a common Toolchain.defs file that can be
        used to manage toolchains in a more configurable way (most of this
        contributed by Mike Smith).

    * Build tools:

      - Renamed tools/winlink.sh to tools/copydir.sh.
      - Several new tools/scripts to support the Windows native build:
        tools/mkdeps.bat, tools/mkdeps.c, tools/link.bat, unlink.bat, and
        copydir.bat.
      - tools/incdir.sh and incdir.bat now support an -s option to generate
        system header file paths.
      - tools/b16.c: Fixed precision math conversion utility.

Bugfixes (see the change log for details).  Some of these are very important
(marked *critical*):

    * RTOS: Fix some backward conditional compilation in the work queue
      logic (Freddie Chopin).

    * File System: Uninitialized variable caused assertions (from Lorenz
      Meier).

    * Drivers: Partial fix for STM32 OTGFS device drivers and fix for short,
      unaligned writes in the flash translation layer (drivers/mtd/ftl.c),
      both from Petteri Aimonen.

    * STM32 Drivers:

      - Qencoder driver and TIM3 driver fixes from Ryan Sundberg.
      - Fix timeout delay calculation in the STM32 OTG FS host driver.

    * LPC17xx Drivers:  Resources not being properly released when I2C
      driver is un-initialized.

    * Graphics:

      - Fix logic when the mouse drags outside of the window; fix
        another "blocked message" handling case (both from Petteri Aimonen).
      - nxtk_filltrapwindow():  Correct an offset problem (also from Peterri
        Aimonen).
      - nxglib_splitline():  Correct the "fat flat line" bug.

    * C Library:

      - nrand() changes to prevent coefficients from becoming zero which
        would "lock up" the random number generate.
      - Add rounding functions to the math library (contributed by Petteri
        Aimonen).

    * Build system:  Changes to MIN definitions in all limit.h header files
      to avoid integer overflows.  For example from (-128) to (-127 - 1)
      (from Petteri Aimonen).

    * Applications: Modbus fixes from Freddie Chopin.

As well as other, less critical bugs (see the ChangeLog for details)

NuttX-6.25
----------

The 92nd release of NuttX, Version 6.25, was made on February 1, 2013,
and is available for download from the SourceForge website.  Note
that release consists of two tarballs:  nuttx-6.25.tar.gz and
apps-6.25.tar.gz.  Both may be needed (see the top-level nuttx/README.txt
file for build information).

This release corresponds with SVN release number: r5595

Note that all SVN information has been stripped from the tarballs.  If you
need the SVN configuration information, you should check out directly from
SVN.  Revision r5595 should equivalent to release 6.25 of NuttX:

    svn checkout -r5595 svn://svn.code.sf.net/p/nuttx/code/trunk nuttx-code

Or (HTTP):

    svn checkout -r5595 http://svn.code.sf.net/p/nuttx/code/trunk nuttx-code

Additional new features and extended functionality:

    * OS Initialization

      - Removed support for CONFIG_BUILTIN_APP_START.  This is not really a
        useful feature and creates a violation of the OS layered
        architecture.

    * Task Creation:

      - Implement a simple vfork().  In NuttX-6.25, this interface is
        available only for ARM7/9, ARMv7-M (Cortext-M3/4), and MIPS32
        (PIC32MX) platforms.
      - exec() now sets the priority of the new task to the same priority as
        the parent task (instead of the arbitrary value of 50).
      - New, partially compliant implementations of execv() and execl().
        These are only partially compliant because they do not overlay any
        existing "process space" but rather create the new task and exit().
      - Add a complete implementation of posix_spawn().  This standard
        interface is a better match for an MMU-less architecture than are
        vfork() plus execv() or execl().
      - Add a task start hook that will be called before the task main
        is started.  This can be used, for example, to schedule C++
        static constructors to run automatically in the context of the
        new task.

    * Task Parentage

      - Repartitioned tasking data structures.  All shared resources are now
        collected together in a "task group".  A task group includes the
        original task plus all of the pthreads created by the task.
      - Added support for remember the parent "task group" when a new task is
        started.
      - Added optional support to record the membership of each thread in
        the "task group".
      - Implement support for retaining child task status in the "task group"
        after the child task exists.  This is behavior required by POSIX.
        But in NuttX is only enabled with CONFIG_SCHED_HAVE_PARENT and
        CONFIG_SCHED_CHILD_STATUS
      - Add internal logic to "reparent" a task.  This is useful,
        for example, where the child task is created through a trampoline
        task that redirects I/O.  Reparenting allows the caller of posix_spawn()
        to be reparented for the eventual child thread.
      - Added support for SIGCHLD.  Sent to all members of the parent task
        group when the file member of the child task group exits.
      - If SIGCHLD and retention of child task exist status are enabled, then
        a more spec-compliant version of waitpid() is enabled.
      - New interfaces waitid() and wait() are also enabled when SIGCHLD
        is enabled.

    * File System

      - dup() and dup2() can new be used with opened files in a mounted file
        system.  This supports re-direction of output in NSH to files.
      - The binfs file system was moved from apps/builtin to fs/binfs.  The
        binfs file system was extended to support execution of "builtin
        applications" using exec(), execv(), execl(), or posix_spawn().
      - Added logic based on SIGCHLD to automatically unload and clean-up
        after running a task that was loaded into memory.

    * Binary Formats

      - Much of the logic for "builtin applications" was moved from
        apps/builtin to nuttx/binfmt/libbuiltin.  Includes some extensions
        contributed by Mike Smith.
      - A binary loader was added for builtin applications to support
        execution of "builtin applications" using exec(), execv(),
        execl(), or posix_spawn().

    * Drivers:

      - Added logic to marshal and serialized "out-of-band" keyboard
        commands (such as cursor controls and key release events) intermixed
        with normal ASCII keypress data.  The encoding is partially integrated
        in the HID keyboard driver and the decoding full integrated into the
        apps/examples hidkbd and keypadtest (the latter contributed by Denis
        Carlikli).
      - Driver for the UG-2864HSWEG01 OLED contributed by Darcy Gong.
      - Add support for removable serial devices (like USB serial).  This
        support is enabled by CONFIG_SERIAL_REMOVABLE.

    * ARMv7-M:

      - Added an option to use the BASEPRI register to disable interrupts
        (instead of the PRIMASK).  This eliminates some innocuous hardfaults
        that interfere with some debug tools.  You need to switch to the
        BASEPRI method only if you have such tool interference.

    * STM32 Drivers

      - Bring STM32 F1 DMA capabilities up to par with the STM32 F2/F4
        (contributed by Mike Smith).
      - Add support for USART single wire mode (Contributed by the PX4
        team).
      - Updates to support for SPI DMA on the STM32 F1/F2/F4.  From
        Petteri Aimonen.

    * STM32 Boards:

      - New configuration to support the UG-2864HSWEG01 OLED on the
        STM32F4Discovery board.
      - Added a posix_spawn() test configuration for the STM32F4Discovery.

    * LM3S/LM4F

       - Files and directories repartitioned to support both LM3S and LM4F
         using the STM32 organization as a model.
       - Partial definitions for the LM4F contributed by Jose Pablo Carballo
         (this is still a work in progress).

    * LM3S Boards

       - Added scripts and documentation to use OpenOCD with the LM3S (from
         Jose Pablo Carballo).

    * LPC176x/LPC178x

       - Files and directories repartitioned to support both LPC175x/LPC176x
         and the LPC177x/LPC178x families using the STM32 organization as a
         model.  The LPC1788 port is a work in progress by Rommel Marcelo.

    * LPC176x/LPC178x Boards:

      - Added a configuration to support the Wave Share Open1788 board.
        This is still a work in progress by Rommel Marcelo.

    * LPC2148 Boards:

      - Add basic support for the The0.net ZP213x/4xPA board (with the LPC2148
        and the UG_2864AMBAG01 OLED).
      - Add an nxlines configuration for the ZP213x/4xPA (with the LPC2148
        and the UG_2864AMBAG01).

    * Simulator:

      - Add an nxlines configuration for the simulator.

    * Networking:

      - Add logic to work around delayed ACKs by splitting packets
        (contributed by Yan T.).
      - Split net_poll() to create the internal interface psock_poll().

    * LCDs:

      - Added support for LCD1602 alphanumeric LCD (HD4468OU controller).

    * Graphics:

      - Added 5x8 monospace font. This tiny font is useful for graph
        labels and for small bitmapped display.  Contributed by Petteri
        Aimonen.

    * Build System:

      - Add an options to better manage toolchain prefixes.
      - Redesigned how the context target works in the apps/ directory.
        The old design caused lots of problems when changing configurations
        because there is no easy way to get the system to rebuild the
        context.  This change should solve most the problems and eliminate
        questions like "Why don't I see my builtin application in NSH?"

    * Kconfig Files:

      - There are several new configurations that use the kconfig-frontends
        tools and several older configurations that have been converted to
        use these tools.  There is still a long way to go before the conversion
        is complete:

        configs/sim/nxwm
        configs/sim/nsh
        configs/stm3220g-eval/nxwm
        configs/stm32f4discovery/posix_spawn
        configs/olimex-lpc1766stk/nsh
        configs/olimex-lpc1766stk/hidkbd
        configs/olimex-lpc1766stk/nettest
        configs/open1788/ostest
        configs/stm32f4discovery/nsh
        configs/stm32f4discovery/usbnsh
        configs/lm326965-ek (all configurations)
        configs/mcu123-214x/nsh
        configs/ubw32/ostest

    * Tools:

      - tools/kconfig.bat:  Kludge to run kconfig-frontends from a DOS shell.
      - tools/configure.c:  configure.c can be used to build a work-alike
        program as a replacement for configure.sh.  This work-alike
        program would be used in environments that do not support Bash
        scripting (such as the Windows native environment).
      - tools/configure.bat: configure.bat is a small Windows batch
        file that can be used as a replacement for configure.sh in a
        Windows native environment.  configure.bat is actually just a
        thin layer that executes configure.exe if it is available. If
        configure.exe is not available, then configure.bat will attempt
        to build it first.

    * Applications:

      - New and modified examples:

        apps/examples/wlan: Remove non-functional example.
        apps/examples/ostest: Added a test of vfork(). Extend signal
          handler test to catch death-of-child signals (SIGCHLD). Add a
          test for waitpid(), waitid(), and wait().
        apps/exampes/posix_spawn: Added a test of posix_spawn().

      - NSH:

        NSH now supports re-direction of I/O to files (but still not from).
        The block driver source argument to the mount command is now
          optional for file systems that do not require a block driver.
        NSH can now execute a program from a file system using posix_spawn().
        Added support for a login script.  The init.d/rcS script will be
          executed once when NSH starts; the .nshrc script will be executed
          for each session:  Once for serial, once for each USB connection,
          once for each Telnet session.

      - Supports a new daemon that can be used to monitor USB trace outpout.
      - Removed non-functional wlan example.

Bugfixes (see the ChangeLog for details).  Some of these are very important:

    * Tasking:

      - Fixed a *critical* task exit bug.  Here is the failure scenario:
        (1) sched_lock() is called increments the lockcount on the current
        TCB (i.e., the one at the head of the ready to run list), (2)
        sched_mergepending is called which may change the task at the head
        of the ready-to-run list, then (3) sched_unlock() is called which
        decrements the lockcount on the wrong TCB.  The failure case that
        I saw was that pre-emption got disabled in the IDLE thread, locking
        up the whole system.

    * Signals:

      - sigtimedwait() would return a bad signal number if the signal was
        already pending when the function was called.

    * Drivers:

      - Some SD cards will appear busy until switched to SPI mode for
        first time.  Having a pull-up resistor on MISO may avoid this
        problem, but this fix from Petteri Aimonen makes it work also
        without pull-up.

    * STM32 Drivers:

      - STM32 FLASH driver counting error (from Freddie Chopin).
      - STM32 F4 maximum SPI frequency was wrong (corrected by Petteri
        Aimonen).

    * STM32 Boards

      - Due to cloning of untested code, the logic to control on-board
        LEDs did not work on any STM32 boards.
      - Serial devices number /dev/ttyS0-5 is there is a serial console,
        but /dev/ttyS1-6 if there is no serial console.

    * Binary Formats

      - C++ static constructors execute now using a start taskhook
        so that they execute in the context of the child task (instead
        of in the context of the parent task).

    * File Systems:

      - Several FAT-related bugs fixed by Petteri Aimonen.

    * Networking:

      - Fix poll/select issure reported by Qiang: poll_interrupt() must call
        net_lostconnection() when a loss of connection is reported.  Otherwise,
        the system will not remember that the connection has been lost and will
        hang waiting on a unconnected socket later.
      - Similar issues corrected for recvfrom() and send().
      - Telnetd would hang in a loop if recv() ever returned a value <= 0.

    * Libraries:

      - fread() could hang on certain error conditions.
      - Can't handle SYSLOG output to a character device from  the IDLE task
        (because the IDLE task can't block).

    * Build System:

      - Serial was driver was not being built if there is no console
        device.  Obviously, the serial driver may be needed even in
        this case.

    * Additional Bugfixes:

      - sig_timedwait() and clock_time2ticks.c: Timing "rounding" logic
      - ARM9 Compilation issue with low vectors.
      - readline() return value
      - Others as detailed in the ChangeLog: HID keyboard, LPC17xx bit
        definitions, strndup(), PL2303, SYSLOG error handling, AT25,
        apps/examples.

NuttX-6.26
----------

The 93rd release of NuttX, Version 6.26, was made on March 15, 2013,
and is available for download from the SourceForge website.  Note
that release consists of two tarballs:  nuttx-6.26.tar.gz and
apps-6.26.tar.gz.  Both may be needed (see the top-level nuttx/README.txt
file for build information).

This release corresponds with SVN release number: r5745

Note that all SVN information has been stripped from the tarballs.  If you
need the SVN configuration information, you should check out directly from
SVN.  Revision r5745 should equivalent to release 6.26 of NuttX:

    svn checkout -r5745 svn://svn.code.sf.net/p/nuttx/code/trunk nuttx-code

Or (HTTP):

    svn checkout -r5745 http://svn.code.sf.net/p/nuttx/code/trunk nuttx-code

Additional new features and extended functionality:

    * OS Initialization:

      - Add an additional call-out to support board-specific driver
        initialization during the boot-up phase (available with
        CONFIG_BOARD_INITIALIZE=y).

    * Tasking:

      - New interface task_spawn() that is like posix_spawn(), but uses
        entry point addresses like task_create().
      - Additional data restructuring as a continuation of the task group
        changes of NuttX 6.25.  These data structures were moved from the
        TCB structure into the task group:  pthread join data,
        atexit/on_exit callbacks, waitpid data structures, and message
        queues.
      - TCBs for tasks and pthreads are now separate structures.  This
        saves a little memory since tasks do not have to carry the overhead
        for threads and vice versa.

    * Kernel Build:

      - Extensive changes were made to support the kernel build mode.  In
        this mode, NuttX is built as a monolithic kernel.  NuttX is built
        as a separate kernel mode "blob" and the applications are built
        as a separate user mode "blob".  The kernel runs in kernel mode and
        the applications run in user mode (with the MPU restricting user
        mode accesses).  Access to the kernel from the user blob is only
        via system calls (SVCalls).
      - Extensive changes were made to the syscall, SVCall, and trapping
        logic.  Many internal interfaces were renamed.
      - The memory manager was extended to support both kernel- and user-
        mode allocations.  Logic within the kernel needs to use the
        correct kernel- or user-space allocator, depending upon the user
        of the allocated memory.
      - The user-space blob now contains a header built in at the beginning
        of the block that provides the same information that was previously
        provided by a kludgy, auto-generated header file (user_map.h).
      - Basic support implemented for the ARMv7-M family with fragments
        also implemetned for the ARMv6-M and MIPS32 families.
      - Kernel build supported added for the LPC17xx Open1788 and for
        the Atmel SAM3U-EK board.  All testing is being performed on the
        Open1788 board.

    * Signals:

      - Delivery of signals to threads within a task group is now compatible
        with the way that signals are delivered to threads within a process.

    * Drivers:

      - Add a driver for the SST29VF NOR FLASH parts.
      - USB device trace/debug feature extended to decode device-specific
        trace events to make the trace output more readable (from Petteri
        Aimonen).
      - USB MSC device driver can not support names of differing sizes
        in the USB descriptor and the SCSI fields (from Petteri Aimonen).
      - Locking added to MMC/SD SPI drivers so that MMC/SD can co-exist on
        the same bus as other SPI devices.  Frequency is reset each time
        that the MMC/SD SPI has the bus locked. (from Petteri Aimonen).

    * ARMv6-M (Cortex-M0):

       - Added support for the ARM Cortex-M0 family.

    * nuvoTon NUC120:

       - Added support for the nuvoTon NUC120 MCU (Cortex-M0).

    * nuvoTon NUC120 Boards:

       - Added basic support for the nuvoTon NuTiny-SDK-NUC120 board (Cortex-M0).

    * LPC17xx:

      - Added support for the LPC177x and LPC178x families.  Most of this is
        the work of Rommel Marcelo.

    * LPC17xx Boards:

      - Added support for Zilogic System's ARM development Kit, ZKIT-ARM-1769.
        From Rashid.
      - The port for the WaveShare Open1788 board is now functional.  Basic
        OS test and NuttShell (NSH) configurations are functional. More
        driver development and testing is needed (from Rommel Marcelo).

    * LPC17xx Drivers:

      - Added an SD card MSI driver for the LPC178x.  The driver is marginally
        functional but requires DMA capability to be reliable.

    * STM32

      - Support extended to handle the STM32 F3 family (Cortex-M4 with F1-like
        peripherals).

    * STM32 Boards

      - Added support the STMicro STM32F3Discovery board (STM32 F3).

    * Stellaris LM3S/LM4F

      - Basic support for the LM4F120 family is in place, but untested (mostly
        from Jose Pablo Carballo).

    * Stellaris LM4F Boards

      - Add support for the LM4F120 LaunchPad (untested).

    * Networking:

      - select() should now allocate a little less memory.

    * Memory Management:

      - Extended to support multiple heaps.  This is used as part of
        the kernel build in order to support separator user- and
        kernel-mode heaps.
      - The stand-alone memory manager test had to be removed.  It
        was too entangled and made extension of the memory manager
        nearly impossible.  This is a loss.

    * Build System:

      - Several configurations converted to use the kconfig-frontends
        configuration tool.  There are still many more that need to
        be converted.

    * C Library:

      - Move the workqueue logic into the C library.  There is now a
        special user-space version of the work queue (which will only
        be used with a NuttX kernel build).
      - Implementation of itoa() contributed by Ryan Sundberg.

    * Applications:

      - The NSH builtin task logic now uses task_spawn() to start builtin
        applications.
      - The OS test now includes a test cased to verify task_restart().

Efforts In Progress.  The following are features that are partially
implemented but present in this release.  Most are expected to be fully
available in NuttX 6.27.

    * LM4F120 LaunchPad port.  Code is in place, but nothing has been tested.

    * WaveShare Open1788 port.  This port as actually complete and
      functional. However, there is still ongoing development and
      testing of drivers.

    * Kernel Build.  Much progress has been made, but there kernel build is
      not yet fully functional due to several user resources that are not yet
      properly disentangled from the kernel blob.

    * Conversion of old configurations to use the kconfig-frontends
      tool is an ongoing effort that will continue for some time.

Bugfixes (see the ChangeLog for details).  Some of these are very important:

    * Tasking:

      - The wrong PID was being signalled with SIGCHLD.  It should be
        the PID of the task that create the task group, not the ID of
        the last thread to leave the task group.
      - Added logic so that some internal resources and states are recovered
        when tasks are deleted or restarted.  Handle cases where there are
        outstanding timed events pending when tasks are deleted or restarted.

    * ARMv7-M:

      - Several fixes to the MPU control logic.

    * Drivers:

      - Removable serial drivers race conditions fixed.
      - MAX11802 timing bug (from Petteri Aimonen).

    * STM32 Drivers:

      - Handle cases were SPI DMA logic fails if sem_wait is awakened
        by a signal.  Need to clear error flags to prevent corruption of
        subsequent transfers.  Also, bit count should not be changed while
        the SPI peripheral is enabled (from Petteri Aimonen).
      - Fixes to the OTG FS device driver from Petteri Aimonen.
      - Fix typos in DMA register header file (from Yan T.)

    * Graphics:

      - Correction to the hyphen in the SANS 17x22 font (from Petteri
        Aimonen).

    * Networking:

      - Corrected errors in the socket poll/select logic.  Additional
        state logic was needed to detect if the socket is still connected
        before starting the poll wait. (bug reported by Qiang Yu).

    * Memory Management:

      - mallinfo() should hold the memory manager semaphore (from Petteri
        Aimonen.

    * Build System:

      - Resolved several build errors reported by Mike Smith.

    * Applications:

      - Fixed an NSH memory leak:  Needed to detach after creating each
        pthread.
      - readline() now returns EOF on any failure (instead of a negated
        errno value).  This is because the underlying read is based on
        logic similar to getc.  The value zero  (meaning end-of-file)
        was being confused with a NUL.  So if a NUL was received, the
        NSH session would terminate because it thought it was the end of
        file.

NuttX-6.27
----------

The 94th release of NuttX, Version 6.27, was made on April 28, 2013,
and is available for download from the SourceForge website.  Note
that release consists of two tarballs:  nuttx-6.27.tar.gz and
apps-6.27.tar.gz.  Both may be needed (see the top-level nuttx/README.txt
file for build information).

Additional new features and extended functionality:

    * OS Initialization:

      - Add missing registration of /dev/zero.  Registration of /dev/null
        should depend upon conditional compilation.  From Ken Pettit.

    * Tasking:

      - Added a new interface to set aside memory on the task's stack.  This
        is used (at least in the kernel build) to hold task arguments.
      - Remove up_assert_code().  One assertion routine is enough.

    * Kernel Build:

      - Extensive changes were made to support the kernel build mode.  In
        this mode, NuttX is built as a monolithic kernel.  NuttX is built
        as a separate kernel mode "blob" and the applications are built
        as a separate user mode "blob".  The kernel runs in kernel mode and
        the applications run in user mode (with the MPU restricting user
        mode accesses).  Access to the kernel from the user blob is only
        via system calls (SVCalls).
      - Kernel build configurations for the Open1788 board and for the
        STM32F4Discovery now execute correctly.
      - Changes were made to task and thread start-up routines, signal
        handling, data structures, ARMv7-M SVCalls, stack management
        interfaces,

    * Drivers:

      - Driver for the ST7567 LCD Display Module from Univision Technology
        Inc.  Contributed by Manikandan.S
      - SPI initialize functions renamed so that multiple SPI blocks can
        be initialized.
      - Extended to support the RAMTRON FM25V01 device. Contributed by
        Lorenz Meier
      - Serial drivers: TIOCSERGSTRUCT ioctls now conditioned on
        CONFIG_SERIAL_TIOCSERGSTRUCT

    * ARMv7-M (Cortex-M3/4):

      - Added support for modifiable interrupt vectors in RAM

    * nuvoTon NUC1xx:

      - Added kernel build support

    * Freescale Kinetis:

      - Add kernel build support
      - Add support for the Kinetis L family of Cortex-M0+ MCUs.  Contributed
        by Alan Carvalho de Assis.

    * LPC17xx:

      - Now holds off sleep mode in the IDLE loop is DMA is in progress
        (because sleep mode will disable CPU SRAM).

    * LPC17xx Boards:

      - ZKIT-ARM-1769:  Now supports the ST7567 LCD display module.  Added
        an nxhello configuration for testing (Manikandan.S).
      - ZKIT-ARM-1769:  Add support for both CAN1 and CAN2.  Contributed by
        M.Kannan

      - Open1788: Basic support for the WaveShare Open1788 board is complete
        with working OS test, NSH, and graphics configurations.
      - Open1788: Integrated the LPC178x LCD driver with the WaveShare display.
        Touchscreen support is included, however, there appears to be an
        issue with the Open1788 touchscreen interrupt signal.
      - Open1788:  Now supports SDRAM (used to provide the LCD framebuffer).
      - Open 1788: Reversed sense of the IDLE LCD. It is now off when the
        LPC17 is sleeping and on when awake.  That is much a better visual
        indication of the dynamic CPU load

    * LPC17xx Drivers:

      - Added an LCD framebuffer driver for the LPC177x/8x family.
      - Implemented LPC17xx GPDMA support.
      - Integrated the LPC17xx GPDMA support into the SD card driver.
      - SSP driver adapted to work with the LPC178x family.
      - Separate LPC176x and LPC178x GPIO logic; this logic is too different
        to maintain in one file with conditional compilation.
      - Re-design of the GPIO logic for the LPC178x family by Rommel Marcelo.

    * LPC43xx:

      - Added kernel build support

    * STM32:

      - Added support for kernel mode build.
      - Added architecture support for the STM32 F427/F437 chips. Contributed
        by Mike Smith

    * STM32 Boards:

      - Added a configuration to support a kernel mode build of the OS test
        on the STM32F4Discovery

    * Stellaris LM3S/LM4F:

      - Added kernel build support
      - Added support for the 7 UARTs on the LM4F120

    * Stellaris LM4F Boards:

      - Added scripts and instructions to simplify use of OpenOCD with ICDI
        (JP Carballo)
      - The basic for the Stellaris LM4F120 Launchpad is complete.  This
        includes support for OS test and NSH configurations.  Additional
        driver development is needed.

    * Build System:

      - Directories where the same sources files are used to build different
        objects in the first and second pass kernel builds need to keep those
        objects in separate directories so that they are not constantly
        rebuilt.

    * Applications:

      - apps/system/ramtest:  Add a simple memory test that can be built
        as an NSH command.

    * Tools:

      - kconfig2html is a new tool which will replace the hand-generated
        documentation of the NuttX configuration variables with auto-
        generated documentation.

Efforts In Progress.  The following are features that are partially
implemented but present in this release.  Most are expected to be fully
available in NuttX 6.28.

    * A port to the Freescale Freedom KL25Z is complete but not yet stable
      enough.  The KL25Z is a low-cost Cortex-M0+ part with 128KB of FLASH
      and 16KB of SRAM.  This is is the effort of Alan Carvalho de Assis.

    * Conversion of old configurations to use the kconfig-frontends
      tool is an ongoing effort that will continue for some time.
      At this time, only 32% of the configurations have been converted
      to use the kconfig-frontends tools.

Bugfixes (see the ChangeLog for details).  Some of these are very important:

    * Tasking:

     - Fixed a critical bug:  When there is pending C buffered output
       and the system is very busy, the a pthread may be blocked at
       a critical point when trying to exit.  Blocking at this critical
       point would cause crashes.  All entire task/thread exit logic
       paths were reviewed and failsafe mechanisms were put in place
       to assure that exitting tasks never block after task teardown
       has been started.

    * ARMv6-M:

      - Fixed parameter passing for all system call inline functions with > 3
        parameters
      - Fixed a major problem:  The Cortex-M0 has no BASEPRI register but the
        logic of NuttX-6.26 was using it to manage interrupts.  Switch to
        using the PRIMASK instead.  This means that hardfaults will (again)
        occur when SVC instructions are executed

    * ARMv7-M:

      - Corrected Correct MPU sub-region settings for unaligned regions.
      - In exception handling with CONFIG_NUTTX_KERNEL, need to explicitly
        set and clear the privilege bit in the CONTROL
      - Fixed parameter passing for all system call inline functions with > 3
        parameters

    * Drivers:

      - Support for O_NONBLOCK was not supported in the "upper half"
        serial driver.
      - PL2303 compilation errors

    * Stellaris LM3S/4F:

      - Corrected typos in alternate function definitions.

    * LPC17xx Drivers:

      - Added a work-around for an ADC errata.  From Chris Taglia
      - Only one ADC pin was configured. Need to configure all that
        are in the ADC0 set.  From MKannan

    * File Systems:

      - The FAT logic was not making a distinction between directory
        non-existence and file non-existence so when it you try to
        create a file in a non-existent directory, it would create a
        file with the name of the missing directory.  Reported by Andrew
        Tridgell
      - Several fixes to the FAT file system from Ronen Vainish.  These
        fixes mostly involve the logic to extend directory clusters for
        the case of long file names but also include a few important
        general fixes (such as for storing 32 bit FAT values)
      - mkfatfs was writing the boot code to the wrong location.  From
        Petteri Aimonen

    * Networking:

      - Fixed a compilation error when socket options are are disabled.
        Reported by Daniel O'Connor

    * C Library:

      - Corrected an error in sscanf.  If %n occurs in the format statement
        after the input data stream has been fully parsed, the %n format
        specifier will not be handled.  Reported by Lorenz Meier
      - strchr(str, '\0') should return a pointer to the end of the string,
        not NULL.  From Petteri Aimonen

    * Build System:

      - Fix naming of NuttX target if EXEEXT is defined.

    * Applications:

      - OS test: Fix timing error in non-cancelable thread test.
      - NSH: Correct the test of the skip input parameter.  Was limiting the
        range to <= count.  From Ken Petit.

NuttX-6.28
----------

The 95th release of NuttX, Version 6.28, was made on June 14, 2013,
and is available for download from the SourceForge website.  Note
that release consists of two tarballs:  nuttx-6.28.tar.gz and
apps-6.28.tar.gz.  Both may be needed (see the top-level nuttx/README.txt
file for build information).

Additional new features and extended functionality:

    * File Systems:

      - SMART FLASH file system (contributed by Add Ken Pettit).

    * MTD (FLASH) Drivers:

      - Add support of MTD partitions via a new MTD driver that manages a
        set of MTD devices, each managing a subset of the FLASH region
        managed by the parent MTD driver.
      - Extended the MTD interface to provide an (optional) method to
        perform byte oriented writes if supported by the FLASH part.
      - M25Px driver re-architected to use the byte write capability (when
        possible) and to use 4KB sectors for the erase block size when the
        part supports it (from Ken Pettit).

    * LCD Drivers:

      - New interface definitions to support audio devices (from Ken Pettit)
        and alphanumeric, segment LCDs.

    * Wireless Drivers:

      - Added new driver for the wireless nRF24L01+ transceiver (from
        Laurent Latil).

    * Calypso:

      - Added support for the Pirelli DP-L10 phone (from Craig Comstock via
        Alan Alan Carvalho de Assis)

    * STM32:

      - Added an option to conditionally disable the "wfi" sleep mode.  This
        is needed with certain JTAG debuggers to prevent the debug session
        from being disconnected (from Ken Pettit).
      - Added support for the STM32L (STM32L15X/STM32L16x) family.
      - Added STM32F103C4 and F103C8 chip support (from Laurent Latil).
      - Added a new interface function, stm32_dmacapable() that can be used
        to determine if DMA is possible from the specified memory address
        (from Petteri Aimonen)

    * STM32 Drivers:

      - If CONFIG_STM32_DMACAPABLE is defined, the STM32 SPI driver now uses
        stm32_dmacapable() to determine if it is possible to perform DMA
        from the specified address.  This change is important for the STM32
        F4 which may have SPI data buffers allocated on the stack in CCM
        memory which cannot support the DMA (from Petteri Aimonen).

    * STM32 Boards:

      - Support added for the MikroElektronika Mikromedia for STM32F4
        development board (from Ken Pettit) with the MIO283QT2 LCD and
        touchscreen.  Several graphics configurations are included.
      - The HY-mini STM32v board now uses the common SSD1289 driver
        and supported the card detect interrupt.  Several new
        configurations also added and some removed (from Laurent Latil).
      - Support added for the R65105-based LCD that comes with some
        HY-Mini STM32v boards (from Christian Faure).
      - Added basic support for the STM32L-Discovery board.  Drivers
        for the on-board segment LCD are included.
      - Added support for the STM32 Tiny development board based on the
        STM32 F103C8T6 MCU.  This includes support for the nRF24L01+
        wireless on the board (from Laurent Latil).

    * Stellaris LM3S/LM4F:

      - Support added for a TI/Stellaris internal FLASH MTD driver (from Max
        Holtzberg).

    * Stellaris LM4F Boards:

      - The LM3S6965-EK now has configurations for the UDP discovery tool and
        for the TCP echo server (both from Max Holtzberg)

    * Atmel ATSAM3/4:

      - Reorganized, renamed, and updated directory structure to better
        support additional members of the SAM3/4 family.
      - Added support for both the ATSAM4S and ATSAM4L families.  The
        ATSAM4S is similar to the ATSAM3U, but the ATSAM4L is quite a
        different beast, really much more akin to the AVR32s SoCs but
        with a Cortex-M4.

    * Atmel ATSAM3/4 Boards:

      - Added support for the Atmel SAM4L Xplained Pro development board.
        This board features the ATSAM4LC4C MCU (Cortex-M4 with 256KB FLASH +
        32KB SRAM).
      - Added support for the Atmel SAM4S Xplained development board.  This
        board features the ATSAM4S16C MCU (Cortex-M4 with 1MB FLASH + 128KB
        SRAM).

    * PIC32MX Boards:

      - Added support for the 1602 segment LCD on-board the Sure PIC32MX
        board.  This board will now also support a USB NuttX console and
        the USB monitor test program.

    * Build System:

      - Clean-up of almost all .gitignore files:  Made scope of ignore to be
        only the current directory; Ignore .dSYM files in directories where
        .exe's may be built.  Also, in Makefiles, clean .dSYM files in
        directories where an .exe may be built.
      - Standardize and consolidated all build-as-an-NSH-application
        configuration settings.  Now only CONFIG_NSH_BUILTIN_APPS is
        sufficient to build an application, test, or or example as an NSH
        builtin application.
      - Added support for a generic ARM, ARMv6-M and ARMv7-M Windows EABI
        toolchains.

    * Libraries:

      - Added encoder/decoder logic to marshal and serialize special segment
        LCD (SLCD) commands intermixed with normal ASCII data.  This is the
        similar to the encoding/decoding logic that is used to marshal
        special commands from a keyboard.
      - Add dprintf() and vdprintf() (the latter from Andrew Tridgell).
      - Add an application that may be built as an NSH builtin command that
        will erase FLASH using a flash_eraseall NSH command (from Ken Pettit).

    * Applications:

      - Added an MTD partition test/examples.  Currently used with (1) the a
        simulation configuration to test MTD partitions on a RAM emulation
        of FLASH and (2) with the Mikroe STM32F4 configuration.
      - Added a test/example to verify alphanumeric, segment LCDs.
      - Added a simple single threaded, poll based  TCP echo server based
        on W. Richard Stevens UNIX Network Programming Book (from Max
        Holtzberg).
      - Added several tests of the SMART block driver and file system (from
        Ken Pettit).
      - Added a runtime configuration for the UDP discover utility (from
        Max Holtzberg).
      - Added an example application to demo the nRF24L01 driver (from
        Laurent Latil).
      - New and modified NSH commands:
        Added a -h option to the df command to show the volume information
        in human readable form (from Ken Petit).
        Add a new mksmartfs command (from Ken Petit).

Efforts In Progress.  The following are features that are partially
implemented but present in this release.  Most are expected to be fully
available in NuttX 6.28.

    * Audio System:

      - A complete audio subsystem include CODECs, higher level management,
        interface definitions, and audio drivers was contributed by Ken
        Pettit.  This work has not been completely verified as of this
        release and so is categorized as a work-in-progress.  At present,
        progress is blocked due to issues interfacing with the VS1053
        audio DAC on the Mikroe STM32F4 board.

    * kconfig-fronted Configuration:

    -  Conversion of old configurations to use the kconfig-frontends
       tool is an ongoing effort that will continue for some time.
       At this time, only 43% of the configurations have been converted
       to use the kconfig-frontends tools.

Bugfixes (see the ChangeLog for details).  Some of these are very important:

    * Tasking:

      - Modify assertion in the priority inheritance logic that is reported
        to cause false alarm assertions.

    * Kernel Build:

      - Typo in syscall proxying logic corrected by Ken Pettit.

    * Networking:

      - Poll setup/teardown logic should ignore invalid (i.e., negative)
        file descriptors (from Max Holtzberg).
      - When readahead data is available, the network poll() logic should
        set POLLIN (or POLLRDNORM), not POLLOUT (from Max Holtzberg).

    * LCD Drivers:

      - Correct power controls in the MIO283QT2 LCD driver.

    * USB Device Controller Drivers:

      - Change the default IN request buffer size from 64 to 96.  This will
        avoid requests of exactly MAXPACKET size and, hence, avoid so many
        NULL packets.  Also, fix the OUT request buffers size to exactly the
        max packet size.  It really cannot be any other size.

    * STM32 Drivers:

      - Correct some bad STM32 F1 DMA definitions that crept into the system
        a few months ago a broke STM32 F1 DMA (from Laurent Latil)
      - Fixed an error in NULL packet handling in the STM32 F1 USB device
        controller driver:  If the NULL-packet needed flag ever got set,
        then it was not being cleared and infinite NULL packets resulted.
        This only affects the CDC/ACM class and was the cause of the
        failures using the USB CDC/ACM device as a NuttX console.  With this
        change the USB works well as an alternative NuttX console device for
        the STM32 F1 family.
      - Correct some bad condition compilation in the RCC logic (CONFIG_
        missing from setting names).  This affects some STM32 FLASH pre-
        fetch settings (from Lorenz Meier).
      - Change for hardware flow control support for STM32. The change also
        fixes incorrect operation of USART2 and UART5 in current master
        (from Lorenz Meier and Mike Smith).
      - Fixed a backward conditional in USB OTG FS host controller driver
        that prevented detection of disconnection events (from Scott).

    * LPC17xx Drivers:

      - I2C interrupt control.  Also correction for a single byte read
        timeout error (from M. Kannan).

    * Freescale Kinetis:

      - Freedom KL25Z pin multiplexing and LED control corrections (from
        Alan Carvalho de Assis)

    * PIC32MX:

     - Fix NULL packet handling in the PIC32 USB device driver.  Without
       this fix the CDC/ACM driver cannot be used reliably with the PIC32
       USB.  With this change the USB works well as an alternative NuttX
       console device.

    * Graphics:

      - Default priorities for NxWidget and NxWM threads should be 100,
        not 50, to be consistent with other default priorities.

    * Applications:

      - Remove the CONFIG_EXAMPLES_NXTEXT_NOGETRUN option from the NXTEXT
        example.  The test logic was bad for the case where this options is
        not selected.  Also, completed the empty Kconfig file.
      - C++ name mangling was occurring when this example is built as an NSH
        built-in application causing the entry to be undefined when called
        from C code.
      - Add some missing NSH library configuration values (from Lorenz
        Meier).

NuttX-6.29
----------

The 96th release of NuttX, Version 6.29, was made on July 31, 2013,
and is available for download from the SourceForge website.  Note
that release consists of two tarballs:  nuttx-6.29.tar.gz and
apps-6.29.tar.gz.  Both may be needed (see the top-level nuttx/README.txt
file for build information).

Additional new features and extended functionality:

    * Drivers:

      - Generalized the SSD1306 driver and added support UG-2832HSWEG04
        which is very similar to the existing support for the
        UG-2864HSWEG01.
      - Added support for a generic bit-bang SPI driver.  This includes
        both a common "upper half" driver as well as a platformp-specific
        "lower half" dirvers based on a common "template."

    * ARMv7-A, Cortex-A5

      - Added support for the ARMv7-A architecture and the Cortex-A5 in particular.

    * ARMv7-M, Cortex-M3/4

      - Modified how some registers are copied during a context switch (with
        lazy FPU register saving).  This should save some context switching
        time when the context switch is due to interrupt level processing.

    * STM32:

      - Added support for a separate CCM heap.  This may be useful for
        segregating allocations for CCM (which cannot be used for DMA)
        from other allocations (that may be used used for DMA).

    * STM32 Drivers:

      - DAC: Added support for DAC DMA (contributed by John Wharington).
      - I2C: An I2C driver for the STM32 F3 family (from John Wharington).

    * Atmel AT91 SAM/4:

      - Add support for SAM3X and SAM3A chips

    * Atmel AT91 SAM/4 Drivers:

      - Re-architect the SAM3/4 SPI driver so that is it compatible with the
        SPI drivers of other MCUs.
      - Added register definition file for the SAM4L LCD peripheral.
      - Added SAM4L PDCA register definition file

    * Atmel AT91 SAM/4 Boards:

      - SAM4L-Xplained: Added support for the SPI-based SD card on the I/O1
        module.
      - SAM4L-Xplained: Added a driver for the LED1 segment LCD module.
      - SAM4L-Xplained: Added support for the UG-2832HSWEG04 OLED on the
        SAM4L Xplained Pro's OLED1 module
      - SAM4S-Xplained: Added support for on-board 1MB SRAM
      - Arduino Due:  Basic support for the Arduino Due (SAM3X) is now
        included.
      - SAM3U-EK:  The touchscreen is now functional.

    * Atmel AT91 SAMA5D3

      - Added support for the Atmel AT91SAMA5D3 Cortex-A5 chip family.

    * Atmel AT91 SAMA5D3 Boards

      - Added support for the Atmel SAMA5D3x-EK boards which use the AT9
        SAMA5D3x chips (x=1,3,4,5).

    * Freescale KL25Z Drivers

      - Freescale KL25Z TSI register definitions and example TSI driver for
        the Freedom KL25Z board from Alan Carvalho de Assis.
      - Added SPI driver and register definitions for the Freescale KL25Z.
      - Added a framework for controlling SPI-related discrete inputs and
        outputs.  Taken from work by Alan Carvalho de Assis

    * Build System:

      - New sub-directories to hold SPI-related files:  includes/nuttx/spi.h
        moved to include/nuttx/spi/.; SPI-related Kconfig info moved from
        drivers/Kconfig to drivers/spi/kconfig.
      - Finally... I changed the naming of configuration variables like
        CONFIG_DRAM_ to CONFIG_RAM_.  This has bothered me for a long time
        since most boards don't have DRAM.  The more generic RAM naming
        should not produce so much cognitive dissonance

    * Libraries:

      - Added CRC16 support.

    * Applications:

      - Added Zmodem file transfer support.  This may be used as an embedded
        library or may be built as 'sz' and 'rz' commands that can be
        executed from NSH.
      - C++ initializers should be set once and, preferably, in the context
        of the task that uses any C++ statically initialized classes.  This
        only becomes an issue if cxxtest or helloxx are built as NSH builtin
        applications.  Then you want the initialization done in cxxtext or
        helloxx and not in NSH (and certainly not twice).  Added
        configuration options to control who does the C++ initialization.
        NSH now does not do C++ initialization be default and must be
        configured to do otherwise.  Conversely, cxxtest and helloxx
        will always do C++ initialization unless configured do otherwise.
      - examples/cxxtext:  Add ostream test as provided by Michael.
      - NSH:  Added a 'cmp' command that can be used to compare two files
        for equivalence.  Returns an indication if the files differ.
        Contributed by Andrew Tridgell (via Lorenz Meier).

Efforts In Progress.  The following are features that are partially
implemented but present in this release.  They are not likely to be
completed soon.

    * Audio System:

      - A complete audio subsystem include CODECs, higher level management,
        interface definitions, and audio drivers was contributed by Ken
        Pettit.  This work has not been completely verified as of this
        release and so is categorized as a work-in-progress.  At present,
        progress is blocked due to issues interfacing with the VS1053
        audio DAC on the Mikroe STM32F4 board.

    * kconfig-fronted Configuration:

    -  Conversion of old configurations to use the kconfig-frontends
       tool is an ongoing effort that will continue for some time.
       At this time, only 45% of the configurations have been converted
       to use the kconfig-frontends tools.

Bugfixes (see the ChangeLog for details).  Some of these are very important:

    * File Systems:

      - Fixed compilation error if no file systems are enabled: Change
        error to ERROR.
      - Read-Ahead/Write buffering: Correct typos that can cause failures
        in some configurations (From Chia Cheng Tsao).

    * Drivers

      - Remove the wait for the touchscreen busy bit in the ADS7843E driver.
        From my reading of the ADS7843 spec, it would not be appropriate to
        wait for the BUSY bit to de-asserted anyway (since it is only de-
        asserted when we read the data).  Most boards do not even bother to
        provide the BUSY bit.
      - MMC/SD SPI based driver:  Driver needs to make sure that the SPI
        mode and data width are correct.
      - ENC28J60:  Change buffer ordering to work around Errata.  From Dave
        (ziggurat29).

    * USB Device Controller Drivers:

      - Fixed a typo in the composite device driver unitialization logic.
        DEV1 should be DEV2 in one case.
      - usbdev.h: Fix some typos that cause compiler errors when
        CONFIG_USBDEV_DMA and CONFIG_USBDEV_DMAMEMORY are selected (From
        Chia Cheng Tsao).

    * ARM9:

      - Fix a bug (uninitialized register error) that crept in the ARM9
        boot-up code several years ago.  Obviously no one has used the
        ARM9 NuttX port for years!

    * STM32 Drivers:

      - Fix STM32 OTF FS endpoint allocation logic.  Apparently the same
        endpoint can be allocated as both an IN or an OUT endpoint.  The
        existing implementation only supported one allocation, either IN or
        OUT.  This resulted in failures to allocate endpoints when used with
        the CDC/ACM + MSC composite driver (From Chia Cheng Tsao).
      - SDIO: Add support for the data block end (DBCKEND) interrupt to
        terminate transfers (From Chia Cheng Tsao).
      - DAC: Fixed numerous DAC driver errors and added support for DAC
        DMA (contributed by John Wharington).

    * SAM3/4:

      - SAM4S: Correct configuration of PIO pins for SAM4S B and C peripherals.
      - Need to disable write protection before configuring PIO pins.
      - GPIO configuration logic must protect against re-entrancy.
      - Clocking must be applied to the SMC module for the 3X and 3A family in
        order for the NFC SRAM to be functional.
      - Fixed some errors for interrupts on ports D-F.

    * SAM3/4 Drivers:

      - Common SPI driver: Fix SPI mode setting.  In the SAM3/4 family, the
        clock phase control (CPHA) is inverted (NPHA).  Also fixed an
        incorrect pointer test.  Was checking if the wrong pointer was NULL.

    * SAM3/4 Boards:

      - SAM3U-EK: Fix polarity of the /PENIRQ signal (it is active low).
        The SAM3U-EK board now runs at 96MHz.

    * Applications:

      - apps/examples/nxhello:  Minor fix for compilation error when the
        display resolution is low (< 8bpp) due to a typo that has been there
        for a long time.  Also Correct default colors when in Y1 code mode.
      - apps/system/ramtest:  The RAM test was not correctly built
        into the configuration and build system.
      - apps/examples/composite: Change to prevent some false alarm debug
        assertions (From Chia Cheng Tao).

NuttX-6.30
----------

The 97th release of NuttX, Version 6.30, was made on September 14, 2013,
and is available for download from the SourceForge website.  Note
that release consists of two tarballs:  nuttx-6.30.tar.gz and
apps-6.30.tar.gz.  Both may be needed (see the top-level nuttx/README.txt
file for build information).

Additional new features and extended functionality:

    * Common Drivers:

      - Extended TERMIOS support for serial and CDC/ACM drivers.  From
        Mike Smith, Andrew Tridgell and Lorenz Meier.
      - Added option to disable serial port reordering.  From Lorenz Meier.
      - Several changes to the USB host control interface and extensions to
        common USB host logic to handle host controllers with multiple
        downstream ports in the root hub.
      - USB device tracing: Extended decoding and stringifying of USB trace
        output to include trace output from class drivers.
      - USB host tracing:  Added support for USB host tracing similar in
        some ways to USB device tracing:  Stringification is an inherent
        part of the trace decoding (not an option).  Only available in the
        SAMA5 USB host drivers now.

    * Networking / Network Drivers

      - Support for the Microchip ENCX24J600 Ethernet driver from Max
        Holtzberg
      - CC3000 Networking.  Initial support for the TI CC3000 network
        module on the Freescale Freedom-KL25Z board from Alan Carvalho
        de Assis.  This is still a work in progress.

    * ARMv7-A, Cortex-A5

      - Restructured some MMU-related logic and header files.
      - Hooks added for Cortex-A8, but not yet used.

    * STM32 Drivers:

      - STM32 SPI: nbits() interface extended to control bit order as well
        as bit width (from Teemu Pirinen)

    * STM32 Boards

      - Olimex STM32-P107:  Incorporate ENCX24J600 networking for the Olimex
        STM32 P107 board.
      - LeafLabs Maple Board:  Add board support for the LeafLabs Maple and
        Maple Mini boards.  From Librae.

    * Atmel AT91 SAMA5D3x

      - Added support for the SAMA5 DMAC controllers.
      - DMA-capable drivers for the SAMA5 SPI peripherals.
      - DMA-capable HSCMCI 0/1/2 drivers.
      - Support for PIO interrupts
      - Utilities for intelligent conversions between physical and virtual
        addresses.
      - Added USB host controller drivers for both the OHCI (low- and full-
        speed) peripheral and the ECHI (high-speed) peripheral.
      - Added USB device controller for the SAMA5 UDPHS peripheral (full-
        and high-speed).
      - Added a Two Wire (TWI) driver.  This is a variant of I2C.

    * Atmel AT91 SAMA5D3x-EK Development Boards

      - Now supports onboard SDRAM.  Modified heap initialization logic
        to include SDRAM if configured.
      - Integrated a FAT file system on the on-board SPI-based AT25 serial
        FLASH
      - Integrated HSMCI0 and HSMCI1 support for the microSD and full file
        SD card slots.  Includes PIO interrupts for card detection events.
      - Integrated USB OHCI and ECHI host and high-speed peripheral support.
        File system on AT25 now exported via Mass Storage Class.  Includes
        PIO VBUS controls.
      - Integrated the TWI driver and the I2C tool.  Added support for an
        external AT24 serial EEPROM.

    * Applications:

      - apps/examples/cc3000.  Initial support for the TI CC3000 network
        module on the Freescale Freedom-KL25Z board from Alan Carvalho de
        Assis. Includes the test to verify the CC3000.
      - apps/examples/usbmsc:  apps/examples/usbstorage renamed usbmsc for
        consistency. Change submitted by CCTSAO.
      - apps/system/usbmonitor:  The USB monitor has been extended so that
        it can be used with USB device or host trace data.

Efforts In Progress.  The following are features that are partially
implemented but present in this release.  They are not likely to be
completed soon.

    * CC3000 Networking

      - CC3000 Networking.  Initial support for the TI CC3000 network
        module on the Freescale Freedom-KL25Z board from Alan Carvalho
        de Assis.  This is still a work in progress.

    * kconfig-fronted Configuration:

      - Conversion of old configurations to use the kconfig-frontends
        tool is an ongoing effort that will continue for some time.
        At this time, only 46% of the configurations have been converted
        to use the kconfig-frontends tools.

Bugfixes (see the ChangeLog for details).  Some of these are very important:

    * File Systems:

      - ROMFS: Fix an error where long (>15) file names were read
        incorrectly from a ROMFS file system.  From Mike Smith
      - NXFFS: Clean up some compiler warnings.

    * Common Drivers

      - MMC/SD driver: Correction for a bad return value when multiple
        block SDIO transfers are suppressed.  By Andrew Tridgell.
      - USB HID keyboard and mass storage host-side class drivers:  Fix some
        compilation errors and warnings when pre-allocated data structures
        are used.
      - USB device-side class drivers:  Fix some compilations errors when
        DUALSPEED (i.e., full- and high-sped) support is enabled.
      - CDC/ACM and PL2303: Don't use max packetsize assigned to the endpoint
        when allocating request buffers; The default value of the endpoint
        max packetsize may be incorrect because the endpoint has not yet
        been configured.  Really only an issue for high-speed endpoints.
      - USB Host Mast Storage Class:  Fixed a problem that was causing some
        devices to fail to initialize: If device is returning fatal transfer
        errors while attempting to initialize, don't bother with the startup
        retries; abort immediately so that the device will be reset and we
        can try again with a better ready device.
      - USB Host Mast Storage Class:  Correct a reference counting error:
        When an MSC device transfer fails while waiting for UnitTestReady,
        the reference count on the class was not being decremented.  The end
        result is a memory leak as can be seen by the USB device numbers
        incrementing: sda, sdb, sdc, ...
      - USB Device CDC/ACM:  Fix backward conditional compilation in the
        CDC/ACM driver with regard to remote wakeup and self-powered
        capabilities.  From the PX4 team via Lorenz Meier,

    * Networking / Network Drivers

      - ARP IP harvesting:  Correct backward condition in netmask task.
        From Max Holtzberg.
      - Network connection monitor: Fixes a race condition where a loss of
        connection may not be detected when the connection is lost before it
        has been accepted (from Max Holtzberg).
      - TCP/IP Backlog:  Fix a critical bug in the TCP/IP backlog
        initialization:  Only the first backlog buffer was getting added to
        the free list.  From Max Holtzberg.
      - ENC28J60:  Fixes and improvements back-ported from the ENCX24J600
        to the ENC28J60 by Max Holtzberg.

    * STM32 Drivers:

      - STM32 I2C fixes for the STM32 F3 family from John Wharington.
      - STM32 I2C Correct an error that crept into the STM32 F1 I2C
        driver with some recent changes.  From Librae
      - STM32 F4: Added some missing CONFIG_SERIAL_TERMIOS support; Fixed
        some STM32 F4 Timer 8 pin configurations.  From CCTSAO.
      - STM32 SDIO: If CONFIG_SDIO_BLOCKSETUP defined, OS would crash.  Now
        Generate an error if CONFIG_SDIO_BLOCKSETUP is defined; that
        option is not yet supported by the STM32 SDIO driver.  From CCTSAO
      - STM32 I2C Timers: Some CCER bit settings changed. Submitted by
        CCCTSAO.
      - STM32 CAN: Fix access to CAN filter registers.  From the PX4 team
        via Lorenz Meier.
      - STM32 Kconfig: Fix STM32 UART7/8 Kconfig names and UART DMA.  From
        the PX4 team via Lorenz Meier.

    * LPC17xx Drivers

      - Fix #endif with missing #if in USB host header file.  Reported
        by Andrew Bradford,

    * SAM3/4 Boards:

      - Corrected DMA-related problems: Bad register definitions, parameters
        reversed in a function call.
      - Correct a race condition in the HSMCI driver when an interrupt
        occurs before the wait for the interrupt begins.
      - Peripheral clock setup:  Correct a typo in a register name.

    * Atmel AT91 SAMA5D3

      - Order of some operations changed in boot-up logic to defer
        enabling of caching of memory regions until SDRAM is initialized.
      - Correct handling of spurious interrupts.

    * Freescale KL25Z Drivers

      - KL25Z SPI: Correct typo in name of a function.  From Alan Carvalho
        de Assis.

    * Applications:

      - apps/examples/composite:  Fix a typo that can cause a configuration
        error.  From CCTSAO.
      - apps/examples/pwm:  Clean-up some configuration confusion.
      - apps/netutils/dhcpd/dhcpd.c:  Fixed calculation of the next lease
        address.  From Paolo Messina.
      - apps/examples/usbmsc:  Don't try to control USB trace if we are
        an NSH built-in task.  In that case our attempts are inadequate
        and only interfere with with other logic that is attempting to
        to do the same thing (in NSH or in the USB monitor).
      - apps/examples/usbmsc:  IMPORTANT bug fix: Change how the msconn
        works.  Because of recent changes the msconn command was hanging.
        This was because the USB MSC start-up logic creates a pthread;
        Now waitpid() will wait until all members of the task group
        exit.  So NSH was hanging in waitpid when msconn started even
        though msconn returned.  The USB MSC logic really should not use
        a pthread, but we are stuck with that for now.  The work-around
        is the msconn now daemonizes itself so that it so that the pthread
        is created in a different task group.
      - apps/nshlib:  Fix NSH listing output for the case of a single file.
        From the PX4 team; provided by Lorenz Meier.

NuttX-6.31
----------

The 98th release of NuttX, Version 6.31, was made on October 28, 2013,
and is available for download from the SourceForge website.  Note
that release consists of two tarballs:  nuttx-6.31.tar.gz and
apps-6.31.tar.gz.  Both may be needed (see the top-level nuttx/README.txt
file for build information).

Additional new features and extended functionality:

    * General:

      - Standardized stack checking logic so the interfaces can be used
        by common stack monitoring logic.

    * Audio Subsystem and Audio Drivers:

      - Ken Pettit has finally released his long awaited audio subsystem.
        This is a generic audio subsystem that is appropriate for the
        deeply embedded MCU.  Current testing has, however, been focused
        on the VS1053 CODEC chip.
      - Ken Pettit's VS1053 audio CODEC driver is now functional.

    * Networking / Network Drivers

      - Add the prefix ETH0 to all PHY configuration selections.  This
        will allow us to support to Ethernet MAC drivers with two different
        PHYs (identified with ETH0 and ETH1).  Enabled with CONFIG_NETDEV_MULTINIC.
      - Add MII/RMII PHY definitions for the Micrel KSZ8051 PHY.
      - Add GMII/GRMII PHY definitions for the Micrel KSZ9021/31 PHY.
      - New network-optimized, higher-performance sendfile() implementation
        from Max Holtzberg.
      - Added a simple routing table.  This table is currently only used (1)
        when we need to look-up an Ethernet device based on an IP address,
        and (2) in the ARP logic when we need to request the MAC address of
        the router, vs the MAC address of the peer.
      - Make net_close() nonblocking and free unestablished connections if
        no free connections available.  From Max Holtzberg.
      - Changed the meaning of the uip_*input functions. They now return
        success when a packet is dropped; This is needed for the ENCX24J600
        driver that must make a decision to return the packet or not:  It
        should not retry dropped packets. From Max Holtzberg.
      - David Sidrane has completed integration of the CC3000 networking.
        This is much more than a network driver:  It is a complete
        replacement for the NuttX networking with off-chip networking support
        in the CC3000.
      - Numerous enhancements to the ENCX24J600 driver from Max Holtberg.

    * Other Common Drivers:

      - The SST25 serial FLASH MTD driver now includes support for the
        SST25VF016B.  From David Sidrane.
      - Add a preflight method to the SDIO interface to support the STM32
        DMA usage model. From Mike Smith.
      - Enhanced the MMC/SD SDIO driver to perform DMA preflight operations
        and fail DMA read/write requests that fail preflighting. From Mike
        Smith.
      - Add an ioctl command that can be used to trigger ADC/DAC conversion
        under application control.

    * File Systems:

      - Enhanced the FAT32 filesystem code to understand DMA preflight
        failures, and to use the file sector buffer as a bounce buffer when
        a user-supplied buffer is not suitable for DMA. From Mike Smith.

    * Atmel AT91 SAMA5D3x

      - Add support so that subsets of the total DRAM (and other external
        memory) can be added to the heap, leaving other memory reserved for
        other purposes (like the LCDC framebuffers).

    * Atmel AT91 SAMA5D3x Drivers:

      - Use more descriptive task names when starting the EHCI and OHCI
        monitor tasks.
      - Added a 10/100Base-T Ethernet (EMAC) driver.
      - Added a 1000Base-T Ethernet (GMAC) driver.
      - Added a Real Time Clock (RTC) driver and integrated with the NuttX
        system time logic.
      - Added support for /dev/random using the SAMA5D3x True Random Number
        Generator (TRNG).
      - Added a Watchdog Timer (WDT) driver.
      - Added a Timer/Counter (TC) library with interface that make be used
        by other drivers that need timer support.
      - Added an ADC driver that can collect multiple samples using the
        sequencer, can be trigger by a timer/counter, and supports DMA data
        transfers.
      - Added a touchscreen driver based on the special features of the
        SAMA5D3 ADC peripheral.
      - Added an LCD controller (LCDC) frame buffer driver.
      - Added a CAN driver.  However, testing has been delayed because of
        cabling issues.
      - Basic header file support is available for the Image Sensor
        Interface (ISI) camera interface.  Work on the camera driver is
        underway and is expected in the next release.

    * Atmel AT91 SAMA5D3x-EK Development Boards

      - Add OS test support for the FPU test.
      - Enable the task name feature board configuration sto provide
        prettier ps command output.
      - Added NX and NxWM configurations to verify the LCD and touchscreen.
        There are still some outstanding issues with the NxWM configuration
        as of this release.
      - The TRNG and /dev/random are now enabled by default in the demo
        configuration.

    * Atmel AT91 SAM3/4 Boards:

      - Add configuration to select revision 3 of the Arduino Due which has
        some small but important differences.  Suggested by gdi@embedders.org.

    * STMicro STM32:

      - Add support for the STM32F207ZE chip. From Martin Lederhilger.

    * STMicro STM32 Boards:

      - Add configuration for the Spark Core.  The initial check-in is
        basically the Maple Mini board and subsequent development by David
        Sidrane is his special Spark emulation hardware.  The configuration
        should be very mature when actual Spark hardware is available.
      - Support for the Olimex STM32 P207 board added by Martin Lederhilger.
      - Configuration for the Mikroe STM32F4 board configuration updated for
        audio support by Ken Pettit.

    * NXP LPC17xx Boards:

      - zkit-arm-1769:  LED1 is now user controllable after booting. From
        Rashid Fatah.

    * Kinetis KL Drivers:

      - PIT and TPM register definitions header files for the from Alan
        Carvalho de Assis.
      - Added low-level getc() function for operation with no file system.
        The KL25Z can now support NSH in a very minimal system that does
        not even have a file system.

    * Kinetis KL Boards

      - A new configuration called minnsh was added is an experiment to
        see how small we can get the NuttX footprint and still support NSH.
        From Alan Carvalho de Assis..

    * TI Calypso Phones:

      - Basic board support for the Motorola C139 (Compal E86) phone.  From
        Craig Comstock.

    * Applications:

      - Moved several useful examples from apps/examples to apps/system.
        This includes USB MSC, USB CDC/ACM, and USB Composite.
      - New addroute and delroute commands added to NSH in order to manage
        the network routing table.
      - Numerous enhancements and updates to the CC3000 example from David
        Sidrane.
      - Add a new stack monitor daemon that can be used to constantly
        monitor stack usage by all threads.
      - Numerous changes to get NSH working with no file system.  Basically
        this suppresses I/O redirection and replaces file I/O with calls to
        low-level console read/write functions.  Suggested by Alan Carvalho
        de Assis.
      - apps/system/nxplayer: A new, command-line media player called
        'nxplayer' from Ken Pettit.
      - apps/examples/random:  Add a simple test that dumps values from
        /dev/random.
      - apps/examples/adc:  Add support so that a ADC driven by software
        triggering can be tested.

    * Build System:

      - The MKDEP tools now support a new argument that identifies the
        object file path.

Efforts In Progress.  The following are features that are partially
implemented but present in this release.  They are not likely to be
completed soon.

    * kconfig-fronted Configuration:

      - Conversion of old configurations to use the kconfig-frontends
        tool is an ongoing effort that will continue for some time.
        At this time, only 48% of the configurations have been converted
        to use the kconfig-frontends tools.

Bugfixes (see the ChangeLog for details).  Some of these are very important:

    * Initialization and Scheduling:

      - IDLE thread initialization logic should not call group_setupidlefiles()
        if there are no file descriptors (and, hence, no file system).
      - Fix some cornercase error handling logic:  If sched_releasetcb() is
        called as part of a failed pthread startup before the flags field in
        the TCB has been initialized, then a crash occurs. Pointed out by
        David Sidrane.

    * Networking / Network Drivers:

      - Look up of a device using subnet will fail if the packet is being
        sent out of our subnet (via a router). The fallback here is just to
        use the only device ("eth0") if the subnet lookup fails (this logic
        was extended to handle multiple Ethernet devices by adding a simple
        routing table).
      - Fix some backward conditional logic in send() that enabled the
        check if the ARP address is in the ARP table.  From Max Holtzberg.
      - Notify the socket layer from the network monitor if a connection is
        lost before the monitoring callback has been registered.  From Max
        Holtzberg.
      - send():  Reset the send timeout when the data is ACKed, not when the
        data is sent.  Remove conditions on checking for timeout.  From Max
        Holtzberg.
      - Correct how the TCP/IP initial minimum MSS is calculated. Max
        Holtzberg.
      - TCP state machine: Move tcp connection into SYN_RCVD state after
        aception instead of bypassing and moving directly into ESTABLISHED.
        From Max Holtzberg.
      - Numerous fixes to the ENCX24J600 driver from Max Holtberg.

    * USB Drivers:

      - Change naming of SELFPOWERED and REMOTEWAKEUP to avoid name
        collisions.  Prepend the name of the driver (for example
        CDCACM_SELFPOWERED).
      - CDC/ACM class driver:  Change the interval for the interrupt
        endpoint from 0xff (invalid) to 10.  This is not a critical
        change but will avoid a complaint from the Linux driver when
        it overrides the 0xff value.

    * ARM Cortex-A5:

      - Fix an error in data cache clean and invalidate functions: Fix of
        addresses to cache line boundaries.

    * Atmel AT91 SAMA5D3x Drivers:

      - Correct some inconsistencies in the way that USB configuration
        settings are used.  This caused compilation errors in SAMA5 OHCI
        when USB debug was ON but USB host tracing was off.
      - When 480MHz UPLL is used to drive OHCI, it should have a divider
        of 10.  However, that does not work.  A divider of 5 does.  Why?.
      - OHCI HCD: Fix a place where DMA-related data needed to be flushed
        to data cache; Fix another where a virtual address was being used
        in a register where a physical address was required.
      - HSMCI Driver: TX DMA disabled.  It is just not reliable. No idea
        why.  RX DMA is still used.
      - STM32F103C pinmapping corrections from David Sidrane.

    * Atmel SAMA5D3x-EK Board

      - Increase the number of pre-allocated watchdog timers.  The default
        number of 4 was easily being exhausted in the more complex
        configurations.

    * STMicro STM32:

      - STM32 F4 DMA definitions: Typo fixes for UART7 and UART8 DMA
        configs.  From Mike Smith.
      - DMA priority configuration corrections from Mike Smith.
      - Changes to the stm32_dmacapable API. In order to correctly
        verify that a buffer can be transferred, the transfer count and
        the CCR value are required.  Implemented stm32_dmacapable for
        stm32f1xx devices. Enhanced stm32_dmacapable for stm32f2xx and
        stm32f4xx devices to check for additional conditions that will cause
        DMA to fail or lose data.
      - STM32 F1 DMA fix from David Sidrane: The DMA_CNDTRx register
        cannot be modified if the DMA channel is disabled.

    * STMicro STM32 Drivers:

      - Fix compilation errors from bad bit definitions in ADC and PWM
        register.  From Martin Lederhilger.
      - DMA-related fixes to the SPI driver from Ken Pettit.

    * NXP LPC17xx Drivers:

      - Remove undefined spi_select() prototype.  This was causing compile
        time warnings.

    * NXP LPC17xx Boards:

      - zkit-arm-1768:  MMC/SD is on SPI, not SSP0.  From Rashid Fatah.

    * C Library

      - scanf() fixes from kfrolov: 1) sscanf() function hangs in the
        following example: sscanf("2", "%u,%u,%u,%u", ...), 2) sscanf()
        returns incorrect number of parsed numbers if some arguments
        can't be parsed: sscanf("=2", "%u,%u,%u,%u",...)==1 instead of
        0, and 3) using of char* instead of const char* in vsscanf
        function leads to warnings from GCC.

    * Build System

      - Dependency generation generation was broken for directories that
        keep objects in a sub-directory.  The MKDEP tools now support a new
        argument that identifies the object file path.
      - tools/define.sh:  'cut' no longer works as it once did.  Script
        adapted to observed behavior.

    * Applications:

      - Remove a warning from the NSH library when DHCP is not enabled.
      - Default NSH IP address should be 0x0a000001 (10.0.0.1), not
        0xa0000001 (160.0.0.1).  Ditto for the gateway.
      - Add some missing options to the OS test Kconfig file
      - Fix some bad conditional compilation in the USB monitor.
      - Fix default I2C frequency used by the I2C tool:  400KHz instead
        of 4MHz.  Suggested by Max Kriegleder.
      - Increase stack size for the system/info command. Ken Petit
        reports that this simple command can exceed its 768 stack size
        under certain conditions.  The size is marginal and has been
        increased to 1024 by default but is also now configurable.
      - apps/Makefile:  Needs to include external/Make.defs if we want
        allow external applications to participate in the NuttX
        configuration.  Suggested by gdi@embedders.org.
      - apps/netutils/telnetd:  Missing argument to debug statement
        can cause crashes in certain error conditions. From David
        Sidrane.
      - apps/examples/can:  Correct an error in a debug statement.  From
        Martin Lederhilger.

NuttX-6.32
----------

The 99th release of NuttX, Version 6.32, was made on December 7, 2013,
and is available for download from the SourceForge website.  Note
that release consists of two tarballs:  nuttx-6.32.tar.gz and
apps-6.32.tar.gz.  Both may be needed (see the top-level nuttx/README.txt
file for build information).

Additional new features and extended functionality:

    * General:

      - Extension and standardization of stack debug logic.  Now includes
        coloration of the IDLE and interrupt stacks as well as the heap.
        Suggested by David Sidrane.

    * Audio Subsystem and Audio Drivers:

      - I2S interface definition.  Integrates with audio sub-system.
      - VS1053 worker thread stack size is now configurable and assigned a
        name via pthread_setname_np(). From Ken Pettit.

    * Networking / Network Drivers

      - Updates and adaptations to support for TI CC3000 wireless module
        from David Sidrane.  These updates include multi-threading support
        and interface and header file changes to integrate more seamlessly
        with NuttX applications.

    * File Systems:

      - procfs:  Add support for a tiny procfs file system.  The initial
        offering is little more that a proof of concept but may be developed
        further in subsequent releases.
      - NXFFS:  An initial attempt was made to integrate NXFFS with the NAND
        MTD driver.  Changes were made to handle bad blocks.  However, I
        later realized that NXFFS cannot handle NAND because the way that
        is re-writes blocks is incompatible with the NAND ECC handling.
        These changes were backed-out so as not to introduce turmoil, but
        can be re-enabled if needed via configuration option.
      - NXFFS: Make the start up scan of the media a configuration option.
        It just takes to long and is not really necessary!  Those rare cases
        where the scan was helpful can be fixed using MDIOC_BULKERASE IOCTL
        command.

    * General Drivers:

      - I2S:  A simple character driver was added to support I2S accesses.
        This driver in its current state is intended only to support I2C
        testing and would not be appropriate to used for any real driver
        application.

    * MTD Drivers

      - Add a container for an MTD device that can be used to provide a
        simple, lightweight interface to configuration data storage that
        resides on some storage media that is wrapped as an MTD device.
        From Ken Pettit.
      - New interface definition for lower half NAND drivers.
      - MTD Nand:  Add MTD NAND driver that will support ONFI devices,
        non-ONFI devices (via table lookup), bad block checking, software
        ECC (Hamming), and will interact with the lower-half, hardware-
        specific, NAND driver.  Based on BSD-compatible Atmel sample code.
      - MTD geometry structure is now packed so that it can support larger
        erase block sizes needed by NAND without increasing the size of
        the geometry structure.
      - SST25:  Add another SST25 SerialFlash driver, sst25xx.c.  This one
        differs from sst25.c in that it supports larger SST25 parts:  In
        the larger parts support page write instead of byte/word writes
        like the smaller parts.  From Ken Pettit.

    * USB Drivers

      - STM32 F1 USB Device: Add support for decoded USB trace strings.
        From David Sidrane.

    * ARM

      - Add more ARM9 cache management functions to flush and invalidate
        D-Cache for DMA support.

    * Atmel AT91 SAMA5D3x Drivers:

      - Many new drivers including CAN, PWM, SSC/I2S
      - PCK:  Add support for programmable clock outputs.
      - NAND: Driver with hardware ECC and DMA support

    * Atmel AT91 SAMA5D3x Boards:

      - SAMA5D3x-EK: Add support for the apps/examples/i2schar test.
      - SAMA5D3x-EK: Provides board-specific memory controller initialize
        for NAND flash.
      - SAMA5D3x-EK: Add support for "auto-mounting" NAND MTD block driver
        or NXFFS file system.

    * Atmel AT91 SAM3/4 Boards:

      - Basic support for the Atmel SAM4E family.  From Mitko.

    * STMicro STM32:

      - Added support for the STM32F429.  From Ken Pettit.
      - Added support for GPIOK and GPIOJ.  From Ken Pettit.

    * STMicro STM32 Drivers

      - STM32 F4 OTG FS/HS Device:  OTG FS device and host drivers extended
        so that they can support either the OTG FS peripheral or the OTG HS
        peripheral (in FS mode).  This was done as a quick way to get USB
        support on the STM32F429 which has only OTG HS.  From Ken Pettit.
      - Added header files and driver framework for the STM32F429 LTDC
        framebuffer driver.  From Ken Pettit.

    * STMicro STM32 Boards:

      - Support for the Spark board was completely by Davide Sidrane.  The
        Spark configuration includes integrated CC3000 wireless support, FAT
        file system on the SerialFlash and a composite device that can be
        used both to export the FAT file system and to provide a serial
        interface.
      - The Mikroe-stm32f4 now uses /dev/config for configuration data
        storage.  From Ken Pettit.
      - Added support for the STM32F429I-Discovery board from Ken Pettit.
      - Added board support for the ViewTool STM32F103/F107 board with the
        STM32F107VCT6 installed.

    * NXP LPC31xx Drivers:

      - USB ECHI HCD:  Add a driver for the low-/full-/high-speed variant
        of the EHCI host controller.

    * NXP LPC31xx Boards:

      - Board-specific USB host support for the Embedded Artists EA3131 board.
        (Missing PCA9532 controls).
      - Add support for the Olimex LPC-H3131 board.  Including USB host
        support (which does not depend on the PCA8532 interface).

    * Kinetis KL Drivers:

      - PWM driver for the Freescale Kinetis KL family from Alan Carvalho
        de Assis.

    * Kinetis KL Boards

      - Freedom-KL25Z:  Add PWM support from Alan Carvalho de Assis.

    * TI Stellaris LM3S

      - Don't initialize .data in start-up logic if not running from FLASH.

    * Applications:

      - apps/platform:  A new home for platform-specific application code.
      - Define a common interface that can be used to manage platform-
        specific configuration data.  From Ken Pettit.
      - apps/examples/configdata:  A unit test for the MTD configuration
        data driver from Ken Pettit.
      - Aapps/platform/mikroe-stm32f4: dd platform-specific storage of
        configuration data for the Mikroe-stm32f4.  From Ken Pettit.
      - apps/examples/cc3000: Fine tuning of memory usage from David Sidrane.
      - apps/system/nxplayer: Play thread stack size is now configurable.
        All NxPlayer threads now have names assigned via pthread_setname_np().
        From Ken Pettit.
      - apps/examples/i2schar:  The I2S test based on the I2S character
        driver.
      - apps/examples/hidkbd/hidkbd_main.c:  Now calls a function named
        arch_usbhost_initialize() that must be provided by the platform-
        specific code.
      - NSH:

          - hexdump:  Add skip= and count= options to the hexdump command.  From Ken Pettit.
          - Allow USB trace without a USB console. From David Sidrane.
          - Mount command updates from Ken Pettit.
          - Add an option to the mkfatfs command to specify FAT12, FAT16, or FAT32.

    * Tools

      - tools/mkctags.sh:  A script for creating ctags from Ken Pettit.

Efforts In Progress.  The following are features that are partially
implemented but present in this release.  They are not likely to be
completed soon.

    * kconfig-fronted Configuration:

      - Conversion of old configurations to use the kconfig-frontends
        tool is an ongoing effort that will continue for some time.
        At this time, only 50% of the configurations have been converted
        to use the kconfig-frontends tools.

Bugfixes (see the ChangeLog for details).  Some of these are very important:

    * File Systems

      - FAT:  In one error return case, the error return value was not being
        set, making the failure look like success. From David Sidrane.
      - mount:  SMART FS must be included in the conditional compilation for
        the set of file systems that require block drivers.  From Daniel
        Palmer.
      - SmartFS: Fixed a minor bug with SMART partition number reporting
        that would only be seen if both partition support and multi-root
        directory support are enabled at the same time.  From Ken Pettit.
      - Deadlock: The inode semaphore must be re-entrant.  Here is the re-
        entrant path that I found:  (1) USB host connects to FLASH drive and
        creates /dev/sda, (2) /dev/sda is mounted, (3) FLASH drive is
        removed but /dev/sda is not destroyed because there is still a
        reference on the device because of the mount, (4) umount() is
        called, taking the inode semaphore, now the driver tries to destroy
        the block driver by calling unregister_blockdriver().  But (5)
        unregister_blockdriver() also takes the inode semaphore causing a
        deadlock if the inode semaphore is not re-entrant.
      - FAT: Fix a typo in the FAT16 formatting logic. Was this ever able to
        format a FAT16 volume?

    * MTD Drivers

      - MTD Partitions:  Fix erase block vs page block confusion. From Ken
        Pettit
      - SST25 Serial Flash:  Improved write performance by fixing a bug that
        prevented operation in the faster write mode.  From David Sidrane.

    * USB Drivers:

      - USB MSC Device:  pthread_join() does not work if called from a
        different task group than the pthread.  This is correct behavior,
        but still a problem.  The correct solution would be configure the
        USB MSC thread to a task, however, this workaround from David
        Sidrane plugs the hole for now.
      - USB CDC/ACM, USB MSC, and Composite Device Classes: Un-initialization
        logic caused re-use of a stale pointer.  Changed to a two pass
        un-initialization for the case of the composite driver:  Memory
        resources are not freed until the second un-initialization pass.
        From David Sidrane.

    * STMicro STM32 Drivers:

      - STM32 F1 USB Device: Fix some errors that cause crashes when the USB
        was disconnected.  From David Sidrane.
      - STM32 F1 USB Device: Correct EP0 state handling logic when buffers
        larger than the EP0 packet size are sent.  From David Sidrane.
      - STM32 F1 USB Device: The long outstanding bug involving the handling
        of OUT SETUP commands has been fixed in the STM32 F1 USB device
        driver by David Sidrane.
      - Kconfig:  Add missing setup of CAN TSEG1 and TSEG2 values.  From
        Martin Lederhilger.

    * Tools

      - tools/mkconfig.c:  SMART FS must be included in the conditional
        compilation for the set of writable file systems.  Noted by Daniel
        Palmer.

    * Applications:

      - apps/platform/Makefile:  Was not dealing with the bin sub-directory
        correctly.
      - apps/system/composite/composite_main.c:  The wrong handle was getting
        nullified.  From David Sidrane.

NuttX-6.33
----------

The 100th release of NuttX, Version 6.33, was made on January 30, 2014,
and is available for download from the SourceForge website.  Note
that release consists of two tarballs:  nuttx-6.33.tar.gz and
apps-6.33.tar.gz.  Both may be needed (see the top-level nuttx/README.txt
file for build information).

Additional new features and extended functionality:

    * Core OS Interfaces

      - nanosleep() added.  sleep() and usleep() are no longer core OS
        interfaces.  These have been moved into the library and re-implemented
        as simple wrappers around nanosleep().

    * File Systems

      - procfs restructured by Ken Pettit.  Added files for MTD status.
      - procfs extended to show uptime and task group status.
      - procfs now shows stack information.

    * Networking

      - Add support for the SO_LINGER socket option.  Extended from logic
        provided by Jason Jiang.  Enabled with  CONFIG_NET_SOLINGER.
      - TCP write buffering support added.  From Jason Jiang.
      - Changes from Max Holtzberg to improve how network status is
        reported.  New controls to manage carrier detect.

    * Graphics

      - Massive reshuffling of files with little or no logic changes.   This
        reshuffling was necessary to build graphics applications with the
        kernel builds where the graphics application lie in user space and
        the core graphic server likes in kernel space.  Moved much logic out
        of nuttx/graphics to a new user library, libnx.

    * Cortex-A5/A8/A9

      - Existing Cortex-A5 support updated to include Cortex-A8/9.
      - Add the syscall.h header file needed for the Cortex-A architecture.
      - Start-up logic now supports execution from FLASH with .data and
        .bss in SDRAM.  This was not possible prior to this because .bss
        and .data were initialized before SDRAM was configured.

    * Allwinner A10:

      - Basic support for the Allwinner A10 (Cortex-A8) is in place.

    * Allwinner A10 boards

      - Support for the pcDuino v1 board has been added.  This support
        is not yet very mature and still lacks many drivers.  It is a
        good starting point, however, if anyone wants to develop A10
        support.

    * Atmel SAMA5D3X

      - Start-up logic now supports execution from FLASH with .data and
        .bss in SDRAM.  This was not possible prior to this because .bss
        and .data were initialized before SDRAM was configured.

    * Atmel SAMA5D3X Boards

      - Partial logic in place to support the OV2640 camera.  Still needs
        quite a bit of additional logic to be useful.

    * ARMv7-M

      - Add support for high priority, nested interrupts. This change
        effects not only core ARMv-7M logic, but all ARMv7-M MCU logic:
        LM3S, LM4F,  LPC17xx, LPC43xx, SAM3, SAM4, and STM32. See
        https://cwiki.apache.org/confluence/display/NUTTX/High+Performance%2C+Zero+Latency+Interrupts

    * STMicro STM32

      - Add clocking support for STM32F107 USB OTG FS (which does not yet
        work)
      - Single-wire UART support for the F1 series from Thomas Grubler.

    * STMicro STM32 Boards

      - The Viewtool board can now be configured to support either the
        STM32F103VCT6 or the STM32F107VCT6.
      - The Viewtool STM32F107VCT6 now supports networking with the
        DP83848C module installed.
      - Add support for Viewtool SSD1289-based LCD on the Viewtool
        STM32F103VCT6 board (untested)
      - Add support for the XPT2046 touchscreen controller on the Viewtool
        LCD module connected to the Viewtool STM32F103 board.
      - Added kernel mode build support for the STM3240G-EVAL board.  Added
        a new kernel mode NxWM build configuration
      - C++ static constructor logic from the nuttx/configs/stm3240g-eval/
        directory to the apps/platform/stm3240g-eval/up_cxxinitialize.c
        where is belongs so that it is available in user-space in the kernel
        mode build.
      - Add native Windows build support for the Olimex STM32 P107.  From
        Max Holtzberg
      - Support for the STM32VL-Discovery board. Contributed by Alan
        Carvalho de Assis
      - Added a configuration for testing simple configurations on the
        PX4FMU v2.

    * ZiLOG ZNEO Boards

      - Add an NSH configuration for the Z16F2800100ZCOG ZNEO board.
      - Added support for the Toyaga 16Z ZNEO board.  The 16Z board is
        based on the ZiLOG ZNEOZ16F2811AL20EG part.  See
        https://github.com/toyaga/16z for further information
      - Developed a patch to work around a compiler error that is revealed
        when building the NSH configuration.

    * Architecture-Independent Drivers

      - OV2640 Camera Driver.
      - Support for the Sharp Memory LCD from Librae.

    * Library

      - Pattern matching logic extended to handle set of characters and
        ranges of character values.  From Ken Pettit.
      - sleep() and usleep() moved into the C library.  These are not
        longer core OS interfaces; they are simple wrappers for the
        nanosleep().
      - Add an implementation of gets_s().
      - Extend fopen() to include support for C11 exclusive open ("x")
        open mode.
      - Add an implementation of stpcpy()
      - strtol(), strtoll, strtoul(), strtoull(), and strtod() from
        libc/string to libc/stdlib where they belong.

    * Header Files

      - Add rsize_t to include/sys/types.h
      - Add the C11 thread.h header file

    * Configuration/Build System

      - Top level Makefile now supports qconfig and/or gconfig targets that
        may be used for configuration.  These may be used if you build
        kconfig-frontends with support for kconfig-qconf and/or
        kconfig-gconf.
      - Add CONFIG_DEBUG_NOOPT.  Now you can independently enable/disable
        debug symbols and optimization
      - File system related header files moved to include/nuttx/fs
      - Video related header files moved to include/nuttx/video
      - Changes for native Windows build: fix creation of a .version file
        if one does not exist.  Make sure that the APPDIR environment
        variable is set before configuring.  From Max Holtzberg.
      - Board configuration sub-directory can now be specified.  The default
        need not be used.  This is  only useful when CONFIG_ARCH_BOARD_CUSTOM
        is selected and there is no meaningful default sub-directory.
      - Many functions renamed to better conform with the naming standard:
        up_buttoninit() renamed to board_button_initialize(), up_buttons()
        renamed to board_buttons(), up_irqbutton() renamed to
        board_button_irq(), up_ledinit() renamed to board_led_initialize(),
        up_ledon() renamed to board_led_on(), and up_ledoff() renamed to
        board_led_off(). All prototypes removed from board.h header files.
        Now ONLY prototypes in include/nuttx/arch.h.

    * Applications

      - NSH: Refactor. Separate NSH command handling and command execution
        from NSH line parsing.
      - NSH: Will now support multiple commands on a command line, each
        separated with a semi-colon.
      - NSH: Add support of commands enclosed in back quotes as command
        arguments.
      - NSH: Can now handle arguments that are concatenations of constant
        strings, command return data, application return data, and
        environment variables.
      - NSH: Add true and false commands.
      - NSH: Add support for while-do-done and until-do-done loops.  These
        only work when executing a script file because they depend on the
        ability to seek in the file to implement the looping behaviors.
        Can be conditionally compiled out to reduce footprint.
      - NSH: Loosen up if-then-else-fi syntax to allow a command to be on
        the same line as the then or else tokens like:
        "if true; then echo true; else echo false; fi".  More like bash.
      - NSH: Add a break command that can be executed with a loop to
        terminate the loop immediately.

      - system/inifile:  A simple .INI file parser.
      - system/vi:  Add support for a tiny, VI work-alike editor.  This is
        a minimal full screen editor that works with a terminal emulator
        that using VT100 commands.

Efforts In Progress.  The following are features that are partially
implemented but present in this release.  They are not likely to be
completed soon.

    * kconfig-fronted Configuration:

      - Conversion of old configurations to use the kconfig-frontends
        tool is an ongoing effort that will continue for some time.
        At this time, only 53% of the configurations have been converted
        to use the kconfig-frontends tools.

Bugfixes (see the ChangeLog for details).  Some of these are very important:

    * Core OS

      - Added missing sem_timedwait() system call.

    * Networking

      - Prevent tcp_connect callback from being double freed.  From Max
        Holtzberg
      - uiplib:  Support new definitions and state passing for network
        device status. From Maz Holtzberg.

    * File Systems

      - FAT:  (1) A correction to FAT cluster allocation, and (2) Fix to some
        root directory logic that was conditionally done only for FAT 32.
        Apparently this needs to done for all FAT types.  Both from Andrew
        "Tridge" Tridgell via Lorenz Meier.

    * Binary Formats

      - Fix a small memory leak when attempting to load a program from a file.

    * Cortex-A8/9

      - Fix some errors in the cache invalidation logic (only seem to matter
        for Cortex-A8).
      - Add more nop's after enabling the MMU.  The cortex-a8 seems to need
        these

    * Graphics

      - Fix a typo that caused a compilation error when
        CONFIG_NXCONSOLE_BPP < 8.  From Librae

    * ARMv7-M

      - Correct alignment of RAM vector table.
      - Interrupt handling: Do not disable and enable the IRQ on each
        entry, (2) this interferes with controlling the IRQ interrupt
        setting from interrupt handlers, and (3) up_disable_irq() does
        not work anyway so that this has never done anything.
      - Fix all implementations of up_disable_irq() for all Cortex-M3 and
        M4 architectures:  To enable an interrupt on the Cortex-M3/4 CPU,
        you need to set a bit in the ISER register.  To disable the
        interrupt, you need to set a bit in the ICER register.  Existing
        logic was trying to disable interrupts by clearing the bit in the
        ISER register.  That will not work; writing a '0' to the ISER
        register has no effect.  That  means that up_disable_irq() was
        doing nothing!  It turns out that that is not really important
        because up_disable_irq() is not really used for that purpose.  But
        some spurions STM32 ADC interrupts have been reported to me and this
        turned out to be the cause in that case.  Thanks to Manuel Stühn for
        the tip.

    * STMicro STM32

      - Fix configuration and pin definitions that would prevent building
        USB for the connectivity and performance lines.
      - STM32L15xx: Fix a typo in USB pin definitions
      - Fix pin definition names for SPI2 MOSI and MISO. Noted by Brian Webb
      - Various fixes for STM32F103ZE SPI3 pin mapping definitions.  From
        Steve Redler IV

    * STMicro STM32 Boards

      - Olimex STM32-P107:  Failed to build if SPI3 for UEXT is not remapped.
        From Max Holtzberg

    * x86 Boards

      - Add a configuration option to select the -m32 compiler option when
        building for a 32-bit target on a native 64-bit compiler.  So far,
        only used for the qemu/i486 configuration.
      - Patch from Matt Campbell to fix 'Error: .size expression for idle_stack
        does not evaluate to a constant".

    * Library

      - strftime(): Needs null termination on the generated string.  From
        Max Holtzberg.
      - Typo in ctype.h macro name: iscntrl(), not iscontrol().
      - If there are no arguments (argc == 1), then getopt() will leave the
        optind variable in an undefined state (2014-1-20).
      - ARMv7-M memcpy(): Assembler changes with the gcc-47 distribution
        from ARM mean that we need to be explicit about branch sizes; one
        or more of the wide branch opcodes results in bad table branching.
        From Mike Smith.

    * Configuration/Build System

      - Fixes for some tools/ for Windows build issues from Max Holtzberg.
      - Config.mk: 'cypath' must be called if we are using a Windows native
        toolchain with the Cygwin 'make' to convert paths to proper
        Windows paths.  From Richard Cochran.
      - ARM Makefile: Dependency directory list is now computed from the
        VPATH.  From Richard Cochran.
      - builtin/Makefile: Fixes for native Windows build from Max Holtzberg.
      - Refactor some configuration dependencies:  NSH networking features
        should depend on netutil selections; netutil selections, in turn,
        should depend on networking selections.

    * Applications

      - NSH: Modified the df -h logic to eliminate truncating numbers in
        conversion (like 7900 -> 7M).  From Ken Pettit.

NuttX-7.1
---------

The 101st release of NuttX, Version 7.1, was made on March 15, 2014,
and is available for download from the SourceForge website.  Note
that release consists of two tarballs:  nuttx-7.1.tar.gz and
apps-7.1.tar.gz.  Both may be needed (see the top-level nuttx/README.txt
file for build information).

  The previous NuttX version was 6.33.  The NuttX minor version number is
  incremented on each release, but the major version number is incremented
  only when an incompatibility with previous versions is included in the
  release.  In this case, the legacy, manual configuration is no longer
  supported by the NuttX build system beginning with NuttX 7.1.  Only the
  newer configurations generated by the kconfig-frontends tools will generate
  viable NuttX configurations.

  All board configurations in the NuttX source tree have been converted to
  use the newer configuration, but if you have some older style configurations
  for you board, you will need to convert those configurations to use the
  kconfig-frontends tools before taking any new code from the repository. See
  https://cwiki.apache.org/confluence/display/NUTTX/Converting+Legacy+Configurations+to+Use+kconfig-mconf
  for some guidelines.

Additional new features and extended functionality:

    * Core OS:

      - System time logic now includes logic to measure and calculate the
        CPU load percentage (from David Alessio).  This CPU load logic
        extended to keep counts on each thread.  The per-thread CPU is
        now reported in the procfs under <pid>/loadavg  An asynchronous,
        "external" clock may be used to drive the CPU load calculations
        for more accurate measurements when needed.

    * File Systems:

      - As mentioned above, the per-thread CPU load information is now
        reported in the procfs under <pid>/loadavg.
      - Many file system interfaces have been extended to operate on the
        top-level NuttX pseudo filesystem.  These include rmdir, mkdir,
        rename, and unlink.  This capability can be disabled with
        CONFIG_DISABLE_PSEUDOFS_OPERATIONS in order to keep the footprint
        small.

    * Networking:

      - Numerous updates and improvements to the CC3000 driver from David
        Sidrane.

    * Common Drivers:

      - Defined a mouse interface that is very similar to a touchscreen
        interface, but allows reporting of all mouse buttons.  Also, unlike
        touchscreen drivers, mouse drivers need to report positional data
        with no button is pressed so that the mouse position can drive a
        cursor.
      - Added support for a USB HID boot mouse device.  Cursor support is
        not integrated and must be provided by the application based upon
        the reported mouse data.
      - Support added for the MIO283QT9A LCD from Toby Duckworth.

    * Atmel SAMA4E:

      - Added complete architecture support for the Atmel AT91 SAM4E
        Cortex-M4F parts.

    * Atmel SAM4E Board Support:

      - Add board support for the SAM4E-EK board.

    * Atmel SAM4E Drivers:

      - Added logic to manage the Cortex-M Cache Control block.
      - Developed and integrated an Ethernet MAC driver for the SAM4E.
      - Backported the SAMA5 SPI driver to the SAM3/4 architecture.  The
        SAMA5 version supports both multiple SPI peripherals as needed by the
        SAM3A and SAM3X and also supports DMAC (but not PDC) needed by the
        SAM4E.

    * Atmel SAM D20:

      - Added basic architecture support for the Atmel AT91 SAM D20
        Cortex-M0+ parts.

    * Atmel SAM D20 Board Support:

      - Added basic support for SAM D2 Xplained Pro board.  Currently, the
        NuttShell (NSH) works reliably over a serial port.  An SPI driver
        has also been developed.  Work with the SAM D20 has been temporarily
        stopped, however, in order to focus on the SAM4E-EK.

    * TI Tiva TMC4C123G:

      - Added architecture support for the TI Tiva TM4C123G parts.  This was
        merged into the existing support for the LM3S and LM4F families.
        All directory, file, and function references changed from lm to tiva.

    * TI Tiva TMC4C123G Board Support:

      - Added basic board support for the TM4C123G-Launchpad.  As of this
        release the TM4C123G-Launchpad board support is untested and likely
        incomplete.

    * STMicro STM32 Boards:

      - The Mikroe STM32F4 can now support the newer MIO283QT9A LCD. From
        Toby Duckworth.
      - Miscellaneous changes to better support FPU on STM32F429 Discovery
        from David Alessio.

    * NXP LPC2378 Drivers:

      - Incorporated I2C and SPI drivers for the LPC23xx from Lizhuoyi.

    * QEMU i486 Drivers:

      - New QEMU keyboard and VGA drivers from Lizhuoyi.

    * Documentation:

      - Added a coding standards document.  See
        https://nuttx.apache.org/docs/latest/contributing/coding_style.html

    * Configuration/Build System:

      - A configuration option, CONFIG_DEFAULT_SMALL, was added to select
        default values for configuration variables based upon whether you
        want a smaller footprint or more features.  This is not very useful
        if you are modifying existing configurations because then the
        default values do not apply.
      - CONFIG_DEFAULT_SMALL has been defined on all tiny MCU configurations
        so that they do not grow so rapidly when new, optional features are
        added.
      - The legacy, manual configuration is no longer supported by the
        NuttX build system.  Only the newer configurations generated by
        the kconfig-frontends tools will generate viable NuttX
        configurations.  All board configurations in the NuttX source tree
        have been converted to use the newer configuration, but if you have
        some older style configurations for you board, you will need to
        convert those configurations to use the kconfig-frontends tools. See
        https://cwiki.apache.org/confluence/display/NUTTX/Converting+Legacy+Configurations+to+Use+kconfig-mconf
        for some guidelines.

    * Applications:

      - NSH can now use an EMACS-like command line editor.  This CLE, is
        really more like the traditional readline than is the default, tiny
        the NuttX readline .
      - The touchscreen example can now be configured to work with either a
        touchscreen or a mouse device.
      - Several NSH commands can now be used to operate on objects in the
        top-level pseudo-filesystem: rmdir, mkdir, mv, and rm.  This
        capability can be disabled with CONFIG_DISABLE_PSEUDOFS_OPERATIONS
        in order to keep the footprint small.
      - If both the CPU load feature and the procfs features are enabled,
        then the NSH 'ps' command will show the CPU load used by each
        thread.

Bugfixes (see the ChangeLog for details).  Some of these are very important:

    * Core OS:

      - task_terminate()  always returned an error because the return value
        was not being set correctly (from Gosha).
      - nanosleep()  Fix a missing call to re-enable interrupts (from Jason
        Jiang).

    * File Systems:

      - Fixed an error in the FAT logic that can cause file corruption.  The
        error conditions are rare and only seen with very large files (from
        Andrew Tridgell).  This replaces a previous, partial fix for the same
        problem.
      - Fixed memory leaks in the NXFFS open() and stat() implementations
        (from Lzyy).
      - The interfaces include opendir(), readdir(), et al, were modified so
        that errors will not be reported if you attempt to list a empty
        pseudo-directory.

    * Networking:

      - Fix one place where the connection reference count was not being
        decremented in the socket close() logic.  This is really a cosmetic
        change BUT when CONFIG_DEBUG_NET is enabled, it will cause assertions.
      - Backed out a small part of the NuttX 6.33 write buffering changed.
        David G says that this causes problems in connecting to a server.
      - In DHCPD, there was a place where the logic was calling ntohl()
        inappropriately; the address was already in the correct order.  How
        could DHCPD have worked with this bug?

    * TI Tiva/Stellaris Drivers:

      - Fixed cut'n'paste error that prevented UARTS2-7 from being used with
        the LM4F120 Launchpad.
      - Fixed several errors there were unmasked with UARTs > UART2 are
        enabled (grom Gosha).

    * Allwinner A10 Drivers:

      - Fixed cut'n'paste error that prevented UARTS2-7 from being used with
        the pcDuino.

    * NXP LPC17xx Drivers:

      - Fix an compilation error that crept into the LPC17xx USB host driver.

    * STMicro STM32 Drivers:

      - Fix cloned typo in the serial driver:  FLOWCONTROL vs FLOWCONROL.
      - Disable SPI before changing DPI CR1 register (from David Sidrane).
      - stm32 TIM: Set the timer CCMR when selecting timer channel.  From
        David Sidrane.
      - Fix typo in a Makefile: stm32_pwm.c not stm32_psm.c.  Noted by Max
        Kriegleder.

    * Library:

      - More sscanf()  bug fixes from David Sidrane.

    * Header files:

      - cstdbool:  Ignore _Bool8 if CONFIG_C99_BOOL8=y

    * Configuration/Build System:

      - Several changes to restore the broken native Windows build

    * NuttShell (NSH):

      - Use strncpy vs strcpy in the Telnet console logic to avoid
        overrunning the username and password buffers (from Bertold Van den
        Bergh).
      - Add a newline after printing the file in the 'cat' command.  This
        prevents the NSH prompt from be in the same line as the final line
        of the file in the case where there is no newline at the end of the
        file.

NuttX-7.2
---------

The 102nd release of NuttX, Version 7.2, was made on April 29, 2014,
and is available for download from the SourceForge website.  Note
that release consists of two tarballs:  nuttx-7.2.tar.gz and
apps-7.2.tar.gz.  Both may be needed (see the top-level nuttx/README.txt
file for build information).

Additional new features and extended functionality:

    * Core OS:

      - Add support for CLOCK_REALTIME.  From Macs N.

    * Network Utilities:

      - Add a very primitive NTP client.
      - DNS resolver:  Long needed major clean up for coding style and
        unification of naming conventions (resolv vs dns).

    * Common Drivers:

      - Add a new MTD driver that can be used to contain another driver and
        force its apparent sector size to be 512 bytes.
      - If DCD can support queuing of stall requests, then the USB MSC stall
        work around delays are not necessary.
      - Redesign threading module used with the USB MSC driver.  It was using
        pthreads before and these were changed to a kernel thread.  The reason
        for this has to do with task grouping:  A pthread is a memory of the
        group of the task that started it.  A kernel thread is independent of
        the task that started in (other than knowing it as the parent).  This
        allows me to remove so kludge logic to "deparent" the pthread on
        startup.
      - Update the MIO183QT-9A LCD driver to support reading from the LCD.
        From Toby Duckworth.
      - Timer "upper half" driver and l"lower half" interface definition from
        Bob Doiron.

    * Atmel SAM4E/4S Board Support:

      - All SAM4E configurations updated to run with 120MHz CPU speed and
        with the CMCC enabled.
      - Support for the SAM4S Xplained Pro board from Bob Doiron.
      - Add watchdog driver.  From Bob Doiron.

    * Atmel SAM4E/4S Drivers:

      - Add a USB full speed device driver (UDP) for the SAM4E.
      - Add support in HSMCI and SPI drivers to invalidate cached memory if
        the CMCC is enabled.
      - Add logic to handle SPI word widths > 8
      - Port RTC driver from SAMA5 to SAM3/4.  From Bob Doiron.
      - HSMCI:  Extensions from Bob Doiron needed to support PDC-based HSMCI
        DMA transfers.  Verified on the SAM4S Xplained Pro.

    * Atmel SAMA5:

      - Add support for the SAMA5D36 chip.
      - Add functions to calculate PLLACK, PCK, and MCK frequencies given
        the main clock frequency.
      - Implemented RAM functions.  When booting directly into NOR flash,
        reconfiguring the PLL while executing out of NOR FLASH causes
        crashes.  This was fixed by David Sidrane by implementing RAM
        functions. The killer code is copied and executed from ISRAM and
        the crash is avoided.

    * Atmel SAMA5 Drivers:

      - Add support for the SAMA5D3 DBGU.

    * Atmel SAMA5 Board Support:

      - Add a board support configuration for the Atmel SAMA5D3 Xplained
        board running out of SDRAM.  When booting from SDRAM, start-up logic
        needd to query the PMC registers to determine the MCK, PCK, etc.
      - For all SAMA5 boards, added support for 528MHz clocking.

    * TI Tiva/Stellaris:

      - Modify the logic to disables the interrupts and sets the default
        interrupt priority so that it uses the ICTR to get the number of
        interrupt lines/registers.  This is instead of using some fixed
        number of initializations based a priori knowledge of the number
        of interrupt lines in the MCU.

    * STMicro STM32

      - Add support for the STM401RE.  From Frank Bennett.

    * STMicro STM32 Boards:

      - STM32F4Discovery:  Add support to register keyboard and mouse
        classes if so configured.  From Leo.
      - Add support for the Nucleo-F401RE board.  From Frank Bennett.

    * STMicro STM32 Drivers:

      - Add STM32 Ethernet IGMP hashing support.  From Manuel Stühn.
      - OTG FS Host:  USB host tracing added by Leo.

    * Freescale Kinetis

      - Modify the logic to disables the interrupts and sets the default
        interrupt priority so that it uses the ICTR to get the number of
        interrupt lines/registers.  This is instead of using some fixed
        number of initializations based a priori knowledge of the number
        of interrupt lines in the MCU.

    * NXP LPC17xx

      - Modify the logic to disables the interrupts and sets the default
        interrupt priority so that it uses the ICTR to get the number of
        interrupt lines/registers.  This is instead of using some fixed
        number of initializations based a priori knowledge of the number
        of interrupt lines in the MCU.

    * ZiLOG ZNEO Drivers

      - Added ZNEO ESPI driver.

    * Library:

      - Finish incomplete support for ferror().  From Macs N.

    * Documentation:

      - UsbTrace.html:  Add some discussion of the USB monitor.

    * Configuration/Build System:

      - compiler.h:  Add macro UNUSED() that can be used to eliminate
        warnings about variables that are set to values that are not
        used.

    * Debugging Support:

      - Add a configuration option to enable dumping of the USB trace buffer
        on assertion.

    * Applications:

      - IGMP Example:  Fill out Kconfig file; update makefile so that the
        IGMP example can be used as an NSH built-in application. From Manuel
        Stühn.
      - lcdrw Example:  Fill out empty Kconfig file.
      - touchscreen Example:  Add a configuration option to indicate if
        architecture-specific initialized is required, yes or no.
      - System usbmsc:  Back out the USBMSC daemon... it is no longer needed
        with the recent fix to the USBMSC class driver.
      - NSH: malloc/free IOBUFFER for 'cat' and 'hexdump' commands instead of
        using the stack.  From Bob Doiron.
      - cpuhog, serialblaster, and serialrx Examples:  Stress test examples
        added by Bob Doiron.

Bugfixes (see the ChangeLog for details).  Some of these are very important:

    * Core OS:

      - errno_get_errno_ptr() and getpid():  Add some checks.  If these
        functions are called very early in initialization before the tasking
        structures are initialized, they would not behave properly.

    * Networking:

      - IGMP-related bug fixes from Manuel Stühn.
      - In netdev_findbyaddr(), skip network devices that are in the "down"
        state.  It does not make sense to consider an address match with a
        "down" device.  From Brennan Ashton.

    * Network Utilities:

      - DHCPD:  The correct value of the PAD option.  Should be zero, not
        one.  From Brennan Ashton.
      - Corrections to the NTP client from Manuel Stuehn.

    * Common Drivers:

      - usbhost.h:  Fix some USB HID-related conditional compilation.  From Leo.
      - USB HID mouse driver: Don't include NAKs from the device in the error
        count.  From Leo.

    * TI Tiva/Stellaris:

      - Add corrected control logic for TM4C125GXL based on logic from Daniel
        Carvalho with modifications.  The LM4F120 also works well with this
        change.

    * STMicro STM32 Drivers:

      - STM32 F2 SPI:  Correct a mapping for SPI MOSI pin.  From dlsitzer.
      - OTG FS Host:  Fixes related to low-speed devices and interrupt
        endpoints from Leo.  Necessary in order to use a USB HID mouse
        device.
      - STM32 SDIO:  The dmaflight method must be conditioned on
        CONFIG_SDIO_PREFLIGHT.  Noted by Pelle Windestam.
      - Sourceforge Ticket #26.  up_prioritize_irq should not be called
        if CONFIG_ARCH_IRQPRIO is not defined.

    * Atmel SAM3/4:

      - Fix some backward conditional compilation in the start-up logic.
      - Fix initialization of the default interrupt priorities.  This is
        a critical bug fix!
      - SAM4S: Fix error in macros that disable peripheral clocking.  From
        Bob Doiron.

    * Atmel SAMA5:

      - Fix double mapping of SDRAM when executing out of SDRAM.  In this
        case, the SDRAM was already mapping in arm_head.S.
      - In clock configuration, the BMS bit handling was fixed to match
        what the HW really does.  From David Sidrane.
      - TLB Bufferable bit did not do what I thought it was going to do.
        I though I was selecting a write-through cache, but the result was
        that all caching was disabled and NOR FLASH accesses were very slow.
      - Move the un-definitions of __ramfuncs__ from the clock configuration
        .c file to the .h file.  Otherwise, the attribute will be applied
        differently for the prototype and the function definition.
        Sourceforge patch 38 from Luciano Neri.

    * Atmel SAMA5 Drivers:

      - Fix a case in the UDPHS driver where received status was not being
        cleared, causing OUT SETUP commands to fail.
      - TWI data sending fails to increment the number of bytes transferred
        on first byte sent.  from David Sidrane.
      - If running from SDRAM, then BOARD_MCK_FREQUENCY is not a constant
        and cannot be used in conditional compilation.  All drivers fixed
        EXCEPT for the PWM and Timer/Counter drivers which will need some
        more extensive redesign.

    * Atmel SAMA5 Boards:

      - SAMA5D3x-EK: The red LED is controlled by PE24 which is also the
        camera/ISI interface reset line.  So if the a camera is installed,
        then we must avoid controlling the red LED or we inadvertently
        also reset the camera module.  Noted by David Sidrane.
      - Header files reference type xcpt_t in certain configurations and
        so must include nuttx/irq.h.  This is Sourceforge bug 25 submitted
        by Luciano Neri.

    * NXP LPC17xx Drivers

      - arm/src/lpc17xx/Kconfig and lpc17_ethernet.c:  The default interrupt
         priority should be default, not the highest priority (2014-4-19).

    * ZiLOG ZNEO

      - Fix calculation of timer reload and prescaler.  The timer frequency
        was way too fast.

    * Library:

      - strncpy():  Change ordering of test and copy.  Logic would have
        failed if n=0; one byte was always copying before testing
        for the end of the copy.
      - Fix a counting error in the return value from sscanf().  Noted by
        kfrolov.  Also, sscanf() should return EOF if no values were
        converted.
      - Fix a logic error in ftell().  It was simply using the file offset
        and did not take into account data buffered in memory.  From Macs N.
      - sccanf():  Use stroul() vs strol() with %u format otherwise, range
        of values is restricted because of sign bit. From kfrolov.

    * Configuration/Build System:

      - Fix a build error that occurs when only USB device tracing is enabled.

    * NuttShell (NSH):

      - Fix NuttShell version number display in the NSH welcome message.
        version.h was not being included.

    * Other Applications:

      - sysinfo:  CONFIG_VERSION_BUILD is a string an needs to be
        printed with %s, not %d.  Noted by Librae.
      - nxplayer:  Compilation failure in one configuration reported by
        Manuel Stuhn.
      - System sdcard:  Remove an STM32 dependency.  From Bob Doiron.
      - telnetd Example:  Naming is confused.  In someplaces 'telnetd',
        and in others 'shell.'  All changes to telnetd.  Noted by Pelle
        Windestam.

NuttX-7.3
---------

The 103rd release of NuttX, Version 7.3, was made on June 25, 2014,
and is available for download from the SourceForge website.  Note
that release consists of two tarballs:  nuttx-7.3.tar.gz and
apps-7.3.tar.gz.  Both may be needed (see the top-level nuttx/README.txt
file for build information).

Additional new features and extended functionality:

    * Core OS:

      - Dynamic loader: Framework to support Pascal P-Code as a binary
        format that can be exec'ed from a file system.
      - Dynamic Loader:  Extend the binfmt interface to handle error
        conditions where format-specific clean-up is needed in the event
        of error conditions.  This is needed by the P-Code binfmt.

    * Networking

      - IOB:  Add a generic I/O buffer chain logic.  This logic uses small,
        pre-allocated buffers that can be chained together to support
        transfers of any size, using fewer resources and also without
        committing in advance to a TCP window size.  There is now only
        one I/O type used in the networking and it is these I/O buffer
        chains.
      - TCP Write Buffering:  TCP write buffering logic converted to use
        I/O buffer chains.
      - TCP Read-Ahead Buffering:  TCP read-ahead buffering logic converted
        to use I/O buffer chains.
      - Includes logic to support throttling of read-ahead buffering if
        the read-ahead buffering is competing with write buffering for
        I/O buffers.
      - Raw Sockets:  Add support for the AF_PACKET socket family.  From
        Daniel Lazlo Sitzer.

    * Common Drivers:

      - W25 Serial FLASH driver extended by Mark Whitehorn to support the
        8Mbit W25Q80BV part.
      - Add support for Fujitsu MB85RS1MT RAMTRON part.  From Charles Ash.
      - Enhancements to the generic timer interface to support capture mode
        from Bob Doiron.
      - Add an rxflowcontrol method to the serial interface to better
        support RX flow control. This involves common changes in addition to minor updates to all MCU-specific serial drivers (only fully implemented for the STM32). From Jussi Kivilinna.

    * Atmel SAM4C

      - Add support for the SAM4CM family.  From Max Neklyudov.

    * Atmel SAM4E/4S Drivers:

      - RTT driver from Bob Doiron.  Also added high resolution RTC
        emulation using the RTT for the sub-second counter.

    * Atmel SAM4E/4S Board Support:

      - The SAM4S Xplained Pro now uses the extended timer/counter
        features. From Bob Doiron.
      - Added a touchscreen and LCD driver for the SAM4E-EK board (the LCD,
        however, not yet fully functional).

    * Atmel SAMA5:

      - Optimized, high performance, assembly language memcpy().  This is
        the same optimized memcpy() function that Mike Smith brought in
        for the ARMv7-M with minor tweaks by David Sidrane to work with
        the ARMv7-A.
      - Basic support added for the SAMA5D4 family.

    * Atmel SAMA5 Drivers:

      - SAMA5D4:  New drivers unique to the SAMA5D4: XDMAC, SAIC, and
        others.

    * Atmel SAMA5 Board Support:

      - SAMA5D4-MB:  Initial board support for the SAMA5D4-MB/EK boards.

    * STMicro STM32

      - Add support for the STM32152 and STM32162 Medium+ density parts
        (plus miscellaneous other improvements to the original STM32151
        logic).  From Jussi Kivilinna and Sami Pelkonen.

    * STMicro STM32 Boards:

      - Support for the Olimex STM32 H405 board contributed by Martin
        Lederhilger.

    * STMicro STM32 Drivers:

      - Implement the rxflowcontrol method to the serial interface to better
        support RX flow control. From Jussi Kivilinna.

    * NXP LPC17xx Drivers:

      - Added support for the RTC, ADC, DAC, Timers, PWM and MCPWM
        drivers.  From Max (himax).

    * NXP LPC17xx Boards:

      - Support for the RTC, ADC, DAC, Timers, PWM and MCPWM integrated
        in the LPCXpresso LPC1768 board support.  From Max (himax).

    * Library:

      - Add support for seek-able streams.

    * Configuration/Build System:

      - Restructured network directories, header files, and naming to
        better modularize the networking and to better integrate the
        networking with the rest of NuttX.

    * Applications:

      - prun:  An NSH built-in application that can be used to run
        Pascal P-Code programs either programmatically or from the NSH
        command line.
      - netpkt:  A "raw" socket test from Lazlo Sitzer.
      - hex2bin:  A library and built-in task to convert from
        Intel HEX to binary format.  It can write the binary data to a file or it can store the binary data to memory (to support, for example, a loader).

Bugfixes.  Only the most critical bugfixes are listed here (see the ChangeLog for the complete list of bugfixes and for additional, more detailed bugfix information):

    * Core OS:

      - Dynamic Loader: Fix an error in a symbol table search function.
        Noted by Pelle Windestam.
      - Dynamic Loader:  Fix a critical error in exec(); argv was not
        being passed.
      - mq_notify:  Test for a valid signal number was inverted; this
        function could not have been working correctly before???  From
        eero.nurkkala.
      - Fix typo in conditional compilation:  CONFIG_CLOCK_MONOTONIC vs.
        CLOCK_MONOTONIC.  From Manuel Stühn.

    * Graphics

      - Fix typos in several RGB conversion macros.

    * Networking:

      - Modify TCP timeout handling to provent situations where connections
        may not be freed. From Max Holtzberg.
      - Improved TCP fallback allocation logic from Max Holtzberg. Also,
        fallback mechanism is disabled when SO_LINGER is to prevent
        deadlocks.
      - Write Buffering:  Add checks from buffer allocation failures. From
        Max/Himax.

    * Network Utilities:

      - webserver: httpd_fs_open() should return OK on success and ERROR on
        failure, not 1 and 0.

    * Common Drivers:

      - Make sure that all references to up_prioritize_irq() are
        conditioned on CONFIG_ARCH_IRQPRIO.  Problem noted by Mike Smith.
      - CC3000: Correct SPI mode for CC3000 is CPOL=0 CHPA=1. From Jussi
        Kivilinna.
      - CC3000: Fix a race condition in thread start-up logic. From Jussi
        Kivilinna.
      - CC3000: Additional fixes including a compilation failure if POLL is
        enabled. From Jussi Kivilinna.

    * USB Drivers:

      - CDC/ACM and PL2303 device:  Reset RX head to avoid resending last
        serial data when USB cable disconnected/re-connected.  From
        Lizhuoyi.

    * TI Tiva/Stellaris Boards:

      - The Nucleo-F401RE has no on-board crystals and, hence, needs to run
        with the PLL input from the on-chip HSI clock.

    * STMicro STM32 Drivers:

      - Serial:  Handle configuration for the case of 8-bit data with
        parity.  From Freddie Chopin.

    * Atmel SAM3/4 Boards:

      - There was a cloned error in all SAM3/4 board configurations (and
        for a few other architectures as well).  Button interrupts not
        being disabled after being detached.  As a result, unexpected
        interrupts could be received after the button interrupt was
        detached.

    * Atmel SAMA5:

      - Fix some critical typos in the SAMA5D3 DMA definitions.

    * STMicro STM32 Drivers

      - I2C: Add an alternative I2C implementation for the STM32 F103 that
        works around errata in that specific part.  From Patrizio Simona.
      - RTCC:  Add retry logic to RTC initialization. It sometimes takes
        longer for the RTC to initialize, at least as noted on an F2 part.
        From Daniel Lazlo Sitzer.

    * NXP LPC17xx Drivers

      - GPDMA:  Fix an error when DMA is started:  The read-modify-write
        fails when the DMA is started.  This is because the value read is
        not the same as the value set (on write it is the number of
        transfers to do; on read it is the number of transfers completed).
        From Lizhuoyi.

    * Library:

      - snprintf():  If the size passed to snprintf() is zero, then
        snprintf() must write nothing, but instead return the size of the
        buffer needed to hold the entire string.  From Sami Pelkonen.

    * Configuration/Build System:

      - The alternate console device CONFIG_NSH_CONDEV must not be defined
        unconditionally. This causes errors when using Telnet sessions.
        This was solved by adding CONFIG_NSH_ALTCONDEV: CONFIG_NSH_ALTCONDEV enables or disables the feature then, if
        enabled, CONFIG_NSH_CONDEV provides the alternative console
        device name.
      - Many files: Convert all old-style GCC variadic macros to the C99
        form.  Recent GCC changes tightens up that behavior and can cause
        some problems (at least for the IAR compiler for some reason).
        Noted by Bob Grimes.
      - tools/configure.sh:  In-place SED edit messes up permissions on
        windows. From Hannes Delago.

    * Build Tools:

      - tools/mkfsdata.pl:  Apparently, the trailing the 0x00 in http
        server files is seen as a bug in javascript and images.  From
        Max/Himax.

    * Other Applications:

      - I2C Tool:  Fix to show the updated register address on each
        fetch (vs. showing the same starting address each time).  From
        Ryan VanSickle.
      - CLE was not returning the terminating newline character. But
        reported by Max kriegleder.

NuttX-7.4
---------

The 104th release of NuttX, Version 7.4, was made on August 15, 2014,
and is available for download from the SourceForge website.  Note
that release consists of two tarballs:  nuttx-7.4.tar.gz and
apps-7.4.tar.gz.  Both may be needed (see the top-level nuttx/README.txt
file for build information).

Additional new features and extended functionality:

    * Core OS:

      - Beginnings of a crypto/ subsystem from Max Neklyudov
      - Tickless operation:  NuttX now supports a mode with no periodic
        timer interrupts.  Rather, timed events are handle via an interval
        timer.  This (1) lowers the rate of interrupt processing to timer
        events, (2) gives much high timing resolution, and (3) allows lower
        power modes of operation where the CPU is not constantly being
        interrupted by the timer.
      - Restructured the OS files under sched/ to better support the already
        modular nature of the RTOS.

    * Networking

      - Substantial directory and header file reorganization and renaming to
        make the NuttX networking implementation more modular.
      - Add network device ioctl to access PHY registers. From Daniel Lazlo
        Sitzer

    * Binary Loader:

      - Various changes associated with symbol tables from Pelle Windestam.

    * Graphics:

      - colorcmp(): New utility to compare two colors.
      - The initial background color is now configurable.  Includes logic to
        eliminates multiple background updates to get the right color.
      - Minor configuration changes to handle mouse X/Y and touchscreen
        X/Y differently.

    * File System/Block Drivers:

      - SmartFS: Increase some variables from uint16_t to uint32_t to handle
        larger device sizes.  From Ken Pettit.
      - Add configurable AES encryption support to the block-to-character
        (BCH) driver.  This allows any block device to be accessed as an
        encrypted character device.  From  Max Nekludov
      - Add an MTD layer that will add read-ahead or write buffering to any
        MTD driver (incomplete).
      - Automounter:  Add support for an auto-mounter that will automatically
        mount and unmount a file system a media is inserted and removed

    * Audio/Audio Drivers

      - WM8904 audio CODEC driver.
      - PCM .WAV file decoder. Fast forward implemented with sub-sampling
        (currently no rewind support).
      - Add a NULL audio device that can be used to simply unit-level testing
        of audio decoders.
      - Audio subsystem now supports interfaces for fast-forward and rewind
        needed by CMediaPlayer; add hooks for equalizer settings needed by
        the WM8904 CODEC.

    * Other Common Drivers:

      - MTD: Extend erase block size to 18-bits in order (decrease block
        size to 14-bits) to handle parts with large erase blocks. From Kosma
        Moczek
      - maxTouch:  Add support for the Atmel maXTouch touchscreen controller.

    * Host Simulation:

      - Provides the timers needed to support the Tickless mode of operation.

    * Atmel SAM4C:

      - Add SAM4CM IPC register header file.  From Max Neklyudov
      - Various fixes PMC and clock configuration for the SAM4CM port from
        Max Neklyudov

    * Atmel SAM4E/4S Drivers:

      - SAM4 AES driver.  Contributed by Max Neklyudov

    * Atmel SAMA5:

      - Add logic to redirect all SAMA5D4 interrupts to the AIC
      - Add a configuration option to reserve DRAM for a framebuffer when
        executing out of DRAM.  This optional was available before when
        executing out of NOR, but needs to work a little differently in
        this case.
      - Add SAMA5 slow (32.768KHz) clock support.
      - Add support for the ARM L2CC-PL310 L2 cache.  The system runs with
        L2CC cache enabled but there is some issues still with the LCD DMA;
        I suspect that the memory timing configuration for L2CC needs to
        be tuned.
      - Provides the timers needed to support the Tickless mode of operation.

    * Atmel SAMA5 Drivers:

      - XDMAC-based HSCMI driver for the SAMA5D4
      - Adapt the SAMA5D3 LCDC driver to work with the SAMA5D4 which has
        no hardware cursor.
      - PIO: Add a new interface sam_pio_forceclk() that can be used to
        force PIO clocking on.  I am afraid I was too conservative with
        PIO clocking in the initial design; this is the price.
      - TWI:  Now supports the up_i2creset() method.
      - TWI:  Use sam_pio_forceclk() so that we can read the current state
        of an open-drain output in the TWI reset logic.
      - SSC:  SCC Frame Synch Delay and Start Delay are now configurable.
      - PCK:  Add the slow clock and the main clocks as options for the
        PCK configuration.
      - Timer/Counter: Can now handle non-constant BOARD_MCK_FREQUENCY. Also
        now supports methods to attach client interrupt handlers
      - One shot and free-running timers.  These are wrappers around the low
        level timer/counter logic to provide one-shot and free-running
        timers.  These were developed to support the Tickless operation, but
        can be used for any purpose.

    * Atmel SAMA5 Board Support:

      - Add a boot loader that runs from ISRAM and loads an Intel HEX file
        into DRAM.
      - Add a configuration that will load a bootloader into AT25 Serial
        FLASH
      - SAMA5D4-EK NSH configuration supports many more features: RTC, HSCMI
        card detection, maXTouch touchscreen, TM7000 LCD, the command line
        media player (currently using the NULL audio device), automounter,
        and others.
      - SAMA5D4-EK:  Add an NxWM configuration using the TM7000 LCD with
        the maXTouch multi-touch touchscreen.
      - SAMA5D4-EK NxWM: Uses new, larger icons in configuration instead of
        scaling.
      - SAMA5D4-EK NxWM: The NxPlayer and audio system are now enabled in
        the default configuration (but currently using the NULL audio
        device).  The automounter is used to automatically mount media
        on an SD card.
      - SAMA5D3x-EK:  Add a configuration to support the command line
        NxPlayer and to verify the WM8904 CODEC driver.

    * STMicro STM32:

      -  Add support for the STM32F103RC and RD.  From Kosma Moczek
      -  Add a procfs entry to show the state of the CCM heap usage.
         From Pelle Winderstam

    * STMicro STM32 Drivers:

      - Unconfigure GPIO pins when closing a serial port to prevent back
        effects from back-powering on the TX pin. From Kosma Moczek

    * NXP LPC17xx Drivers:

      - ADC:  Added burstmode ADC conversion mode, with CONFIG_ADC_BURSTMODE
        option in Kconfig.  From Max
      - Ethernet: Added option to use the kernel worker thread to do most of
        the workload with CONFIG_NET_WORKER_THREAD option in Kconfig.  From Max
      - Ethernet: Critical bugfix: From time to time (after some hours) the
        Ethernet receiver would lose one receive interrupt and the IP stack
        never recover because there is no receive watchdog as the transmit
        watchdog.  From Max

    * NXP LPC17xx Boards:

      - mbed: Port ADC, DAC, and PWM logic from the configs/zkit-arm-1769.
        From Max
      - mbed:  Eliminated a problem with PHY DP83848C : it doesn't need a
        specific initialization on mbed.  From Max

    * Library:

      - Adds support for localtime.  From Max Neklyudov

    * Configuration/Build System:

      - Make variable definitions 'static const' when possible to save RAM
        usage.  From Kosma Moczek

    * Applications:

      - system/mdio:  New PHY tool from Daniel Lazlo Sizter.
      - NSH:  Networking logic modified to handler the case of SLIP
        transport.  From Max Neklyudov.
      - NSH:  Add a configuration to use a USB keyboard for the stdin
        device.
      - NSH:  Software assigned MAC address is now configurable. From Lazlo.
      - NSH:  Also add an option to let platform-specific logic select the
        MAC address.
      - NSH:  There is now a configuration option that will bring up the
        network on an separate thread.  Since the network bring-up is
        asynchronous, there are no serial console start-up delays due
        to the network negotiation time.
      - NxPlayer: Changes to integrate with Ken's NxWM::CMediaPlayer.
      - NxPlayer: Add interfaces for fast-forward and rewind needed by
        CMediaPlayer; add interface for equalizer settings needed by the
        WM8904.
      - NxPlayer:  Supports new way of identifying the end of the audio
        stream (see the Audio section above).
      - Sudoku:  Add a sudoku game.

Bugfixes.  Only the most critical bugfixes are listed here (see the ChangeLog for the complete list of bugfixes and for additional, more detailed bugfix information):

    * Graphics:

      - NxConsole: Fix scrolling for the case of the framebuffer device.  In
        this case, the logic for clearing the vacated region at the bottom
        was missing so garbage would scroll up from the last, uncleared
        line.

    * Networking:

      - Important fix to the read-ahead buffer queue management: Consumed
        bytes were being trimmed from the head of the queue, but the queue
        head itself was not being updated.  From Rony XLN.
      - Fix an error in SLIP escaping.  From Max Neklyudov

    * Network Utilities:

      - Fix an include file ordering problem when CONFIG_NET_STATISTICS=y.
      - Move statistics from uip.h to new netstats.h  to remove a circular
        inclusion problem
      - Various fixes for networking and tiny webserver from Max
      - webclient:  Fix to offset calculation from Rony Xln.  Prevents 0x0a
        at the beginning of lines.
      - webserver:  Fix some configuration usage issues.  From Max.
      - webserver:  Missing logic to close sockets on loop termination.

    * File System / Block Drivers:

      - SmartFS:  Fix for a bug that would show up if CONFIG_MTD_BYTE_WRITE
        was not selected and the SMART sector size was larger than the MTD
        device's block size (like it would be if using SMARTFS on larger
        flash devices).  From Ken Pettit.

    * Audio:

      - Change how the end of the audio stream is detected by the leaf audio
        component.  This used to be done by looking for the first partial
        buffer.  That does not work with the in-place sub-sampling performed
        by the PCM decoder:  That always reduces the size of the buffer so
        that all buffers only partially filled by the time they get to the
        leaf.  Now, a flag is set in the audio buffer flags set to indicate
        the final buffer in the stream.

    * Common Drivers:

      - RAMLOG putc() method needs to set the errno and return EOF on a
        failure.
      - Add missing configuration option to select the MAX11802 touchscreen
        controller. From Petteri Aimonen

    * Atmel SAMA5D3/4:

      - Fix logic in conversion of physical and virtual DRAM addresses when
        running out of DRAM.  This is an important bug fix for the SAMA5D3
        and 4 when running out of DRAM .
      - Critical SAMA5D3 and 4 bug fix:  PIO clocking must be enabled for
        all input pins or else the value that is read never changes.

    * Atmel SAMA5D3/4 Drivers:

      - OHCI: Fix an error in a DEBUGASSERT statement.  Caused an
        assertion to fire inappropriately when a low- or full-speed device
        was removed and CONFIG_DEBUG=y
      - OHCI: Pointers to allocated port values were not being
        nullified after being deallocated.  This caused some assertions
        to fire when debug was enabled
      - SSC:  Needs to account for data offset in audio buffer

    * ARMv7-M:

      - Correct the initial value of the BASEPRI register.  This was
        apparently never being initialized! From Max

    * STMicro STM32 Drivers:

      - I2C:  Fix missing configuration of GPIO pins in I2C driver.  Fix
        from Alex D.
      - STM32 OTGFS device:  Various changes to try to reduce that amount of
        time in interrupts handles and with interrupts disabled.  From
        Petteri Aimonen

    * Atmel SAM3/4 Drivers:

      - Ethernet: Wrong bits being cleared before OR-ing in new settings.
      - Ethernet: Fix an error in the function that determines the number
        of free TX descriptors.  This is an important bugfix on busy
        networks.
      - I2C: Test for read or write operation was reversed.  How could
        this have worked before?

    * Atmel SAM3/4 Boards:

      - SAM4S Xplained-Pro:  Correct description of LEDs and usage. From
        Kosma Moczek

    * Atmel SAMA5:

      - PIO: Fix definitions that could disable PIO interrupt support if only
        PIOE interrupts were enabled
      - PIO: Macro SAM_PION_VBASE is not define-able for the SAMA5D4 and must
        be replaced with a table lookup.
      - PIO: Fix a typo in Schmitt trigger configuration; Configure pin as a
        vanilla input first so that final pin configuration is more read-able
        (i.e., easier to debug)
      - PIO: Logic for Schmitt trigger selection backward
      - SAMA5D4:  Correct system timer frequency.  Input clock is MCK/2, not MCK.

    * Atmel SAMA5 Drivers:

      - Ethernet: Wrong bits being cleared before OR-ing in new settings.
      - Ethernet: Fix an error in the function that determines the number
        of free TX descriptors.  This is an important bugfix on busy
        networks.
      - HSMCI: The 8-byte SCR transfer was failing silently with the DMA
        transfer, leaving the SD card in single bit mode.  Fixed by adding
        a non-DMA read transfer mode.
      - HSMCI: Fix a problem on card insertion/removal callback handling.
        Interrupts were being disable so that the callbacks occurred with
        interrupts disabled.  This resulted in loss of some interrupts and
        some not-so-good behaviors.  The solution is to perform all
        callbacks on the work thread unconditionally

    * Atmel SAMA5 Boards:

      - PIO: Fix some cloned errors in SAM GPIO interrupt setup

    * NXP LPC17xx Drivers:

      - Ethernet:  Comment out an assertion that is reported to fire
        inappropriately.  From Max

    * Library:

      - stdint.h: Correct naming of [U]INT_LEASTn_{MAX|MIN} and
        [U]INT_FASTn{MAX|MIN}. From Kosma Moczek
      - unistd.h: POSIX definitions should be defined to a value. rom Kosma
        Moczek
      - Fixes associated with rint() and related interfaces in the math
        library.

    * Configuration/Build System:

      - NAME_MAX not available on SunOS; use FILENAME_MAX or MAXNAMELEN.
        Noted by Douglas Beattie

    * Applications:

      - NSH: if # appears on line, need to comment ignore additional
        commands on the line
      - NxPlayer:  Check for file read errors and end-of-file with zero
        bytes read.  Other error handling corrected as well.
      - NxPlayer:  NxPlayer needs to set curbyte field to zero before
        enqueuing a buffer.  Otherwise, it looks like beginning of the
        buffer has already been consumed.

NuttX-7.5
---------

The 105th release of NuttX, Version 7.5, was made on September 28, 2014,
and is available for download from the SourceForge website.  Note
that release consists of two tarballs:  nuttx-7.5.tar.gz and
apps-7.5.tar.gz.  Both may be needed (see the top-level nuttx/README.txt
file for build information).

Additional new features and extended functionality:

    * Core OS:

      - Watchdog Timer Allocation:  (1) If we run out of pre-allocated
        watchdog times, the logic will now allocate additional timers
        from the heap.  A reserve of pre-allocated watchdog timers is
        maintained so that there will always be timers available for
        interrupt handlers. (2) Added support for statically allocated
        watchdog timer
      - Address Environment Support:  (2) New OS APIs integrated into all
        platform-specific context switching logic (up_block_task(),
        up_unblock_task(), _exit(), and others).
      - Kernel Build Support: (1) The MPU based "kernel build" renamed to a
        protected build (CONFIG_BUILD_PROTECTED); added support for the a
        new MMU-based "kernel build" (CONFIG_BUILD_KERNEL), (2) The system
        call library can now be built with CONFIG_NUTTX_KERNEL.  New
        selection: CONFIG_LIB_SYSCALL.
      - System Startup:  Add configuration options to start the system from
        a program on a file system (versus an address in memory).
      - Startup Parameter Passing. There used to be two ways to pass
        parameters to new tasks, depending upon the configuration:  Either
        (1) argv[] as created as an array with each string strdup'ed.  Or
        (2) argv[] array and strings were created on the stack before the
        new task was started.   Now, there is only one way, way (1).  Way
        (2) might be slightly more compact, but this is not worth carry the
        complexity of two different ways of doing the same thing.
      - Board Initialization: Add capability to perform initial board
        initialization on a separate worker thread.  This is needed because
        there are many cases where initialization logic cannot execute on
        the start-up/IDLE thread.  That is because blocking or waiting is
        not permitted on the IDLE thread.

    * Memory Management:

      - Granule Allocator:  (1) Add a new function to reserve un-allocatable
        regions in the granule heap.  (2) Add interfaces to support
        un-initializing a granule allocator.
      - Page Allocator:  Add a simple physical page allocator based on the
        existing NuttX granule allocator.  I am not certain if the granule
        allocator is sufficiently deterministic for long range use, but it
        gets get a page allocator in place for testing very quickly.
      - Remove CONFIG_MM_MULTIHEAP.  Non-multiheap operation is no longer
        supported.
      - sbrk():  sbrk() is now supported in the kernel build to permit
        dynamically sized, per-process heaps.
      - Per-Process Heaps:  Space at the beginning of the process data space
        is now reserved for user heap management structures.  In the kernel
        build mode, these heap structures are shared between the kernel and
        use code in order to allocate user-specific data.
      - User Heap Management:  When a privileged thread exits, we have to
        use the kernel allocator to free memory; when an unprivileged thread
        exits, we don't have to do anything... heap memory will be cleaned
        up when the address environment is torn down.
      - Inter-Process Shared Memory Support:  (1) Add implementation and
        documentation for shmget(), shmctl(), shmat(), and shmdt().  (2)
        Add system system calls to support the user call gate to the shared
        memory interfaces.  (3) Add platform-specific interface definitions
        needed to support the shared memory feature.
      - Virtual Page Allocator:  Add support for a per-process virtual page
        allocator.  This is a new member of the task_group_s structure.  The
        allocator must be initialized when a new user process is started and
        uninitialize when the process group is finally destroyed.  It is
        used by shmat() and shmdt() to pick the virtual address onto which
        to map the shared physical memory.

    * File Systems/Block Drivers/MTD:

      - SMART FS and SMART FS procfs updates from Ken Pettit.
      - The MTD Read-ahead/Write buffer layer appears is now functional.

    * Binary Formats:

      - Add logic to initialize the per-process user heap when each user
        process is started.

    * Graphics:

      - Change all occurrences of NxConsole to NxTerm.

    * Networking:

      - PHY Interrupts: (1) Standardize a PHY interrupt attachment
        interface. (2) Add support for an ioctl that can be used to notify
        an application when there is a change in the network status
        signalled by a PHY interrupt.
      - Improved Send Logic:  In the past, the first packet send to a new
        network peer would fail; there would be no entry in the ARP table
        for the peer and so an ARP request could replace that first packet.
        Now as an option if CONFIG_NET_ARP_SEND=y, all send logic will (1)
        check if the peer MAC address is in the ARP table and, if not, (2)
        send ARP requests periodically to get the mapping and (3) wait for
        the ARP response.  Then (4) when the ARP response is received then
        the actual send logic will be initiated.  Thus there may be a delay
        with the first packet sent to a new peer, but the packet should not
        be lost

    * Host Simulation:

      - Emulated SPI FLASH driver for the sim target from Ken Pettit.

    * Intel x86:

      - The default host is now x86_64 and the -m32 option will be
        automatically selected for simulation builds.

    * Intel 8051 Family:

      - Removed all support for the 8051 family architecture from the NuttX
        source tree.  The obsoleted code along with the removal patch can
        now be found at misc/Obsoleted/.  This code was removed because (1)
        although some functionality has been demonstrated, I am not aware of
        any really successful ports of NuttX to any 8051, and (2) the 8051,
        with its hardware stack, forces limitations and complications to the
        other architectures and make growth and development of NuttX more
        complex.

    * ZiLOG ZNeo Boards:

      - configs/16z:  Support for this board has been removed from the NuttX
        source tree (but still can be found in the misc/Obsoleted
        directory). This port is not ready for usage but may return to the
        NuttX tree at some point in the future.

    * Atmel SAM3/4 Boards:

      - SAM4E-EK: Add (1) a fully-functional ILI9341-based LCD driver and
        (2) a fully-functional NxWM configuration.

    * ARMv7-A:

      - Address Environments:  Add support for application address
        environments using the Cortex-A MMU.  Implement standardized
        platform-specific interfaces of NuttX address environment
        support.
      - Cache Operations:  Implement standardized, platform-specific cache
        operations.  These are called from the ELF loader in order to flush
        D-cache and invalidate I-cache after an ELF module has been loaded
        into memory. With this change, ELF modules work correctly on the
        SAMA5/Cortex-A platform.
      - Kernel Build: (1) Add implementations of system call gate. (2) Add
        CRT0 start-up file that can be linked with separately built user
        programs.  (3) Add support for delivery of use-mode signals in the
        kernel build.  (4) Add logic to initialize the per-process user heap
        when each user process is started.  (5) ARMv7-A exception handling
        needs to work a little differently if we support user mode
        processes.  This is because R13 and R14 are paged differently
        between user and SVC mode.
      - Shared Memory Support:  (1) Add logic necessary to handle remapping
        of shared memory on context switches.  (2) Extend virtual/physical
        address conversions to include addresses in shared memory.  (3) Add
        implementation of platform-specific shared memory support.

    * Atmel SAMA5D Drivers:

      - Implement all network ioctls, including the new ioctl to setup PHY
        event notifications.
      - In kernel build with address environment, need logic to map user
        virtual addresses to physical addresses, and vice versa.

    * Atmel SAMA5D Boards:

      - SAMA5D3 Xplained, SAMA5D3-EK, and SAMA5D4-EK:  Convert existing
        board specific PHY interrupt interfaces to use newly defined
        standard interface.
      - SAMA5D4-EK: Add a configuration for testing the kernel build
        configuration.  There are configurations to boot either from an SD
        card or from and in-memory ROMFS file system.
      - SAMA5D4-EK: Add documentation/support for Rev E. board.

    * STMicro STM32 Drivers:

      - Ethernet: Modified to support the change to the network ioctl
        signature changes.  Also add support for new ioctl to setup PHY
        event notifications.

    * STMicro STM32 Boards:

      - STM32F4Discovery with STM32F4DIS-BB: Add a network enabled NSH
        configuration for the STM32F4Discovery board with the STM32F4DIS-BB
        base board installed.  Includes support for the microSD card slot on
        the STM32F4DIS-BB base board.

    * TI Tiva Drivers:

      - Add support for the TI CC3200. From Jim Ewing.

    * TI Tiva Boards:

      - Add support for the TI CC3200 Launchpad. From Jim Ewing.

    * C Library:

      - Re-implemented poll() delay using sem_timedwait().

    * Configuration/Build System:

      - Export Target:  In the kernel or protected builds, (1) only the user
        libraries should be exported,  (2) do not copy internal header files
        or build scripts if this is a kernel or protected build, and (3)
        needs to bundle up the user C startup file (crt0), not the kernel
        head object for the kernel and protected builds.
      - Add logic that will permit us to build user libraries with different
        CFLAGS than kernel code.  This is needed because we need the
        -fno-common option when building ELF code to prevent SHN_COMMON
        relocations.

    * Applications:

      - NSH:  Extend the NSH network initialization logic.  There is now an
        option that will create a network monitor thread that will monitor
        the state of the link.  When the link goes down, the code will
        attempt to gracefully put the Ethernet driver in a down state; When
        the link comes back, the code will attempt to bring the network back
        up.
      - ELF Example:  The ELF test/example has been extended so the
        individual ELF test programs can link against the SYSCALL library
        (if it is available) or against the C library to eliminate or
        minimize the need for symbol tables.
      - Change all occurrences of NxConsole to NxTerm.
      - MTDRWB Example:  Add an example to test MTD R/W buffering.
      - OS Test Example:  Add a trivial test of sem_timedwait.

    * Application Configuration/Build System:

      - Import Target:  (1) Add logic that will allow building applications
        against a NuttX export package (vs. the nuttx/ source tree).  (2)
        Add .config file to export package.  (3) Create apps/import.  Create
        apps/import/Make.defs that does things like define CFLAGS; ELF build
        requires -fno-common in CFLAGS. Copy some base logic from
        nuttx/tools/Config.mk to apps/import/Make.defs.  (4) Add
        apps/import/scripts/gnu-elf.ld GCC linker script for ELF import
        builds.
      - All Makefiles:  (1) Add an install target to all makefiles.  For
        the import build, the top-level Makefile now does two passes: (1)
        builds libapp.a, then (2) installs the programs into apps/bin.  (2)
        Add program installation for CONFIG_BUILD_KERNEL in all Makefiles
        that build a main().  (3) For kernel build, the object file
        containing main cannot go into library because of name collisions.
        The object file must be handled as a special case in every Makefile.
      - All Built-In Programs:  With kernel build (CONFIG_BUILD_KERNEL),
        entry point to all tasks is main(), not some xyz_main().
      - NSH: Several commands must be disabled in the kernel build because
        they depend on interfaces that are not available outside of the
        kernel: dd, df, losetup, mkfatfs, mkdr, and ps.
      - apps/tools/:  (1) Add mkimport.sh to expload an NuttX import package
        and install in apps/import.  (2) Add mkromfsimg.sh  script to create
        a BOOT ROMFS filesystem image.
      - ELF and NxFLAT Examples: Do not build test cases that use
        task_create() if there is an address environment.

    * Tools:

      - refresh.sh: Add a tool to make refreshing configurations easier
        when you want to do a lot of them.
      - mksyscall.c: Build syscalls that do not need header files.
      - mkexport.sh: Add .config file to export package.
      - See above for new apps/tools scripts.

Efforts In Progress.  The following are features that are partially
implemented but present in this release.  They are not likely to be
completed soon.

    * Processes.  Much of the work in this release is focused on the
      realization of Unix-style user processes in NuttX.  There is more to
      be done, however.  The full roadmap and status is available at:
      https://cwiki.apache.org/confluence/display/NUTTX/Memory+Configurations

    * XMega:  There are some fragments in place for an XMega port.  That
      port has not really started, however.

    * Galileo:  Similarly, there are fragments in place for an Intel Galileo
      port.  The port not been started in earnest either.

Bugfixes.  Only the most critical bugfixes are listed here (see the ChangeLog for the complete list of bugfixes and for additional, more detailed bugfix information):

    * Core OS:

      - Kernel build fixes: (1) IDLE TCB setup needs to indicate that the
        IDLE thread is a privileged, kernel thread.  (2) Don't build
        task_create() or task_spawn() interfaces if there is an address
        environment.  (3) posix_spawn() kernel proxy thread should be a
        kernel thread, not a user task.
      - Several pthread interfaces: Add const storage class to phthread
        parameters.  From Freddie Chopin.
      - sched/clock: Remove vestiges of g_tickbias;  need, instead, to apply
        time bias to g_basetime in order to provide the correct system time.
      - System Calls:  (1) Several typos fixed; corrected integration of
        exevc(), execvl(), posix_spawn, and posix_spawnp system calls. (2)
        If we are configured to use a kernel stack while in SYSCALL handling,
        then we need to switch back to the user stack to deliver a signal.

    * File Systems/Block Drivers/MTD:

      - procfs: Fix some procfs breakage introduced by reorganizing some
        non-reorganizable data structures.  From Ken Pettit.
      - AT45: In at45db_bwrite , the buffer is not increased when writing
        more than 1 page.  Sourceforge bug #34.

    * Binary Formats:

      - ELF relocations.  Some relocation types do not have a named symbol
        associated with them.  The design did not account for that case.
      - ELF Loader: Critical bugfix.. BSS was not being cleared.

    * Memory Management:

      - Granule allocator initialization uses wrong allocator to setting
        aside kernel memory.
      - Add a flag to group structure:  If the group is created by a kernel
        thread, then all resources in the group must be privileged.

    * Cryptogrphic Support:

      - crypto/cryptodev.c: Path segments reversed in include file path. Noted by Brennan Ashton.

    * Common Drivers:

      - Common CAN upper-half: In can_txdone, waiters on the semaphore
        should be informed regardless of the return value of can_xmit. First
        it returns -EIO if there are no new packets, and second the
        information of the waiters is about the last transferred packet.
        From  Daniel Lazlo Sitzer.

    * ARM:

      - System Calls: Fix a typo in system call when fetching parameter from
        the stack:  regs[REG_PC]+4 is the address, not regs[REG_PC+4].

    * STMicro STM32 Drivers:

      - STM32 F401 UART: Correct support for USART6 on this chip.  From
        Freddie Chopin.
      - STM32 FLASH fixes: use size_t instead of uint16_t, make interface
        more generic.  From Freddie Chopin.
      - Fix for UART7 and UART8 on STM32 clock enable from Aton.
      - CAN: At the end of the interrupt handler, the interrupts were being
        disabled, if all packets have been transferred when the interrupt
        handler was invoked. This is problematic, because the interrupt
        handler calls can_txdone of the upper half which can enqueue new
        packets to send. Removed the block altogether, because can_txdone
        calls can_xmit which disables interrupts if there are no new packets
        to send.  From  Daniel Lazlo Sitzer.
      - Additional STM32 CAN correction suggested by Max Holtzberg.

    * STMicro ST32 Boards:

      - configs/mikroe-stm32f4: Fix a few compile bugs and minor corrections
        to the mikroe-stm32f4 configuration source.  From Ken Pettit.

    * ARM9/ARMv7-A:

      - System Calls: Fix ARM7/9 and Cortex-A SYSCALLs:  For threads in SVC
        mode, the SVC instructions clobbers R14.  This must be taken account
        in the inline assembly.
      - Task Setup:  All tasks, even user mode tasks, must start in
        supervisor mode until they get past the start-up trampoline.
      - ARMv7-A:  Modify up_fullcontextrestore() for CONFIG_BUILD_KERNEL.
        It changed CPSR while in kernel.  That will crash if the new CPSR is
        user mode while executing in kernel space.  Fixed by adding a
        SYS_context_restore system call.  There is an alternative, simpler
        modification to up_fullcontextrestore() that could have been done:
        It might have been possible to use the SPSR instead of the CPRSR and
        then do an exception return from up_fullcontextrestore().  That
        would be more efficient, but I never tried it.

    * Atmel SAM3/4 Boards:

      - SAM3X/Arduino Due: Fix typo in sam3x_periphclks.h; add SCLK
        definitions to board.h header file.  From Fabien Comte.
      - SAM3 RTT: Only SAM4 family has RTTDIS bit in the MR register.
        SourceForge bug #33 from Fabien Comte.

    * C Library:

      - sscanf(): NuttX libc tried to guess how many characters to parse,
        extracted them into a buffer, then ran strtol() on that buffer.
        That guess was often wrong.  A better approach would be to call
        strtol() directly on the input data, using the endptr return value
        to determine how many characters to skip after parsing.  From Kosma
        Moczek.
      - Corrected atan2 implementations from Denis Arnst.
      - Change to lib_dtoa() to fix precision error from trailing zeroes.
        From Bob Doiron.

    * Applications:

      - Fix NSH PS command:  If there are no arguments, it could print
        garbage for argument list.

    * Configuration/Build System:

      - Null Example:  Need to include config.h it order know if this is or
        is not a kernel build.  This problem still exists in several other
        file that may need to define main().

NuttX-7.6
---------

The 106th release of NuttX, Version 7.6, was made on November 26, 2014,
and is available for download from the SourceForge website.  Note
that release consists of two tarballs:  nuttx-7.6.tar.gz and
apps-7.6.tar.gz.  Both may be needed (see the top-level nuttx/README.txt
file for build information).

Additional new features and extended functionality:

    * Core OS:

      - Moved name semaphore and message queue support out of the OS and
        into the VFS.  These improves the architecture by unifying the
        management of named resources, removes redundant resource management
        logic, and makes named semaphores and message queues  visible in the
        file system.  By default, these are visible at /var/lock and
        /var/mqueue.
      - Add SIGPOLL for use as part of the AIO implementation.
      - Remove CONFIG_MAX_TASK_ARGS configuration.  There is now no
        predetermined limit on the number of arguments that may be passed
        to a new task on start-up.

    * Work queues:

      - Add support for priority inheritance on the low priority worker
        queue.  That is, if a higher priority thread has scheduled work, the
        priority of the low priority worker thread(s) will be boost to the
        priority of the queuing thread.  At work is performed at at least
        thread priority of the scheduling thread.  If there are multiple
        worker threads, then all threads get reprioritized.  Currently
        only implemented for AIO.
      - Add support for multiple low-priority work queue threads.  This
        allows individual worker threads to block indefinitely for I/O as
        necessary without halting the entire work queue.

    * VFS/General Drivers:

      - Implement create() (as a macro).
      - Add pread() and pwrite().   Also added pread() and pwrite()
        system calls.
      - AIO: Add aio_read(), aio_write(), aio_return(), aio_error(),
        aio_suspend(), aio_canel(), lio_listio(), and aio_fsync().  This
        logic minimizes the creation of new threads by using the new
        features also added to the low priority work queue with this
        release.  It uses the new low priority worker thread interface
        to adjust the priority of the worker thread according to the
        priority of the AIO client thread
      - Implement standard syslogmask() to control logging (also removing
        the non-standard syslog_enable()).

    * File Systems/Block Drivers/MTD:

      - Extend MTD support to the M25P16. From Sébastien Lorquet.

    * Drivers:

      - BCH (Block-to-Character): Add support for seeking in BCH.  From
        Sébastien Lorquet.

    * Graphics Support/Graphics-Related Drivers:

      - Add support for a generic ILI9341 LCD driver.  From Marco Krahl.
      - Add ANSI/VT100 foreground and background color commands.
      - Add driver for ST7565 LCD that works with NHD-C12864KGZ display.  From Pierre-noel Bouteville.

    * Networking:

      - Verify that multiple networks can be supported.
      - Add support for the case where there are multiple networks:  One
        being Ethernet and the other not (SLIP, PPP, ...).  The primary
        difference from the standpoint of the stack is that (1) ARP may or
        may not be necessary, (2) the size of the link layer header will
        vary, and (3) different MTUs and TCP receive windows may be used
        with each link.  Suggested by Brennan Ashton.
      - Extensions to UDP and TCP connection structures for the case of
        multiple networks.  In this case, assigned port numbers only have to
        be unique with respect to the IP address.  So, for example, you
        could have multiple port 80's, one on each network.

    * Host Simulation:

      - Removed the old, strange up_stdio.c and implemented a simulated UART
        driver to provide the console input.  The new logic starts a
        separate, Linux domain pthread to read the console input in raw mode
        and provides the incoming data to NuttX via standard NuttX domain
        IPCs.
      - Add support for 64-bit longjmp/setjmp in simulator platform.  This
        will permit operation of the simulation natively on a 64-bit
        platform.

    * ARMv7-M:

      - Add ARMv7-M CMSIS ITM header file and library.  From Pierre-noel
        Bouteville.
      - Add ARMv7-M CMSIS DWT and TPI header files. From Pierre-noel
        Bouteville.
      - Add ARMv7-M support to use ITM for SYSLOG debug output. Includes
        logic from Pierre-noel Bouteville.

    * Atmel SAM3/4 Drivers:

      - Add support for SAM3/4 basic serial TERMIOS and flow control.
        There are issues with IFLOW control: PDC or DMAC support is
        required.

    * Atmel SAM3/4 Boards:

      - SAM4E-EK: Add support for PHY interrupt.

    * Atmel SAMA5D Boards:

      - SAMA5D3-Xplained:  Add a configuration that provides a simple test
        for the EMAC and GMAC on the SAMA5D3 working together.
      - SAMA5D4-EK:  Add a configuration that provides a simple test for the
        EMAC0 and EMAC1 on the SAMA5D4 working together.

    * Freescale KL:

      - Add an I2C header file for the Freescale KL family.  From Alan
        Carvalho de Assis.

    * NXP LPC32xx:

      - Add support for tickless operation using the NXP LPC43xx.  From
        Brandon Warhurst.

    * SiLabs EFM32:

      - Add a basic port for the SiLabs EFM32 family.  Includes many files
        contributed by Pierre-noel Bouteville .

    * SiLabs EFM32 Boards:

      - Add board support for the EFM32 Gecko Starter Kit.
      - Add board support for the Olimex EFM32G8809128 STK.  NOTE: I am
        unable to test this configuration due to tool-related issues.
      - Add board support for the SiLbas EFM32GG Giant Gecko Starter kit.

    * STMicro STM32:

      - Add support for the STM32 F411RE from Serg Podtynnyi.
      - Add support for the STM32F103RG.  From Murilo Ponte.

    * STMicro STM32 Drivers:

      - STM32 F4:  Add logic that implement true high speed support for the
        STM32 OTGHS peripheral and concurrent support for both LS and HS
        OTG.  New OTGHS drivers provided for both device and host. From
        Brennan Ashton.

    * STMicro STM32 Boards:

      - STM32 Nucleo-F411RE: Extend this board configuration to also support
        the Nucleo-F411RE.  From Serg Podtynnyi.
      - Add support for the STM32F429i Discovery's LCD (SPI based).  From
        Marco Krahl.
      - configs/stm32f100rc_generic:  Removed this generic board configuration.
        I have decided to stop support of generic board configurations.  Generic
        board configurations do not provide support for any specific hardware
        but can be useful only if there are not other examples for the setup
        for a particular architecture. Not the case here.

    * C Library:

      - Add a mostly bogus wchar.h header file.  This file is mostly bogus
        because none of the wide character operations are currently
        supported in the NuttX C library.  The file does provide the wchar_t
        types needed by some software, however.
      - Add isatty() function. From  Alan Carvalho de Assis.
      - Add mktemp(), mkstemp(), tmpnam() and tempnam().

    * Configuration/Build System:

      - Add a PRELINK macro to Config.mk.  From Kriegleder.
      - compiler.h:  Defines inline functions as not instrumented - this is
        relevant for anyone using instrumentation.  From Lorenz Meier.

    * Applications:

      - apps/interpreter/bas:  Added in the Michael Haardt's BAS 2.4 adapted
        for use by NuttX by Alan Carvalho de Assis.   Includes support for
        VT100 terminals and color commands.
      - Examples:  Added bastest/ which holds a special version of Michael
        Haardt's BAS 2.4 test files adapted for use by NuttX on a ROMFS file
        system.
      - Examples:  Add a simple UDP relay bridge for testing configurations
        with multiple networks.  Includes a host-side test driver for
        testing the bridge.
      - Netutils: Add implementation of timeouts for the netutils webclient.
        From Brennan Ashton
      - NSH: Add support for a custom NSH ROMFS startup image header file
        location.  From Martin Lederhilger.
      - OS test:  Add a simple test of named semaphores.
      - OS test:  Add AIO test case in OS test.

Efforts In Progress.  The following are features that are partially
implemented but present in this release.  They are not likely to be
completed soon.

    * Processes.  Much of the work in this release is focused on the
      realization of Unix-style user processes in NuttX.  There is more to
      be done, however.  The full roadmap and status is available at:
      https://cwiki.apache.org/confluence/display/NUTTX/Memory+Configurations

    * XMega:  There are some fragments in place for an XMega port.  That
      port has not really started, however.

    * Galileo:  Similarly, there are fragments in place for an Intel Galileo
      port.  The port not been started in earnest either.

Bugfixes.  Only the most critical bugfixes are listed here (see the
ChangeLog for the complete list of bugfixes and for additional, more
detailed bugfix information):

I ran cppcheck against the entire code base and correct many latent bugs
including things as serious as memory leaks,  two locations where interrupts
were be disabled but never re-enabled, and errors in the Tickless mode of
operation.  My thanks to the developers of cppcheck!  I am impressed!

    * Core OS:

      - vfork():  Now that arguments are kept on the stack, the way that
        arguments are passed from parent to child in vfork() must change.
        This bug has always been present, but was not visible with the
        old strdup() way of passing arguments.
      - vfork() problem: If we get to vfork() via system call, then we
        need to clone some system call information so that the return form
        the cloned system call works correctly.
      - Fixes to tickless operation code, especially in alarm mode.  From
        Brandon Warhurst.
      - Fix an important bug in the watchdog timer creation logic.
      - Calling mq_timedreceived() with immediate timeout was getting stuck
        and not timing out. Immediate timeout is achieved by setting absolute
        timeout value to past time, for example abstime={ .tv_sec=0,
        .tv_nsec=0 }. However absolute time was converted to relative time
        using unsigned integer arithmetic and resulted large ticks count by
        clock_abstime2ticks, instead of expected negative ticks value.
        Change corrects clock_abstime2ticks() to return negative ticks, if
        absolute time is in the past.  From Jussi Kivilinna.

    * Memory Management:

      - Fix a place in the memory manager where it explicitly assumed that
        the size of a pointer is 4 bytes.  That assumption was OK if the
        actual size is smaller but made the heap unstable when used with
        the x86_64 host simulation.
      - Granule Allocator:  If the INTR granule allocator mode is enabled,
        there is no semaphore to destroy.  From Lorenz Meier.

    * Networking:

      - Network routing:  I don't think that the net_route() function has
        ever worked correctly.  The source IP was updated in the match
        struct instead of the route IP.  From Brennan Ashton.
      - Move and rename IP header flag definitions.  The problem fixed here
        is that there IP header flag definitions were not available when TCP
        was disabled.  The IP flags are used in ICMP and IGMP.
      - Network routing:  Refuse to perform routing table lookups for the
        Broadcast IP address.  From Brennan Ashton.
      - Network routing:  Add logic to netdev_findbyaddr() to return the
        correct network device for the case where a broadcast
        address is used.  This change caused trivial ripples through other
        files because additional parameters are required for
        netdev_findbyaddr() when CONFIG_NET_MULTINIC.

    * File Systems/Block Drivers/MTD:

      - NXFFS Dump: Fix problems with redefinitions of fdbg macro.  With the
        fix to the syslog prototype, a LOG priority must now be the first
        parameter.  Fixed by replacing all occurrences of fdbg with
        syslog(LOG_DEBUG, and eliminating the macro redefinitions.  Noted
        by Sebastien Lorquet.
      - poll() was not waking up from signals (for example mq_notify()
        events).  From Jussi Kivilinna.
      - poll():  Add proper handling for sem_timedwait errnos.  From Jussi
        Kivilinna.
      - include/nuttx/fs/fs.h: Fix typo in conditional compilation.  From
        Alan Carvalho de Assis.

    * Graphics/Graphic-Related Drivers:

      - Remove warnings when CONFIG_NXTK_BORDERWIDTH is set to zero.  From
        Pierre-Noel Bouteville.

    * Common Drivers:

      - Make standard syslog and vsyslog POSIX compliant (also modify
        non-standard syslog functions for compatibility).
      - R/W buffering: Fix typo that can cause compilation error.

    * Atmel SAM3/4:

      - SAM4S: Add missing SPI0 clock configuration macro for the SAM4S.  From spasbyspas.

    * Atmel SAM3/4 Drivers:

      - SAM4E-EK: Fix an error in a USART1 pin number.

    * Atmel SAMA5D3/4 Drivers:

      - SAMA5DF4: Fix several typos that will prevented EMAC1 from
        initializing properly.

    * NXP LPC43xx:

      - Fixes to allow compile of lpc43_gpioint.c.  From Brandon Warhurst.

    * STMicro STM32:

      - Add missing ADC pinmap definitions for the STM32 F103R from Martin
        Lederhilger.

    * STMicro STM32 Drivers:

      - STM32 EXTI: Correct STM32 RTC EXTI bit definition.  From Lazlo.
      - STM32 IWDG, WWDG, DBGMCU: Fix watchdog stop bit usage.  From Lazlo.
      - STM32 OTGFS: Correct a typo in the STM32 OTGFS register bit definitions.

    * ARM:

      - ARM up_internal.h: Add protection from C++ name mangling in the
        ARM up_internal.h.  From Lorenz Meier.

    * MicroChip PIC32MX:

      - PIC32MX7: DEVCFG0 bit 2 must be set.  Writing bit 2 as zero can
        brick the CPU on some versions.  From Cris Kvist.

    * C Library:

      - The implementation of access() as vararg macro has the issue that
        any function call with the same name (even in a C++ class) will
        match with it and result in a compile error.  Replaced with a small
        function. This resolves the compile issue, and shouldn't have
        negative side effects for users of the function. From Lorenz Meier.
      - The definition of strncpy() is that empty space should be zero-
        filled, the change adds the zero filling (See the POSIX spec here:
        http://pubs.opengroup.org/onlinepubs/7908799/xsh/strncpy.html). From
        Lorenz Meier.
      - limits.h:  Remove the definition of INT_FAST32_MIN which is already
        defined in stdint.h (the correct location).  From Lorenz Meier.

    * Applications:

      - apps/: Correct everything under apps to use the corrected syslog
        interfaces.  Remove any non-portable uses of syslog.
      - NSH: Fix ls -l output for regular files.
      - NSH: Fix reversed in/out file closing in DD command when an error
        occurs.  From Ken Pettit.
      - NSH:  Add logic to restart the console wait if an error occurs
        while reading from the console.  In USB console startup, the logic
        must be able to open the USB serial and receive 3 newlines.
        However, it the USB driver is disconnected or otherwise fails before
        the 3 newlines are received, the receive loop becomes a killer,
        infinite loop, CPU hog.  Noted by spasbyspas.
      - Netutils: Fix memcpy of host address in netlib_gethostaddr().  From
        Brennan Ashton.
      - Netutils:  If you make a DNS request before the DNS address it would
        cause an assertion. The state of the IP setting is not something the
        application should be aware of, it should only be concerned with
        whether or not the name was resolved.  From Brennan Ashton.
      - Netutils: Fix md5 hashing when digest[$i] islower that 16. From
        Sergey.
      - Stack Monitor: Fix compile problems introduced when the syslog()
        prototype changed; Also update Makefile for kernel build From
        Radoslaw Adamczyk.
      - Examples: Update NxTerm makefile for kernel-build issues. From
        Radoslaw Adamczyk.
      - Examples: Fixes to keypadtest from Pierre-Noel Bouteville.
      - Examples: These examples all set the IP address of eth1 but the
        netmask and gateway of eth0 if DHCP is enabled:  discover, tcpecho,
        webserver, xmlrpc. That can't be right.

NuttX-7.7
---------

The 107th release of NuttX, Version 7.7, was made on January 26, 2015,
and is available for download from the SourceForge website.  Note
that release consists of two tarballs:  nuttx-7.7.tar.gz and
apps-7.7.tar.gz.  Both may be needed (see the top-level nuttx/README.txt
file for build information).

Additional new features and extended functionality:

    * Core OS:

      - Task exit handling:  Add logic to clean up after task_delete() or
        pthread_cancel() if the task happens to be waiting on a semaphore
        when was is cancelled.
      - Stack coloration:  Removed CONFIG_DEBUG_STACK and replaced it with
        CONFIG_STACK_COLORATION that does the same thing but without enabling
        debug.  From David Sidrane.

    * Common Drivers:

      - Discrete joystick driver: Added an interface definition and upper
        half driver for a discrete joystick device (where X/Y changes are
        indicated with button presses).
      - Analog joystick driver: Added an interface definition and upper
        half driver for a analog joystick device (where X/Y positions are
        sampled, numeric values).
      - Add driver support for the ADXL345 accelerometer.  From  Alan
        Carvalho de Assis
      - Generic serial driver:  Add watermark levels to the serial RX flow
        control logic.  Modify the rxflowcontrol method to accept the number
        of bytes in the buffer and a boolean indication of which watermark
        was crossed.

    * File Systems/Block Drivers/MTD:

      - Add procfs write support.  From Ken Petit.
      - Implemented wear-leveling in the SmartFS.  From Ken Pettit.
      - MMC/SD Interface: MMCSD SDIO:  Add support for a new
        SDWAIT_WRCOMPLETE condition.  The previous logic used a busy-wait
        loop to poll the card R1 status to determine when the card was
        ready for the next transfer.  That busy-wait can be quite long --
        up to hundreds of milliseconds.  An alternative is to look the SD D0
        pin which will change state when the card is no longer busy.  This
        change avoids the busy-wait poll by reconfiguring the SD D0 pin as a
        GPIO interrupt, then waiting for the card to become ready without
        taking up CPU cycles. From David Sidrane.

    * Drivers:

      - Add support for a generic EEPROM driver that accesses EEPROM as a
        character driver (vs. an MTD driver).  From Sébastien Lorquet.

    * Graphics Support:

      - Many new fonts converted for use with NuttX and added by
        Pierre-noel Bouteville

    * Networking:

      - IPv4 support is now conditioned on CONFIG_NET_IPv4.
      - Implemented and verified IPv6 support conditioned on
        CONFIG_NET_IPv6.  Either IPv4 or IPv4 or both may be selected.
        Sockets, of course, must be bound to one or the other. Added support
        for IPv6 ioctls to manipulate IP addresses.
      - Integrated support for ICMPv6 and the ICMPv6 Neighbor Discovery
        Protocol and ICMPv6 ECHO request/reply needed to support ping logic.
      - All Ethernet drivers:  Modified to support.  Most, however, are
        still missing address filtering logic required for ICMPv6 Neighbor
        Discovery Protocol.  See
        https://cwiki.apache.org/confluence/display/NUTTX/IPv6
      - Also added missing raw/packet socket support to all Ethernet drivers.

    * Host Simulation:

      - Add a configuration build and test the Traveler first person game
        using the simulator.
      - Add an X11 mouse-based simulation of an analog joystick device

    * Atmel SAMA5D Boards:

      - Add analog Joystick shield support for the SAMA5D3 Xplained board.

    * Freescale KL Drivers:

      - Add GPIO interrupt capability for the KL architecture. From Alan
        Carvalho de Assis

    * Freescale KL Boards:

      - Freedom-KL25Z: Add board support for the ADXL345 accelerometer. From
        Alan Carvalho de Assis
      - Freedom-KL25Z: Update the Freedom KL25Z board CC3000 support to use
        the current CC300 interfaces.  From Alan Carvalho de Assis

    * NXP LPC43xx Boards:

      - A port of NuttX to the LPC4357-EVB from Toby Duckworth.  This port
        is a leverage of the LPC3330-Xplorer port and still have a some
        misinformation from that port that needs to be updated for the
        LPC4357-EVB.

    * SiLabs EFM32 Drivers:

      - Serial: Add support for serial termios TCGET and TCSET.  For the
        moment, only set/get speed is implemented.  From Pierre-noel
        Bouteville.
      - RMU: Add support for the EFM32 reset management unit (RMU).  From
        Pierre-noel Bouteville.

    * SiLabs EFM32 Boards:

      - Add support for timer/PWM on the EFM32GG.  From Pierre-noel
        Bouteville

    * STMicro STM32:

      - Enable support for the STM32 F102.  From the PX4 team.

    * STMicro STM32 Drivers:

      - STM32 F429 LTDC: Add interface to perform hardware accelerated layer
        operation. Provides access to a reference of a specific ltdc layer.
        From Marco Krahl
      - STM32 F429 LTDC support: Implemented LTDC framebuffer support for the
        generic nuttx framebuffer interface. Also implements the interface to
        perform hardware accelerated layer operation by the ltdc controller
        and dma2d controller later. From Marco Krahl.
      - STM32:  Add support for the internal low speed clock (LSI) as a
        source of the RTC clock.  Some  boards do not have the external
        32kKhz oscillator installed, for those boards we must fallback to
        the crummy internal RC clock.  From Kevin Hester
      - STM32 SDIO:  Add support for the new SDWAIT_WRCOMPLETE condition.
        From David Sidrane

    * STMicro STM32 Boards:

      - Add a discrete Joystick support for the STM3210E-EVAL.
      - Add analog Joystick shield support for the Nucleo F4x1RE boards.
      - STM32 F429i-Disco:  Add support for initializing of the ltdc
        controller and the lcd device connected on the stm32f429i-disco.
        From Marco Krahl.
      - Removed the px4-v2_upstream configuration.  This was not the
        official configuration for the PX4 board and has led to confusion
        by NuttX users.  The board configuration also requires some ongoing
        maintenance and customization to support ongoing PX4 testing and
        evaluation.  It is best retained the PX4 repositories where it can
        be properly maintained and not in the upstream NuttX repository.

    * TI Tiva:

       - Add support for the TI Tiva TM4C 129X family.  Some unverified
         support for the TM4C 1294 is also in place.

    * TI Tiva Drivers:

      - Added support for Tiva I2C driver.  Verified on the Tiva TM4C123G
        and TM4C129X.
      - Added a Tiva TM4C129X Ethernet driver.
      - Add a timer library for generic support of Tiva timers
      - Add a driver lower half for drivers/timer.c.  Only 32-bit periodic
        timers are supported.  This provides userspace access to timers.

    * TI Tiva Boards:

      - TM4C123G Launchpad:  Add initialization logic for an external AT24
        EEPROM.  This is intended only to support testing of the Tiva I2C
        driver.
      - Board support for the Tiva DK-TM4C129x Connected Development Kit.
      - DK-TMC129X:  Add an IPv6-enabled NSH configuration.

    * C Library/Header Files:

      - Added support for a variadic ioctl() function.  The ioctl()
        interface is a non-standard, Unix interface.  NuttX has always used
        the older, three-parameter version.  Most contemporary systems now,
        however, use a variadic form of the ioctl() function.  Added an
        option to insert a shim layer to adapt the three-parameter ioctl()
        to use the variadic interface form.  Internally, the ioctl handling
        is the same three-parameter logic.  The only real complexity to the
        shim is in how the system calls must be handled.
      - Added sys/custom_file.h.  Used when CUSTOM_FILE_IO is define and
        avoids  re-definition errors about the FILE define.  From Thomas
        Gruber via the PX4 repository
      - Add CRC8 support to the C library. From Ken Pettit.
      - math.h: Added support for the expm1 functions. From Brennan Ashton

    * Applications:

      - apps/examples/djoystick:  Add a test of the discrete  joystick
        driver.
      - apps/examples/ajoystick:  Add a test of the analog joystick
        driver.
      - apps/examples/ltdc: Add ltdc test example. From Marco Krahl
      - apps/system/lm75:  Add a tiny application to read the temperature
        from an LM-75 (or compatible) temperature sensor
      - apps/examples/timer:  Add a trivial test of the timer driver

      - apps/system/cu: Add a minimalist implementation  of the 'cu'
        terminal program (part of Taylor UUCP for ages). Using it, you can
        simply open a serial port and interact with it. Using '~.' you can
        leave the terminal program and drop back to nsh.  This  might come
        in handy for people that have e.g. GSM modems, GPS receivers or
        other devices with text based serial communications attached to
        their NuttX systems. From Harald Welte
      - apps/interpreters/micropython:  A port of Micro Python to NuttX.
        Contributed by Dave Marples

      - apps/netutils/dnsclient:  Can select to be either IPv4 or IPv6, but
        not both (IPv6 still does not compile)
      - apps/netutils/netlib:  Add new library functions to manipulate IPv6
        addresses.
      - apps/examples/nettest:  Update test so that it can be used to test
        IPv6 TCP sockets
      - apps/examples/udp:  The UDP test example has been extend to support
        IPv6 domain sockets

      - apps/nshlib:  Add logic to initialize IPv6 addresses
      - apps/nshlib:  Add the ping6 command to support checking IPv6 networks.
      - apps/nshlib: Clean up network status presentation for IPv6

Efforts In Progress.  The following are features that are partially
implemented but present in this release.  They are not likely to be
completed soon.

    * IPv6.  While basic IPv6 support was completed in NuttX-7.7,
      there are lingering issues with getting IPv6 compatibility
      with applications and network utilities.

    * Processes.  Much of the work in this release is focused on the
      realization of Unix-style user processes in NuttX.  There is more to
      be done, however.  The full roadmap and status is available at:
      https://cwiki.apache.org/confluence/display/NUTTX/Memory+Configurations

    * XMega:  There are some fragments in place for an XMega port.  That
      port has not really started, however.

    * Galileo:  Similarly, there are fragments in place for an Intel Galileo
      port.  The port probably will not happen (I gave my Galileo board away!).

Bugfixes.  Only the most critical bugfixes are listed here (see the
ChangeLog for the complete list of bugfixes and for additional, more
detailed bugfix information):

    * Core OS:

      - POSIX message queues: msg type should be char * not void * in
        mq_send, mq_timedsend, mq_receive, and mq_timedreceive.  Noted by
        Pierre-Noel Bouteville
      - POSIX message queues: In message queue creation return ENOSPC error
        if size exceeds the configured size of pre-allocated messages; Use
        ENOSPC vs ENOMEM per OpenGroup.org.  From Pierre-Noel Bouteville.
      - Task Names: strncpy() will not copy the terminating \0 into the
        destination if the source is larger than the size of the
        destination. Ensure that the last byte is always zero and let
        strncpy() only copy CONFIG_TASK_NAME_SIZE bytes. The issue of
        unterminated names can be observed in ps when creating a pthread
        while CONFIG_TASK_NAME_SIZE is set to 8.  From  Daniel Willmann

    * Memory Management:

      - Granule allocator: Fixes some issues found by the PX4 team using
        Coverity.  From Pavel Krienko

    * Networking:

      - Several fixes correcting issues with the CC3000 networking.  From
        Jussi  Kivilinna
      - CC3000 Fix: Data can be unaligned.  When dereferenced as an input
        ntosh(), a bad value is returned.  Reported by Alan Carvalho de
        Assis
      - Correct naming of fields in struct sockaddr_in6:  sin6_port and
        sin6_family, not sin_port and sin_family.
      - accept(): Correct the value returned by accept() in the case where
        net_lockingwait() is called.  It was returning -1 and losing the
        errno value.  Noted by Rony Xln

    * Common Drivers:

      - Loop device should return -EINTR is interrupted by a signal.
      - M25P serial flash driver:  Add subsector size of the M24P16 part.
        From Lazlo
      - Common serial driver: In case a thread is doing a blocking operation
        (e.g. read()) on a serial device, while it is being terminated by
        pthread_cancel(), then uart_close() gets called, but the semaphore
        is still blocked. This means that once the serial device is opened
        next time, data will arrive on the serial port (and driver
        interrupts handled as normal), but the received characters never
        arrive in the reader thread.  The problem was fixed by re-
        initializing the semaphores on the last uart_close() on the device.
        From Harald Welte
      - Pipes: Fixes some issues found by the PX4 team using Coverity.  From
        Pavel Krienko
      - CDC/ACM driver: Fixes some issues found by the PX4 team using
        Coverity.  From Pavel Krienko

    * NXP LPC43xx Drivers:

      - LPC4357: Changes required to get USART 2 & 3 working on the
        lpc4357-evb.  From Toby Duckworth.

    * STMicro STM32:

      - Several fixes correcting issues with the STM32 header files from
        Jussi Kivilinna

    * STMicro STM32 Drivers:

      - Ported Tridge's STM32 I2C noise resilience logic from the PX4
        repository.
      - STM32 F2 and F4:  Set the GPIO_SPEED_50MHz on all F2 and F4 SPI pin
        configurations.  This is based on an F411 SPI1 errata but the fixed
        is generalized to all SPI and all F2 and F4.  Discovered and fixed
        by Sebastien Lorquet.
      - Fix for STM32 OTGHS device driver working in FS mode.  From Ken
        Pettit.
      - For STM32 OTG HS DEV (in FS mode): Disable ULPI clock enable in RCC
        AHB1 Register.  If Both ULPI and the FS clock enable bits are set in
        FS mode, then the ARM never awakens from WFI due to a chip issue.
        This is only an issue if you are using the internal PHY.  From Ken
        Pettit.
      - STM32 F429 LTDC: Add missing clut register definition. From Marco
        Krahl
      - STM32 serial: fix declaration and definition of up_receive() and
        up_dma_receive() to match fields in the interface definition of
        struct uart_ops_s.  From Freddie Chopin.

    * TI Tiva Drivers:

      - Fix Tiva IRQ control logic; was limited to only 64 IRQs.  That is a
        problem for higher numbered IRQs on many platforms

    * C Library/Header Files:

      - avsprintf():  Fix a bug in usage of va_list on x86.  On x86,
        va_list is a pointer to a single copy on the stack.  avsprintf()
        calls lib_vsprintf() twice and so traverses the va_list twice using
        va_start.  va_start modifies that single copy on the stack so that
        the second call to lib_vsprintf() fails.  This appears to be an
        issue with x86 only so far.
      - stdint.h:  Don't use hex values to specify minimum values of fixed
        width, signed values.  Hex values are inherently unsigned and not
        usable for this purpose in all contexts.
      - strncpy():  Would trash a lot of memory if n == 0.  From Yasuhiro
        Osaki.
      - sscanf().  Accept %X and %F as well as %x %f as a format specifiers.
        From Sébastien Lorquet

    * Applications:

      - apps/examples/romfs: fix romfs example builtin app registry issue.
        From Librae
      - apps/system/cdcacm, composite and usbmsc:  Fix some strangely placed
        conditional compilation.  Looks like an automated update went awry
      - apps/netutils/telnetd:  Add protection when CONFIG_SCHED_HAVE_PARENT
        is enabled:  Call sigaction with SA_NOCLDWAIT so that exit status is
        not retained (no zombies) and block receipt of SIGCHLD so that
        accept is not awakened by a signal.  If accept() is awakened by a
        signal, do not do anything crazy like exit.  Most from Rony Xln
      - apps/nshlib/: NSH TFTP get command:  Wrong file name used for the
        destination.  From Lazlo

NuttX-7.8
---------

The 108th release of NuttX, Version 7.8, was made on February 11, 2015,
and is available for download from the SourceForge website.  Note
that release consists of two tarballs:  nuttx-7.8.tar.gz and
apps-7.8.tar.gz.  Both may be needed (see the top-level nuttx/README.txt
file for build information).

This release is primarily a bugfix release for the NuttX-7.7 version that
was release just two weeks prior.  That release included substantial
modifications in the NuttX networking to accommodate support for IPv6.  This
release follows close behind NuttX-7.7 in order to correct some the problems
discovered in that networking code.  This release does, however, include a
small number of new features and bug fixes unrelated to NuttX networking.

Additional new features and extended functionality:

    * Core OS:

      - Tickless Mode:  added limit of maximum delay that can be request
        by the scheduler tickless logic.  This is necessary so that the
        tickless logic does not request a delay beyond the capability of the
        underlying hardware.  From Macs Neklyudov.

    * Common Drivers:

      - VFS Unlink: Add an unlink method to both the character and block
        driver interface.  This is important because if the driver inode is
        unlinked and there are no open references to the driver, then the
        driver resources will be stranded.  On the unlink call, the driver
        has the opportunity (1) check if there an any open references, and
        if not, (2) free the driver resources.
      - Pipes and FIFOs:  Implement the unlink method.  If the pipe/FIFO is
        unlinked, it will marked the pipe/FIFO as unlinked.  If/when all
        open references to the driver are closed, all of the driver
        resources will be freed.
      - Added an option to use the syslog'ing device as the system console.
        This option enables a low-level, write-only console device at
        /dev/console (similar to the low-level UART console device).  From
        Pierre-noel Bouteville.

    * File Systems/Block Drivers/MTD:

      - RAM/ROM disk:  Add logic to dispose of the driver and RAM buffer
        when the RAM disk has been unlinked and all open references to the
        RAM disk have been closed.  Add new parameters to romdisk() to
        specify what should be done with the RAM/ROM buffer in this case --
        Should it be freed or not?  Changed all calls to ramdisk() to use
        these new parameters.

    * Networking:

      - Add support for local, Unix domain sockets.  Support included for
        both SOCK_STREAM and SOCK_DGRAM style local socket.
      - UDP enhancement:  Add UDP read-ahead support.  In addition to
        eliminating the main reason for lost UDP packets, then change
        enables support for for poll/select on UDP sockets and also non-
        blocking UDP sockets.  From Macs Neklyudov.
      - SLIP interface improvements.  From Macs Neklyudov.
      - IPv6 Neighbor Solicitation: Added logic to support verification
        that we have the IPv6 address in the Neighbor Table before sending
        any packets.  If not, then the Neighbor Solicitation message is
        sent.  This feature is important because otherwise the first packet
        sent to a remote peer will fail (it would have been replaced with a
        Neighbor Solicitation).
      - IPv6 Autonomous Auto-Configuration:  Added support for sending
        ICMPv6 Router Solicitation and receiving Router advertisement.  The
        local IPv6 address, mask, and router address are then auto-configured
        from the response..
      - IPv6 Router Support:  Add logic to behave like a router (if so
        configured) only in the sense that NuttX will send the router
        advertisement message in response to any received router solicitation
        messages.  Thus, one NuttX node in a network can configure the IPv6
        addresses of all other nodes in the network.
      - Optional IPv6 address filtering added to all Ethernet drivers for
        the all-routers multicast address.

    * Atmel AVR:

      - Added architecture support for the Atmel AVR ATMega1284P MCU.  From
        Jedi Tek'Unum.

    * Atmel AVR Boards:

      - Added support for the LowPowerLab MoteinoMEGA that is based on the
        Atmel AVR ATMega1284P MCU.  From Jedi Tek'Unum.

    * Atmel SAMA4:

      - Add support for Tickless mode of operation for the SAM4CM platform.
        From Macs Neklyudov.

    * Atmel SAMA4 Drivers:

      - Ethernet: The SAM4E Ethernet driver can now be configuration to
        perform all network processing on the work queue.  This greatly
        reduces the amount of interrupt level processing to service Ethernet
        packets.
      - SAM4E Ethernet: Add support multicast address matching and IPv6.

    * Atmel SAMA4 Boards:

      - SAM4E-EK: The nsh configuration now configures the Ethernet driver
        for execution on the work thread.

    * Atmel SAMA5D Drivers:

      - SAMA5D4 Ethernet: The SAMA5D4 Ethernet driver can now be configuration
        to  perform all network processing on the work queue.  This greatly
        reduces the amount of interrupt level processing to service Ethernet
        packets.
      - SAMA5D3 and SAMA5D4 Ethernet: Add support multicast address matching
        and IPv6.

    * Atmel SAMA5D Boards:

      - SAMA5D4-EK;  Added a configuration to testing IPv6.
      - SAMA5D4-EK:  Converted the nsh and ipv6 configurations to configure
        the Ethernet driver to use the work queue (vs. interrupt level
        processing).

    * Freescale KL:

      - Add architectural support for the K26Z128VLH4 chip.  From Derek B. Noonburg.

    * Freescale KL Boards:

      - Add board support for the Freedom KL26Z board.  From Derek B. Noonburg.

    * NXP LPC17xx Drivers:

      - Ethernet: Add support multicast address matching and IPv6.

    * SiLabs EFM32:

      - Add configurable option to unconditionally enable LE clocking. Even
        you don't use core clock LE as source for LFA or LFB, to read are
        write any register not clocked by HFPERCLK or HFCORECLK,  HFCORECLKLE
        should be enabled.  From Pierre-noel Bouteville.

    * SiLabs EFM32 Drivers:

      - EFM32 RTC:  RTC driver using BURTC. From Pierre-Noel Bouteville.

    * STMicro STM32 Drivers:

      - AES: Add driver for STM32L162XX AES peripheral.  From Juha Niskanen.
      - Ethernet: The STM32 Ethernet driver can now be configuration to
        perform all network processing on the work queue.  This greatly
        reduces the amount of interrupt level processing to service Ethernet
        packets.
      - Ethernet: Add support multicast address matching and IPv6.

    * STMicro STM32 Boards:

      - Added an IPv6 configuration for the STM32F4-Discovery board (with the
        STM32-DISCO_BB base board).
      - Converted all STM32F4-Discovery configurations (with base board) to
        configure the Ethernet driver to use the work queue (vs. interrupt
        level processing).

    * TI Tiva Drivers:

      - Added support for TM4C123G timers.  From Calvin Maguranis.
      - Added a Tiva ADC driver.  From Calvin Maguranis.

    * TI Tiva Boards:

      - Added TM4C123G timers on the TM4C123G Launchpad.  From Calvin Maguranis.
      - Added Tiva ADC support to the TM4C123G-Launchpad.  From Calvin Maguranis.

    * C Library/Header Files:

      - Math Library: Added support for inverse hyperbolic functions,
        isfinite(), error functions, nan(), copysign(), and trunc()
        functions.  From Brennan Ashton.

    * Applications:

      - apps/examples/ustream:  Add a simple test of Unix domain stream
        sockets.
      - apps/examples/udgram:  Add a simple test of Unix domain datagram
        sockets.
      - apps/netutils/netlib:  Add utilities to convert to/from prefix
        lengths from/to 128-bit network masks.
      - apps/nshlib: Modify the NSH IPv6 ifconfig command to show the more
        standard post-pended prefix value, rather than the full 128-bit
        netmask.

Efforts In Progress.  The following are features that are partially
implemented but present in this release.  They are not likely to be
completed soon.

    * Processes.  Much of the work in this release is focused on the
      realization of Unix-style user processes in NuttX.  There is more to
      be done, however.  The full roadmap and status is available at:
      https://cwiki.apache.org/confluence/display/NUTTX/Memory+Configurations

    * XMega:  There are some fragments in place for an XMega port.  That
      port has not really started, however.

Bugfixes.  Only the most critical bugfixes are listed here (see the
ChangeLog for the complete list of bugfixes and for additional, more
detailed bugfix information):

    * Core OS:

      - Work Queues:  Fix a backward calculation when determining the time
        to the next interesting event. .  From Liio Chen via the PX4
        repository.
      - clock_systimespec():  Fixes for compilation errors in certain
        configurations.  From Macs Neklyudov.

    * Graphics

      - Fixed a problem with one of the font files.  From Pierre-noel Bouteville.

    * Networking:

      - IOB Deadlock: There were issues with the TCP write-ahead buffering
        if CONFIG_NET_NOINTS was enabled:  There is a possibility of
        deadlocks in certain timing conditions:  The network should never
        wait for TCP read-ahead buffering space to be available.  It should
        drop the packets immediately if no buffering is available. This was
        fixed by duplicating most of the IOB interfaces:  The versions that
        waited are still present (like iob_alloc()), but now there are non-
        waiting versions of the same interfaces (like iob_tryalloc()).  The
        TCP read-ahead logic now uses only these non-waiting interfaces.
      - TCP Deadlock: Fix another deadlock when CONFIG_NET_NOINTS is enabled.
        tcp_write_buffer_alloc() calls sem_wait() with network locked.  That
        worked if CONFIG_NET_NOINTS was not defined because interrupts are
        automatically restored when the wait happens.  But with
        CONFIG_NET_NOINTS=y, the wait blocks with the network locked -- bad
        style and also can lead to a deadlock condition.
      - ARP response waiting: Fixes another CONFIG_NET_NOINTS issue.  When
        called sem_timedwait() with the network locked, the network stays
        locked while we wait which is not what we want (without CONFIG_NET_NOINTS,
        interrupts are re-enabled while we wait and all is well).
      - TCP accept():  Fix a major TCP bug introduced with the NuttX-7.7
        IPv6 changes:   Some connection logic was reordered; setting the
        socket as 'connected' got moved to BEFORE the point where the check
        was made if the socket was already connected.  The resulting behavior
        was odd:  Telnet would connect, but then when you exit and reconnect,
        it would fail to connect.  But then if try again, it would connect
        okay. So the symptom was connect-fail-connect-fail-...
      - Lots of build problems introduced into multiple NIC support with the
        IPv6 changes of NuttX-7.7.   Many places where conditional logic based
        on CONFIG_NETDEV_MULTINIC is  confused with CONFIG_NET_MULTILINK.
        Lots of code changed with IPv6 that was never compiled with MULTINIC
        enabled.

    * Common Drivers:

      - Pipes and FIFOs: Fix a race condition between FIFO buffer operations
        and the opening and closing of FIFOs which necessary when the FIFOs
        are used to support Unix domain, datagram sockets.  The default
        policy is the deallocate FIFO buffering when the last client closes
        the pipe.  When when used for datagram communications, packets left
        in the FIFO will be lost. Some like UDP read-ahead is needed:  The
        buffered data in the FIFO needs to be retained until the reader gets
        a chance to re-open the FIFO.  Added an ioctl (PIPEIOC_POLICY) to
        control the buffer policy.  Default (0) is the legacy behavior; Unix
        domain datagram logic sets the alternative policy so that the packet
        data persists after the FIFO is closed.
      - RAMTRON:  Table of parts is not terminated properly if
        CONFIG_RAMTRON_FRAM_NON_JEDEC is not defined.  Noted by David
        Sidrane.

    * All Architectures:

      - Removed all occurrences of up_maskack_irq() that disables interrupts
        with up_ack_irq() that only acknowledges the interrupts.  This is only
        used in interrupt decoding logic.  Also remove the logic that
        unconditionally re-enables interrupts with the interrupt exits.  This
        interferes with the drivers ability to control the interrupt state.
        This is a necessary, sweeping, global change and unfortunately
        impossible to test.

    * ARM

      - ARMv7-A and ARMv7-M memcpy(): Optimized ARM assembly language
        memcpy's were not returning a value in R0 they are required to do.
        From David Sidrane.
      - ARMv7-A interrupt handler should not automatically re-enable interrupts
        on interrupt return.  That interferes with the driver's ability to
        manage interrupts.  Analogous change made to all other architectures
        as well (ARM7, ARM9, HC, SH, x86, z16, z80, etc,.  See above.).

    * STMicro STM32:

      - GPIO Interrupts: Disabling any of EXTI 5-9 interrupts was disabling
        interrupts for all EXTI 5-9. Same issue with EXTI 10-15.  From Jussi
        Kivilinna.

    * STMicro STM32 Drivers:

      - RTCC:  Fix for recent changes that caused compilation failrues with
        STM32L15XX configurations.  From Jussi Kivilinna.
      - SPI: The source clock for SPI 4,5, and 6 should be PCLK2, not PCLK1
        (for F411, F427, and F429).  Per David Sidrane.

    * C Library/Header Files:

      - execl():   Fix bad logic in counting the number of arguments.
        execl() parameter passing could never have worked.  Noted by
        Pierre-noel Bouteville.

    * Applications:

      - Fix for building with parallel make. Build-server sometimes failed
        'make -j24' with errors in the builtin line or or sometimes silently
        succeeds but generated builds that contain a random subset of
        configured NuttX applications. There are two root causes for this:
        (1) Recipes for building builtin_list.h and builtin_proto.h are
        not linearizable, and (2) Nothing ensures that 'make context' is run
        first for apps/builtin.  This change address both issues. From Juha
        Niskanen.

NuttX-7.9
---------

The 109th release of NuttX, Version 7.9, was made on April 14, 2015,
and is available for download from the SourceForge website.  Note
that release consists of two tarballs:  nuttx-7.9.tar.gz and
apps-7.9.tar.gz.  Both may be needed (see the top-level nuttx/README.txt
file for build information).

Additional new features and extended functionality:

    * Core OS:

      - Assertions: Add support for dumping board-specific information on
        assertions. From David Sidrane.
      - boardctl(): :  Add a new non-standard OS interface called boardctl().
        This is similar to a driver IOCTL call.  But this is an IOCTL call
        directly on the board logic.  This function will eventually replace
        all of the ad hoc OS interfaces that are current used to perform
        application specific initialization and application driver test
        configuration.  It essentially formalizes and institutionalizes
        these rogue interface in to at least a single crazy call.

    * Graphics:

      - Line Joins:  Line drawing graphic functions now take an argument that
        will draw a circular "cap" on the ends of lines to support cleaner
        joining of lines segments..

    * Common Drivers:

      - SPI iInterface:  Add an SPIDEV_USER so that there can be board-
        specific definitions of SPI devices.
      - I2C Interface:  Add a user provided void * argument to the I2C
        callback method for the I2C slave interface.  Suggested by Nate
        Weibley.
      - AT24 EEPROM Driver: Add support for (1) the byte-oriented read()
        method, (2) devices that have extended memory regions, and (3)
        devices that use 8-bit addressing.
      - Freescale MPL115A barometer: Add driver for the Freescale MPL115A
        barometer.  From Alan Carvalho de Assis.
      - CS2100-CP: Add a driver for the CS2100-CP Fractional-N Multipler
        chip.
      - RTC IOCTls:  Added the definitions of a driver based RTC interfaces
        and RTC upper half driver.

    * File Systems/Block Drivers/MTD:

      - umount2():  Added to support un-mount flags. umount() is now a macro
        that just calls umount2() with flags = 0.
      - File system interface: Pass the umount2() flags to every unbind()
        implementation.  That is where the decision to umount or not and how
        to umount will be made.
      - FAT unbind: Add support for umount2(target, MNT_FORCE) in the FAT
        file system.

    * Networking:

      - netdev_register(): Improve the network device registration logic.
        When multiple link types are used, modify how each interface number
        is assigned to the device name by incrementing the device number
        individually for each interface link type.  From Max Neklyudov.
      - Add TUN network device.  Used to support the Netutils PPPD
        implementation. From Max Neklyudov.

    * ARMv7-M

      - ARM Cortex-M7:  Add basic support for the Cortex-M7 architecture.
      - ARMv7 Common Lazy Exception handling. Add common support for lazy
        FPU state saving.  MCU-specific lazy FPU saving was already in place.
        This change just makes the code share-able.

    * Atmel SAMA5D3/4 Drivers:

      - SAMA5 Serial:  Backport support for flowcontrol and termios from
        SAM3/4.

    * Atmel SAMV7:

      - Atmel SAMV7:  Add architecture support for the Atmel SAMV7 family
        (Cortex-M7)

    * Atmel SAMV7 Boards:

      - Atmel SAMV71 Xplained Ultra:  Add board support for this SAMV7 board.
        This initialize release includes support for: SDRAM, TWI/I2C, SPI,
        Ethernet, HSMCI, DMA, GPIOs, UARTs, AT24 EEPROM and the maXTouch
        Xplained Pro LCD.  Drivers are available for SSC/I2C, the WM8904,
        the maXTouch trouchscreen, and USB device but have not yet been
        fully integrated in this release.

    * SiLabs EFM32 Drivers:

      - EFM32 USB Device is now functional with the efforts of From Pierre-
        noel Bouteville.
      - EFM32 I2C:  Add I2C driver.  From Pierre-noel Bouteville.

    * STMicro STM32:

      - STM32F372/F373: Adds architecture support for this STM32 parts.
        Tested on STM32F373CC.  Contributed by  Marten Svanfeldt.

    * STMicro STM32 Drivers:

      - STM32 RTCC: Break out a new internal interface, stm32_rtc_setdatetime().
        This eliminates some un-necessary time conversions.  From Freddie Chopin.
      - STM32 RTCC: Add an implementation of the RTC lower half interface
        for the STM32.
      - STM32 RTCC: Extend the RTC interface to support reading subseconds.
        From Jussi Kivilinna.
      - STM32 BBSRAM: Adds the ability to use the STM32F2 and STM32F4 Battery
        Backed SRAM in the file system. With an option to Save Panic context
        to one of the files. From David Sidrane.

    * STMicro STM32 Boards:

      - Olimexino-STM32: Board support for the Olimexino STM32 board from David
        Sidrane.
      - Viewtool-STM32F107:  Add support for an optional, add-on Freescale
        MPL115A baramoter.  From Alan Carvalho de Assis.

    * TI Tiva:

      - TM4C1294:  Add support for the TM4C1294.  Contributed by Frank Sautter.

    * TI Tiva Drivers:

      - Tiva ADC:  Updated files to allow for ADC and PWM triggering by a
        timer.  Refactoring of ADC implementation.  From Calvin Maguranis.
      - Tiva Timer: Refactoring by Calvin Maguranis

    * TI Tiva Boards:

      - TM4C123G-launchpad: Add ADC support.  From Calvin Maguranis.
      - TM4C123G-launchpad: Add board button interrupt support.  From Calvin
        Maguranis.
      - TM4C1294 Launchpad:  Add support for the TM4C1294 Launchpad.
        Contributed by Frank Sautter.

    * Microchip PIC32

      - PIC32MZ:  Add architectural support for the PIC32MZ (MIPS32 M14k).
        Includes contributions from Kristopher Tate.

    * Microchip PIC32MZ Boards

      - PIC32MZ Starter Kit: Add basic board support for the PIC32MZ.
        Includes contributions from David Sidrane.

    * C Library/Header Files:

      - gettimeofday():  This function is no longer a core OS interface.  It
        is only a wrapper around clock_settime().
      - settimeofday(): Added. gettimeofday has been deprecated in POSIX
        2008. settimeofday() was never part of POSIX, but I decided to add
        it to libc as well just for symmetry.
      - Day-of-Week: Add CONFIG_TIME_EXTENDED to support the last 3 members
        of the tm struct and support for filling them in with the day of the
        week. From David Sidrane.
      - sighold(), sigrelse(), sigignore(), sigset() and sigpause():  New
        signal handling functions.
      - sys/select.h: Extend the fd_set type definition so that it can
        handle more than 32 descriptors (if so configured).  From Max
        Neklyudov.
      - netdb.h:  Add a mostly-commented-out version of the standard netdb.h
        header file.
      - include/nuttx/board.h:  Remove common board function prototypes from
        other files and consolidate them in this new header file.

    * Applications:

      - OS test: Improved error checking for sem_timedwait() from Juha
        Niskanen.
      - OS test: Add a simple test of sigprocmask, sighold, and sigrelse.
      - PPPD test:  Add PPPD test case.  Split out from the PPPD daemon by
        Brennan Ashton.
      - Netutils: Add a PPP daemon.  From Max Neklyudov.
      - NSH:  NSH initialization now calls boardctl(BOARDIOC_INIT) instead
        of nsh_archinitialize().   Remove support for CONFIG_NSH_ARCHMAC.
        It is not used and there are better ways to do that operation.
      - NSH:  Allow NSH 'date' command with no hardware RTC.  This command
        is useful without an RTC too.  Also, this permits testing on the
        simulator which never has an RTC.
      - apps/examples/:  Several tests changed (touchscreen adc, pwm,
        graphics).  No longer call directly into the OS, but rather
        indirectly via boardctl().
      - Modbus: Includes extensions to support RTU master mode by
        Armink(383016632@qq.com): https://github.com/armink/FreeModbus_Slave-Master-RTT-STM32.
        Ported to NuttX by Darcy Gong.
      - TZ database:  All logic to build timezone database needed for
        localtime() support.  Does not do much else yet.

Efforts In Progress.  The following are features that are partially
implemented but present in this release.  They are not likely to be
completed soon.

    * Processes.  Much of the work in this release is focused on the
      realization of Unix-style user processes in NuttX.  There is more to
      be done, however.  The full roadmap and status is available at:
      https://cwiki.apache.org/confluence/display/NUTTX/Memory+Configurations

    * XMega:  There are some fragments in place for an XMega port.  That
      port has not really started, however.

Bugfixes.  Only the most critical bugfixes are listed here (see the
ChangeLog for the complete list of bugfixes and for additional, more
detailed bugfix information):

    * Core OS:

      - atexit(): Fix compile failure due to reference to undefined variable
        in certain configurations.  From Juha Niskanen.
      - syscalls: Last changes to message queue prototypes did not make it
        into call gate logic.  Some additional errors had crept as well since
        the system calls are seldom used.
      - waitpid(): Do not use uninitialized boolean in waitpid().  From Juha
        Niskanen.
      - Timing functions:  Fix some nanosecond comparisons.  Comparisons should
        be greater than OR EQUAL TO 1000000000 for maximum value of nanoseconds
        in struct tm.  From Juha Niskanen.
      - Time initialization: Fix an error in time initialization when there
        is no RTC and the time is initialized from a fixed configured value.
        The call to clock_calendar2utc() was returning the time in units of
        seconds.  The initialization logic, however, was expecting to get
        time in units of days.  This problem has been there forever but
        obviously has not significant impact to behavior in systems where
        time is not visible.
      - mq_timedsend():  Should not check for valid time if there is space
        in the message queue.  Noted by Freddie Chopin.
      - select() and sem_timedwait(): Fix places where the errno value was
        being overwritten by subsequent actions so that the returned errno
        value was incorrect.  From Max Neklyudov.
      - clock_systimer64(): Fix a problem in clock_systimer64 that occurs
        when (1) the 64-bit system time is enabled, and (2) the value of
        CONFIG_USEC_PER_TICK is less than 1 milliseconds (such as when using
        the tickless mode of operation).  In that case, the conversion of
        time to 64-bit millisecond value in clock_systmer64() causes some
        bad times to be returned.  Time was converted to milliseconds, then
        to configured ticks.  Precision was lost in the millisecond
        conversion. The fix is to first convert time to a 64-bit microsecond
        value, then to the configured tick value. Noted by David Sidrane.
      - clock_systimespec():  When an RTC is used clock_systimespec() must
        subtract the basetime from the returned time.  It needs to return
        the time since power up, no the current time.  Issue noted by Max
        Neklyudov.
      - AIO: correct some backward tests in aio_read() and aio_write():
        Socket descriptors have higher numbers than file descriptors.  In
        aio_contain(),  Copy u.ptr (void *) when initializing aioc and not
        the case specific u.aioc_filep.  From Michal Ulianko.

    * File Systems/Block Drivers/MTD:

      - procfs:  Fix potential NULL pointer dereference of 'node'.  From
        Juha Niskanen.
      - FAT: fat_unbind() was accessing 'fs->fs_sem' after freeing the 'fs'
        struct. From Juha Niskanen.
      - mkfatfs:  Use DMA memory for mkfatfs when needed. This makes mkfatfs
        use fat_dma_alloc() when CONFIG_FAT_DMAMEMORY is set. This is needed
        to ensure mkfatfs operates with boards that use DMA for microSD.
        From Andrew Tridgell via the PX4/NuttX repository.
      - FAT unmount: Fix a bug in the FAT unbind() logic.  There were
        problems with the way certain internal list handling was
        implemented. The end result is that newly opened or cloned file
        structures were never being added to the list of open files.  So
        when the unmount() happens, it always looked like there were not
        open files and a crash could ensue.
      - FAT mounting:  Fix misthink when CONFIG_ENDIAN_BIG=y.  From Lwazi Dube.

    * Common Drivers:

      - CAN upper half driver: Some lines had to be reordered in the can_open
        function otherwise the open count will only be incremented from 0 to
        1. This caused problems when trying to open the can bus from two
        different tasks. SourceForge Patch #46.

    * Crypto:

      - crypto:  Fix issues when AES support was added for the STM32L1.
        From Juha Niskanen.

    * Networking:

      - Network initialization: Divide net_intiialize() into net_setup() and
        net_initialize() to solve a chicken-and-egg problem.  net_setup()
        must be called before up_initialize() is called so that networking
        data structures are ready to register new network devices.
        net_initialize() now does only timer related operations and is
        called AFTER up_initialize() where the timers are configured.
        Problem noted by Max Neklyudov.
      - netdev_unregister():  Fix a list handling error.  From Max Neklyudov.
      - Socket dup: Do not call sockfd_socket() twice.  From Juha Niskanen.

    * Common Drivers:

      - max11802 touchscreen:  Fix possible unmatched IRQ restore (not
        normally a problem, but could happen in certain configurations).
        Noted by Juha Niskanen.
      - MMCSD SPI Multi-block transfers: ACMD23 must be preceded with CMD55
        command as any other ACMD commands. Also, after the block reading
        wait loop must be inserted before writing the next block of data to
        the sd card.  From Dmitry Nikolaev via Jussi Kivilinna.
      - MMCSD SDIO:  Fix some bad logic when file system debug is turned on:
        Arguments to syslog were missing so that garbage was being printed.
      - Common upper-half serial driver: Report correct number of bytes free
        in serial buffer with FIONWRITE.  From Sami Pelkonen via Jussi Kivilinna.
      - Pipes/Fifos: Fix zero-lenth writes to pipes/FIFOs. From Jussi Kivilinna.
      - USB device MSC: Add NULL pointer check.  From Juha Niskanen.
      - BCH driver: Avoid NULL pointer dereference when bch->refs  == 255.
        From Juha Niskanen.
      - Various drivers: The inode unlink method should not be support if
        operations on the root pseudo-filesystem are disabled.

    * ARMv7-M

      - ARMv7M MPU:  Bad syntax in ARMv7-M MPU logic would cause failure to
        write the correct value to the MPU_RASR register. From Juha Niskanen.

    * Atmel SAM3/4 Drivers:

      - SAM3/4 Serial TERMIOS:  A side-effect of changing serial settings
        via TERMIOS (such as tcsetattr) is that serial interrupts were being
        left disabled.  This is not a problem if the serial configuration is
        changed when there are no open references to the serial device.  In
        that case, serial interrupts are disabled and will not be enabled
        enabled until the serial device is first opened.  But it is fatal if
        the serial device is already opened and if there is a task waiting
        to receive data.  In that case, the side-effect of disabling
        interrupts is fatal:  That task is then left hanging with interrupts
        disabled.
      - SAM3/4 Serial: The IMR register is read-only.  This means that
        sam_restoreints() did not actually re-enable UART interrupts
        (Fortunately, that function was not being used up to this point).
      - SAMA5 HSMCI:  Fix a bug in SAMA5 HSMCI.  The bitfield mask and shift
        values were reversed resulting in a trashed value for the number of
        blocks in the BLOCKR register.  This was sufficient to prevent DMA
        writes from working.

    * Atmel SAMA5 Drivers:

      - SAMA5 Timer/Counter: Fix typos in timer/counter header file.  From
        Bob Doiron.

    * STMicro STM32 Drivers:

      - STM32 PWR and RTC: Changes to support fully write protecting the
        backup domain. N.B. stm32_pwr_enablebkp did not account for the delay
        from enable to the domain being writable. The KISS solution is a
        up_udelay. A more complex solution would be a negated write test
        with restore.  From David Sidrane.
      - STM32 SPI:  Add missing SPI callback functions to the STM32 SPI
        driver.  From Freddie Chopin.
      - STM32 I2C: Add missing NULL check.  From Juha Niskanen.
      - STM32 USB device: Fix stale initialization invalidating later NULL
        check.  From Juha Niskanen.
      - STM32 UART: Fix RX DMA setup for UART5.  From  Jussi Kivilinna.
      - STM32 UART: Make input hardware flow-control work with RX DMA.  From
        Jussi Kivilinna.
      - STM32 RTC and clock control:  The STM32F4Discovery board doesn't
        come with a Low speed external oscillator so the default LSE source
        for the RTC doesn't work. In stm32_rtcc.c the up_rtc_initialize()
        logic doesn't work with the LSI. The check on RTC_MAGIC on the BK0R
        register lead to rtc_setup() call that rightfully enables the LSI
        clock; but the next times, when the rtc is already setup, the
        rtc_resume() call does NOT start the LSI clock! The right place to
        put LSE/LSI initialization is inside stm32_stdclockconfig() in
        stm32fxxxxx_rcc.c.  Doing this I checked the possible uses of the
        LSI and the LSE sources: the LSI can be used for RTC and/or the
        IWDG, while the LSE only for the RTC (and to output the MCO1 pin).
        This change is not verified for any other platforms.  From Leo
        Aloe3132

    * Tiva Drivers:

      - Tiva GPIO driver needed small fixes in the configuration routines and
        discovered false-positive bugs in interrupt testing: interrupts are
        now verified to actually be working reliably. From Calvin Maguranis .

    * MIPS32:

      - mips32/Toolchain.mk: Current Pinguino toolchain uses the prefix p32-
        instead of mips-.

    * C Library/Header Files:

      - sigaddset() and sigdelset(): Need to set errno if a bad signal
        number is received.
      - sfrtime():  Missing implementation of %C in sfrtime() C (was being
        treated as %y).  From Freddie Chopin.
      - pthread.h: Fix PTHREAD_COND_INITIALIZER.
      - ungetc.c: Fix NULL pointer dereference in ungetc() if 'stream' was
        NULL, 'stream->fs_oflags' was evaluated.  From Juha Niskanen.
      - Fixes to asinh(), atanh(), and sinh():  The 'basic' expansions all
        exhibited bad cancellation errors near zero (<= 1E-10). This can be
        easily seen e.g. with x = 1E-30, the results are all zero though they
        should be extremely close to x. The cutoff values (1E-5, 1E-9) are
        chosen so that the next term in the Taylor series is negligible (for
        double). Functions could maybe be optimized to use only first term (x)
        and a smaller cutoff, just bigger than where the cancellation occurs
      - localtime(): Inconsistent configuration name: CONFIG_LIBC_TZDIR vs
        CONFIG_LIBC_TZ_TZDIR.  Former wins.

    * Applications:

      - Modbus:  Fix some compile problems when TCP is enabled.

NuttX-7.10
----------

The 110th release of NuttX, Version 7.10, was made on June 9, 2015,
and is available for download from the SourceForge website.  Note
that release consists of two tarballs:  nuttx-7.10.tar.gz and
apps-7.10.tar.gz.  Both may be needed (see the top-level nuttx/README.txt
file for build information).

Additional new features and extended functionality:

    * Binary Loader:

      - ARMv-7M, binfmt/, STM32: Add support uClibc++ exceptions.  This
        involved additional handling for relative relation types, additional
        support for unwinding, as well as additional changes.  The
        culmination of a big effort from Leo Aloe3132.

    * Graphics/Graphic Drivers:

      - RA8875 LCD driver contributed by Marten Svanfeldt.

    * File Systems/Block Drivers/MTD:

      - Union File System: Add support for a union file system that can be
        used to overlay and merge the content of two mounted file systems.

    * USB Host:

      - USB Hub Support: Bring in USB hub-related files from
        https://github.com/kaushalparikh/nuttx.  This is the work of Kaushal
        Parikh.  This is quite a bit more hub logic was needed in before the
        USB hub support was fully functional.  This involved changing many
        USB host controller driver interfaces and modifications to many
        drivers.
      - USB host CDC/ACM class driver:  Added initial implementation of a
        host-side CDC/ACM driver.  Initial version was a great learning
        experience, but probably should be partially redesigned (as
        discussed in the top-level TODO file).
      - IPv6 Routing: Complete implementation of the IPv6 routing logic.
        From Max Neklyudov.

    * Networking:

      - Local Sockets: Add poll support for Unix stream sockets.  From Jussi
        Kivilinna.
      - net/: ARP, ICMP, ICMPv6, PKT, TCP, and UDP now all receive event
        notifications from both network device packet processing, but now
        also from Device-specific events such as when the network goes down.
        The device notification callback structure is now supports dual
        linkages so that the client can receive notifications from both
        source; The device structure now includes a list of clients that
        want to receive device related notifications.  This prevents network
        actions from hanging when the device goes down and will be an
        essential part of future support for removable network devices.
        Some of the core logic was contributed by Max Neklyudov.
      - TUN: Misc. improvements to the TUN driver, mostly related to poll().
        Also several bugfixes. From Max Neklyudov.

    * Simulation Platform:

      - Simulator: Add logic to test localtime and TZ database.  See
        apps/system/README.txt for info.
      - Simulation:  Add a configuration for testing the Union File System.

    * Calypso:

      - Calypso Compal-E86: Updates for execution out of FLASH on the C139
        phone.  From Craig Comstock.

    * Atmel SAMD/L:

      - SAML21 Support: And chip definitions, configuration framework,
        memory map and pin configuration files for SAML21 support.

    * Atmel SAMD/L Boards:

      - SAML21-Xplained:  Add a board support for the SAML21 Xplained Pro.
        This is based on the similar SAMD20 Xplained Pro board.

    * Freescale/NXP KL:

      - KL25Z64: Added support for the KL25Z64.  The KL25Z64 is a lower
        memory variant of the KL25Z128 and is used on the Teensy LC.  From
        Michael as SourceForge patch 50.

    * Freescale/NXP KL Boards:

      - Teensy-LC: Add board support for the Teensy LC board.  Support is
        based off the Freedom KL25Z board.  LED, PWM, and UART0 have been
        tested. The SPI pins are mapped correctly but have not yet been
        tested.  From Michael Hope as SourceForge patch 51.

    * NXP LPC111x:

      - LPC111x:  Support for the LPC11xx family (the LPC1115 MCU in
        particular).  Contributed by Alan Carvalho de Assis.

    * NXP LPC111x Boards:

      - LPCXpresso LPC1115:  Support for the LPCXpression LPC1115
        board.  Contributed by Alan Carvalho de Assis.

    * NXP LPC17xx Drivers:

      - LPC17xx Ethernet: Add support for the Micrel KSZ8041 PHY to the
        LPC17xx Ethernet driver.

    * NXP LPC17xx Boards:

      - Lincoln60:  Add a network enabled configuration for the Lincoln60
        board.

    * Atmel SAM3/4 Drivers:

      - SAM4CM:  Add support for optical mode for the SAM4CM UART1.  From
        Max Neklyudov.

    * Freescale (NXP) Kinetis:

      - Kinetis K20: Basic support for the Kinetis K20 architecture.  Taken
        from PX4.  This is the work of Jakob Odersky.

    * Atmel SAMV7 Boards:

      - SAMV71-Xplained w/maXTouch Xplained Pro:  A TWIHS fix was the last
        barrier to getting the touchscreen working in the maXTouch Xplained
        Pro LCD.  Added the NxWM integrated graphics demonstration
        configuration.

    * STMicro STM32:

      - STM32: Added support for STM32F302K8 and STM32F302K6.  From Ben Dyer
        via PX4/David Sidrane.
      - STM32F205RG: Add basic support for the STM32F205RG.  From SourceForge
        Ticket 40 (anonymous, 2015-05-31).
      - STM32 F3:  Add DBGMCU register definitions for the F3 family.  From
        Greg Meiste.

    * STMicro STM32 Drivers:

      - STM32 LCDC: Defined a second interface for the dma2d controller.
        LTDC only controls the display visibility but the DMA2D controller
        changes the content of the frame buffer (buffer of the layer). From
        Marco Krahl.
      - STM32 PVD: Added support for STM32's Programmable Voltage Detector
        (PVD) feature. By Dmitry Nikolaev, submitted by Juha Niskanen.

    * STMicro STM32 Boards:

      - STM32F429i-Disco: Add support for the new DMA2D features to the LTDC
        configuration.  From Marco Krahl.

    * TI Tiva Boards:

      - TM4C1294 Launchpad:  Added TM4C1294NCPDT EN0_LED2 (10/100-Base-Tx);
        removed all booster pack pin definitions. From Frank Sautter.

    * C Library/Header Files:

      - libc:  Add an option to disable support for long long formats in
        lib_vsprintf().  On very tiny platforms, this reduces the footprint
        by omitting large libgcc.a libraries to perform the 64-bit
        arithmetic operations. From Alan Carvalho de Assis.

    * Applications: apps/system:

      - nuttx/zoneinfo:  Add logic to build a ROMFS file system
        containing the timezone data.

    * Applications: apps/nshlib:

      - Add poll support for Unix stream sockets.  From Jussi Kivilinna.
      - Enhancements to NSH ifconfig for case of multi-link operation, TUN
        device and local connections.  From Max Neklyudov.
      - Enhanced output to NSH ping command from Max Neklyudov.
      - The NSH mount command now recognizes the Union filesystem type when
        listing mounted file systems.

    * Applications: apps/netutils:

      - apps/netutils/thttpd/ and apps/examples/thttpd/: Add support for
        using binfs/ with the Union FS instead of NXFLAT.  NXFLAT is
        probably the better solution but recently compiler changes make it
        unusable.  binfs or ELF are fallback binary formats.  This commit
        adds an option to use binfs with the Union FS.

    * Applications: apps/examples:

      - Modify/simpify apps/examples build files.  From Roman Saveljev.
      - apps/examples/ltdc:  Add testing support for the STM32 LTDC's 2D DMA.
        From Marco Krahl.
      - apps/examples/ostest: Add a test of nested signals.  There are no
        failures to handle signals but neither am I getting any nested signal
        handling.
      - apps/examples/elf: Add configuration options to support building the
        hello++4 example that depends upon having uClibc++ available.  Also
        add hello++5 to the ELF example  From  Leo aloe3132.
      - apps/examples/unionfs: Add a test of the union file system to
        apps/examples.

Efforts In Progress.  The following are features that are partially
implemented but present in this release.  They are not likely to be
completed soon.

    * Processes.  Much of the work in this release is focused on the
      realization of Unix-style user processes in NuttX.  There is more to
      be done, however.  The full roadmap and status is available at:
      https://cwiki.apache.org/confluence/display/NUTTX/Memory+Configurations

    * XMega:  There are some fragments in place for an XMega port.  That
      port has not really started, however.

Bugfixes.  Only the most critical bugfixes are listed here (see the
ChangeLog for the complete list of bugfixes and for additional, more
detailed bugfix information):

    * Core OS:

      - boardctl():  Add missing case causing that caused failures of PWM
        test.
      - pthread_kill(): Re-implemented pthread_kill().  It was just a simple
        wrapper around kill() but since the correct dispatching of signals
        for multi-threaded task groups has been implemented, calling kill()
        does not do what pthread_kill() is supposed to do.  The corrected
        implementation of pthread_kill() will direct the signal specifically
        to the specific pthread and no other.
      - uint32_t callbacks: Update the type passed to watchdog timer
        handlers.  Using uint32_t is a problem for 64-bit machines because
        it is too small to pass a pointer.  uintptr_t is a more appropriate
        type.
      - mq_timedreceive(): move the location where the errno value is set;
        the ETIMEDOUT errno setting was being overwritten by subsequent
        actions before returning.  Noted by Freddie Chopin.
      - POSIX message queues:  Move mq_setattr() and mq_getattr() from
        nuttx/libc/mqueue to nuttx/sched/mqueue.  Also add syscall support
        for mq_setattr() and mq_getattr().  This is necessary in protected
        and kernel builds because in those cases the message queue
        structure is protected and cannot be accessed directly from user
        mode code.

    * File Systems/Block Drivers/MTD:

      - MTD:  Increase the size of the fields in the geometry structure
        (again) to support larger FLASH sizes.  Needed by Sebastien Lorquet.

    * Common Drivers:

      - poll(): Fix resource leak and memory corruption on poll failure.
        From Jussi Kivilinna.

    * USB Host:

      - LPC31xx and SAMA5Dx EHCI:  Fix cache related problem in LPC31 and
        SAMA5Dx EHCI drivers. All buffers are now aligned with the cache
        line size in both starting address and in length.  This cause major
        problems in unlucky builds where the USB host buffers where
        unaligned and abutting other data. The cache flush and invalidate
        operations could be subverted by accesses to adjacent data or could
        have unexpected side effects.  This bug has been in the ECHI drivers
        forever, but was only revealed due to unlucky memory allocations
        during the integration of the hub feature.

    * USB Device:

      - All USB device class drivers:  There needs to be a check to make
        sure that the size of a returned string does not exceed the size of
        the allocated request buffer.  Strings such as vendor names or
        product names will be truncated to fit in the request buffer.

    * Networking:

      - TCP:  Correct failures in long Telnet sessions by increasing th
        size of the number of bytes sent from uint16_t to uint32_t.  This
        avoids an integer overflow that causes a long Telnet session to be
        closed unexpectedly.  From Rony XLN.
      - Network locks: Correct some network lock logic:  Two error
        conditions where the network was not being unlocked and one where it
        was getting unlocked twice.  From Jussi Kivilinna.
      - Local Sockets: Local stream sockets had problem of double releasing
        pipes (both server and client attempt release), which causes wrong
        pipe pair being closed in multi-client case. Solve by adding per
        connection instance ID to pipe names.  From  Jussi Kivilinna.
      - TCP:  Fix an important TCP networking bug: 16-bit flags was being
        converted to 8-bits in a few locations, causing loss of status
        indications.
      - TCP: net_startmonitor() always returned OK.  In the race case
        where a socket has already been closed, it correctly handled the
        disconnection event but still returned OK.  Returning OK caused the
        callers of net_startmonitor() to assume that the connection was
        okay, undoing the good things that net_startmonitor() did and
        causing the socket to be incorrectly marked as connected.  This
        behavior was noted by Pelle Windestam.
      - setsockopt() failed when setting timeouts to values less tha 100
        msec.  That is because the timeout is limited to stops of 1
        decisecond and because the conversion of structure timeval was
        truncating the microsecond remainder.  The utility
        net_timeval2dsec() now accepts and option to determine how it
        handles the remainder:  truncate, discarding the remainder, use
        the remainder to round to the closed decisecond value, or use any
        non-zero remainder to the next larger whole decisecond value.  Bug
        discovered by Librae.
      - TCP: In the TCP connection operation, it was trying to setup the
        network monitor BEFORE the socket was successfully connected.  This,
        of course, has ALWAYS failed because the socket is not yet connected
        and the TCP state is not yet correct for a connected socket.  However,
        because of other changes net_startmonitor() now returns a failure
        condition that causes worse problems when trying to connect.  The fix
        is to move the logic that starts the network monitor to AFTER the
        socket has been successfully connected.

    * Atmel SAM3/4 Drivers:

      - SAM4CM and SAMA5D Free-running timer: Logic that samples the free
        running counter reads the pending interrupt status register and can
        cause interrupts to be lost.  So, if when the status register is
        read, the logic must also handle the timer overflow event. Found
        and fixed by Max Neklyudov.

    * Atmel SAMA5 Drivers:

      - SAM3/4 Serial:  When reconfigured, serial does not receive bytes
        from UART.  This happens because RX interrupt was disabled in the
        setup routine.  Fixed this I save interrupt configuration before
        UART shutdown and restore it after.  From Max Neklyudov.

    * NXP LPC17xx Drivers:

      - LPC176x GPIO:  Reorder steps when an output GPIO is configured in
        order to avoid transient bad values from being output.  From Hal
        Glenn.
      - LPC17 USB OHCI:  Correct some initialization of data structures.
        When hub support is enabled, it would overwrite the end of an array
        and clobber some OS data structures.
      - LPC17xx Ethernet:  Review, update, and modify the Ethernet driver so
        that it works better with CONFIG_NET_NOINTS=y.  Also, update all
        LPC17xx networking configurations so that they have
        CONFIG_NET_NOTINTS=y selected.

    * SiLabs EMF32 Drivers:

      - EFM32 SPI: Add missing SPI GPIO pin initialization.  From Pierre-noel
        Bouteville.

    * STMicro STM32:

      - STM32 F3:  Added missing EXTI definitions for the STM32 F3; Correct
        an error the port D base address in the STM32 F30x and F37x memory
        maps.  From Greg Meiste.

    * STMicro STM32 Drivers:

      - STM23 RTC: Fix an error introduced into stm32_pwr_enablebkp().
        That function must preserve the previous state of backup domain
        access on return.
      - STM32 RTC counter: Now need to enable backup domain write access
        when setting the time.  From Darcy Gong.
      - STM32 OTG FS and HS: Added protection in the event that out-of-bound
        endpoint numbers are received.  From David Sidrane.

    * STMicro STM32 Boards:

      - STM32F429i Disco: (1) Fix a bad return value if the LCD driver is
        already initialized. (2) The LCD driver initialization is now
        performed during the early boot sequence.  (3) Increased the size
        of the message queue from 32 to 64 in the lcd configuration.  From
        Marco Krahl.

    * TI Tiva

      - Fixes for Tiva TM4C1294NCPDT.  From Frank Sautter.

    * Atmel SAMV71 Drivers:

      - SAMV7 TWIHS: Fix SAMV TWIHS logic that performs multi-message
        transfers with and without repeated starts.

    * Atmel SAMA5D3/4 Dirvers:

      - SAMA5 CAN: Fix SAMA5 CAN frame construction.  From Max Holtzberg.

    * C Library/Header Files:

      - stdlib.h:  MAX_RAND should be RAND_MAX.
      - assert.h: Wrap definitions of assertion macros in do while so that
        they are valid C statements.  Numerous places throughout the code
        where semicolons were missing at the end of an assertion also had to
        be fixed. Suggested by orbitalfox.
      - inetntoa(): Correct errors in printing IP address when type char is
        signed and the value is >= 128.  From Max Neklyudov.

    * Tools:

      - Tools: Fix test for the existence of the apps/ directory in
        configure.c. Fix backward interpretation of options, -l was selecting
        Windows and -w was selecting Linux. This was SourceForege Ticket #39.

    * Applications: apps/nshlib:

      - apps/nshlib/nsh_timcmds.c: Check return values from time functions.
      - apps/nshlib/: Fix handling of gmtime_r return value in time commands.
        gmtime_r returns a pointer, not an int.

    * Applications: apps/netutils:

      - apps/netutils/ntp: Fix mismatched sched_lock/unlock.  Noted by Juha
        Niskanen.

    * Applications: apps/examples:

      - apps/examples/nxlines:  Fix missing right bracket that causes
        compile error when CONFIG_NX_XYINPUT=y.  From Librae.
      - apps/examples: When boardctl() fails, need to print errno not the
        returned value which will always be -1.
      - apps/examples: Correct use of the BOARDIOC_GRAPHICS_SETUP boardctl()
        call.

NuttX-7.11 Release Notes
------------------------

The 111th release of NuttX, Version 7.11, was made on August 13 2015,
and is available for download from the Bitbucket.org website.  Note
that release consists of two tarballs:  nuttx-7.11.tar.gz and
apps-7.11.tar.gz.  These are available from:

    https://bitbucket.org/patacongo/nuttx/downloads
    https://bitbucket.org/nuttx/apps/downloads

Both may be needed (see the top-level nuttx/README.txt file for build
information).

Additional new features and extended functionality:

    * Core OS:

      - clock_gettime(): Use up_timer_gettime for CLOCK_MONOTONIC in
        tickless mode.  From  Max Neklyudov.
      - waitpid(): Implement WNOHANG for waitpid() only and for the case of
        CONFIG_SCHED_HAVE_PARENT not selected.  From Max Neklyudov.
      - SCHED_SPORADIC:  Add a sporadic scheduler to NuttX.
      - Extend the processor-specific interface to include information to
        support the Sporadic Scheduler.
      - sem_tickwait():  Added this function for internal use within the OS.
        It is a non-standard but more efficient version of sem_timedwait()
        for use in higher performance device drivers.

    * Binary Loader:

    * Graphics/Graphic Drivers:

      - Graphics:  Implement anti-aliasing in order to clean the drawing of
        all edges.  Anti-aliasing is supported in the horizontal, raster
        direction only.
      - SSD1306 LCD Driver: Modify the SSD1306 LCD driver to support either
        the SPI or I2C interface.  From Alan Carvalho de Assis.

    * File Systems/Block Drivers/MTD:

      - mount: Add the ability to mount a file system on top of en existing
        node in the pseudo-file system.
      - epoll(): Add a very simple epoll layer just around poll calls. To
        satisfy build app requirements.  From Anton D. Kachalov.

    * Common Device Drivers:

      - IOCTL: Add relay IOCTL definitions. From Max Neklyudov.
      - I/O Expander Framework:  Add an I/O expander driver framework. From
        Sebastien Lorquet
      - NXP PCA9555 I/O Explander.  Add PCA9555 driver.From Sebastien
        Lorquet
      - BMP180 Barameter: Add support to Bosch BMP180 barometer.  From
        Alan Carvalho de Assis.
      - CAN IOCTLs:  Add CAN IOCTL command definitions to manage CAN message
        filtering
      - CAN Driver:  Add configuration to support DLC to byte conversions
        needed for CAN FD mode.
      - SPI Slave Interface:  Add a definition of an SPI slave interface.
      - LM92 Temperature Sensor:  Add a driver for the LM92 temperature
        sensor.  Contributed by Paul Alexander Patience.
      - AS5048B Rotary Magnetic Sensor: Add support for an AS5048B rotary
        magnetic sensor.  From Paul Alexander Patience.
      - Ramtron Driver:  Update to include supportf for newer RAMTRON parts.
        From David Sidrane.
      - MB7040 Sonar Driver: Add support for a MB7040 sonar driver.  From
        Paul Alexander Patience.
      - ms5805 Altimeter Driver: Add support for an MS5805 altimeter.  From
        Paul Alexander Patience.

    * Networking:

      - DNS Client: Implement the low-level network DNS packet protocol to
        request and receive IPv6 address mappings.
      - NetDB:  Add support for a DNS host name resolution cache.  This can
        save a lot of DNS name server lookups (but might also have the
        negative consequence of using stale IP address mappings.
      - NetDB:  Name resolution logic now supports lookups from a file like
        /etc/hosts.
      - Network Initialization: Add CONFIG_NETDEV_LATEINIT that can be
        used to suppress calls to up_netinitialize() from early in
        initialization.
      - FTMAC100 Ethernet MAC Driver. Add support for Faraday FTMCA100
        Ethernet MAC/ From Anton D. Kachalov.
      - UDP Networking:  Add support for send() for connected UDP sockets.

    * Crypto:

      - Add CFB and MAC AES modes.  From Max Neklyudov.

    * Simulation Platform:

      - Simulation: Implement board_power_off() for the simulation platform.
        This allows for a graceful exit from the simulation.

    * MoxaRT:

      - MoxaRT SoC: Add support for MoxaRT SoC found in the most Moxa serial
        converters such as NP51x0, NP66xx, UC72xx.  From Anton D. Kachalov.

    * MoxaRT Boards:

      - Moxa NP51x0: Moxa NP51x0 series of 2-port advanced RS-232/422/485
        serial device servers.  From Anton D. Kachalov.

    * ARMv6-M:

      - ARMv6-M Assertions: Port some per-process stack dumping logic from
        ARMv7-M to ARMv6-M.  From Alan Carvalho de Assis.

    * Atmel SAMD/L Boards:

      - SAML21: DMA: Add SAML21 DMA support.
      - SAMD21: Add architecture support for the SAMD21 family.
      - SAMD21-Xplained:  Board configuration for the SAMD21 Xplained board.

    * Atmel SAM3/4 Drivers:

      - SAM4E: Add default loop optimization if EEFC_FMR is available in the
        configuration (i.e., for SAM4S and 4E). From Marco Aurélio da Cruz.
      - crypto/ and SAM4CM: Add CFB and MAC AES modes.  From Max Neklyudov.
      - SAM3/4:  Add a TWI driver for the SAM4CM.  From  Max Neklyudov.

    * Freescale (NXP) Kinetis:

      - Kinetis: Add support for MK20DN--VLH5 and MK20DX---VLH5.  Needed
        for backward compatible support for Teensy-3.0.

    * Freescale (NXP) Kinetis Boards:

      - Teensy 3.x:  Add board support for the PJRC Teensy-3.0 and
        Teensy-3.1 boards.

    * Atmel SAMV7 Drivers:

      - SAMV7:  Add an MCAN driver for the SAMV7 platform.
      - SAMV7 SPI Slave Driver: Add the an SPI slave driver.

    * STMicro STM32:

      - STMicro STM32 F7:  Add architecture support for the STMicro STM32
        F7.
      - STM32 F446:  Add support for the STMicro STM32 F446.  From David
        Sidrane.

    * STMicro STM32 Drivers:

      - STM32 F7:  Add an STM32 F7 Ethernet driver.
      - STM32 F7:  Port the STM32 F4 DMA driver.
      - STM32 F4 ADC:  Add DMA support to the ADC driver for STM32 F4.  From
        Max Kriegler.

    * STMicro STM32 Boards:

      - STM32F762G-Disco:  Add support for the STMicro STM32 F7 Discovery
        board.
      - STM32F4-Disco: Add support to BMP180 driver on the STM32F4 Discovery.
        From Alan Carvalho de Assis.

    * C Library/Header Files:

      - Add asctime(), asctime_r(), ctime(), and ctime_r().
      - sethostname(): Add support for sethostname().
      - gethostbyname() and gethostbyaddr():  Add support for
        gethostbyname() and gethostbyaddr().  Also support included for the
        non-standard gethostbyname_r() and gethostbyaddr_r().  This moves
        the DNS client logic from apps/ into the NuttX libc implementation.

    * Tools:

      - testbuild.sh:  Add a script that can be used to perform building
        testing for several board configurations.

    * Build/Configuration System:

      - apps/ Build System:  No longer depends on hardcoded lists of
        directories. Instead, it does a wildcard search to find all
        appropriate directories.  This means that to install a new
        application, you simply have to copy the directory (or link it) into
        the apps/ directory.  If the new directory includes a Makefile and
        Make.defs file, then it will automatically be included in the build.
      - mkkonfig.sh: Add the tool mkkconfig.sh that dynamically builds the
        apps/Kconfig file at configuration time.  The hardcoded
        configuration file has been removed and now the top-level Makefile
        executes tools/mkkconfig.sh to auto-generate the top-level Kconfig
        file.  A new apps/ make target call preconfig: was added to support
        this operation.  Now you do not have to modify the top-level Kconfig
        file to add a new directory into the configuration; the top-level
        subdirectory simply needs to include a Kconfig file and it will
        automatically be included in the configuration.  The native Windows
        build is temporarily broken until a new apps/tools/mkconfig.bat
        script is generated.
      - mkkconfig.bat:  Add the Windows script corresponding to
        apps/tools/mkkconfig.sh.  Needed for a Windows native build.

    * Applications: apps/nshlib:

      - NSH shutdown command: NSH will now support an (optional) shutdown
        command if the board provides the option CONFIG_BOARDCTL_POWEROFF.
        The command can also be used to reset the system if
        CONFIG_BOARDCTL_RESET=y.
      - NSH uname command:  Add support for a uname command.
      - NSH nslookup command:  Add an nslookup command.

    * Applications: apps/system:

      - NetDB:  Add a system command to access the network database.
      - readline():  Add support for Unix-style tab complete to readline.
         Contributed by Nghia Ho.
      - readline():  Extended the tab-completion support to also expand NSH
        command names.
      - readline():  Add support for an in-memory command line history that
        can be retrieved using the up and down arrows.  Contributed by Nghia
        Ho.

    * Applications: apps/netutils:

      - DNS client:  Moved the DNS client logic into the NuttX C library.
        It is a necessary part for the full implementation of the netdb logic
        and provides more flexibility in that location.
      - Replace calls to the non-standard dns_gethotip() with calls to
        standard gethostbyname().
      - NetLib: Create netlib wrapper functions around dns_getserver() and
        dns_setserver() to isolate application code from changes to those
        interfaces.

    * Applications: apps/examples:

      - OS test:  Extend the OS test to include a test of
        pthread_mutex_trylock() for recursive mutexes. From Juha Niskanen.
      - OS test: Add a test for the sporadic scheduler.

Bugfixes.  Only the most critical bugfixes are listed here (see the
ChangeLog for the complete list of bugfixes and for additional, more
detailed bugfix information):

    * Core OS:

      - pthreads: Use -1 instead of 0 as PID for unclaimed mutexes.  From
        Juha Niskanen.
      - pthreads: Implement pthread_mutex_trylock() for recursive mutexes.
        From Juha Niskanen.
      - pthread_create():  Group binding needs to be cleared before
        sched_releasetcb(), as otherwise group_leave() will be called and
        group->tg_nmembers decremented or group being released. group_leave()
        should be called only after group_join() is called, not after
        group_bind().  From Jussi Kivilinna.
      - Protected Mode User Memory Allocator: Redesigned how the user space
        heap is accessed from the kernel code in protected mode.  It used to
        call memory management functions in user space via function pointers
        in the userspace interface.  That is inefficient because the first
        thing that those memory management functions do is to trap back into
        the kernel to get the current PID.  Worse, that operation can be
        fatal is certain fragile situations such as when a task is exiting.
        The solution is to remove all of the memory management function
        calls from the interface.  Instead, the interface exports the users
        pace heap structure and then kernel size implementations of those
        memory management functions will operate on the userspace heap
        structure. This avoids the unnecessary system calls and, more
        importantly, failures do to freeing memory when a test exits.
      - pthread_create(): Fix an (unlikely) error in fallback value in the
        event of a failure (which should never occur).

    * Common Drivers:

      - STMPE811 Driver:  In stmpe811_instanciate() when
        CONFIG_STMPE811_MULTIPLE is enabled, and the call to
        stmpe811_checkid() fails, then the linked device list is not
        restored to its previous state. From Sebastien Lorquet.
      - CAN driver:  Fix an issue in the CAN driver where the rx_sem count
        can grow beyond bounds.

    * File System/Block Drivers:

      - NFS client: Fix prototype of unbind method.  The function prototype
        was not updated for NFS after a recent change to the file system
        interface.  From Manuel St??.

    * Networking/Network Drivers:

      - netconfig.h:  Fix some backward compilation that was emitting #error
        in the wrong condition when SLIP was enabled.
      - SLIP Driver:  Fix a missed name change when many of network
        interface names changed sometime back but were apparently never
        updated for SLIP.
      - Networking:  Allow receipt of empty UDP packets.  From Max Neklyudov.

    * ARMv6-M:

      - ARMv6-M: Fix Cortex-M0 assembly error when the interrupt stack is
        enabled.  From Alan Carvalho de Assis.

    * Atmel SAMD/L Drivers:

      - SAMD20, D21, L21: In the SAML21, SERCOM5 uses a different SLOW clock
        channel (and, hence, also a different SLOW GCLK generator).  This
        means that the channel selection cannot be a global definition but
        must be a per SERCOM configuration setting.
      - SAMD/L:  Several fixes to register definitions and types. From
        Janne Rosberg.

    * Atmel SAM3/4 Drivers:

      - SAM3/4 UART: Back out an error introduced with commit
        02c33f66c5a8be774034cd40e4125e9323c7b4d8.  Causes an infinite loop in
        up_lowputc().  From Max Neklyudov.
      - SAM4CM: Fix SUPC register definitions. From Max Neklyudov.
      - SAM3/4 WDT: Correct some problems with SAM3/4 watchdog driver.
        Includes some small improvements.  From Max Neklyudov.

    * Atmel SAMV7 Drivers:

      - SAMV7 UART: Also back the bad cloned change o sam_lowputc.c for
        SAMV7 platform.

    * NXP LPC43xx Drivers:

      - LPC4350: Correct some LPC4350 GPIO pin configurations.  From
        Alessandro Temil.

    * SiLabs EMF32 Drivers:

      - EFM32 SPI: Correct write to incorrect register in EFM32 SPI driver.
        From Pierre-noel Bouteville.

    * STMicro STM32 Drivers:

      - STM32 F15x: STM322 F15x stm32_stdclockconfig() was calling
        stm32_pw_setvos() which accessed PWR_CR via an inactive APB From
        Juha Niskaneni.
      - STM32 Ethernet: Extend STM32 Ethernet operating frequency to 180MHz.
        From Sebastien Lorquet.

    * STMicro STM32 Boards:

      - SAMV7 Xplained: In clock configuration, divider was set to 25 to get
        25*12MHz=300MHz CPU clock.  The correct multiplier is 24 because the
        calculation if (24+1)*12MHz.  So the board was running at 312MHz.
        From Efim Monjak.

    * ARMv7-A:

      - Cortex-A5 vfork():  Fix a Cortex-A compilation error when system
        calls are enabled in modes other than CONFIG_BUILD_KERNEL.

    * Atmel SAMA5 Drivers:

      - SAMA5Dx EHCI:  Fix some bad conditional compilation that left a
        function undefined if CONFIG_USBHOST_ASYNCH is not selected.

    * C Library/Header Files:

      - getopt():  Uninitialized variable can cause hardfault from getopt()
        if required argument is missing. From George McWilliams.

    * Applications: apps/nshlib:

      - NSH/THHPD:  Change decoding to handle the increased size of the
        scheduling policy field in the TCB.

    * Applications: apps/netutils:

      - THTTPD:  Fix compilation problems when
        CONFIG_THTTPD_GENERATE_INDICES is defined.
      - THTTPD: Missing gci-src as a dependency path when building with
        BINFS enabled.

    * Applications: apps/examples:

      - poll() example: Fix a few bit-rot compilation errors.
      - Nx Lines example:  If CONFIG_NX_ANTIALIASING=y, then the nxlines
        example now erases a line that is 2 pixels longer and 2 pixels wider
        than the line it drew.  That eliminates edges effects due to
        applying the anti-aliasing algorithm twice.  A better solution
        would be to make anti-aliasing an option for each graphics call so
        you would rend the line with anti-aliasing ON and clear it with
        anti-aliasing OFF. but I don't have the wherewithal for that change
        today.
      - OS test: Improve synchronization in round robin tests. On very fast
        processors, there are race conditions that make the test fail.
        Need better interlocking to assure that the threads actually do start
        at the same time.

NuttX-7.12 Release Notes
------------------------

The 112th release of NuttX, Version 7.12, was made on October 1, 2015,
and is available for download from the Bitbucket.org website.  Note
that release consists of two tarballs:  nuttx-7.12.tar.gz and
apps-7.12.tar.gz.  These are available from:

    https://bitbucket.org/patacongo/nuttx/downloads
    https://bitbucket.org/nuttx/apps/downloads

Both may be needed (see the top-level nuttx/README.txt file for build
information).

Additional new features and extended functionality:

    * Graphics/Graphic Drivers:

      - Added SSD1351 OLED controller support.  Contributed by Paul
        Alexander Patience.

    * Common Device Drivers:

      - MS58xx: Generalize the MS5805 altimeter driver to support other
        family members. From Paul Alexander Patience.
      - CAN driver interface: Add an error indication bit to the CAN
        message report.
      - Developed a new interface for QSPI.  Most QSPI hardware (such as the
        SAMV71) used a programmed interface to access the QuadSPI FLASH.
        That programmed interface is no compatible with the simpler NuttX
        SPI data transfer interface.
      - Added a driver for ST25L1*K QuadSPI parts.
      - Renamed the battery driver interface to battery_gauge since it
        really only implements a battery fuel gauge.  From Alan Carvalho de
        Assis.
      - Added a new framework to support a batter charger interface.  From
         Alan Carvalho de Assis.
      - Added a BQ24250 battery charger driver. From Alan Carvalho de Assis.

    * Networking:

      - Added support for the local loopback device (dev lo, hostname localhost).
      - Added NetDB support for the local loopback device.
      - Network initialization:  Automatically initialize all the TUN and
        loopback devices if they arein the configuration.

    * Simulation Platform:

      - The simulation now runs under Cygwin64.  Modern Cygwin X86_64
        machines follow the Microsoft ABI for parameter passing.  The Linux
        System 5 ABI would not work on X86_64-based Cygwin machines.  Newer
        Cygwin tool chains do nor pre-pend symbol names with the underscore
        character.

    * Atmel SAMA5Dx:

      - Added architectural support for the Atmel SAMA5D2 parts.  Not fully
        verified in this NuttX release.

    * Atmel SAMA5Dx Boards:

      - Added support for the Atmel SAMA45D2 Xplained Ultra board.  Not
        fully verified in this NuttX release.

    * Atmel SAMV7 Drivers:

      - SAMV7 USBHS DCD: The device controller driver is (finally)
        functional.

    * NXP LPC17xx:

      - Implement options to use external SDRAM and or SRAM for the heap.
        From Pavel Pisa.

    * NXP LPC43x:

      - Added architectural support for the LPC4370.  From Lok Tep.

    * NXP LPC43xx Drivers:

      - Added Ethernet support.  From Ilya Averyanov.
      - Added LPC43xx EHCI driver from Ilya Averyanov.

    * NXP LPC43xx Drivers:

      - Added support for the NXP LPC4370-Link2 development board from Lok
        Tep.

    * STMicro STM32:

      - Added architectural for STM32F303K6, STM32F303K8, STM32F303C6,
        STM32F303C8, STM32F303RD, and STM32F303RE devices.  From Paul
        Alexander Patience.

    * STMicro STM32 Drivers:

      - Added OTG support for STM32F44x.  From David Sidrane.

    * STMicro STM32 Boards:

      - Added support for the STMicro Nucleo F303ERE board from Paul
        Alexander Patience.

    * C Library/Header Files:

      - stdlib: Add support for div() to the C library.  From OrbitalFox.
        Also added ldiv() and lldiv() which are equivalent to div() with
        long and long long types, respectively, instead of int.
      - Added an implementation of the standard shutdown function.

    * Tools:

      - tools/mksymtab: declare g_symtab array as const to occupy RO section
        (Flash).  From Pavel Pisa.

    * Build/Configuration System:

      - Simplify configs/ Makefiles by combining common logic into a new
        Board.mk Makefile fragment.  From Paul Alexander Patience.

    * Applications: apps/system:

      - apps/system/symtab: Optional canned symtab inclusion to the build.
        When option CONFIG_SYSTEM_SYMTAB is selected and symbol table file
        libc/symtab/canned_symtab.inc is prepared then application can use
        system provided complete symbol table. The option has substantial
        effect on system image size. Mainly code/text. If loading of
        applications at runtime is not planned do not select this.  From
        Pavel Pisa.

    * Applications: apps/canutils:

      - apps/canutils/uavcan: Add support for libuavcan.  From  Paul Alexander Patience.

    * Applications: apps/examples:

      - apps/examples/can:  Extend the CAN loopback test by adding more
        command line options.
      - apps/examples/usbserial: Can now be run as an NSH builtin-function.
        Now uses a configurable IO buffer size.
      - apps/examples/nettest: Add option to suppress network initialization.
        This is necessary if the nettest is run from NSH which has already
        initialized the network.
      - apps/examples/nettest: Extend test so that can be performed using
        the local loopback device.
      - apps/examples/netloop:  Add a test of the local loopback device.
      - apps/examples/udpblaster: Add a test to stress the network by
        sending UDP packets at a very high rate. .
      - apps/examples/uavcan: libuavcan example from Paul Alexander Patience.

Bugfixes.  Only the most critical bugfixes are listed here (see the
ChangeLog for the complete list of bugfixes and for additional, more
detailed bugfix information):

    * Core OS:

      - wd_create():  Correct a counting error in the number of available
        watchdog timers.  When the number of free timers is low, the counter
        could be incremented below zero.
      - mq_open(): When message queue is opened, inode_reserve() leaves the
        reference count at zero.  mq_open() logic must assure that the
        reference count of the newly created inode is one.
      - work_queue(): Logic that sets the queued indication and the logic
        that does the actual queuing must be atomic.

    * Binary Loader:

      - Fix a memory leak in the built-in application logic: File was not
        being closed. From Bruno Herrera.

    * File System/Block Drivers:

      - poll():  If we fail to setup the poll for any file descriptor, for
        any reason, set the POLLERR bit.
      - rwbuffer: Fix some logic errors.  From Dmitry Nikolaev via Juha
        Niskanen.
      - ROMFS: One allocation was not being freed if there was a subsequent
        failure to allocation I/O buffers resulting in a memory leak on
        certain error conditions.  From Bruno Herrera.

    * Networking/Network Drivers:

      - Fix a bug in tun interface driver.  From Max Neklyudov.
      - recvfrom(): Correct wait for new data when NET_UDP_READAHEAD is
        enabled.  Fix size accounting when recvfrom_udpreadahead() sets
        state.rf_recvlen == -1.  I have not checked if data are accumulated
        to the right position in the buffer however. From Pavel Pisa.
      - networking:  Correct return value from psock_tcp_accept().  From
        SaeHie Park.
      - TCP: Fix a problem in when there are multiple network devices.
        Polls were being sent to all TCP sockets before. This is not good
        because it means that packets may sometimes be sent out on the wrong
        device.  That is inefficient because it will cause retransmissions
        and bad performance.  But, worse, when one of the devices is not
        Ethernet, it will have a different MSS and, as a result, incorrect
        data transfers can cause crashes. The fix is to lock into a single
        device once the MSS is locked locked down.
      - net/tcp:  The logic that binds a specific network device to a
        connection was faulty for the case of multiple network devices.  On
        bind(), the local address should be used to associate a device with
        the connection (if the local address is not INADDR_ANY); On connect(),
        the remote address should be used (in case the local address is
        INADDR_ANY).  On accept(), it does not matter but the remote address
        is the one guaranteed to be available.
      - net/tcp: Fix unbuffered send compilation error when Ethernet is not
        enabled.  From Alan Cavalho de Assis.

    * ARMv7-M:

      - All ARMV7-M IRQ setup:  Always set the NVIC vector table address
        unconditionally.  This is needed in cases where the code is running
        with a bootload and when the code is running from RAM.  It is also
        needed by the logic of up_ramvec_initialize() which gets the vector
        base address from the NVIC.  Suggested by Pavel Pisa.
      - Fix some H/W floating point logic: In the original implementation,
        !defined(CONFIG_ARMV7M_CMNVECTOR) was a sufficient test to determine
        if lazy floating point register saving was being used.  But recents
        changes added common lazy register as well so now that test must be
        (!defined(CONFIG_ARMV7M_CMNVECTOR) || defined(CONFIG_ARMV7M_LAZYFPU)).
      - ARMv7-M, all "lazy" interrupt stack logic.  Assembly instruction
        that fetches the saved value is incorrect; replace with more
        traditional push and pop.  This is an important fix.  Noted by
        Stefan Kolb.
      - All ARMV7-M: Force 8-byte stack alignment when calling from assembly
        to C to interrupt handling.
      - up_schedulesigaction(): Fix logic that determines if there is a
        pending signal action before scheduling the next signal action.
        Both the test and the scheduling action need to be atomic.  This
        problem was fixed on the ARMv7-M but also ported to other
        architectures that had the same issue.

    * NXP LPC43xx:

      - LPC43xx: Fix NVIC_SYSH_PRIORITY_STEP define.  From Ilya Averyanov.
      - LPC43xx: Fix missing #define in eeprom.  From Ilya Averyanov.

    * NXP LPC43xx Drivers:

      - Fixed the SPI driver.  From Ilya Averyanov.

    * Atmel SAMA5 Drivers:

      - LPC31 and SAMA5D EHCI: Fix qh_ioccheck to move bp to next QH.  From
        Ilya Averyanov.
      - LPC31 and SAMA5D EHCI:  Performance improvement:  Do not disable the
        asynchronous queue when adding a new QH structure.  From  Ilya
        Averyanov.

    * C Library/Header Files:

      - gethostbyname(): correct returned address format when DNS is used.
        The hostent.h_addr_list should point to raw in_addr or in6_addr
        as defined in the standard. Original implementation used that for
        numeric addresses but for DNS lookup returned pointer to whole
        sockaddr_in or sockaddr_in6.  From Pavel Pisa .
      - asin(): The function did not convert for some input values.  asing()
        did not convert for values which do not belong to the domain of the
        function. But aside of that the function also did not converge for
        allowed values.  I achieved a conversion of the function by
        reducing the DBL_EPSION and by checking if the input value is in
        the domain of the function. This is a fix for the problem but the
        function should always terminate after a given number of iterations.
        From Stefan Kolb.
      - Change all references from avsprintf to vasprintf.  From Sebastien
        Lorquet.

    * Applications: apps/nshlib:

      - Fix error handling in 'cat' command.  On a failure to allocate
        memory, a file was not being closed.  From Bruno Herrera.
      - Fix error handling in 'mv' command.  On a failure to expand the
        second path, the memory allocated for the expansion of the first
        path was not being freed.  From Bruno Herrera.

    * Applications: apps/system:

      - apps/system/netdb:  Failed to build if CONFIG_NET_HOSTFILE was not
        defined because gethostbyaddr() was not available.  Noted by
        OrbitalFox.

    * Applications: apps/netutils:

      - Various Kconfig files in netutils:  Fix some changes from from
        NETUTILS_DNSCLIENT to NETDB_DNSCLIENT.  From Pavel Pisa.

    * Applications: apps/modbus:

      - Macros PR_BEGIN_EXTERN_C and PR_END_EXTERN_C were not defined in
        all contexts.  Replace with explicit expansion in all cases. From Stefan Kolb.

NuttX-7.13 Release Notes
------------------------

The 113th release of NuttX, Version 7.13, was made on December 5, 2015,
and is available for download from the Bitbucket.org website.  Note
that release consists of two tarballs:  nuttx-7.13.tar.gz and
apps-7.13.tar.gz.  These are available from:

    https://bitbucket.org/patacongo/nuttx/downloads
    https://bitbucket.org/nuttx/apps/downloads

Both may be needed (see the top-level nuttx/README.txt file for build
information).

Additional new features and extended functionality:

    * Core OS:

      - External RTC:  Added OS support for external RTC chips.
      - boardctl():  Add a command to the boardctl() interface to obtain a
        board unique ID.

    * File Systems:

      - TMPFS:  Add support for a new TMPFS, RAM file system.  The TMPFS
        file system does not require any significant amount of memory
        itself.  It will grow dynamically as files are added and shrink back
        when files are deleted.  A very low overhead way to retain temporary
        files.
      - VFS:  The VFS was extended to support standard file operations on
        block drivers (open, close, read, write, etc.).  The open() interface
        accomplishes this by creating a temporary character driver to mediate
        the character oriented accesses to the block driver.
      - HOSTFS:  Added a HOSTFS file system for use with the simulator.  The
        HOSTFS file system mounts in the simulated NuttX context by provides
        proxied access to the file system on the host PC.  This is useful for
        providing file system content and nonvolatile storage of files in the
        simulation environment.  From Ken Pettit.
      - MTD/PROCFS:  Add an interface to un-register an MTD procfs entry.
        From Ken Pettit.
      - filemtd:  A new MTD conversion layer that will convert a regular file
        (or driver file) to an MTD device.  This is useful for testing on the
        simulation using the HOSTFS.  From Ken Pettit.
      - PROCFS:  Extended to include networking entries in the procfs. Device
        status, device statistics, and network statistics are now available
        from the PROCFS.
      - PROCFS:  The PROCFS file system can now be configured so that it
        supports runtime registration of PROCFS entries with
        CONFIG_FS_PROCFS_REGISTER=y.

    * Graphics/Graphic Drivers:

      - ST7565 Driver:  Extend to include support for the ERC12864-3. From
        Pierre-noel Bouteville.

    * Common Device Drivers:

      - User buttons: Added a character driver to support application access
        to board buttons.  Supports notification of button activity via
        signals.
      - User LEDs:  Added a character driver to support application access
        to on-board LEDs.
      - Zero Cross: Added a Zero Cross device driver support.  From Alan
        Carvalho de Assis.
      - MAX6675:  Added support to Thermocouple-to-Digital converter MAX6675.
        From Alan Carvalho de Assis.
      - BCH:  Block-to-character (BCH) driver should forward ioctl() calls
        to the contained block driver.
      - S25FL1xx:  Added a S25FL1xx QuadSPI FLASH driver.
      - On-Chip FLASH: Added an upper half MTD device that can use the
        interfaces defined in included/nuttx/progmem.h to provide a
        standard MTD driver.
      - Serial: Implemented high level DMA infrastructure for serial
        devices.  From Max Neklyudov.
      - AT24XX:  Add support for multiple AT24xx EEPROM parts, each with
        unique I2C addresses, but otherwise identical.
      - External RTC:  Added drivers for external I2C RTC chips: DS3102,
        DS1307, DS3231, DS3232, and NXP PCF85263.
      - W25: Added support for byte write mode to the W25 FLASH driver. From
        Ken Pettit.
      - dev/loop:  Added a loop character device.  losetup() and loteardown()
        should not be called directory from applications. Rather, these
        functions are now available as IOCTL commands to the loop driver.
      - dev/smart:  Added support for a /dev/smart loop device. From Ken
        Pettit.

    * Networking:

      - Driver Statistics: Most network drivers do not support statistics.
        Those that do only supported them when DEBUG is enabled.  Each
        driver collected an architecture specific set of statistics and
        there was no common mechanism to view those statistics.  Thus,
        the driver feature was mostly useless.  This release standardizes
        the driver statistics and puts the definition in the common network
        device structure defined in netdev.h where they can be accessed by
        network applications.  All Ethernet drivers that collect statistics
        have been adapted to use these common statistics.

    * Simulation Platform:

      - W25 FLASH:  Added support for W25 FLASH simulation. From Ken Pettit.
      - HOSTFS: Added support for the HOSTFS file system (see "File Systems",
        above).

    * Atmel SAMV7:

      - SAME70:  Added support for the SAME70 family of chips.
      - Tickless: SAMV7 now supports the tickless mode of operation.

    * Atmel SAMV7 Drivers:

      - MPU:  Added MPU and protected build support.
      - QSPI:  Added a QuadSPI FLASH driver.  This driver operates in the
        memory-mapped, Serial Memory Mode (SMM).
      - FLASH:  Added support to write on-chip FLASH.
      - Timer/Counter:  TC driver ported to SAMV7 from the SAMA5.  Free-running
        and one-short timer logic also ported.
      - PCK: Brought programmable clock (PCK) logic from SAMA5 into SAMV7.
      - Timer/Counter:  Support PCK6 as an optional source for the timer/
        counter clock.

    * Atmel SAMV7 Boards:

      - SAME70-Xplained:  Add NSH and networking configurations for the
        SAME70 Xplained board.  Includes verified support for serial console,
        LEDs, buttons, SDRAM, HSMCI SD card, and networking.
      - SAMV7-XULT and SAME70-Xplained: If Tickless mode is selected then
        enable PCK6 as a timer/counter clock source

    * STMicro STM32:

      - CCM PROCFS: Is no longer a part of the 'base' procfs entries and can
        now only be supported via run time registration with
        CONFIG_FS_PROCFS_REGISTER=y.

    * STMicro STM32 Drivers:

      - Timers:  Add a compatible lower-half timer driver for use with the
        common timer upper-half driver.  From Wail Khemir.

    * STMicro STM32 Boards:

      - STM32F4-Discovery: Add low level support for the Zero Cross driver
        for the STM32F4-Discovery.  From Alan Carvalho de Assis.
      - STM32F4-Discovery: Add board config to support for the MAX6675. From
        Alan Carvalho de Assis.

    * C Library/Header Files:

      - bsearch():  Added the bsearch() function from NetBSD.
      - freopen():  Added support for freopen().
      - strftime():  Added day-of-week support (when available).

    * Tools:

      - nxstyle: Add crappy style checking tool nxstyle.c.  See thee tools/
        README file for more info.

    * Applications: NSH

      - mksmartfs command: Add configuration option to supported multiple
        rootdirectories. From Ken Pettit.
      - Add support for 'basename' and 'dirname' commands.
      - set command:  Like bash, NSH set command now strips off any leading
        or trailing whitespace.
      - mount command: The mount commands now accepts mount options
        (currently needed only for the hostfs file system).  From Ken
        Pettit.
      - losetup command:  NSH no longer calls losetup() and loteardown
        directly. Now it opens /dev/loop and accomplishes these things
        using ioctl() calls.
      - ifconfig command:  If CONFIG_NETDEV_STATISTICS=y, then print the
        network driver statistics in the ifconfig.
      - ifconfig, ifup, and ifdown:  These commands now uses /proc/net/<dev>
        to view network device configuration and status and /proc/net/stat
        to show network statistics.  A consequence of this is that you
        cannot view this network information if the procfs is not enabled
        and mounted at /proc.
      - losmart command:  Added a new NSH losmart command.  losmart setups
        up a loop device for the smart MTD driver similar to losetup but
        with different syntax.  From Ken Pettit.
      - ps command:  The 'ps' command now uses /proc/<pid>/ to obtain task
        status information.  A consequence of this is that you cannot use
        the 'ps' command if the procfs is not enabled and mounted at /proc.

    * Applications: apps/system:

      - apps/system/hexed:  Port the hexed command line hexadeciamal editor
         to NuttX.  See http://apps.venomdev.net/hexed/.

    * Applications: apps/fsutils:

      - apps/fsutils/smartfs: Move into apps/fsutils from kernel, now uses
        only open and ioctl.  From Ken Pettit.

    * Applications: apps/examples:

      - apps/examples/fstest:  Add a generic file system test.  This is
        essentially the same as examples/smart, but has all of the SmartFS
        specific logic ripped out.  This was created for testing the new
        TMPFS.
      - apps/examples/zerocross: Add a Zero Cross application example. From
        Alan Carvalho de Assis.
      - apps/examples/media:  Add a simple test for access of media via a
        block driver or MTD driver.

Bugfixes.  Only the most critical bugfixes are listed here (see the
ChangeLog for the complete list of bugfixes and for additional, more
detailed bugfix information):

    * Core OS:

      - Fixed an error in clock_timespec_subtract().  Found by Lok.
      - pthreads: CRITICAL BUGFIX: Logic was wiping out the indication that
        of the type of a pthread.  Hence, it could be confused as a task.
        Found because this was causing a crash when /proc/nnn/cmdline was
        printed.

    * File System/Block Drivers:

      - SMART MTD: Fix some Smart wear-leveling bugs.  Fixed SmartFS wear
        level error that occurs when the logical sector size is too small to
        save all wear level status bytes in a single sector.  Logical
        sectors 1 and 2 were simply not being allocated and then the
        read_sector and write_sector routines were failing.  From Ken
        Pettit.

    * Graphics/Graphic Drivers:

      - ILI9432:  Fixed errors in orientation. Portrait, RPortrait, and
        Landscript should work correly now.  They were displayed mirrored.
        From  Marco Krahl.

    * Common Drivers:

      - CAN:  Fix a problem in the CAN upper-half driver that occurs only
        for CAN hardware that support a H/W FIFO of outgoing CAN messages.
        In this case, there can be a hang condition if both the H/W and
        S/W FIFOs are both full.  In that case, there may be no event to
        awaken the upper half driver.  Add a new (conditional) CAN upper
        half interface called can_txready() that can be used by the lower
        half driver to avoid this hang condition.
      - MS58xx:  Fix some issues with initialization and with CRC
        calculation.  From Karim Keddam.
      - W25: Fixed W25 FLASH driver page read/write logic. From Ken Pettit.

    * Atmel SAMV7 Drivers:

      - USART1 pin configuration: Reconfigure System I/O when using USART1.
        From Frank Benkert.
      - MCAN:  Added a call to can_txready() to the MCAN driver.

    * STMicro STM32 Drivers:

      - stm32 F4:  Fix some TIM12 pin mappings.  From Max Kriegleder.

    * STMicro STM32 Boards:

      - STM32F429i-Disco:  Calculated partition boundaries based on page
        block sizes but mtd_partition() is expecting calculations based on
        erase block size. From Alan Carvalho de Assis.

    * C Library/Header Files:

      - sys/types.h: When building on a 64-bit machine, the size of size_t
        should be 64-bits. In general, I believe that sizeof(size_t) should
        be the same as sizeof(uinptr_t).  mmsize_t should always be 32-bits
        in any event.  The last change to stddef has been backed out.  With
        these changes, the simulator builds without errors or warnings an a
        64-bit machine.

    * Applications: apps/nshlib:

      - The I/O buffer, g_iobuffer, should not be a global buffer.  That
        will not work in an environment where there are multiple NSH
        sessions.  The I/O buffer must, instead, be a part part of the
        session-specific data defined in nsh_console.h.

NuttX-7.14 Release Notes
------------------------

The 114th release of NuttX, Version 7.14, was made on January 28, 2016,
and is available for download from the Bitbucket.org website.  Note
that release consists of two tarballs:  nuttx-7.14.tar.gz and
apps-7.14.tar.gz.  These are available from:

    https://bitbucket.org/patacongo/nuttx/downloads
    https://bitbucket.org/nuttx/apps/downloads

Both may be needed (see the top-level nuttx/README.txt file for build
information).

Additional new features and extended functionality:

    * Core OS:

      - modules:  Add support for kernel modules:  insmod, rmmod, support
        functions.  procfs support for user lsmod functioniality.
      - SIGEV_THREAD:  Add support for the SIGEV_THREAD notification method
        in struct sigevent.  This initial implementation will only work in
        the FLAT build since it utilizes the work queue for signal
        callbacks.  See the top-level TODO file for additional details.
      - 64-Bit Timer:  If the 64-bit timer is selected, then use it whenever
        clock_systimer() is called rather then chopping the 64-bit timer
        down to 32-bits.  Add a new type, systime_t to represent the 32- or
        64-bit system timer. This eliminates clock_systimer32() and
        clock_systime64(); there is now only clock_systimer().

    * Common Device Drivers:

      - Telnet Driver: Move the Telnet driver from apps/ to
        nuttx/drivers/net.  It is a driver a belongs in the OS.   Now works
        like the loop device:  A new interface called telnet_initialize()
        registers a telnet session "factory" device at /dev/telnet.  Via
        ioctl, the factory device can create instances of the telnet
        character devices at /dev/telnetN to support Telnet sessions.
      - PCA9635PW:  Add a driver for the PCA9635PW I2C LED driver IC which
        can be used to control the intensity of up to 16 LEDs.  From
        Alexander Entinger.
      - MCP9844: Driver for the MCP9844 I2C digital temperature sensor with
        a selectable resolution.  From Alexander Entinger.
      - PN532: Add driver for the NXP PN532 NFC-chip.  From Janne Rosberg
        and others at Offcode Ltd.
      - LSM9DS1:  Add driver for the STMicro LSM9DS1 chip. The LSM9DS1 is a
        system-in-package featuring a 3D digital linear acceleration sensor,
        a 3D digital angular rate sensor, and a 3D digital magnetic sensor.
        From Paul Alexander Patience.
      - CAN Interface:  Add more extensive error reporting capaibility to
        the CAN interface definitions.  From Frank Benkert.
      - SPI Interface:  Add an optional hwfeatures() method to the SPI
        interface.

    * Simulation Platform:

      - NSH configuration uses the custom start up scriptwith a read-only
        passwd file.  Includes hooks for an MOTD message.

    * ARMv7-R

      - ARMv7-R:  Add basic architecture support for the ARMv7-R processor
        family.

    * Atmel AVR:

      - Atmega2560:  Add support for the Atmega2560.  From Dimitry Kloper.
      - debug.h: Add an AVR-specific header file used when the AVR MEMX
        pointer is used.  From Dimitri Kloper.

    * Atmel AVR Boards:

      - Arduino-Mega2560: Add support for the Arduino-Mega2560.  From
        Dimitry Koper.

    * Atmel SAMV7 Drivers:

      - Port the TRNG driver from the SAMA5D3/4 to the SAMV7.
      - Port the WDT driver from the SAMA5D3/4 to the SAMV7.
      - Add an RSWDT driver.

    * Atmel SAMV7 Boards:

      - SAMV71-XULT:  Add configuration for testing OS modules.

    * Freescale Kinetis:

      - MK60N512VLL100: Add support for the MK60N512VLL100 Kinetis part.
        From Andrew Webster.

    * Freescale Kinetis Boards:

      - ENET:  Numerous updates to the Kinetis ENET driver. That driver is
        now functional. From Andrew Webster.

    * NXP LPC43xx Boards:

      - WaveShare LPC4337-WS:  Support for the WaveShare LPC4337-WS board.
        From Lok Tep.

    * STMicro STM32 Drivers:

      - Timer Capture:  Add timer input capture driver.  From Pierre-Noel
        Bouteville.

    * STMicro STM32 Boards:

      - Olimex STM32 H407:  Added a port to the Olimex STM32 H407 board.
        This board features the STMicro STM32F407ZGT6 (144 pins).
        Contributed by Neil Hancock.

    * TI TMS550 Boards:

      - TI LaunchXL-TMS57004:  Add basic board support for TI LaunchXL-
        TMS57004.  Still a work in progress.

    * C Library/Header Files:

      - sys/time.h: Add timeradd(), timersub(), timerclear(), timerisset(),
        and timercmp() as macros. These are non-POSIX interfaces, but
        included in most BSD deriviatives, including Linux.  From Manuel St??.
      - AVR support: Introduce support for Atmel toolchain in-flash strings.
        Atmel toolchain AVR compiler provides a transparent in-flash object
        support using __flash and __memx symbols. The former indicates to
        compiler that this is a flash-based object.  The later used with
        pointer indicates that the referenced object may reside either in
        flash or in RAM. The compiler automatically makes 32-bit pointer
        with flag indicating whether referenced object is in flash or RAM
        and generates code to access either in run-time. Thus, any function
        hat accepts __memx object can transparently work with RAM and flash
        objects.
        For platforms with a Harvard architecture and a very small RAM like
        AVR this allows to move all constant strings used in trace messages
        to flash in the instruction address space, releasing resources for
        other things. This change introduces IOBJ and IPTR type qualifiers.
        The 'I' indicates that the object may lie in instruction space on a
        Harvard architecture machine. For platforms that do not have __flash
        and __memx or similar symbols IOBJ and IPTR are empty, making the
        types equivalent to, for example, 'const char' and 'const char*'.
        For Atmel compiler these will become 'const __flash char' and
        'const __memx char*'.  All printf() functions and syslog() functions
        are changed so that the qualifier is used with the format parameter.
        From Dimitry Kloper.
      - debug.h:  Add configuration to support an architecture-specific
        debug.h header file. From Dimitri Kloper.
      - netdb:  Add support for the use of a DNS resolver file like
        /etc/resolv.conf.
      - TEA:  Add an implementation of the Tiny Encryption Algorithm.
      - math32.h:  Add some utilities to support 64-bit arithmetic
        operations for platforms that do not support long long types.

    * Tools:

      - tools/cnvwindeps.c:  Add a tool that will convert paths in
        dependencies generated by a Windows compiler so that they can be
        used with the Cygwin make.
      - tools/mkwindeps.sh: A script that coordinates use of cnvwindeps.exe.
        Dependencies now work on the Cygwin platform when using a Windows
        ative toolchain.

    * Applications: NSH

      - Module Commands:  Add module commands: insmod, rmmod, and lsmod.
      - Time Command:  Add a 'time' command that may be used to time the
        execution of other commands.
      - Password Commands:  Add useradd, userdel, and passwd commands.
      - MOTD:  Now supports a Message of the Day (MOTD) that will be
        presented after the NSH greeting.
      - Session Logins:  All sessions may be protected with logins using the
        encrypted password in /etc/passwd.
      - Extended Logins.  Added optional platform-specific function to
        perform password verification and optional delay after each failed
        login attempt.

    * Applications: apps/fsutils:

      - apps/fsutils/passwd: Utility library for accessing a password file
        like /etc/passwd.

    * Applications: apps/netutils:

      - apps/netutils/telnetd:  Now creates Telnet sessions by opening a new
        factory device at /dev/telnet and then using ioctl calls to create
        the session character drivers at /dev/telnetN.
      - apps/netutils/netlib:  Add netlib_get_dripv4addr() and
        netlib_get_ipv4netmask().  From Pelle Windestam.

    * Applications: apps/examples:

      - apps/examples/module:  Add a test harness for verifying NuttX kernel
        modules.
      - apps/examples/pca9635:  Add a simple test of PCA9635PW PWM LED driver.
        From Alan Carvalho de Assis.
      - apps/examples/ostest:  Add a test of POSIX timers using SIGEV_THREAD.

Bugfixes.  Only the most critical bugfixes are listed here (see the
ChangeLog for the complete list of bugfixes and for additional, more
detailed bugfix information):

    * Core OS:

      - pthreads: CRITICAL BUGFIX: Logic was wiping out the indication that
        of the type of a pthread.  Hence, it could be confused as a task.
      - waitpid:  CRITICAL BUGFIX.  Add a reference count to prevent waitpid
        from using stale memory released by the waited-for task group.
      - clock_systimespec():  Fix an error in a time conversion.

    * File System/Block Drivers:

      - poll(): Fix handling of sem_tickwait() return value sem_tickwait()
        does not return an -1+errno, it returns a negated errno value.
        Noted by Freddie Chopin.

    * Common Drivers:

      - TUN Driver:  Fix a compile time error in the TUN driver.  From
        Vladimir Komendantskiy.
      - USB Host HID Parser:  Wrong size used in memcpy().  From Hang Xu.
      - PCA9555: Fixed a bug in the function pca9555_setbit which occurs if
        someone tries to set one of the pins 8-15. The problem is that
        after the check if the pin is greater than 7 the variable addr is
        incremented and used in the Call I2C_WRITEREAD. But later in the
        call to the I2C_WRITE buf[0] is used as address but this address is
        not incremented as it should be. Note address does mean the address
        to the register in the ioexpander and not the I2C address.  From
        Stefan Kolb.

    * Networking:

      - TCP/IOB:  Numerous fixes, mostly relate to TCP and IOB buffering
        and race conditions.  These were necessary for for the NuttX
        networking later to be stable in some stress testing.  From Andrew
        Webster.

    * Atmel SAMV7 Drivers:

      - USBHS Device: In USBHS device driver, fix check if zero length
        packet is needed.

    * STMicro STM32 Drivers:

      - OTG FS Host:  Fix some backward arguments to stm32_putreg().  Note
        by Hang Xu.

    * Tools:

      - tools/mkdeps.c:  Extended/fixed support for --winpath option.
        Dependencies now work under Cygwin with a native Windows toolchain.

    * Build System:

      - apps/platform/Makefile:  Use a relative path to the board directory
        link rather than the absolute path.  For Cygwin, the absolute would
        would need converted with cygpath.  But just using the relative path
        is a simpler solution.

NuttX-7.15 Release Notes
------------------------

The 115th release of NuttX, Version 7.15, was made on March 27, 2016,
and is available for download from the Bitbucket.org website.  Note
that release consists of two tarballs:  nuttx-7.15.tar.gz and
apps-7.15.tar.gz.  These are available from:

    https://bitbucket.org/patacongo/nuttx/downloads
    https://bitbucket.org/nuttx/apps/downloads

Both may be needed (see the top-level nuttx/README.txt file for build
information).

Additional new features and extended functionality:

    * Core OS:

      - Add a state variable that provides the current level of OS
        initialization.  This is needed by some logic that may attempt to
        run early in the start-up sequence but cannot run if a sufficient
        level of initialization has not yet occurred.
      - Spinlocks:  Add interface definitions for to support spinlocks as
        needed for multi-CPU configurations.
      - SMP support.  Support for Symmetric Multi-Processing (SMP) added.
        This affects many internal data structures, spinlock extensions
        and renaming of interrupt enable/disable interfaces, new platform
        interfaces to support CPU initialization and inter-actions, and
        new application interfaces to manage CPU affinity.  The changes
        are too extensive to summarize here; see the SMP Wiki page at
        https://cwiki.apache.org/confluence/display/NUTTX/SMP.  The
        new platform interfaces are also described in the NuttX porting
        guide: https://nuttx.apache.org/docs/latest/quickstart/organization.html.
        Only partially verified; awaiting hardware for the complete
        verification.
      - TLS:  Basic definitions needed to support thread local storage
        (TLS).  TLS is not used anywhere yet (and may not be used in the
        near future either).
      - Performance Monitoring:  Add a configuration option to buffer
        RTOS instrumentation data in an in-memory buffer.
      - boardctl():  Add boardctl() support that will permit applications
        to control USB devices.

    * File Systems/Block Drivers:

      - procfs:  Add /proc/kmm entry that shows that state of the kernel
        heap.  Only useful in PROTECTED and KERNEL build modes where there
        is a kernel heap.
      - procfs:  Add support for showing CPU in the taste status if SMP is
        enabled.

    * Networking:

      - ARP: Add support for IOCTL commands to manage the ARP table.
      - IEEE 802.15.4 and 6LowPAN:  There are some radio drivers and a
        directory structure is in place.  However, most of this
        development is occurring on a fork and is not yet available in the
        NuttX repositories.  Hopefully in NuttX-7.16.

    * Common Device Drivers:

      - ADS1242:  Driver for the  24-Bit Differential Input ADC ADS1242 that
        communicates via SPI with a MCU. Reading the ADC conversion result
        as well as configuring the ADC, setting the input channel, etc. is
        implemented via ioctl calls.  However, it does not yet implement
        the standard ADC interface.  From Alexander Entinger.
      - U-Blox Modem:  Add an upper half driver for the U-Blox Modem.  From
        Vladimir Komendantskiy.
      - I2C: Add an I2C, "upper half", character drivers to support raw I2C
        data transfers for test applications.
      - RGB LED: Add a driver to manage a RGB LED via PWM.  From Alan
        Carvalho de Assis.
      - Performance Monitoring:  Add a character driver that will allow an
        application to read buffered scheduler instrumentation data.

    * Simulation Platform:

      - SMP:  Add multi-CPU support to the simulation to support SMP
        investigation.  There are issues with the simulation and it is less
        than perfect but sufficient for some very preliminary testing of
        the core SMP feature.

    * ARMv7-A, ARMv7-R, and ARMv7-M:

      - ARMv7-A, ARMv7-R, and ARMv7-M: Add test-and-set logic and
        definitions needed to supports spinlocks.
      - ARMv7-A: Added MPCOre Generic Interrupt Controller (GICv2) and
        Global Timer support
      - ARMv7-A: Now includes in MCU-specific hooks needed for SMP support.

    * Atmel SAMV7 Drivers:

      - HSMSI: HSMCI driver can now be configured to handle unaligned data
        buffers.

    * NXP Freescale LPC11xx/17xx/43xx and LPC2378 Drivers:

      - I2C: Backported the LPC43XX I2C driver, replacing the LPC11XX,
        LPC17XX, and LPC2378 I2C drivers.  This gives us the I2C_TRANSFER
        method in all I2C drivers.

    * NXP Freescale LPC17xx Boards:

      - Support for the u-blox GSM and GPS module evaluation board with
        NXP LPCExpresso LPC1768.  The GSM module is one of LISA-C200,
        LISA-U200 or SARA-G350. The GPS module is one of MAX-M7 or
        MAX-M8.  From Vladimir Komendantskiy.

    * NXP Freescale i.MX6:

      - Basic support is in place for the i.MX6 Quad/Dual MCUs.
        Verification is, however, waiting for the receipt of hardware.

    * NXP Freescale i.MX6 Boards:

      - Sabre-6Quad:  Basic support for the NXP/Freescale Sabre 6Quad
        board is in place but waiting for hardware for verification.

    * STMicro STM32:

      - STM32F46xx:  Support for STM32F46xx from Paul Alexander Patience
      - STM32L4:  Add support for the STM32L4 family.  From Sebastien
        Lorquet.

    * STMicro STM32 Boards:

      - STM32F4 Discovery: Add PWM support for the onboard RGB LED. From
        Alan Carvalho de Assis.
      - Nucleo-L476:  Add support for the Nucleo-L476 board.  From Sebastien
        Lorquet.
      - STM32L476VG Discovery: Add support for the STM32L476VG Discovery
        board.  From Dave.

    * Tools:

      - tools/refresh.sh now has a --silent option so that it can be used in
        batch modes without human input.

    * Build System:

      - Added a 'make olddefconfig' target that will refresh a .config file
        without interaction.

    * Applications: NSH

      - 'arp':  Add an 'arp' command that will support access to the OS ARP
        table.
      - 'ps':  The 'ps' command will show CPU if SMP is enabled.

    * Applications: apps/netutils:

      - apps/netutils/chat: Chat logic contributed by Vladimir
        Komendantskiy.
      - apps/netutils/netlib:  Add utility functions to support accesses to
        the ARP table.

    * Applications: apps/examples:

      - apps/examples/chat: Chat example contributed by Vladimir
        Komendantskiy.
      - apps/system/ubloxmodem:  Example to control the power
        state of the modem in nsh.  From  Vladimir Komendantskiy.
      - apps/examples/leds: An example to demonstrate use of LED driver.
      - apps/examples/smp:  Add a test to verify SMP configurations.
      - apps/examples/rgbled:  Example using the RGB LED driver to drive an
        RGB LED via PWM.  From Alan Carvalho de Assis.
      - apps/examples/ostest:  Add a test of TLS.
      - apps/examples/sched_note:  Add a simple example to exercise the
        scheduler instrumentation logic.

Bugfixes.  Only the most critical bugfixes are listed here (see the
ChangeLog for the complete list of bugfixes and for additional, more
detailed bugfix information):

    * Core OS:

      - Signals:  Move the list of signal actions from the TCB to the group
        structure.  Signal handlers are not per thread but, rather, per task
        group.  I know, I preferred it the other way too, but this is more
        compliant with POSIX.
      - Semaphores: Add an internal, non-standard interface to reset a
        semaphore count.  This is sometimes needed by drivers in order to
        recover from error conditions.  Were previously using sem_init()
        which is both inappropriate and incorrect if the semaphore count is
        negative.
      - Low-Priority Work Queue:  Fix logic to find an IDLE worker thread;
        the test for busy was backward.  From Linfei Chen.

    * File System/Block Drivers:

      - FAT:  Add an option to force all transfers to be performed
        indirectly using the FAT file system's internal sector buffers.
        This is a fix for the case where the user provided buffers are not
        properly aligned for DMA (as with THTTPD).
      - MTD:  Increase block size in mtd_geometry_s to 32-bits.

    * Common Drivers:

      - I2C:  Restructured the I2C interface as necessary to eliminate some
        thread-safety issues inherent in the legacy I2C interface design.
        This effects the interface definition, all I2C clients, and all low-
        level I2C drivers.  I have used caution, but I still expect a change
        of this magnitude to introduce some errors. Any bug reports of bug
        fixes will be much appreciated.
      - I2C_RESET:  Eliminate up_i2creset().  It should not be a global
        function; Now it is an I2C interface method.
      - PCA555:  Add logic to make the PCA555 driver thread safe.
      - syslog: If syslog timestamping is enabled, don't try to get the time
        if the timer hardware has not yet been initialized.
      - AT24xx driver: Correct missing address calculation logic.  From Frank
        Benkert.

    * Networking:

      - Networking drivers that support CONFIG_NET_NOINTS:  Fix a race
        condition that can cause the TX poll timer to stop running.  From
        Manuel Stuhn.
      - Timer Poll:  Fix some logic when there are multiple network
        interfaces.  In this case, TCP timeout events can really only being
        processed when the poll from the correct device is received.

    * Atmel SAMV7 Drivers:

      - SAMV7 USB HS device:  The USB driver has had some issue that would
        occasionally cause loss of packets.  Back last December, a fix was
        put in for this but the fix apparently worsens the problem; now
        causing hangs.  The basic problem is that the number of busy banks
        (NBUSYBKS) status is not real time but is delayed.  This was fixed;
        now when the DMA completes and NBUSYBKS > 0, the NBUSYBK is
        interrupt is enabled and the operations are deferred until NBUSYBKS
        is truly zero.

    * Tools:

      - tools/testbuild.sh:  .config files were not being updated because
        (a) kconfig-conf was being called in the wrong directory and (b)
        apps/Kconfig had not yet been created.  Now uses 'make
        olddefconfig'.

    * Applications: apps/system:

      - apps/system/i2c:  The I2C tool now obeys it OS interfacing: it now
        uses an I2C character driver to access the I2C bus.
      - apps/system/cdcacm, usbmsc, and composite:  Use new boardctl()
        instead of calling directly in the OS when possible.

    * Applications: apps/netutils:

      - apps/netutils/dhcpd: DHCPD no longer calls directly into the OS but
        uses the new network IOCTL commands to modify the ARP table.

    * Applications: apps/modbus:

      - apps/modbus/nuttx/portserial.c:  Was not returning an error on
        failure to open the device driver.  From Olololshka kokoko.

    * Applications: apps/examples:

      - apps/examples/usbserial, composite, usbterm:  Use new boardctl()
        instead of calling directly in the OS when possible.  There are
        still a few bad OS calls for USB device interfaces that do not yet
        have boardctl() commands.

    * Applications: apps/platform:

      - Moved C++ initialization logic out of the RTOS and into the
        application space, specifically to apps/platform/board, where it
        belongs.

NuttX-7.16 Release Notes
------------------------

The 116th release of NuttX, Version 7.16, was made on June 1, 2016,
and is available for download from the Bitbucket.org website.  Note
that release consists of two tarballs:  nuttx-7.16.tar.gz and
apps-7.16.tar.gz.  These are available from:

    https://bitbucket.org/nuttx/nuttx/downloads
    https://bitbucket.org/nuttx/apps/downloads

Both may be needed (see the top-level nuttx/README.txt file for build
information).

Additional new features and extended functionality:

    * Core OS:

      - Power Management: Add activity domain to all PM interfaces and
        driver callbacks.  If CONFIG_PM_NDOMAINS == 1, then the legacy
        behavior is preserved.  If CONFIG_PM_NDOMAINS > 1, then multiple
        PM domains are supported.  This will allow separate control for
        certain power management groups.  For example, a network can be
        shut down without affect an ongoing UI (and vice versa).
      - board_app_initialize():  board_app_initialize() now accepts an
        argument that may be used to support initialization in different
        configurations.

    * File System and Block and MTD Drivers:

      - N25Qxxx: Add MTD support for Micron N25Qxxx family of QSPI flash.
        From Dave (ziggurat29).
      - SST26F:  Add an MTD driver for SST26F spi/qspi flash devices (SPI
        mode only).  From Sebastien Lorquet.
      - File Descriptor Detach: Add logic to detach a file structure from a
        file descriptor. This is for use only within the OS.  It permits an
        open file or driver to be used across multiple threads.

   * Networking and Network Drivers:

      - listen()/accept():  Separate out psock_listen() and psock_accepti()
        for internal, thread independent OS usage (i.e., without a socket
        descriptor).
      - VNC Server:  Add support for a VNC server.  This logic is code
        complete and functional, but not well tested.

    * Graphics and Graphic Drivers:

      - Framebuffer driver:  Add a display number to each interface in order
        to support multiple display devices.
      - VNC Server:  Add support for a VNC server.  This logic is code
        complete and functional, but not well tested.
      - LCD Backpack: Add support for PCF8574 LCD Backpack driver. This
        driver supports an interface board that is based on the PCF8574 I/O
        expander and supports the HD44780-based (or compatible) LCD modules.
        There are a myriad of different vendors of such, but they are
        principally the same, save wiring and minor features like jumpers
        for I2C addresses. This driver supports known and unknown variants.
        From Dave (ziggurat29).

    * Common Device Drivers:

      - RTC:  Simplify the RTC interface.  The old interface was way too
        complex and was not fully implemented anywhere.
      - BH1750FVI:  Add a character driver for Rohm Ambient Light Sensor
        BH1750FVI.  From Alan Carvalho de Assis.
      - CAN:  Improve CAN error reporting. From Frank Benkert.
      - aes.h:  Modifications to the crypto API needed for LPC43xx.  From
        Alexander Vasiljev.
      - ADC:  Interface no longer uses global adc_receive() call.  Added a
        new bind() method to the ADC interface.  Now the ADC upper half
        driver will register its receipt-of-data callback.  This change
        allows the ADC lower half driver to be used with a differ ADC upper
        half.

     * Simulation Platform:

      - Linux Host Networking:  Enhance networking support for the
        simulation under Linux. Includes updated support for Linux TUN/TAP,
        and the addition of support for Linux bridge devices.  From Steve.

    * ARMv7-A, ARMv7-R, and ARMv7-M:

      - ARMv7-M:  Convert more assembly language files for use with the IAR
        toolchain.  From Kha Vo.
      - ARMv7-A:  Complete re-design of SMP-related logic to initialize each
        CPUn, n > 0, when CONFIG_SMP=y.

    * Atmel SAMV7:

      - Add a JTAG config and ERASE config to Kconfig to set the
        CCFG_SYSIO SYSIO Pins.  From David Sidrane.
      - System Reset: Add the up_systemreset interface to the samv7 arch.  The
        approach is slightly different in that: 1) It enables ARCH_HAVE_RESET
        and allows the user to set if, and for how long, to drive External
        nRST signal. It also does not contain a default board_reset, as that
        really should be done in the config's src if CONFIG_BOARDCTL_RESET
        is defined.  From David Sidrane.

    * Atmel SAMV7 Boards:

      - SAMV71-XULT: Add configuration(s) that were be used to verify VNC
        graphics output as well as mouse and keyboard input.

    * NXP Freescale i.MX6 Boards:

      - Sabre-6Quad:  The basic i.MX6 port is complete.  This is a minimal
        port at present and probably still has some as-of-yet-undiscovered
        issues.
      - Sabre-6Quad: Basic SMP NSH configuration is now working.  But this
        is probably only because the SMP test case does not stress the
        logic.  There are know outstanding SMP issues as noted in the
        Sabre-6Quad README.txt file.

    * NXP Freescale LPC43xx:

      - LPC4337jet100: Add definitions for the LPC4337jet100 chip.  From
        Alexander Vasiljev.

    * NXP Freescale LPC43xx Drivers:

      - AES:  Add AES support.  From Alexander Vasiljev.

    * STMicro STM32:

      - STM32 L4: Add configuration options to allow SRAM2 to be used for
        heap, or not at all, and to zero-initialize it on OS start, or not
        at all. From Dave dev@ziggurat29.com.
      - STM32 L4: Add support for HSE and MSI clocks, and auto trim of MSI
        to LSE (needed for USB).  From Dave (ziggurat29)
      - STM32 L4: Add support for unique id function to arch; modified board
        to support unique id boardctl.  From Dave (ziggurat29)

    * STMicro STM32 Drivers:

      - STM32 F4 RTC: Add a custom RTC driver with support for alarms.  From
        Neil Hancock.
      - STM32 L4 QSPI: Add a QSPI driver with DMA support and (optional
        memory mapped mode support. From Dave ziggurat29).
      - STM32, STM32 L4, and STM32 F7 Serial:  Add support for compliant
        SD-style breaks. From David Sidrane.
      - STM32 L4 CAN: Add CAN support for STM32L4.  From Sebastien Lorquet.
      - STM32 1-Wire:  Add support for a custom 1-wire driver.  The serial
        driver already supports a 1-wire interface, but this driver uses the
        same serial logic to implement a lower half driver much like the
        I2C lower half driver.  From Aleksandr Vyhovanec.
      - STM32 L4 SPI: Add support for SPI 4 and 5 on stm32f411 chips. From
        Konstantin Berezenko.
      - STM32 ADC: Allow omitting use of channels in a lower part of PWM.
        From Pierre-noel Bouteville.
      - STM32 L4 I2C: Get I2C working for STM32L4.  From Dave (ziggurat29).

    * STMicro STM32 Boards:

      - STM3220G-EVAL:  Add support for both the IAR and uVision GCC IDEs.
        From Kha Vo.
      - STM32F429I Discovery:  Add support for the uVision GCC IDE.   From
        Kha Vo.
      - STM32F4 Discovery: Integrate BH1750FVI driver in the STM32F4 Discovery
        board.  From Alan Carvalho de Assis.
      - STM32L476VG Discovery:  Add support for QSPI based N25Qxxx flash.
        From Dave (ziggurat29)
      - STM32L476VG Discovery: Add board ioctls for allowing user application
        to cause QSPI memory mapped mode to be engaged and disengaged.  Also
        partitioned QSPI flash for file system and other (eventually xip).
        From Dave (ziggurat29)
      - Nucleo-144: Basic port for the Nucleo-144 board with the STM32F746ZG
        MCU.  From Kconstantin Berezenko.
      - STM32F103 Minimum: Add support for this minimual STM32F103CBT6 "blue"
        board.  From Alan Carvalho de Assis.
      - STM32F411E Discovery:  Add basic configuration for stm32f411e-disco
        board with STM32F411VE chip.  From Konstantin Berezenko.

    * Build/Configuration System:

      - Moved NuttX repository to https://bitbucket.org/nuttx/nuttx.
        Eliminated use of sub-modules.
      - Add support for the IAR toolchain for the limited case of the ARMv7-M
        architecture and the STM32 chip.  From Aleksandr Vyhovanec.
      - make export: Pass top-level make to the script to allow -j greater
        than 1.  From David Sidrane.
      - fs/Kconfig:  Allow CONFIG_FS_WRITABLE to be manually selectable. This
        is needed when there are no writable file systems, but write support
        is still needed in BCH or FTL.
      - arch/*/Makefile: Add definitions that can be overrided to use GCC
        instead of LD in the final link.  From Paul Alexander Patience .

    * Applications: apps/netutils:

      - apps/netutils/esp8266:  ESP8266 driver application.  From Pierre-noel
        Bouteville.

    * Applications: apps/examples:

      - apps/examples/alarm:  Add a simple test of the ALARM iotcl calls of
        the RTC driver.
      - apps/examples/nximage:  Add a configuration option to select
        greyscale.

    * Platforms: apps/platform:

      - apps/platform/nucleo-144: Add platform files for NUCLEO-144
        (NUCLEO-F746ZG).  From Mark Olsson.
      - apps/examples/media:  You can now override the default device driver
        path by providing an alternal path on the command line.  From
        Sébastien Lorquet.

Works-In-Progress:

    * IEEE802.14.5/6LowPAN.  Hooks and framework for this effort were
      introduced in NuttX-7.15.  Work has continued on this effort on
      forks from the main repositories, albeit with many interruptions.
      The completion of this wireless feature will postponed until at
      least NuttX-7.17.

    * i.MX6 SMP.  Partially functional, but there is more that still
      needs to be done.

Bugfixes.  Only the most critical bugfixes are listed here (see the
ChangeLog for the complete list of bugfixes and for additional, more
detailed bugfix information):

    * Core OS:

      - Various places:  Search for places where a stray semicolon following
        an if condition cause the if body to be executed unconditionally.
        Fixes in all SAM DMA logic, unionfs, OS signalling logic, and others.
      - enter/leave_critical_section() may attempt to access task lists
        before they have been initialized in the SMP configuration.

    * File System/Block Drivers:

      - SMART MTD:  Return code of smart_scan not checked, can cause success
        result in failure case, leading to 'dev' pointer being invalid. From
        Dave (ziggurat29)
      - mount: Fix a backward debug assertion.  Noted by David Sidrane.

    * Common Drivers:

      - NRF24L01: Fix backward calculation of relative frequency.  Noted by
        Henry Zhang.
      - PCA9555 I/O expander: Fix an error in the PCA9555 driver: Under
        certain error conditions, interrupts were not being re-enabled.
        Sebastien Lorquet.
      - ADS1255: Must not do SPI access from interrupt handler.  Use the
        worker thread instead.  Must also lock the SPI bus before using it.
      - Several SPI-based drivers modified.  All drivers that use SPI must
        call SPI_LOCK and SPI_UNLOCK.  This is not optional.
      - MS583730:  Fix a bug in crc computation for ms583730. Implement
        POSIX read.

    * Atmel SAMV7:

      - Fix typo in MATRIX register definitions.  From Stefan Kolb.
      - SAMV7 Tickless Mode: This is a fix to a problem in the handling of
        the oneshot timer. Due to a wrong assumption concerning the behavior
        directly after the start of the timer/counter the function
        sam_oneshot_cancel calculates the wrong remaining time. The code
        assumes that the counter register is zero directly after the start
        of the timer, but this is not true. To start the time/counter a
        software trigger is invoked, this trigger starts the timer/count and
        sets the counter register to zero, but the reset of the counter
        register is not performed instantly. According to the datasheet:
        "The counter can be reset by a trigger. In this case, the counter
        value passes to zero on the next valid edge of the selected clock."
        Thus the counter is set to zero between 0 and USEC_PER_TICK
        microseconds after the clock was started.
        In my fix I use the freerun count value to determine if at least one
        tick passed since the start of the timer and thus if the value of
        the oneshot counter is correct. I also tried to use the function
        up_timer_gettime to achieve this but, at least if compiled with
        no optimization the problem vanishes without using the value of the
        function, the function call takes too long.
        Another problem treated in the fix is that if the oneshot timer/counter
        is canceled, we only know the remaining time with a precision of
        USEC_PER_TICK microseconds. This means the calculated remaining time
        is between 0 and USEC_PER_TICK microseconds  too long. To fix this I
        subtract one tick if the calculated remaining time is greater than
        one tick and otherwise set the remaining time to zero. By doing so
        the measured times are much more precise as without it.  From Stefan
        Kolb.

    * Atmel SAMA5:

      - SAMA5:  Stefan Kolb's change to the SAMV7 Oneshot Timer should also
        be applied to the SAMA5 oneshot time since the drivers are identical.

    * Atmel SAM3/4:

      - SAM3/4:  Stefan Kolb's change to the SAMV7 Oneshot Timer should also
        be applied to the SAM3/4 oneshot time since the drivers are identical.

    * Atmel SAMV7 Drivers:

      - SAMV7 TWIHS (as well as SAM3/4 and SAMA5:  Ensure that the TWIHS
        (i2c) hw gets its clock set when the sequence of
        sam_i2cbus_initialize(), sam_i2cbus_uninitialize(), then
        sam_i2cbus_initialize() or twi_reset() is called.  I found this a
        while back in the stm32 family, so there may be more arch-es with
        this sort of bug. I suppose any driver that has the notion of "do
        not set the freq if it is already set" could be suspect.  From David
        Sidrane.
      - USBHS Device: Remove disabling of whole USB on suspend of USBHS.
        This fix removes the disabling of the whole USB peripheral on
        suspend interrupt. Its enough to freeze the clock instead. When
        disabling the whole peripheral, the next wakeup-interrupt comes up
        with an disabled clocking. The unfreeze clock has no effect, because
        the master clock is disabled. This makes all registers, including
        the IDR unwriteable and the IRQ falls in an endless loop blocking
        the whole system. Furthermore the disabling of the peripheral clock
        prevents hotplugging or reconnecting the USB.  From  Frank Benkert.
      - MCAN: Fix missing unlock of device in MCAN mcan_txempty().  From
        Frank Benkert.

    * STMicro STM32:

      - STM32 L4 Clocking: Problem with resetting backup domain clears
        clocking options set up before in *rcc.c use INITS flag to avoid
        magic reg value to detect power up reset state of RTC correct a
        problem clearing interrupt flags (they weren't) which prevented an
        alarm from ever being used more than once per reset cycle.  From
        Dave (ziggurat29)

    * STMicro STM32 Drivers:

      - STM32L4 SPI: That STM32Lr SPI driver is quite different. They now
        handle frames of arbitrary size between 4 and 16 bits. It was broken
        before a new bit has to be set (RX fifo threshold) to handle <= 8-bit
        transactions. If not set, the default is 16-bit packed >=8-bit
        frames and the RXNE bit is never set (it is set when 16-bits are
        received). weird things as always. This also add 8-bit access
        routines to the data register, because a 16-bit access to the data
        register when the frame size is below 9 bits is interpreted as a
        packed dual frame exchange. Sebastien Lorquet.
      - STM32:  Correct some bad commits that broke the LTDC display example.
        From Marco Krahl.
      - STM32 F4 RTC: Fix logic in F4 RTCC driver that prevent ALARM
        interrupt.  From Neil Hancock.
      - STM32 F1 ADC: Fix STM32 ValueLine ADC IRQ number selection. From
        David Sidrane.

    * STMicro STM32 Boards:

      - STM32F429I Discovery:  Correct some bad commits that broke the LTDC
        display example.  From Marco Krahl.

    * TI Tiva:

      - GPIO Interrupts: Fix a bug of GPIO falling-edge interrupt for tiva.
        From Young.

    * C Library:

      - math: Add a NAN test on 'x' in asin function of lib_asin.c. Suggested
        by Pierre-noel Bouteville.

    * Build/Configuration System:

      - Several Makefiles: Add .PHONY definitions to prevent 'clean up to date'
        message weirdness when 'make clean' is done with no .config or
        Make.defs file.

NuttX-7.17 Release Notes
------------------------

The 117th release of NuttX, Version 7.17, was made on July 25, 2016,
and is available for download from the Bitbucket.org website.  Note
that release consists of two tarballs:  nuttx-7.17.tar.gz and
apps-7.17.tar.gz.  These are available from:

    https://bitbucket.org/nuttx/nuttx/downloads
    https://bitbucket.org/nuttx/apps/downloads

Both may be needed (see the top-level nuttx/README.txt file for build
information).

Additional new features and extended functionality:

    * File System and Block and MTD Drivers:

      - drivers/mtd: Add a driver of IS25xP SPI flash devices.  Based on
        sst25xx driver.  From Marten Svanfeldt.

    * Networking and Network Drivers:

      - Break out internal interface psock_ioctl().

    * Common Device Drivers:

      - PTYs: Added support for pseduo-terminals: Device drivers that can be
        used for communications between tasks (usually with re-directed I/O).
        Based on existing pipe logic.
      - Button upper half driver:  Added support for poll().
      - CAN:  Add support for poll. From Paul Alexander Patience.
      - GPIO:  Add support for a simple GPIO driver.  It supports only pre-
        configured input, output, and interrupting pins with basic input and
        output operations.  Interrupt events can lead to notification via a
        signal.
      - I/O Expander: Shadow-Mode: The output- and configuration registers of
        the IO-Expander are held in the microcontrollers memory and only
        written to the IO-Expander.  This reduces bus traffic and is more
        error-proof than the normal read-modify-write operation. Retry Mode:
        If enabled and an error occurs while writing to the IO-Expander the
        current transmission is automatically repeated once. From Michael
        Spahlinger.
      - Pipes/FIFOs:  Add support to allocating different sizes for pipe and
        fifo buffers.  Adds mkfifo2() and pipe2() which are just like mkfifo()
        and pipe(), but allow control of the size of the underlying, in-memory
        circular buffer.  Move pipe() and mkpipe() to the C library, they are
        no longer core OS interfaces.  Capability currently used only by PTY
        logic to support, configurable, smaller buffers for PTYs.

    * SYSLOG/Debug Output:

      - SYSLOG: Consolidated all SYSLOG logic in drivers/syslog.  Added an
        abstraction layer that supports:  (1) redirection of SYSLOG outpout.
        This is usually so that you can boot with one SYSLOG output but
        transition to another SYSLOG output when the OS has initialialized,
        (2) adds common serialization of interrupt output as a configuration
        option.  Without this configuration setting, interrupt level output
        will be asynchronous.  And (3) vsyslog is now a system call and is
        usable with other-than-FLAT builds.
      - SYSLOG: syslog() will now automatically redirect output to
        lowsyslog() if called from an interrupt handler.
      - Extended SYSLOG logic so that we can send SYSLOG output to a file.
      - SYSLOG character device channel will now expand LF to CR-LF.
        Controllable with a configuration option.
      - Add a SYSLOG character device that can be used to re-direct output
        to the SYSLOG channel (Not be be confused the SYSLGO output to a
        character device).
      - Debug features are now enabled separately from debug output.
        (1) CONFIG_DEBUG is gone. It is replaced with CONFIG_DEBUG_FEATURES.
        (2) The macros dbg() and vdbg() have renamed as _err() and _info(),
        respectively. This also applies to all of the variants as well,
        XXdbg() and XXvdbg().  (3) Add a new debug level, _warn() (and
        all variants XXwarn(), XXvwarn(), etc.). (4) Debug assertions can
        now be enabled separately from debug output. (5) You can now enable
        subsystem/device driver debug output at different output levels. For
        example, CONFIG_DEBUG_FS no longer enables file system debug output
        It enables general file system debug logic and enables selection of
        CONFIG_DEBUG_FS_ERROR, CONFIG_DEBUG_FS_WARN, and CONFIG_DEBUG_FS_INFO.
      - Since the SYSLOG layer now automatically handles low-level vs.
        high-level output, the low-level (ll) variants of the debug macros
        were eliminated.
      - Reviewed all uses of *err().  These macro family should indicate
        only error conditions.  Convert *err() to either *info() or add
        ERROR:, depending on if an error is reported.
      - _alert(): New debug macro: _alert().  This is high priority,
         unconditional output and is used to simplify and standardize crash
         error reporting.
      - Many CONFIG_DEBUG_* options did not have matching macros defined in
        include/debug.h.  Rather, there were various definitions scattered
        throughout the sourse tree.  These were collected together and
        centralized with single macro definitions in include/debug.h

    * Simulation Platform:

      - Added the simulated QSPI (N25Q) flash to the simulation and extended
        flash simulation capabilities to run with MTD drivers based on config
        options (currently m25p, sst26 and w25). From Ken Pettit.

    * Atmel SAMV7 Drivers:

      - SPI: SPI-Freq. 40MHz; VARSELECT; hw-features This change adds the
        following improvements:

          o Increase the allowed SPI-Frequency from 20 to 40 MHz.
          o Correct and rename the "VARSELECT" option   This option was
            included in the code as "CONFIG_SPI_VARSELECT" but nowhere
            defined in a Kconfig file. The change renames it to
            "CONFIG_SAMV7_SPI_VARSELECT" and corrects the implementation
            according the datasheet of Atmel. In short, this option
            switches the processor from "fixed peripheral selection"
            (single device) to "variable peripheral selection" (multiple
            devices on the bus).
          o Add a new Function to the interface to control the timing and
            delays of the chip according the ChipSelect lines. This function
            can control the delay between the assertion of the ChipSelect and
            the first bit, between the last bit and the de-assertion of the
            ChipSelect and between two ChipSelects. This is needed to tune
            the transfer according the specification of the connected devices.
          o Add three "hw-features" for the SAMV7, which controls the behavior
            of the ChipSelect:
              - force CS inactive after transfer: this forces a (short) de-
                assertion of the CS after a transfer, even if more data is
                available in time
              - force CS active after transfer: this forces the CS to stay
                active after a transfer, even if the chip runs out of data.
                Btw.: this is a prerequisite to make the LASTXFER bit working
                at all.
              - escape LASTXFER: this suppresses the LASTXFER bit at the end
                of the next transfer. The "escape"-Flag is reset automatically.

        From Frank Benkert
      - TWISHS:  Driver improvements from Michael Spahlinger.
      - GPIO-Driver fixed for Open-Drain Pins:

          o sam_gpioread: Now the actual line level from the pin is read
            back.   This is extremely important for Open-Drain Pins, which
            can be used bidirectionally
          o Re-Implemented twi_reset-function and enhanced it so it can be
            called from inside the driver (see next point)
          o Glitch-Filter: Added a configuration option to enable the twi-
            built-in glitch filter
          o Added a "Single Master Mode": In EMC Testing the TWI-Bus got
            stuck because the TWI-Master detected a Multi-Master access (but
            there is no second master). With the option "Single Master" we
            detect these events and automatically trigger a twi_reset. We
            also do an automatic recovery if a slave got stuck (SDA stays
            low).

        With the above changes I2C-Bus reliability in harsh environments (eg.
        EMC) is greatly improved. The small change in the GPIO-Driver was
        necessary because otherwise you cannot read back the correct line
        status of Open-Drain Outputs and this is needed by the twi_reset
        function.  From Michael Spahlinger

    * NXP Freescale LPC43xx Drivers:

      - EMC: Extend LPC43xx EMC code to support SDRAM on a dynamic memory
        interface.  From Vytautas Lukenskas.

    * NXP Freescale Kinetis:

      - Kinetis K64:  Add basic support for the K64 family.  I leveraged the
        changes from https://github.com/jmacintyre/nuttx-k64f and merged
        into the existing kinetis code  with a lot of changes and additions
        (like pin multiplexing definitions).

    * NXP Freescale Kinetis Drivers:

      - Add a KinetisUSB device controller driver.  Derived from the pic32mx
        usb driver, which uses the same usb controller.  From kfazz.
      - Kinetis pwm support, based on the KL pwm driver.  From kfazz.
      - Kinetis Ethernet:  Add support for the KSZ8081 PHY.
      - Kinetis Ethernet:  Modified Ethernet driver to try all PHY addresses
        and then only fail if the driver cannot find a usable PHY address.
        This means that you no longer have to specific the PHY address in
        advance.
      - Kinetis Ethernet:  Add support for CONFIG_NET_NOINTS.  The driver no
        longer runs the networking at interrupt level but can defer interrupt
        work to the high-priority work queue.

    * NXP Freescale Kinetis Boards:

      - Teensy-3.x:  Add USB support and a usbnsh configuration.
        From kfazz (2016-06).
      - Freedom-K64F: Add support for the NXP Freedom-K64F board at 120MHz.
        This is primarily the work of Jordan Macintyre.  I leveraged this
        code from https://github.com/jmacintyre/nuttx-k64f which was, itself,
        a leverage from the old K60 TWR configuration.  This includes
        significant corrections (LEDs, buttons, README, etc) and extensions
        and updates to match more recent BSPs.
      - Freedom-K64F:  Added a configuration that supports networking.

    * STMicro STM32:

      - STM32 F1-4: Added support for the STM32F105R.  From Konstantin
        Berezenko.
      - STM32 F4: Added support for the STM32FF76xxx and STM32FF7xx
        families. From David Sidrane.
      - STM32 F1-4:  Add support for Tickless mode (two timer
        implementation).  From Max Neklyudov.
      - STM32 L4: Add support for tickless OS, and incidentally timers,
        PWM, oneshot, free-running....  From ziggurat29.

    * STMicro STM32 Drivers:

      - STM32 F1-4: Add the up_getc() function to STM32 in order to support
        the minnsh configuration.  From Alan Carvalho de Assis.
      - STM32 F7: Add SPI driver.  From David Sidrane.
      - STM32 F7: Add SPI, I2C, and ADC drivers.  From Lok Tep.
      - STM32 L4: Add ioctls to set/get CAN bit timing in stm32l4.  Add
        ioctl hooks to allow future management of can id filters. From
        Sebastien Lorquet.
      - STM32 L4: Add some CAN mode IOCTL calls.  These will be useful for
        device autotest when the application boots.  They are redundant
        with the CONFIG_CAN_LOOPBACK option, which can now just be
        interpreted as a default setting.  From Sebastien Lorquet.
      - STM32 F1-4: Port STM32L4 CAN IOCTLs to STM32.  From Sebastien Lorquet.
      - STM32 L4: Implementation of loopback IOCTLs.  From Sebastien
        Lorquet.
      - STM32 F7: Added SDMMC1 support for stm32F7 74-75.  From Lok Tep.
      - STM32 F7: Add USB support.  From Lok Tep.
      - STM32 F7: Added PWR, RTC, and BBSRAM support for stm32f7. From David
        Sidrane.
      - STM32 F7: Added STMF7xxx RTC.  From David Sidrane.
      - STM32 F7: Added STM32F7 DBGMCU.  From David Sidrane.
      - STM32 L4: Port support for both RX FIFOs from STM32 CAN.  From Paul
        Alexander Patience.

    * STMicro STM32 Boards:

      - Added a minnsh configuration for the STM32F103-Minimum board.  From
        Alan Carvalho de Assis .
      - Added support for the Nucleo-F767ZI board. From David Sidrane.
      - Nucleo-144/Nucleo-F767ZI:  Add test for STM32 F7 SPI.  From David
        Sidrane.
      - Nucleo-144: Added SDMMC support to Nucleo-144. From David Sidrane.
      - Olimex STM32-E4077:  Add support for Olimex STM32 E407 board.  From
        Mateusz Szafoni.
      - Nucleo-144: Added USB OTG device to Nucleo-144.  From David Sidrane.
      - Nucleo-144: Added bbsram test to Nucleo-144.  From David Sidrane.
      - STM32F4 Discovery:  Add CAN support for STM32F4 Discovery.  From
        Matthias Renner.
      - STM32F4 Discovery:  added a canard configuration files.  From
        Matthias Renner.
      - STM32F4 Discovery: Add FPU support for ostest for the STM32F4
        Discovery platform. From David Alessio.
      - STM32L476 Discovery: Update stm32l476 disco to include init code for
        smartfs and nxffs for cases where those fs are included in build.
        From ziggurat29.

    * C Library/Header Files:

      - include/assert.h: Check if NDEBUG is defined.  From Paul Alexander
        Patience.
      - assert.h: Define static assert for C++ usage.  From Paul Alexander
        Patience.
      - Add crc64 support. From  Paul Alexander Patience.
      - hex2bin:  Move the portable library portion of apps/system/hex2bin
        the C library with the OS internals.  It is used in certain internal
        boot-loader builds.
      - Add raise().
      - libm: This change should significantly improve the performance of
        single precision floating point math library functions. The vast
        majority of changes have to do with preventing the compiler from
        needlessly promoting floats to doubles, performing the calculation
        with doubles, only to demote the result to float. These changes only
        affect the math lib functions that return float. From David Alessio.
      - printf(): If there are no streams, let printf() fall back to use
        syslog() for output.
      - Move pipe() and mkpipe() to nuttx/libc, they are no
        longer core OS interfaces.  Capability currently used only by PTY logi
        to support, configurable, smaller buffers for PTYs.
      - Move driver-related files from include/nuttx to include/nuttx/drivers.
        Move driver related prototypes out of include/nuttx/fs/fs.h and into
        new include/drivers/drivers.h.
      - include /nuttx/lib: Move library-related files from include/nuttx to
        include/nuttx/lib.

    * Build/Configuration System:

      - Custom Board Configuration: Add logic to support custom board
        directories that include a Kconfig file.  During the context phase
        of the build, any Kconfig file in the custom board directory is
        copied into configs/dummy, replacing the existing Kconfig file with
        the target Kconfig file.
      - Remove the includes/apps link to apps/include.  It is no longer
        used.  From Sebastien Lorquet.

    * Tools:

      - tools/tesbuild.sh will now build NxWM configurations.

    * Application Build/Configuration System:

      - Change to the way that apps/ Kconfig files are generated in
        order to better support reuse of the apps/ directory in NuttX
        products.  Changes include: Make the full tree use wildcards
        make.defs, Add empty preconfig rules to 'leaf' makefiles, Use
        directory.mk for recursive dir makefiles, Individual app kconfig
        fixes, Recursive Kconfig autogeneration, Add kconfig files for
        pcode and tiff, and fix a gitignore rule,  From Sébastien Lorquet.
      - apps/include directory structure reorganized.  There are no longer
        any header files in the apps/include/. directory.  Rather, sub-
        directories were added to match the partitioning of apps/ sub-
        directories and the header files were moved into the appropriate
        sub-directory.  This change is intended to help with some changes
        being considered by Sébastien Lorquet.
      - Call all includes from <apps/bla/bla.h> to "bla/bla.h". From Sebastien
        Lorquet.
      - Add apps/include to include path in top-level Make.defs file.

    * Applications: apps/nshlib:

      - Make NSH net-initialization be a configuration option. From Marten
        Svanfeld.
      - Add NTP client initialization in NSH network startup logic.  From
        David S. Alessio .
      - 'ps' command now prints out the stack usage if stack coloration is
        enabled.  From Frank Benkert.
      - Allow stack usage to be disabled on constrained systems. From David
        Sidrane.

    * Applications: apps/netutils:

      - NTP Client:  Add retries.  From David S. Alessio.
      - NTP Client:  The NTP client will now optionally use pool.ntp.org as
        the NTP server; and reset the retry count upon success -- more robust.
        From David Alessio.
      - ESP8266: Add logic to set the BAUD rate.  From Pierre-noel Bouteville.
      - ESP8266: In Kconfig, select ARCH_HAVE_NET when NETUTILS_ESP8266 is
        selected.  This allows, among other things, support for network debug
        output.  From Pierre-noel Bouteville.

    * Applications: apps/fsutils:

      - flash_eraseall: IOCTL wrapper for MDCIO_BULKERASE command.   Was in
        nuttx/drivers/mtd.  Moved to apps/fsutils because the call directly into
        the OS was incorrect.

    * Applications: apps/canutils:

      - canlib: Basic CAN utility library. From Sebastien Lorquet.

    * Platforms: apps/system:

      - flash_eraseall: Now uses the IOCTL wrapper at apps/fsutils/flash_eraseall.

    * Platforms: apps/platform:

      - Add platform files for Olimex STM32 E407.  From Mateusz Szafoni.

    * Applications: apps/examples:

      - apps/examples/canard:  Add canard example application.  From
        Matthias Renner.
      - apps/examples/pty_test: PTY test program.  From Alan Carvalho de
        Assis.

Works-In-Progress:

    * IEEE802.14.5/6LowPAN.  Hooks and framework for this effort were
      introduced in NuttX-7.15.  Work has continued on this effort on
      forks from the main repositories, albeit with many interruptions.
      The completion of this wireless feature will postponed until at
      least NuttX-7.18.

    * i.MX6 SMP.  Partially functional, but there is more that still
      needs to be done.

Bugfixes.  Only the most critical bugfixes are listed here (see the
ChangeLog for the complete list of bugfixes and for additional, more
detailed bugfix information):

    * Core OS:

      - semaphores: Need to set errno to EINVAL on errors in sem_post()
        and sem_wait(). From Paul Alexander Patience.

    * File System/Block Drivers/MTD Drivers:

      - Several MTD FLASH drivers nullify the freed 'priv' structure and
        failed to return NULL as stated in the comments. Result, will
        operate on a NULL pointer later.  Noted by David Sidrane.
      - VFS ioctl().  Per comments from David Sidrane, file_ioctl() should
        not return succeed if the ioctl method is not supported.  It
        probably should return ENOTTY in that case.
      - SST26 Driver: Before accessing the sst26 flash, the "Global Unlock"
        command must me executed, which I do in the sst26 driver.  BUT re-
        reading the datasheet, the WREN instruction is required to enable
        the execution of this command. This was not done. I have no idea how
        the driver currently works except by chance. The writes should never
        happen at all, the flash is half-enabled!  From Sebastien Lorquet.
      - N25Qxx Driver: Alter the notion of 'blocksize' to be equivalent to
        'flash write page size' in order to align with assumptions in the
        smartfs driver (at least, maybe other things do as well).  Correct a
        bug that was previously masked by having blocksize=eraseblocksize
        which would cause buffer overflows and delicious hardfaults.
        Trivial spelling changes in comments, etc.  From ziggurat29.
      - SmartFS: Fix a 32-byte memory leak.  From Ken Pettit.
      - SMART MTD layer: Fixes freesector logic error when sectorsPerBlk=256,
        adds DEBUGASSERT for invalid geometry and additional memory debug
        logic.  Also fixes the dangling pointer on error bug.  From Ken
        Pettit.

    * Common Drivers:

      - USB CDC/ACM Device Class: cdcacm_unbind leaks write request objects.
        This arises due to freeing the bulk IN endpoint before the loop
        that frees the requests via cdcasm_freereq.  That function checks
        the parameters and skips the freeing if either is NULL.  Freeing
        the bulk IN endpoint will cause the first param to be NULL, thereby
        bypassing the free operation.  To fix, I moved the release of the
        bulk IN endpoint until after to loop (much as was the case for the
        OUT and read requests, which did not exhibit the problem).  From
        ziggurat29.
      - Pipes and FIFOs: Add missing configuration for pipe ring buffer
        size.  From Frank Benkert.
      - UART 16550: Handle when CONFIG_SERIAL_UART_ARCH_IOCTL is not
        enabled. From Heath Petersen.
      - Common Serial Upper Half:  Fix a race condition noted by Stefan
        Kolb.  Between the test if the TX buffer is full and entering a
        critical section, bytes may be removed from the TX buffer making
        the wait unnecessary.  The unnecessary wait is an inefficiency,
        but not really a problem.  But with USB CDC/ACM it can be a problem
        because the entire TX buffer may be emptied when we lose the race.
        If that happens that uart_putxmitchar() can hang waiting for data
        to be removed from an empty TX buffer.
      - USB MSC Device Class: Add locks when removing request from queue.
        From Wolfgang Reissnegger.
      - USB MSC Device Class: Fix reversed logic on waiting for SCSI thread
        start.  The scsi thread was waiting for the wrong condition.
        However, this was masked by the fact that the code creating the
        scsi thread was also holding usbmsc_scsi_lock(priv) while
        initializing data, hence this lock synchronized the scsi thread
        start with init completion.  From Wolfgang Reissnegger.

    * Graphics and Graphic Drivers:

      - Correct conditional compilation in ST7565 LCD driver.  From Pierre-
        noel Bouteville

    * Networking:

      - In both IPv6 and IPv4 incoming logic:  (1) Should check if the
        packet size is large enough before trying to access the packet
        length in the IP header.  (2) In the comparison between the IP
        length and the full packet length, need to subtract the size of
        he link layer header before making the comparison or we will get
        false positives (i.e., the packet is really too small)
      - TCP Networking: While working with version 7.10 I discovered a
        problem in TCP stack that could be observed on high network load.
        Generally speaking, the problem is that RST flag is set in
        unnecessary case, in which between loss of some TCP packet and its
        proper retransmission, another packets had been successfully sent.
        The scenario is as follows:  NuttX did not receive ACK for some sent
        packet, so it has been probably lost somewhere. But before its
        retransmission starts, NuttX is correctly issuing next TCP packets,
        with sequence numbers increasing properly. When the retransmission
        of previously lost packet finally succeeds, tcp_input receives the
        accumulated ACK value, which acknowledges also the packets sent in
        the meantime (i.e. between unsuccessful sending of lost packet and
        its proper retransmission). However, variable unackseq is still set
        to conn->isn + conn->sent, which is truth only if no further
        packets transmission occurred in the meantime.  Because of incorrect
        (in such specific case) unackseq value, few lines further condition
        if (ackseq <= unackseq)is not met, and, as a result, we are going to
        reset label.  From Jakub Lagwa.

    * ARMv7-M:

      - ARM stack check: Fix double fault on IDLE task with stack size = 0.
        From David Sidrane.

    * Atmel SAMV7 Drivers:

      - CAN: CAN Message Filtering fixed: (1) stdfilters didn't work because
        the filter was never enabled (wrong number of bits to shift), and
        (2) Filters were never used because the configuration register
        cannot be written without using the initialization mode. Both bugs
        are fixed by this change. Filtering has been tested with both
        standard and extended identifiers and is now working properly. From
        Michael Spahlinger.

    * Atmel SAMA5:


    * Atmel SAM3/4 Drivers:

      - Fix some errors in AFEC header file.  From OrbitalFox.
      - DAC: DACC_WPMR_WPKEY_MASK -> DACC_WPMR_WPKEY.  From Wolfgang
        Reissnegge.
      - Timer:  Fix ops check in TCIOC_STOP.  From Wolfgang Reissnegge.
      - I2C: Fix reversed logic in twi_startmessage().  From Wolfgang
        Reissnegger.
      - SAM3/4 UDP: Fix handling of endpoint RX FIFO banks.  This fixes
        a race condition where the HW fills a FIFO bank while the SW is
        busy, resulting in out of sequence USB packets.

    * Atmel SAMV7 Drivers:

      - USBHS Device:  This change solves a problem which causes data loss
        while sending data via USB. This problem is caused by an incorrect
        handling of the endpoint state in the USB driver sam_usbdevhs.  This
        leads under some circumstances to situations in which an DMA
        transfer is setup while a previous DMA transfer is currently active.
        Amongst other things I introduced the new endpoint state
        USBHS_EPSTATE_SENDING_DMA for the fix.  To reproduce the problem, I
        used a program which send as many data as possible via a CDC/ACM
        device and verified the received data on the PC.  From Stefan Kolb.

    * NXP Freescale Kinetis Drivers:

      - Timers: Support up to 8 channels per timer.  From kfazz.

    * NXP Freescale Kinetis Boards:

      - Teensy 3.x clock fixes:  The High Gain bit in MCG_C1 was preventing
        teensy from booting except after a programming session. The second
        change doesn't appear to change any functionality, but complies with
        restrictions in the k20 family reference manual on FEI -> FBE clock
        transiions.  From kfazz.

    * NXP Freescale LPC17xx Drivers:

      - LPC17 Ethernet:  Needs to correctly ignore PHYID2 revision number
        when comparing PHY IDs.

    * NXP Freescale LPC43xx Drivers:

      - Fix errors in GPIO interrupt logic.  From v01d (phreakuencies)
      - Ethernet:  Correct auto-negotiation mode in the LPC43xx Ethernet.
        From Alexander Vasiljev
      - Writing zero to NVIC_IRQ_ENABLE has no effect.  Disable interrupts
        with  NVIC_IRQ_CLEAR. From Paul Alexander Patience.
      - SPIFI: If CONFIG_SPIFI_SECTOR512 undefined, lpc43_bwrite doesn't do
        actual write (probably copy/paste errors). Still not sure about
        current state of lpc43_spifi implementation, but for me NXFFS works
        with this change.  From Vytautas Lukenskas.

    * Qemu-i486:

      - Fix qemu-i486/ostest/Make.defs test for M32.  From Heath Petersen.

    * SiLabs EFM32 Drivers:

      - Fix EFM32 FLASH conditional compilation.  From Pierre-noel
        Bouteville
      - Writing zero to NVIC_IRQ_ENABLE has no effect.  Disable interrupts
        with  NVIC_IRQ_CLEAR. From Paul Alexander Patience.

    * STMicro STM32:

      - STM32 F1-F4:  In PWM driver, just update duty if frequency is not
        changed and PSM started.  This removeis glitch or blinking when
        only duty is frequently changed.  From Pierre-noel Bouteville.

    * STMicro STM32 Drivers:

      - STM32 F7: Fixed STM32F7 DMA stm32_dmacapable.  DMA working on SDMMC.
        From David Sidrane.
      - STM32 F1-F4 Timer Driver: Change calculation of per- timer pre-scaler
        value.  Add support for all timers
      - STM32 F1-F4: Correct conditional compilation in STM32 timer capture
        logic.  From Pierre-noel Bouteville
      - STM32 F1-F4: Fix STM32 DMA code and configuration for STM32F37X chips.
        From Marten Svanfeldt.
      - STM32 F1-F4: Fix compilation errors in debug mode of stm32_pwm.c.
        From Konstantin Berezenko.
      - STM32 F1-F4: Correct the CAN2 RX IRQ number for stm32f10xx chips.
        From Konstantin Berezenko.
      - STM32 F1-F4: Move backup domain reset to earlier in the
        initialization sequence (stm32_rcc.c() in order to avoid disabling
        LSE during RTC initialization.  From Alan Carvalho de Assis.
      - STM32 F1-F4: When configuring a GPIO via stm32_configgpio() the
        function will first set the mode to output and then set the initial
        state of the gpio later on.  If you have an application with an
        externaly pulled-up pin, this would lead to a glitch on the line
        that may be dangerous in some applications (e.G. Reset Line for
        other chips, etc).  This changes sets the output state before
        configuring the pin as an output.  From Pascal Speck .
      - STM32 F7: Apply Pascal Speck's GPIO STM32 change to STM32 L4.
      - STM32 L4: Apply Pascal Speck's GPIO STM32 change to STM32 L4.
        From Sebastien Lorquet.
      - STM32 F7:  BUGFIX: PLLs IS2 and SAI P Calculation. From David
        Sidrane.
      - STM32 L4:  STM32 CAN fixes need to be backported to STM32L4 as well.
      - STM32 F1-F4 and L4: Writing zero to NVIC_IRQ_ENABLE has no effect.
        Disable interrupts with  NVIC_IRQ_CLEAR. From Paul Alexander
        Patience.
      - STM32 F7: STMF7xxx RTC: (1) Remove proxy #defines, (2) Ensure the
        LSE(ON) etal are set and remembered in a) A cold start (RTC_MAGIC
        invalid) of the RTC, and b) A warm start (RTC_MAGIC valid) of the
        RTC but a clock change.  The change was needed because in bench
        testing a merge of the latest's STM32  53ec3ca (and friends) it
        became apparent that the sequence of operation is wrong in the
        reset of the Backup Domain in the RCC code.  PWR is required before
        the Backup Domain can be futzed with. !!!This Code should be tested
        on STM32 and if needed rippled to the STM32 families.  From David
        Sidrane.
      - STM32 F1-F4: STM32 BBSRAM fixed (and formatted) flags.  From David
        Sidrane.
      - STM32 F7: STM32F7 BBSRAM fixed (and formatted) flags. From David
        Sidrane.
      - STM32 L4: Fix incorrect clock setup for LPTIM1.  From ziggurat29.
      - STM32 F4/L4 RTC ALARM: were enabling interrupts too early in the
        power-up sequence,  BEFORE the interrupt system was being
        initialized.

    * STMicro STM32 Boards:

      - STM32 board.h: Fix STM32 timer input clock definitions.  From David
        Sidrane.

    * TI Tiva Drivers:

      - Bug Fix in tiva_serial.c - UART5, UART6 and UART7 were not being
        configured as TTYS0 for printing over serial console. From Shirshak
        Sengupta.

    * C Library/Header Files:

      - include/signal.h:  Change type of SIG_ERR, SIG_IGN, ... to
        _sa_handler_t.  The type void does not work with the IAR toolchain.
        From Aleksandr Vyhovanec.
      - crc16: fix error. From  Paul Alexander Patience.
      - strtoul() and strtoull():  Fix errno settings required by function
        definition.  Resolved Bitbucket Issue #1. From Sebastien Lorquet.

    * Build/Configuration System:

      - Build system: This change fixes a build problem that only occurs
        when reconfiguring from Linux to Windows or vice-versa.  It is a
        problem that was present but not usually experienced until two
        things happened: (1) The pre_config target was added to run before
        the menconfig operation and (2) the context target was added before
        the pre_config target in order to set up the correct symbolic links
        (in the apps/platform directory) needed by the pre_config target.
        But then now if you start with a Linux system and run 'make
        menuconfig' to switch to Linux, the context target will execute
        first and set up POSIX style symbolic links before doing the
        menuconfig.  Then after the menuconfig, the make will fail on
        Windows if you are using a Windows native toolchain because that
        native toolchain cannot follow the Cygwin- style symbolic links.
        The fix here is to also execute the clean_context AFTER executing
        menuconfig.  A lot more happens now:  It used to be that doing
        'make menuconfig' only did the menuconfig operation.  Now it does
        context, pre_config, menuconfig, clean_context.  Not nearly as
        snappy as it used to be.
      - Need to build the drivers/ directory even it file descriptors are
        not supported.  There are things in the drivers/ directory that are
        still needed (like SYSLOG logic).
      - Remove all inclusion of header files from the apps/include
        directory from NuttX core logic.  There should be no dependency on
        logic within NuttX on logic within apps/.  This caused a lot of
        reshuffling of logic:  binfmt pcode support, usbmonitor is now a
        kernel thread, TZ/Olson database moved to libc/zoneinfo.

    * Application Build/Configuration System:

      - Make sure that APPNAME is defined in all Makefiles that generate
        applications.  From Sebastien Lorquet.

    * apps/builtins:

      - apps/builtins: exec_builtin was not using the provided open flags.
        As a result >> redirection was not working; it was treated the same
        as >.

    * apps/nshlib:

      - apps/nshilib: PS Command: When Priority Inheritance is enabled, the
        format of /proc/<PID>/status changes to show both the current
        priority and the thread's base priority.  This messes up the format
        of cmd_ps. From David Alessio.

    * apps/netutils:

      - apps/netutils, uIP webserver:  Fix a data declaration in a header
        file.

    * apps/canutils:

      - apps/canutils/libuavcan: Fix for recent change to STM32 timer
        frequency definiitions.

    * apps/examples:

      - apps/examples/alarm: ioctl call was clobbering file descriptor.
      - apps/examples/can: Some variables were not declared in all required
        cases. From Sebastien Lorquet.
      - apps/examples/media: media example was intended to take either a
        command line argument, or a compiled-in default value from config.
        However, the default was ignored, leading to confusing error
        messages. From ziggurat29.

NuttX-7.18 Release Notes
------------------------

The 118th release of NuttX, Version 7.18, was made on October 8, 2016,
and is available for download from the Bitbucket.org website.  Note
that release consists of two tarballs:  nuttx-7.18.tar.gz and
apps-7.18.tar.gz.  These are available from:

    https://bitbucket.org/nuttx/nuttx/downloads
    https://bitbucket.org/nuttx/apps/downloads

Both may be needed (see the top-level nuttx/README.txt file for build
information).

Additional new features and extended functionality:

    * Core OS:

      - Add standard adjtime() interface and basic timekeeping support.
        Normally used with an NTP client to keep system time in
        synchronization.  From Max Neklyudov.
      - Use the oneshot timer with optional entropy to measure CPU load if
        so configured.

    * File System and Block and MTD Drivers:

      - Add Fujistu MB85RS256B ramtron support.  From Beat Küng.
      - SPI-based MTD driver for Macronix MX25L3233F or MX25L6433F.  From
        Aleksandr Vyhovanec.

    * Graphics/Display Drivers:

      - SH1106 0.96 OLED module support (SSD1306 compatible) + I2C fixes.
        From v01d (phreakuencies).

    * Sensor Drivers:

      - Add KXTJ9 Accelerometer driver from the Motorola Moto Z MDK.
      - Add MFRC522 RFID ISO14443 and Mifare transceiver driver.  From Alan
        Carvalho de Assis.
      - Add driver for the LIS3MDL 3 axis magnetometer.  From Alexander
        Entinger.
      - Add driver for the MLX90393 3 axis magnetometer. From Alexander
        Entinger.
      - Add driver for the LIS3DSH 3 axis accelerometer. From Alexander
        Entinger.
      - Add driver for the Bosch BMG160 3 axis gyroscope. From Alexander
        Entinger.
      - Add support for the  Sensixs XEN1210 3D-board. This sensor is used
        on NANOSATC-BR2 a Brazilian CUBESAT project.  From Alan Carvalho
        de Assis.
      - Add a new ioctl command (set MAXPOS) for Tiva QEI.  From Young.

    * Other Common Device Drivers:

      - I/O Expander: Remove hard-coded PCA9555 fields from ioexpander.h
        definitions.  Add support for an attach() method that may be used
        when any subset of pin interrupts occur.
      - I/O Expander Interface:  Encode and extend I/O expander options to
        include interrupt configuration.
      - PCA9555 Driver:  Replace the signalling logic with a simple callback
        using the new definitions of ioexpander.h.  This repartitioning of
        functionality is necessary because (1) the I/O expander driver is
        the lower-lower part of any driver that uses GPIOs (include the GPIO
        driver itself) and should not be interacting directly with the much
        higher level application layer.  And (2) in order to be compatible
        with the GPIO driver (and any arbitrary upper half driver), the
        PCA9555 should not directly signal, but should call back into the
        upper half.  The upper half driver that interacts directly with the
        application is the appropriate place to be generating signal.
      - Add a skeleton I/O Expander driver (based on the PCA9555 driver).
      - Add PCF8574 I/O Expander driver.
      - GPIO driver:  Add IOCTLs to get the pin type and to unregister a
        signal handler.
      - Add a GPIO lower-half driver that can be used to register a GPIO
        character driver for accessing pins on an I/O expander.
      - Add an SPI helper function that encapsulates and manages a sequence
        of SPI transfers.
      - Add an SPI character driver that will permit access to the SPI bus
        for testing purposes.
      - Add oneshot timer lower half interface definition.
      - Add an upper-half, oneshot timer character driver.
      - Add Audio Tone Generator for NuttX.  From Alan Carvalho de Assis.
      - Add USB host support for composite devices.  This feature is not
        well tested.
      - drivers/ioexpander: Add an (untested) TCA64XX I/O Expander driver
        leveraged from Project Ara.

    * Simulation Platform:

      - Add a simulated I/O Expander driver.
      - Add simulator-based test support for apps/examples/gpio.
      - Add a configuration useful for testing Mini Basic.
      - Add a simulated oneshot lowerhalf driver.

    * Atmel SAM3/4 Drivers:

      - SAM4CM: Add option to support oneshot timer without free-running
        timer.  Add oneshot lower half driver.

    * Atmel SAMA5 Drivers:

      - SAMA5D: Add option to support oneshot timer without free-running
        timer.  Add oneshot lower half driver.

    * Atmel SAMV7 Drivers:

      - SAMV71/SAME70: Add option to support oneshot timer without
        free-running timer.  Add oneshot lower half driver.
      - Add support for SAMV7 DACC module.  From Piotr Mienkowski.

    * NXP Freescale Kinetis Drivers:

      - Add support for I2C and RTC.  From v01d (phreakuencies).

    * NXP Freescale Kinetis Boards:

      - Add teensy 3.x I2C support.  From v01d (phreakuencies).

    * STMicro STM32:

      - Add IAR-style STM32F1xx vectors. Tested on STM32F103RB and
        STM32F107RC.  From Aleksandr Vyhovanec.

    * STMicro STM32 Drivers:

      - Add timekeeping support for the STM32 tickless mode.  From Max
        Neklyudov.
      - Add a oneshot, lower-half driver for STM32.
      - STM32 L4: Add oneshot lower half driver for STM32 L4.
      - STM32 L4: Add support for quadrature encoders on STM32L4. Sebastien
        Lorquet.

    * STMicro STM32 Boards:

      - stm32f103-minimum: Add board support to MFRC522 driver.  From Alan
        Carvalho de Assis.
      - Add oneshot board initialization to stm32f103-minimum.  From Alan
        Carvalho de Assis.
      - stm32f103-minimum: Add board configuration to initialize Audio Tone
        Generator.  From Alan Carvalho de Assis.
      - stm32bufferfly2: Add support for the Kamami stm32butterfly2
        development board with optional ETH phy.  From  Michal Lyszczek.
      - stm32f103-minimum: Add board config support to SPI LCD module
        JLX12864G-086.  From Alan Carvalho de Assis.
      - stm32l476-mdk: Support basic booting and nsh on Motorola MDK. The
        Motorola MDK is based off of an earlier version of NuttX.
        This only provides a basic NSH shell.  From Jim Wylder.
      - STM32 F4 Discovery:  Add support for XEN1210 3D-board.  From Alan
        Carvalho de Assis.
      - stm32f103-minimum:  Add stm32_bringup support and userled example to
        STM32F103 Minimum board.  From Alan Carvalho de Assis.
      - Add support for qencoders on various nucleo boards.  From Sebastien
        Lorquet.
      - olimex-stm32-e407: Add some networking configurations.  From Mateusz
        Szafoni.

    * TI Tiva Drivers:

      - Add tiva PWM lower-half driver implementation. From Young.
      - Tiva QEI:  Add QEI lower-half driver for Tiva series chip.  From
        Young.

    * C Library/Header Files:

      - Separate XorShift128 PRNG from /dev/urandom and make it generally
        available.
      - Add POSIX type sig_atomic_t.  From Sebastien Lorquet.
      - Add the difftime() function.  The function depends on the toolchain-
        dependent CONFIG_HAVE_DOUBLE so is not available on tiny platforms.
        From Sebastien Lorquet.
      - Add support for remove().  From Sebastien Lorquet.
      - Add system() to stdlib.h.  Actual implementation is in
        apps/system/system.

    * Build/Configuration System:

      - Rename arch/sh to arch/renesas.
      - Remove contactless drivers from drivers/wireless to drivers
        contactless.  From Sebastien Lorquet.
      - Move all modem-related IOCTL commands to a common file to assure
        that they will be unique.

    * Tools:

      - Add sethost.sh.   This is a script that you can use to quickly
        change the host platform from Linux to Windows/Cygwin. Might save
        you a lot of headaches.

    * Applications: apps/nshlib:

      - Add logic to support an NSH-specific system command.
      - Add printf command to NSH, e.g., controlling /dev/userleds from
        command line: nsh> printf \x01 > /dev/userleds. From Alan Carvalho
        de Assis.

    * Platforms: apps/system:

      - Port tee command from NetBSD.
      - Add a generic system command.  Current implementation cannot use
        /bin/sh and spawns the custom NSH system command directly.

    * Platforms: apps/platform:

      - Add C++ support for STM32L476-MDK.

    * Platforms: apps/interpreters:

      - Add a port of Mini Basic, version 1.0, written by Malcom McLean and
        released under the Creative Commons Attribution license.

    * Applications: apps/examples:

      - Add a simple test of the GPIO driver.
      - Add RFID_READUID sample application. From Alan Carvalho de Assis.
      - Add Oneshot timer example.
      - Add a simple test of the system command.

Works-In-Progress:

    * IEEE802.14.5/6LowPAN.  Hooks and framework for this effort were
      introduced in NuttX-7.15.  Work has continued on this effort on
      forks from the main repositories, albeit with many interruptions.
      The completion of this wireless feature will postponed until at
      least NuttX-7.19.

Bugfixes.  Only the most critical bugfixes are listed here (see the
ChangeLog for the complete list of bugfixes and for additional, more
detailed bugfix information):

    * Core OS:

      - Explicitly initialize the group tg_exitsem with sem_init().  The
        existing logic worked because the correct initialization value is
        all zero, but it is better to initialize the semaphore explicitly.
      - The TCB nchildren field should not be incremented when pthreads are
        created.
      - Move fields related to parent/child task relationship out of TCB
        into group structure where they belong.  Child is a group, not a
        thread.
      - mq_send() was not setting the errno value on certain failures to
        allocate a message.
      - Define 'group' even if HAVE_GROUPID is not set.  From Mateusz
        Szafoni.
      - Vector table should have dimension NR_IRQS, not NR_IRQS+1. From
        Sagitta Li.
      - pthreads:  When a pthread is started, there is a small bit
        of logic that will run on the thread of execution of the new
        pthread.  In the case where the new pthread has a lower
        priority than the parent thread, then this could cause both the
        parent thread and the new pthread to be blocked at the priority of
        the lower priority pthread (assuming that CONFIG_PRIORITY_INHERITANCE
        is not selected). This change temporarily boosts the priority of the
        new pthread to at least the priority of the new pthread to at least
        the priority of the parent thread.  When that bit of logic has
        executed on the thread of execution of the new pthread, it will then
        drop to the correct priority (if necessary) before calling into the
        new pthread's entry point.

    * File System/Block Drivers/MTD Drivers:

      - FAT performance improvement. In large files, seeking to a
        position from the beginning of the file can be very time consuming.
        ftell does lssek(fd, 0, SET_CURR).  In that case, that is wasted
        time since we are going to seek to the same position.  This fix
        short-circuits fat_seek() in all cases where we attempt to seek to
        current position.  Suggested by Nate Weibley.
      - MTD: Fixed cloned typos in several FLASH drivers.  From Aleksandr
        Vyhovanec.
      - mount: Corrects a bad assertion noted by Pierre-noel Bouteville.
        Also fixes a reference counting problem in an error condition:
        When the mountpoint inode is found but is not an appropriate
        mountpoint, the reference count on the inode was not being
        decremented.

    * Common Drivers:

      - Various serial drivers: Fix FIONWRITE and add FIONSPACE.  All
        implementations of FIONWRITE were wrong.  FIONWRITE should return
        the number of bytes waiting in the outgoing send queue, not the free
        space.  Rather, FIONSPACE should return the free space in the send
        queue.
      - Add missing prototype for btn_lower_initialize().
      - Make DAC sample structure packed.  From Marc Rechté.

    * Networking:

      - TCP:  tcp_ipvX_bind() not actually using the port selected with
        port==0.  Also removes duplicate call to pkt_input().  Issues noted
        by Pascal Speck.
      - drivers/net: NET_TUN=y => NET_MULTIBUFFER=y.  From Vladimir
        Komendantskiy.
      - slip driver: Fix calculations using MSEC_PER_TICK.  If
        USEC_PER_TICK is less than 1000, then MSEC_PER_TICK will be
        zero.  It will be inaccurate in any case.

    * Atmel SAM3/4 Drivers:

      - SAM3/4 GPIO: Enable peripheral clock for GPIO port when GPIO is
        configured as input. The value of a GPIO input is only sampled when
        the peripheral clock for the port controller the GPIO resides in is
        enabled.  Therefore we need to enable the clock even when polling a
        GPIO.  From Wolfgang Reissnegger.
      - All SAM Ethernet Drivers: Add support so that the drivers can be
        built with CONFIG_NET_MULTIBUFFER=y.
      - SAM3/4: Fix GPIO pull-up/down code. Enabling the pull-down resistor
        while the pull-up resistor is still enabled is not possible. In this
        case, the write of PIO_PPDER for the relevant I/O line is discarded.
        Likewise, enabling the pull-up resistor while the pull-down resistor
        is still enabled is not possible. In this case, the write of
        PIO_PUER for the relevant I/O line is discarded.  From Wolfgang
        Reißnegger.

    * Atmel SAMV7 Drivers:

      - All SAM Ethernet Drivers: Add support so that the drivers can be
        built with CONFIG_NET_MULTIBUFFER=y.
      - SAM GPIO: Apply Wolfgang's change for SAM3/4 to SAMA5 and SAMV7.

    * Atmel SAMA5:

      - Add missing oneshot max_delay method.
      - All SAM Ethernet Drivers: Add support so that the drivers can be
        built with CONFIG_NET_MULTIBUFFER=y.
      - SAM GPIO: Apply Wolfgang's change for SAM3/4 to SAMA5 and SAMV7.

    * NXP Freescale LPC43xx Drivers:

      - LPC43xx serial: Fix typos in LPC43 serial driver.  Found by Vytautas
        Lukenskas.
      - LPC43xx Serial: There are some small problems in LPC43xx RS485 mode
        configuration. In particular: (1) UART0,2,3 do not have DTR pins
        (different from UART1), so, Kconfig needs to be adjusted. (2)
        lpc43_uart.c in RS485 mode only configures DIR pin, but doesn't
        enable pin output for UART0,2,3. (3) should be option to reverse DIR
        control pin output polarity. (4) lpc43xx/chip/lpc43_uart.h doesn't
        have USART3 definitions.  NOTE: I didn't modified and didn't tested
        USART1, as it has different hardware.  From Vytautas Lukenskas.
        From Vytautas Lukenskas.

    * SiLabs EFM32 Drivers:

      - EFM32 SPI drivers adopted incompatible conventions (See STM32 for
        details of the issue).

    * STMicro STM32 Drivers:

      - STM32, STM32 L4, and EFM32 SPI drivers adopted incompatible
        conventions somewhere along the line.  They set the number of bits
        to negative when calling SPI_SETBITS which had the magical side-
        effect of setting LSB first order of bit transmission.  This is not
        only a hokey way to pass control information but is supported by no
        other SPI drivers.  This change three things:  (1) It adds
        HWFEAT_LSBFIRST as a new H/W feature. (2) It changes the
        implementations of SPI_SETBITS in the STM32 and EFM32 drivers so
        that negated bit numbers are simply errors and it adds the
        SPI_HWFEATURES method that can set the LSB bit order, and
        (3) It changes all calls with negative number of bits from all
        drivers: The number of bits is now always positive and
        SPI_HWFEATURES is called with HWFEAT_LSBFIRST to set the bit order.
      - Add missing SPI2 and SPI3 support for STM32F3F3.  Add STM32F37XX DMA
        channel configuration.  For STM32F37XX, SYSCFG_EXTICR_PORTE defined
        twice.  From Alan Carvalho de Assis.
      - STM32: Make stm32_pwr_enablebkp thread safe.  From Max Neklyudov.
      - Fix bad pllmul values for STM32F1XX connectivity line. STM32F1XX
        connectivity line supports only x4, x5, x6, x7, x8, x9 and x6.5
        values. From Michal Lyszczek.
      - STM32F3 SPI:  Fix the number of bit setting for the F3.  That and
        data packing work differently on the STM32F3 than for other STM32
        parts.
      - STM32 and STM32 L4: Enabling SPI DMA loses other bits in CR2.
      - STM32F3 SPI:  Cannot write always 16-bit value to DR register
        because of how the F3 implements data packing.
      - STM32F411 and STM32F446 map i2c2_sda_4 to different alternate
        function numbers.  From Konstantin Berezenko.
      - STM32 DMA Fix: Change stm32 adc dma callback to send channel
        number instead of index.  From Konstantin Berezenko.
      - STM32 OTGFS device: Fix for lost first word from FIFO

        1) Do not overwrite Reserved Bits in GINTSTS (per ref manual)*
        2) Acknowledge all pending int on entry to ISR that are Only rc_w1*
        3) Do not disable RXFVL*
        4) Loop until RXFVL is cleared*
        5) Only clear the NAK on the endpoint on the OTGFS_GRXSTSD_PKTSTS_SETUPDONE to not loose the first WORD of FIFO all the data  (Bug Fix)

        Changed marked *are just driver clean up and ensure ints are not lost. The bug fix is #5

        Test case open putty and observer the Set/Get LineCoding. Without this fix #5 the Get will not match the Set, and in fact the data might be skewed by 4 bytes, that are lost from the FIFO if the OTGFS_DOEPCTL0_CNAK bit is set in the OTGFS_GRXSTSD_PKTSTS_SETUPRECVD as opposed to the OTGFS_GRXSTSD_PKTSTS_SETUPDONE

        Set Line Coding DATA1: 4B | 00 c2 01 00 00 00 08 | c8 1B
        Get Line Coding DATA1: 4B | .. .. .. .. 00 00 08   c8 .. 00 00 07 | 7a 72

        From David Sidrane.
      - STM32 L4 OTGFS device: Apply stm32 fix to stm32l4.  From Sebastien
        Lorquet.
      - STM32 F7: Remove duplicate call to pkt_input from Ethernet driver.
        Issues noted by Pascal Speck.
      - STM32 L4: Add support for USART3-USART5.  For STM32L4 parts, the
        higher number USART ports supported varies.  Add the HAVE_USARTx
        definitions to the configuration to allow enabling the higher
        numbered USART ports. From Jim Wylder.
      - STM32 USB: Set USB address to avoid a failed assertion.  From
        Pierre-noel Bouteville.
      - STM32 L4 and L7 USB: Pierre's assertion-avoidance change should
        also be applied to STM32 F7 and L4.
      - STM32, L4, and F7:  Remove GPIO_ETH_RMII_TX_CLK. TX_CLK is not
        present in RMII. Mateusz Szafoni.
      - STM32 Ethernet: Correct typo in conditional logic.  From Neil
        Hancock.
      - STM32 L4 USB Device: Fixed L4 USB Driver by avoiding SETUPDONE and
        EPOUT_SETUP.  From David Sidrane.
      - STM32 SPI: stm32_modifycr2 should be available on all platforms if
        DMA is enabled.
      - STM32 DMA2D: fix an error in up_dma2dcreatelayer where an invalid
        pointer was returned when a certain underlying function failed.
        From Jens Gräf.

    * TI Tiva Drivers:

      - Fix two bugs of tiva pwm lower-half driver implementation. From
        Young.
      - Tiva Ethernet:  Needs support for CONFIG_NET_MULTIBUFFER=y.

    * C Library/Header Files:

      - lib_dumpbuffer() now prints a large on-stack buffer first to avoid
        problems when the syslog output is prefixed with time.  From
        Pierre-noel Bouteville.
      - libc/math: This fixes the following libc/math issues: (1) asin[f l]()
        use Newton's method to converge on a solution. But Newton's method
        converges very slowly (> 500,000 iterations) for values of x close to
        1.0; and, in the case of asinl(), sometimes fails to converge (loops
        forever). The attached patch uses an trig identity for values of
        x > sqrt(2). The resultant functions converge in no more than 5
        iterations, 6 for asinl().  (2) The NuttX erf[f l]() functions are
        based on Chebyshev fitting to a good guess. The problem there's a
        bug in the implementation that causes the functions to blow up with
        x near -3.0. This patch fixes that problem. It should be noted that
        this method returns the error function erf(x) with fractional error
        less than 1.2E-07 and that's fine for the float version erff(), but
        the same method is used for double and long double version which
        will yield only slightly better precision. This patch doesn't
        address the issue of lower precision for erf() and erfl(). (3) a
        faster version of copysignf() for floats is included. From David S.
        Alessio.
      - strtod() was not returning endptr on error conditions.
      - libc/math: floor(), floorf(), and floorl():  Fix logic error.  Was
        not correctly handling negative integral value.
      - isatty() should be prototyped in unstid.h, not termios.h.  From
        Sebastien Lorquet.
      - nxglib: Fix handling of near-horizontal lines of width 1 in
        nxgl_splitline().  Missing handling for degenerate condition caused
        width 1 lines such as (0, 0) - (100, 10) to have gaps in the
        drawing. From Petteri Aimonen.

    * Build/Configuration System:

      - Top-Level Makefiles:  Fix a chicken-and-egg problem. In the menuconfig
        target, the context dependency was executed before kconfig-mconf.  That
        was necessary because the link at apps/platform/board needed to be set
        up before creating the apps/Kconfig file.  Otherwise, the platform
        Kconfig files would not be included.  But this introduces the chicken-
        and-egg problem in some configurations. In particular:  (1) An NX
        graphics configuration is used that requires auto-generation of
        source files using cpp, (2) the configuration is set for Linux, but
        (3) we are running under Cygwin with (4) a Windows native toolchain.
        In this case, POSIX-style symbolic links are set up but the Windows
        native toolchain cannot follow them. The reason we are running
        'make menuconfig' is to change from Linux to Cygwin, but the target
        fails.  During the context phase, NX runs CPP to generate source files
        but that fails because the Windows native toolchain cannot follow
        the links.  Checkmate.  This was fixed by changing all of the make
        menuconfig (and related) targets.  They no longer depend on context
        being run.  Instead, they depend only on the dirlinks target.  The
        dirlinks target only sets up the directory links but does not try
        to run all of the context setup; the compiler is never invoked; no
        code is autogenerated and things work.
      - CXXFLAGS:  Add -fcheck-new whenever -fno-exceptions is used. From
        Beat Küng.

    * Tools

      - tools/refresh.sh: Recent complexities added to apps/ means that
        configuration needs the correct Make.defs file in place in order to
        configure properly.
      - tools/kconfig2html.c: Update to handle absolute paths when sourcing
        Kconfig files.
      - tools/mkfsdata.pl was still generating the old-style apps/include
        inclusion paths.

    * Application Build/Configuration System:

      - Add DIRLINK and DIRUNLINK tool definitions to apps/Make.defs.

    * apps/nshlib:

      - Fix FIFO_SIZE vs PIPE_SIZE.
      - Fix hex representation of IP address in Kconfig.  Noted by Michal
        Lyszczek.
      - nsh_syscmds.c: missing semicolon.  From Mateusz Szafoni.
      - In system command, don't try to flush output streams if stdio
        buffered I/O is not supported.

    * apps/canutils:

      - libuavcan: Under certain circumstances, DELIM is not be defined in
        Makefile.
      - Add definition for APPNAME in apps/canutils/canlib.  From Sebastien
        Lorquet.

    * apps/gpsutils:

      - Fix an error minmea.  From Aleksandr Vyhovanec.

    * apps/examples:

      - apps/examples/oneshot:  If the requested delay is > max_delay, then
        break the delay up into several pieces.

NuttX-7.19 Release Notes
------------------------

The 119th release of NuttX, Version 7.19, was made on December 26, 2016,
and is available for download from the Bitbucket.org website.  Note
that release consists of two tarballs:  nuttx-7.19.tar.gz and
apps-7.19.tar.gz.  These are available from:

    https://bitbucket.org/nuttx/nuttx/downloads
    https://bitbucket.org/nuttx/apps/downloads

Both may be needed (see the top-level nuttx/README.txt file for build
information).

Additional new features and extended functionality:

    * Core OS:

      - sched/semaphore, sched/phread/, libc/semaphore, libc/pthread: Add
        pthread_mutexattr_get/set_protocol and non-standard
        sem_get/set_protocol. These may use to enable or disable priority
        inheritance on a single semaphore.
      - Spinlocks:  Added capability to provide architecture-specific memory
        barriers.
      - SMP: Add spin_trylock().  Use this in conditions where other CPUs need
        to stopped but we cannot call enter_critical_section().
      - sched note:  Extend OS instrumentation to include some SMP events.
        Also add spinlock instrumentation;  In SMP configurations, add a
        filter mask to log only notes from certain CPUs.
      - sched note:  Permit spinlock and critical section notes in in-memory
        buffer iff sched_not_get() interfaces is disabled.
      - sched note:  Add additional note to see if/when CPU is started in SMP
        mode.
      - sched note:  Record ID enumeration now results on constant values; ID
        values do not change with configuration.  This makes writing post-processing software much easier.
      - boardctl:  Add new boardctl() command, BOARDIOC_NX_START, to start the
        NX server as a kernel thread.
      - pthreads:  Add pthread_cleanup_push() and pthread_cleanup_pop().
      - pthreads: Added pthread_setcanceltype() and pthread_testcancel().
      - pthreads: Add support for cancellation points.
      - task_delete() now obeys all cancellation point semantics.
      - Add task_setcancelstate(), task_setcanceltype(), and
        task_testcancel().  These are non-standard interfaces analogous to the
        corresponding pthread_ interfaces that provide cancellation controls
        for tasks.

    * Graphics/Display Drivers:

      - boardctl:  Add new boardctl() command, BOARDIOC_NX_START, to start the
        NX server as a kernel thread.

    * Networking/Network Drivers:

      - Network drivers:  Add option to use low-priority work queue to all
        Ethernet and MAC level drivers.
      - Network Drivers:  Adapt all Ethernet (and other MAC) drivers to work
        as though CONFIG_NET_MULTIBUFFER were set.  Remove all references to
        CONFIG_NET_MULTIBUFFER.
      - Eliminate CONFIG_NO_NOINTS.  There is no longer any support for
        interrupt level processing of the network stack. Lots of files changed.

    * Other Common Device Drivers:

      - Vishay VEML6070:  Add Vishay VEML6070 driver.  From Alan Carvalho de
        Assis.

    * ARMv7-A

      - ARMv7-A/i.MX6:  Add SCU register definitions.  Add some controls to
        enable SMP cache coherency in SMP mode.  Makes no difference, however
        -- cache still incoherent on i.MX6.
      - ARMv7 GIC: SGIs are non-maskable but go through the same path as
        other, maskable interrupts.  Added logic to serialize SGI processing
        when necessary.

    * Atmel SAM3/4:

      - SAM3/4:  Add SMP support for the dual-core SAM4CM.  From Masayuki
        Ishikawa.

    * Atmel SAM3/4 Drivers:

      - Add support for the SAM5CMP-DB board.  From Masayuki Ishikawa.

    * Atmel SAM3/4 Boards:

      - SAM4CMP-DB:  Add support for the Atmel SAM4CMP-DB board running in an
        SMP configuration.  From Masayuki Ishikawa.
      - SAM4CMP-DB: Add hooks to auto-mount the procfs file system on startup
        in board bring-up logic.

    * Atmel SAMV7 Drivers:

      - SAMv7:  Register the watchdog device at the configured device path
        CONFIG_WATCHDOG_DEVPATH vs. hard-coded /dev/wdt.  From Frank Benkert.

    * Calypso

      - Calyps: Remove all Calypso board configurations.  Remove Calypso
        architecture support and support for Calypso SERCOMM driver.

    * Misoc LM32:

      - Misoc LM32:  Adds basic support for the Misoc procoessors and the LM32
        in particular.  From Ramtin Amin.
      - Misoc LM32:  Add signal handling logic.  From Ramtin Amin.
      - Misoc LM32:  Add logic to flush/invalidate caches.  From Ramtin Amin.

    * Misoc LM32 Drivers:

      - Misoc LM32 Serial:  Add interrupting Misoc serial driver.  From Ramtin
        Amin.
      - Misoc LM32 Timer:  Add timer driver.  From Ramtin Amin.
      - Misoc LM32:  Add Misoc Ethernet driver  From Ramtin Amin.

    * Misoc LM32 Boards:

      - Misoc LM32 Qemu:  Board support for testing Misoc LM32 with Qemu. From
        Ramtin Amin.
      - Misoc LM32 Qemu:  Integrate network support into configs/misoc/hello.
        From Ramtin Amin.
      - Misoc LM32 Qemu:  Remove configs/misoc/include/generated directory.  I
        suppose the intent now is that this is a symbolic link?  DANGER!
        This means that you cannot compile this code with first generating
        these files a providing a symbolic link to this location!   There is a
        sample directory containing generated sources.  This is really only
        useful for performing test builds.  You really must generate the Misoc
        architecture for a real-life build.  From Ramtin Amin.

    * NXP Freescale i.MX6 Drivers:

      - i.MX6:  Add an untested SPI driver taken directly from the i.MX1 port.

    * NXP Freescale Kinetis:

      - Kinetis:  Added missing headers.  Kinetis broke out SPI to
        kinetis/kinetis_spi.h. Broke out DMA to use the modern NuttX chip
        inclusion - still STUBS.  Add Kinetis support for ARMV7-M Common
        Vector and FPU.  Allow CONFIG_ARMV7M_CMNVECTOR,
        CONFIG_STACK_COLORATION, CONFIG_ARCH_FPU.  Fix  i2c driver offset
        swapped for value in kinetis_i2c_putreg.  From David Sidrane.

    * NXP Freescale Kinetis Drivers:

      - Kinetis: Add UID Unique ID.  From Neil Hancock.

    * NXP Freescale Kinetis Boards:

      - Freedom-K64F board: Add support for UID Unique ID.  From Neil Hancock.

    * NXP Freescale LPC17xx Boards:

      - Olimex-LPC1766-STK:  Enable procfs in NSH configuration. Automount
        /proc on startup.

    * NXP Freescale LPC43xx Drivers:

      - LPC43xx: Add timer driver:  From Alan Carvalho de Assis.
      - LPC43xx GPDMA driver:  The GPDMA block is basically the same as the
        LPC17xx.  Only the clock configuration is different and LPC43xx has
        four different DMA request sources, where LPC17xx has only two. From
        Alan Carvalho de Assis.

    * NXP Freescale LPC43xx Boards:

      - Bambino 200E:  Add basic support to Micromint Bambino 200E board.
        This includes contributions from Jim Wolfman.  From Alan Carvalho de
        Assis.
      - Bambino 200E:  Add support for timer driver.  From Alan Carvalho de
        Assis.

    * RGMP:

      - Remove RGMP and RGMP drivers.

    * RISC-V:

      - RISC-V: Add support for the RISC-V architecture and
        configs/nr5m100-nexys4 board.  The board support on this is pretty
        thin, but it seems like maybe a good idea to get the base RISC-V stuff
        in since there are people interested in it.  From Ken Pettit.

    * STMicro STM32 Drivers:

      - STM32 F3:  Implementation of the STM32 F37xx SDADC module. There are
        also changes to ADC, DAC modules. SDADC has only been tested in DMA
        mode and does not support external TIMER triggers. This is a work in
        progress.  From  Marc Rechté.
      - STM32 F3:  Add PWM driver support for STMF37xx.  The changes have been
        tested successfully for TIM4 and TIM17 (different IPs).  From  Marc
        Rechté.
      - STM32 F4:  Support oversampling by 8 for the STM32 F4. From David
        Sidrane.
      - STM32 F4:  Added Timers 2-5 and control of SAI and I2S PLLs.  Added
        support for stmf469 SAI and I2S PLL configuration and STM446 fixes.
        From David Sidrane.
      - STM32 F4:  Expanded OTGFS support to stm32F469 and stm32f446.  Added
        missing bit definitions, Used stm32F469 and stm32f446 bit
        definitions,  Removed unused header file.  From David Sidrane.
      - STM32 F4:  Allow dma in 1 bit mode in STM32F4xxx.  From David Sidrane.
      - STM32 F7:  Allow the config to override the clock edge setting.  From
        David Sidrane.
      - STM32 L4:  Support Complementary PWM outputs on STM32L4.  From
        Sebastien Lorquet.
      - STM32 L4:  Add implementation of dumpgpio for stm32l4, was required
        for pwm debug. From Sebastien Lorquet.

    * STMicro STM32 Boards:

      - STM32F103 Minimum:  Add button support.  From Alan Carvalho de Assis.
      - STM32F103 Minimum:  Add support to PWM on STM32F103-Minimum board.
        From Alan Carvalho de Assis.
      - STM32F103 Minimum:  Add RGB LED support on STM32F103 Minimum board.
        From Alan Carvalho de Assis.
      - STM32F103 Minimum:  Add Vishay VEML6070 driver support to the
        STM32F103-Minimum board.  From Alan Carvalho de Assis.
      - Nucleo-F303RE:  Add STM32 F303RE hello configuration.   From Marc
        Rechté.
      - Nucleo-L476:  Support PWM testing on board Nucleo L476.  From
        Sebastien Lorquet.
      - Nucleo L476:  Add support for timers to Nucleo L476.  From Sebastien
        Lorquet.
      - Hymini STM32v:  Enable CONFIG_RTC in the hymini-stm32v/nsh2
        (kitchensink) config. From Maciej Wójcik.
      - Olimex STM32-p407:  Add support for the Olimex STM32 P407 board.

    * TI Tiva Drivers:

      - Tiva PWM: Support PWM_PULSECOUNT feature for TI tiva.  From Young.Mu.

    * Xtensa/ESP32

      - Xtensa ESP32:  Basic architectural support for Xtensa processors and
        the Espressif. ESP32 added.
      - Xtensa ESP32:  Add EXPERIMENTAL hooks to support lazy Xtensa
        co-processor state restore in the future.
      - Xtensa ESP32:  Basic port is function in both single CPU and dual CPU
        SMP configurations.  There is an NSH configuration for each CPU
        configuration.  Outstanding issues include missing clock configuration
        logic, missing partition tables to support correct configuration from
        FLASH, and some serial driver pin configuration issues.
      - Xtensa ESP32: Add stack checking logic.

    * Xtensa/ESP32 Boards:

      - ESP32 Core v2:  Basic support for Espressif ESP32 Core v2 board
        added.  The initial release includes an NSH and an SMP test
        configuration.
      - ESP32 Core v2:  Add configuration to support linking NuttX for
        execution out of IRAM.
      - ESP32 Core v2:  Automatically mount /proc at start-up.
      - ESP32 Core v2:  Add an OS test to verify the port.

    * C Library/Header Files:

      - libc/locale:  Add a dummy setlocale() function to avoid drawing the
        function from newlib.  Add clocale header file.
      - include/locale.h:  Modify locale.h to add localeconv() and lconv
        structure.  From Alan Carvalho de Assis.
      - libc/locale:  Allows c++ code to compile with or without
        CONFIG_LIBC_LOCALE and will generate a link error if
        CONFIG_LIBC_LOCALE is not defined and setlocale is referenced. With
        CONFIG_LIBC_LOCALE defined setlocale will act as if MB string is not
        supported and return "C" for POSIX. C and "". From David Sidrane.
      - libc/wchar:  Add wcslen, wmemchr, wmemcmp, wmemcpy wmemset, btowc,
        mbrtowc, mbtowc, wcscmp, wcscoll, and wmemmove to NuttX.  From Alan
        Carvalho de Assis.
      - libc/wctype:  Add functions wcrtomb, wcslcpy, wcsxfrm, wctob, wctomb,
        wctype, localeconv, strcoll, strxfrm, swctype, towlower, towupper and
        wcsftime.   Add wctype.h; Move lib_wctype.c to libc/wctype.  From Alan
        Carvalho de Assis.
      - include/ctype.h : Add isblank() macro to ctype.h.  From Alan Carvalho
        de Assis.
      - lic/stdlib:   Add strtof() and strtold() as simply a copy of strtod
        with types and limits changed.
      - sscanf():  Use strtof() instead of strtod() if a short floating point
        value was requested.  The should help performance with MCUs with
        32-bit FPU support with some additional code size.
      - sscanf(): Add scansets to the scanf function. Enabled
        CONFIG_LIBC_SCANSET option.  From  Aleksandr Vyhovanec.
      - include/inttypes.h: Add architecture-specific inttypes.h.  From Paul
        A. Patience.
      - C Library:  Allow option to enable IP address conversions even when
        the IP address family is not supported.

    * Build/Configuration System:

      - The Smoothie project needs to compile C++ inside config/boardname/src/
        to use with High Priority Interruption, then I modified the board
        configs Makefile to support it.  It works fine for the first time
        compilation, but if we execute "touch config/boardname/src/Pin.cxx"
        and execute "make" it will not detect that Pin.cxx was modified. I
        think there is some other place I should modify, but I didn't find
        it.  From Alan Carvalho de Assis.

    * Tools:

      - tools/: Add tools/showsize.sh.

    * NSH: apps/nshlib:

      - NSH: dd command will show statistics.  From  Masayuki Ishikawa.

    * Applications: apps/system:

      - apps/system/sched_note:  Extend to include additions to instumentation
        for SMP.
      - apps/system/sched_note:  Add support for spinlock notes.
      - apps/system/sched_note:  Add support for new scheduler instrumentation.

    * Platforms: apps/platform:

      - ESP32 Core v2:  Add platform support for the ESP32 core v2 board.
      - Olimex STM32-p407: Add platform support for the Olimex STM32 P407.

    * Graphics: apps/graphics

      - graphics/traveler/tcledit and libwld:  Add an X11 Tcl/Tk tool that can
        be used to edit Traveler world files.
      - Graphics: Remove all NX server taks.  Instead, call boardctl() to the
        NX server kernel thread.

    * Applications: apps/examples:

      - examples/buttons:  Add a new buttons example that uses the button
        character driver instead of the architecture buttons directly. From
        Alan Carvalho de Assis.
      - examples/cctype:  Add an example to verify cctype functions.
      - Remove RGMP example.
      - examples/ostest:  Extend the pthread cancellation test to exercise
        pthread_cleanup_push() (and pthread_cleanup_pop() indirectly via
        pthread_cancel() and pthread_exit().
      - examples/ostest: enhance pthread cancellation test some.

Works-In-Progress:

    * IEEE802.14.5/6LowPAN.  Hooks and framework for this effort were
      introduced in NuttX-7.15.  Work has continued on this effort on
      forks from the main repositories, albeit with many interruptions.
      The completion of this wireless feature will postponed until at
      least NuttX-7.20.

Bugfixes.  Only the most critical bugfixes are listed here (see the
ChangeLog for the complete list of bugfixes and for additional, more
detailed bugfix information):

    * Core OS:

      - sched/semaphore: Within the OS, when a thread obtains a semaphore
        count it must call sem_addholder() if CONFIG_PRIORITY_INHERITANCE is
        enabled.  If a count is available, then sem_wait() calls
        sem_addholder(), otherwise it waited for the semaphore and called
        sem_addholder() when it eventually received the count.  This caused a
        problem when the thread calling sem_wait() was very low priority.
        When it received the count, there may be higher priority threads
        "hogging" the CPU that prevent the lower priority task from running
        and, as a result, the sem_addholder() may be delayed indefinitely.
        The fix was to have sem_post() call sem_addholder() just before
        restarting the thread waiting for the semaphore count.  This problem
        was noted by Benix Vincent who also suggested the solution.
      - Many files: Make sure that priority inheritance is not enabled for
        semaphores whose primary use is signaling (vs locking of resources) by
        calling sem_setprotocol().
      - sched/semaphore:  sem_trywait() no longer modifies the errno value
        UNLESS an error occurs.  This allows these functions to be used
        internally without clobbering the errno value.  From Freddie Chopin.
      - sched/clock: Correct clock initialization.  The correct range for the
        month is 0-11 but is entered as 1-12 in the .config file.  Add ranges
        to START_YEAR, MONTH, and DAY in sched/Kconfig.
      - sched/clock:  Correct calculation for the case of Tickless mode with a
        32-bit timer.  In that case, the calculation was returning millisecond
        accuracy.  That is not good when the timer accuracy is < 1 msec.  From
        Rajan Gill.
      - Work Queue:  When queuing new LP work, don't signal any threads if
        they are all busy.  From Heesub Shin.
      - Work Queue: Signal sent from work_signal() may interrupt the low
        priority worker thread that is already running. For example, the
        worker thread that is waiting for a semaphore could be woken up by the
        signal and break any synchronization assumption as a result. It also
        does not make any sense to send signal if it is already running and
        busy. This change fixes it.  From Heesub Shin.
      - Fix DEBUGASSERT() in group_signal.c.  From Masayuki Ishikawa.
      - Eliminate bad boardctl() commands:  Remove all references to
        BOARDIOC_PWMSETUP and board_pwm_setup(). Remove all references to
        BOARDIOC_ADCSETUP and board_adc_setup(). Remove
        BOARDIOC_CAN_INITIALIZE.  CAN initialization is now done in the board
        initialization logic just like every other device driver.
      - pthreads:  Fix an error in pthread_mutex_destroy().  An error could
        occur while destroying a mutex after a pthread has been canceled while
        holding the mutex.
      - task_restart: Make sure new task starts with pre-emption disabled and
        not in a critical section.
      - Enter/leave Critical Sections.  Major redeign to
        enter/leave_critical_section logic to deal with the case where
        interrupts are disabled only on the local CPU.  In this case, some
        rather complex spinlocks must be used to maintain the critical section
        across all CPUs.
      - SMP Critical Sections:  Fixes for the SMP case: (1) Change order for
        SMP case in enter_critical_section:  (1) Disable local interrupts
        BEFORE taking spinlock and (2) If SMP is enabled, if any interrupt
        handler calls enter_critical_section(), it should take the spinlock.
      - SMP wdogs:  Wdog timers use a tasking interface that to manipulate
        wdogs, and a different interface in the timer interrupt handling logic
        to manage wdog expirations.  In the single CPU case, this is fine.
        Since the tasking level code calls enter_critical_section, interrupts
        are disabled and no conflicts can occur.  But that may not be the case
        in the SMP case.  Most architectures do not permit disabling
        interrupts on other CPUs so enter_critical_section must work
        differently:  Locks are required to protect code. this change adds
        locking (via enter_critical section) to wdog expiration logic for the
        the case if the SMP configuration.
      - SMP vfork():  Fix a race condition in the SMP case.  Existing logic
        depended on the fact that the child would not run until waitpid was
        called because the child had the same priority as the parent.  BUT in
        the SMP case that is not true... the child may run immediately on a
        different CPU.
      - SMP: This change adds a new internal interfaces and fixes a problem
        with three APIs in the SMP configuration.  The new internal interface
        is sched_cpu_pause(tcb).  This function will pause a CPU if the task
        associated with 'tcb' is running on that CPU.  This allows a different
        CPU to modify that OS data structures associated with the CPU.  When
        the other CPU is resumed, those modifications can safely take place.
        The three fixes are to handle cases in the SMP configuration where one
        CPU does need to make modifications to TCB and data structures on a
        task that could be running running on another CPU.  Those three cases
        are task_delete(), task_restart(), and execution of signal handlers.
        In all three cases the solutions is basically the same:  (1) Call
        sched_cpu_pause(tcb) to pause the CPU on which the task is running,
        (2) perform the necessary operations, then (3) call up_cpu_resume() to
        restart the paused CPU.
      - SMP: Add logic to avoid a deadlock condition when CPU1 is hung waiting
        for g_cpu_irqlock with interrupts interrupts and CPU0 is waiting for
        g_cpu_paused.
      - SMP: Enforce this rule: Tasks which are normally restored when
        sched_unlock() is called must remain pending (1) if we are in a
        critical section, i.e., g_cpu_irqlock is locked , or (2) other CPUs
        still have pre-emption disabled, i.e., g_cpu_schedlock is locked.  In
        those cases, the release of the pending tasks must be deferred until
        those conditions are met.

    * File System/Block Drivers/MTD Drivers:

      - AT24XX EEPROM MTD driver:  Added EEPROM timeout.  Fromo Aleksandr
        Vyhovanec.
      - fs/procfs:  Fix procfs status for SMP case.

    * Graphics/Graphic Drivers:

      - Fonts:  Correct some default font IDs.  From Pierre-Noel Bouteville.

    * Common Drivers:

      - usbhost/enumerate:  Fix possible buffer overwrite.  From Janne Rosberg.
      - usbhost/composite:  Fix compile; missing semicolons.  From Jann Rosberg.
      - syslog:  Fixes required for file syslog output.  From Max Kriegleder.
      - SPI configuration:  Fix Kconfig warning.  This change moves the
        ARCH_HAVE_SPI options outside the check for SPI.  Those options don't
        depend on SPI, and Kconfig files  in arch/ enable them even if SPI
        isn't  enabled.  Source the driver's Kconfig in drivers/Kconfig only
        if support for the driver is enabled prevents us from defining these
        ARCH_HAVE options in the driver's Kconfig. We should probably remove
        the other checks in drivers/Kconfig and check if the drivers are
        enabled only in their Kconfig.  From Paul A. Patience.
      - drivers/timer:  Remove the timer driver TIOC_SETHANDLER IOCTL call.
        This calls directly from the timer driver into application code.  That
        is non-standard, non-portable, and cannot be supported.  Instead, add
        timer driver hooks to support signal notification of timer
        expiration.  Signal notification logic added by Sebastien Lorquet.
      - All timer lower half drivers.  Port Sebastien's changes to all other
        implementations of the timer lower half.
      - USB MSC Device:  Fix length of mode6 sense reply packet.  From
        Wolfgang Reißnegger.
      - USB Composite Host:  Fix end offset in usbhost_copyinterface().  From
        Janne Rosberg.
      - USB CDC/ACM Host:   Add CDC_SUBCLASS_ACM and CDC_PROTO_ATM to
        supported class and proto.  From Janne Rosberg.
      - SSD1306:  Fix errors in SPI mode configuration.  From Gong Darcy.
      - CDC/ACM Device Class:  uart_ops_s portion of cdcacm will not be
        initialized with correct functions if CONFIG_SERIAL_DMA is selected.

    * Networking/Network Drivers:

      - drivers/net/tun.c: Fix bug in TUN interface driver.  From  Max Nekludov.

    * ARMv7-A:

      - ARMv7-A SMP: Add SMP logic to signal handling.

    * ARMv7-M:

      - ARMv7-M: Fix double allocation of MPU region in mmu.h.

    * ARMv7-R:

      - ARMv7-R:  Fix compilation error.  This change fixes compilation errors
        on MPU support for ARMv7-R.  From Heesub Shin.
      - ARMv7-R: fix invalid drbar handling.  In ARMv7-R, [31:5] bits of DRBAR
        is physical base address and other bits are reserved and SBZ. Thus,
        there is no point in passing other than the base address.  From Heesub
        Shin.
      - ARMv7-R:  Remove the redundant update on SCTLR. mpu_control() is
        invoking cp15_wrsctlr() around SCTLR update redundantly.  From Heesub
        Shin.
      - ARMv7-R:  Add new Kconfig entries for D/I-cache. Unlike in ARMv7-A/M,
        Kconfig entries for data and instruction caches are currently missing
        in ARMv7-R. This change adds those missing Kconfig entries. Actual
        implementation for those functions will be added in the subsequent
        patches.  From Heesub Shin.
      - ARMv7-R: Add cache handling functions.  This change adds functions for
        enabling and disabling d/i-caches which were missing for ARMv7-R.
        From Heesub Shin.
      - ARMv7-R: Fix typo in mpu support.  s/ARMV7M/ARMV7R/g. From Heesub Shin.
      - ARMv7-R: Fix CPSR corruption after exception handling.  A sporadic
        hang with consequent crash was observed when booting. It seemed to be
        caused by the corrupted or wrong CPSR restored on return from
        exception. NuttX restores the context using code like this:  msr spsr,
        r1.  GCC translates this to:  msr spsr_fc, r1.  As a result, not all
        SPSR fields are updated on exception return.  This should be: msr
        spsr_fsxc, r1.  On some evaluation boards, spsr_svc may have totally
        invalid value at power-on-reset. As it is not initialized at boot, the
        code above may result in the corruption of cpsr and thus unexpected
        behavior. From Heesub Shin.
      - ARMv7-R: Fix to restore the Thumb flag in CPSR.  Thumb flag in CPSR is
        not restored back when the context switch occurs while executing thumb
        instruction.  From Heesub Shin.

    * Atmel SAM3/4 Drivers:

      - SAM3/4 UDP:  Add delay between setting and clearing the endpoint RESET
        bit in sam_ep_resume().  We need to add a delay between setting and
        clearing the endpoint reset bit in SAM_UDP_RSTEP. Without the delay
        the USB controller will (may?) not reset the endpoint.  If the
        endpoint is not being reset, the Data Toggle (DTGLE) bit will not to
        be cleared which will cause the next transaction to fail if DTGLE is
        1. If that happens the host will time-out and reset the bus.  Adding
        this delay may also fix the USBMSC_STALL_RACEWAR in usbmsc_scsi.c,
        however this has not been verified yet.  From Wolfgang Reißnegger.
      - SAM3/4: Remove unused 'halted' flag from UDP driver.  From Wolfgang
        Reißnegger.
      - SAM3/4: Remove 'stalled' flag from the UDP driver.  This flag is not
        necessary because the state of the endpoint can be determined using
        'epstate' instead. From Wolfgang Reißnegger.

    * Atmel SAM3/4 Boards:

      - SAM4S Xplained Pro: Configuration uses old, improper timer interface.
        CONFIG_TIMER disabled in configuration.  Remove obsolete timer
        initialization logic.

    * Atmel SAMV7 Drivers:

      - SAMv7 USBDEVHS:  A problem occurred with the SAMV7 USBDEVHS driver  if
        the USB cable is unplugged while a large amount of data is send over
        an IN endpoint using DMA. If the USB cable is plugged in again after a
        few seconds it is not possible to send data over this IN endpoint
        again, all other endpoints work as expected.  The problem occurs
        because if the USB cable is unplugged while an DMA transfer is in
        flight the transfer is canceled but the register SAM_USBHS_DEVDMACTRL
        is left in an undefined state.  The problem was fixed the problem by
        resetting the register SAM_USBHS_DEVDMACTRL to a known state.
        Additionally all pending interrupts are cleared.  From Stefan Kolb.
      - SAMV7 MCAN: Prevent Interrupt-Flooding of ACKE when not connected to
        CAN-BUS. An Acknowledge-Error will occur every time no other CAN Node
        acknowledges the message sent. This will also occur if the device is
        not connected to the can-bus. The CAN-Standard declares, that the Chip
        has to retry a given message as long as it is not sent successfully
        (or it is not cancelled by the application). Every time the chip tries
        to resend the message an Acknowledge-Error-Interrupt is generated. At
        high baud rates this can lead in extremely high CPU load just for
        handling the interrupts (and possibly the error handling in the
        application). To prevent this Interrupt-Flooding we disable the ACKE
        once it is seen as long we didn't transfer at least one message
        successfully.  From Frank Benkert.
      - SAMV7 MCAN:  Make delete_filter functions more robust.  From Frank
        Benkert.

    * Atmel SAMA5 Drivers:

      - SAMA5 PWM:  Driver does not build when executing from SDRAM before
        board frequencies are not constant.  Rather, the bootloader configures
        the clocking and we must derive the clocking from the MCK left by the
        bootloader.  This means lots more computations.  This is untested on
        initial change because I don't have a good PWM test setup right now.

    * Misoc LM32:

      - Misoc LM32: Corrects a bug that never occurred in qemu on simulation or
        real fpga. The error was that the r1 register was being modified out
        of context switching and not restoring it.  From Ramtin Amin

    * NXP Freescale i.MX6:

      - i.MX6 interrupt handling:  Additional logic needed to handle nested
        interrupts when an interrupt stack is used.  Nesting can occur because
        SGI interrupts are non-maskable.

    * NXP Freescale LPC43xx Drivers:

      - LPC43xx serial: Fix a typo in ioctl TIOCSRS485 ioctl.  From Vytautas
        Lukenskas.
      - LPC43xx serial:  Restore RS485 mode on serial port open (if RS485 is
        enabled via menuconfig).  From Vytautas Lukenskas.
      - LPC43xx SD/MMC:  Correct some definitions on SMMC control register in
        lpc43_sdmmc.h.  From Alan Carvalho de Assis.
      - LPC43xx SD card:  Correct pin configuration options needed for SD card
        pins.  From Alan Carvalho de Assis.

    * SiLabs EFM32:

      - EFM32: Fix a compilation error.  From Pierre-noel Bouteville.

    * STMicro STM32 Drivers:

      - STM32 CHxN channels are always outputs.  From Sebastien Lorquet.
      - STM32 DAC:  Fix shift value whenever there are is a DAC2 and, hence,
        up to three interfaces.  From Marc Rechté.
      - STM32 F1:  Add TIM8 to STM32F103V pinmap.  From Maciej Wójcik.
      - STM32 F1: Fix for F1 RTC Clock, tested on F103.  From Maciej Wójcik.
      - STM32 F3:  STM32F303xB and STM32F303xC chips have 4 ADCs.  From Paul
        A. Patience.
      - STM32 F4:  A new implementation of the STM32 F4 I2C bottom half.  The
        common I2C as this did not handled correctly in the current
        implementation (see also https://github.com/PX4/NuttX/issues/54).  The
        changes almost exclusively affect the ISR.  From Max Kriegleder.
      - STM32 F4  OTGHS Host:  If STM32F446 increase number of channels to
        16.  From Janne Rosberg.
      - STM32 F4:  I think, that Size is (highest address+1 - Base address).
        Base address has been removed and if address+count >= size we are
        outside of the Flash.  From David Sidrane.
      - STM32 F4:  Fix ADC compilation error when DMA isn't enabled. From Paul
        A. Patience.
      - STM32 F4:  STM32F427 was rebooting. Over reached family.  From David
        Sidrane.
      - STM32 F4:  Added STM32F469 RAM size and deliberated STM32F446 size.
        From David Sidrane.
      - STM32 F4:  Typo in stm32f76xxxx_pinmap.h edited online with
        Bitbucket.  From David Sidrane.
      - STM32 F7:  stm32_i2c.c Dejavu.  Fixes a bug previously found in the
        F4. From David Sidrane.
      - STM32 F7:  OTGDEV fixed typo.  From David Sidrane.
      - STM32 F7:  Fix to SPI-Master driver.  Without this the chip select
        decoding feature will not work properly.  From Michael Spahlinger.
      - STM32 F7:  STM32F7 SD/MMC driver depends on CONFIG_SDIO_DMA which is
        only defined in stm32/Kconfig.  Changed to CONFIG_STM32F7_SDMMC_DMA
        and defined in stm32f7/Kconfig.
      - STM32 F7:  Fix some STM32F7 copy paste errors.  From David Sidrane.
      - STM32 L4:  Complementary PWM outputs on STM32L4"  (1) too many
        parentheses when calculating max chan count and (2) channel 4 does not
        have a complementary output. From Sebastien Lorquet.
      - STM32 L4:  Fix I2C devices RCC registers.  From Sebastien Lorquet.
      - STM32 L4:  Enable and renaming for 32l4 UARTs 4 and 5. From Sebastien
        Lorquet.
      - STM32 L4:  Change the way to configure quadrature encoder prescalers.
        From Sebastien Lorquet.
      - STM32 L4:  Correct USART1/2 definitions.  Use default mbed UART4
        settings.  From Sebastien Lorquet.

    * STMicro STM32 Boards:

      - STM32F103 Minimum: Fix Timers 2 to 7 clock frequencies. From Alan
        Carvalho de Assis.
      - Nucleo-F303RE:  Remove duplicate setting from board.h.   From  Marc
        Rechté.
      - Nucleo F303RE: Various fixes to get the ADC configuration building
        again after PR.  Refresh all configurations.
      - Nucleo L476RG: Add better selection of timer.

    * TI Tiva Boards:

      - DK-TM4C129x: Typo fix.  From Wolfgang Reißnegger.

    * Xtensa ESP32:

      - ESP32 core v2:  Flush the UART TX buffer in the esp32 serial shutdown
        routine. The ROM bootloader does not flush the FIFO before handing
        over to user code, so some of this output is not currently seen when
        the UART is reconfigured in early stages of startup.  From Angus
        Gratton.
      - Xtensa ESP32:  Corrects a problem with dispatching to signal
        handlers:  Cannot vector directly to the signal handling function as
        in other ABIs under the Xtensa Window ABI.  In that case, we need to
        go through a tiny hook when performs the correct window call (call4)
        otherwise registers will be scrambled in the signal handler.

    * Xtensa ESP32 Boards:

      - ESP32 core v2:  Changes the openocd config file's default flash
        voltage from 1.8V to 3.3V. This is not necessary right now, but may
        save some hard-to-debug moments down the track (3.3V-only flash
        running at 1.8V often half-works and does weird things...).  From
        Angus Gratton.

    * C Library/Header Files:

      - libc/stdio:  Fixes sscanf() %sn where strlen(data) < n.  From David
        Sidrane.
      - libc/stdio:  Include wchar.h in lib_libvsprintf.c to fix compilation
        error.  From Alan Carvalho de Assis.
      - include/sys/time.h: timersub macro modified per recommendations of
        phreakuencies.
      - include/ctype.h and cxx/cctype:  Implement ctype.h functions as inline
        if possible.  cctype can then properly select namespace.
      - include/: Fix a number of header files with mismatched 'extern C {'
        and '}'.
      - libc/unisted:  Change brings strtol() and related functions more
        conformant with POSIX.  Corner cases like strtol(-2147483648, NULL,
        10) now pass clang -fsanitize=integer without warnings.  From Juha
        Niskanen.
      - libc/unistd: sleep() was returning remaining nanoseconds (kind of),
        instead the remaining seconds.  From Eunbong Song.
      - termios.h:  Fix CRTSCTS define to include input and output flow. From
        Lorenz Meier.

    * Build/Configuration System:

      - configs/*/defconfig: The buttons example was changed to archbuttons.
        As a result all of the button configurations are broken and need some
        renaming in the defconfig files.  Noted by Frank Berkert.
      - config/*/defconfgs: More fallout from name change of
        apps/examples/buttons to archbuttons.
      - configs:  All QE encoder files.  Last change made timer hard-coded to
        3. Make configurable.
      - configs: Remove all traces of the no-longer existent ARCHBUTTONS
        example.  Remove all button configurations that depended on the
        obsoleted ARCHBUTTON example.
      - minnsh Configurations:  Remove minnsh configurations and support
        logic:  up_getc() and lowinstream.  This was an interesting exercise
        to see just how small you could get NuttX, but otherwise it was not
        useful:  (1) the NSH code violated the OS interface layer by callup
        up_getc() and up_putc() directly, and (2) while waiting for character
        input, NSH would call up_getc() which would hog all of the CPU.  Not a
        reasonable solution other than as a proof of concept.

    * Application Build/Configuration System:

      - Make.defs:  Using wrong link script if native window tool used with
        Cygwin.

    * apps/platform:

      - ESP32 Core v2 Platform: Fix some naming that prevented building the
        C++ support.

    * apps/nshlib:

      - NSH Library:  nsh_getdirpath(), use snprint instead of sprintf to
        avoid possibility of buffer overrun.  Noted by Chung Hwan Kim.

    * apps/system:

      - Remove std_readline().  This called up_getc() and up_putc() directly,
        violating the POSIX OS interface.

    * apps/netutils:

      - FTPD: Fixed bug that didn't free ftpd resources on exit.  From Pascal
        Speck.
      - NTP client: Fix missing left parenthesis.  From Pierre-Noel Bouteville.
      - cJSON: Import patch to fix:cJSON_PrintUnformatted() behaves unexpected
        if an empty array shall be printed to text. from Jerome Lang
        2012-04-19. From Pierre-Noel Bouteville.
      - esp8266 update cosmetic and many bug fix.  From Pierre-Noel Bouteville.
      - FTPD:  Fix bug un ftpd file or socket may be not closed.  From
        Pierre-Noel Bouteville.

    * apps/modbus:

      - Modbus Master is missing many files and doesn't compile at all. More
        details in
        https://groups.yahoo.com/neo/groups/nuttx/conversations/topics/13734.
        From Vytautas Lukenskas.

    * apps/examples:

      - The examples/qencoder app was trying to init the encoder by a direct
        call into the board, cheating in a local header to declare the
        normally unavailable function prototype.  From Sebastien Lorquet.
      - apps/examples/timer: Should detach signal handler before exiting.
      - examples/qencode: The examples/qencoder app was trying to init the
        encoder by a direct call into the board, cheating in a local header to
        declare the normally unavailable function prototype.  From Sebastien
        Lorquet.
      - apps/examples/archbuttons:  Removed because it violates OS interface
        principles.
      - examples/adc, pwm, can: Remove all usage of BOARDIOC_ADCTEST_SETUP,
        BIOARDIOC_PWMSETUP.  Remove BOARDIOC_CAN_INITIALIZE.  CAN
        initialization is now done in the board initialization logic just like
        every other device driver.
      - examples/ostest: Add some delays to the pthread cancellation test.
        With deferred cancellation enabled, things happen more asynchronously.

NuttX-7.20 Release Notes
------------------------

The 120th release of NuttX, Version 7.20, was made on March 8, 2017,
and is available for download from the Bitbucket.org website.  Note
that release consists of two tarballs:  nuttx-7.20.tar.gz and
apps-7.20.tar.gz.  These are available from:

    https://bitbucket.org/nuttx/nuttx/downloads
    https://bitbucket.org/nuttx/apps/downloads

Both may be needed (see the top-level nuttx/README.txt file for build
information).

Additional new features and extended functionality:

    * Core OS:

      - Kernel Modules:  Module initializer may now return a symbol table.
      - Modules:  Extend the module interface so that we can access symbols
        exported by the module.
      - Shared Libraries:  In the FLAT build mode, kernel modules may be
        used to provide minimal shared library functionality.
      - Modules/Shared Libraries:  Add support for dependencies between
        modules.
      - Module Library:  Add build a configuration logic for a shared module
        library.
      - Shared Libraries: Implement module based shared libraries for the
        PROTECTED mode build.
      - Interrupt handling:  irq_attach() now includes an argument of type
        xcpt_t that retained with the handler address.  That argument is
        then provided to the interrupt handler when the interrupt occurs.
        The common parameter passing replaces the ad hoc parmater passing
        implemented in current drivers.  From Mark Schulte.
      - Adapt many drivers to utilize the IRQ argument feature.
      - All functions that used to return an xcpt_t old handler value, now
        return an int error code.  The oldhandler value is no longer useful
        with the recent changes to the interrupt argument passing.  Some of
        the functions effected include board_button_irq(), arch_phy_irq(),
        STM32 EXTI functions (Alarm, COMP, PVD), GPIO interrupt logic like
        kinetis_pinirq(), stm32_gpiosetevent(), and others.
      - IRQ subsystem:  Add support for smaller interrupt tables as
        described at
        https://cwiki.apache.org/confluence/display/NUTTX/Smaller+Vector+Tables.
        This is partially the work of Mark Schulte.

    * File Systems/Block and MTD Drivers

      - Pseudo File System:  Add support for soft links in the top-level
        pseudo file system.
      - Soft links:  Add an implementation of readlink().
      - Add fstat() support.  Implement fstat() method in binfs, romfs,
        unionfs, tmpfs, nxffs, nfx, hostfs, procfs, and smartfs.
      - fstat:  Add fstat() support to FAT.  From Alan Carvalho de Assis.

    * Graphics/Display Drivers:

      - Fonts: Add support for Tom Thumb small mono-space font. From Alan
        Carvalho de Assis.
      - Graphics:  Separated of font cache from graphics/nxterm.  Now in
        libnx/nxfronts where it can be shared with other graphics
        applications.

    * Networking/Network Drivers:

      - Ethernet drivers:  Add framework for serialization in the case where
        multiple low-priority work queues are used.

    * Other Common Device Drivers:

      - Add capabilities() method to SDIO interface.  Remove
        CONFIG_SDIO_WIDTH_D1_ONLY.  That should not be a global propertie,
        but rather a capability/limitation of single slot when there may be
        multiple slots.
      - Removed dmasupported() method from the SDIO interface.  That is now
        a bit in the capability set.
      - drivers/sensors: Add driver for the ST L3GD20 3 axis gyro.  From
        raiden00.

    * Atmel SAM3/4:

      - SAM3/4: Add support for ATSAM4S4C.  From Wolfgang Reißnegger.

    * NXP Freescale i.MX6 Boards:

      - Sabre 6quad:  Enable examples/smp test in i.MX6 SMP/NSH
        configurations.

    * NXP Freescale Kinetis:

      - Kinetis:  Added support for CHIP_MK60FN1M0VLQ12 chip.  From Maciej
        Skrzypek.
      - Kinetis:  Add support for K64/K66 RTC lower half driver. From Neil
        Hancock.
      - Kinetis:  Extensive modification of MCG support based feature
        configuration.  From David Sidrane.
      - Kinetis:  Add support for K66 family.  From David Sidrane.
      - Kinetis:  Created a kinetis SIM versioning scheme pulled in by
        Kinetis chip.h.  From David Sidrane.
      - Created a kinetis PMC versioning scheme pulled in by Kinetis
        chip.h.  From David Sidrane.
      - Kinetis: Extend clock configuration logic.  Refactor
        implementation.  From David Sidrane.

    * NXP Freescale Kinetis Drivers:

      - Kinetis Ethernet:  Kinetis Support RMII clock source select.  This
        defined the RMII clock source select bits and allows the selection
        to be made via Kconfig. From David Sidrane.  Freedom-K66F uses
        ENET_1588_CLKIN as RMII clock
      - Kinetis Serial:  Added configurable 1|2 stop bits.
        HAVE_SERIAL_CONSOLE -> HAVE_UART_CONSOLE to be consistent with
        HAVE_LPUART_CONSOLE naming. From David Sidrane.
      - Kinetis LPserial:  Add LPUART serial driver and Clock
        configuartaion to freedom-k66f board.  From David Sidrane.
      - Kinetis USB device:  Refactor clocking in kinetis_usbdev.  From
        David Sidrane.

    * NXP Freescale Kinetis Boards:

      - Add support for NXP Freedom-k66f development board.  From David
        Sidrane.
      - Kinetis Freedom K66F:  Add Ethernet support.  From David Sidrane.
      - Add twr-k64f120m config.  From Marc Rechté.

    * NXP Freescale LPC43xx Boards:

      - Bamboo-200E: Add netnsh configuration.  From Alan Carvalho de Assis.
      - Add usbnsh config to Bambino 200E board.  From Alan Carvalho de
        Assis.

    * STMicro STM32:

      - STM32 F7: Allow board to configure HSE clock in bypass-mode. This
        is needed to enable HSE with Nucleo-F746ZG board.  From Jussi
        Kivilinna.
      - STM32 F7: stm32_allocateheap: allow use DTCM memory for heap.
        STM32F7 has up to 128KiB of DTCM memory that is currently left
        unused.  This change adds DTCM to main heap if
        CONFIG_STM32F7_DTCMEXCLUDE is not enabled.  From Jussi Kivilinna.
      - Add basic support for the STM32F334.  From Mateusz Szafoni.
      - STM32F33XX DAC, OPAMP, COMP, ADC, HRTIM headers.   From Mateusz
        Szafoni.

    * STMicro STM32 Drivers:

      - STM32 F7 SDMMC:  Add support for single bit operation on SDMMC2.
      - STM32 L4:  Port STM32L4 SAI driver from MDK.
      - STM32 L4:  Bring power management logic from Motrola MDK into NuttX.
      - STM32 L4:  Bring LPTIM driver in from the Motorola MDK.
      - STM32 L4 COMP: Port from Motorola MDK.

    * STMicro STM32 Boards:

      - STM32F429i Discovery: Add support for NxWM on STM32F429i-Disco
        board. From Alan Carvalho de Assis.
      - STM32F103 Minimum: Add support for nRF24 on STM32F103-Minimum
        board. From Alan Carvalho de Assis.
      - Olimex STM32 P407: Add a NSH protected build configuration; Enable
        procfs/ in all configurations.
      - Olimex STM32 P407: Add support for on-board microSD slot.
      - STM32F429i Discovery:  Add support for the L3GD20 driver.  From
        raiden00.
      - STM32F103 Minimum: Add support to QEncoder on STM32F103 Minimum
        board.   From Alan Carvalho de Assis.
      - Olimex STM32 P407:  Add external SRAM support.
      - Add basic support for the Nucleo F334R8 board.  From Mateusz
        Szafoni.
      - STM32F103 Minimum: Add SDCard support over SPI on STM32F103-Minimum
        board.  From Alan Carvalho de Assis.
      - STM32F103 Minimum: Add support to USB Device on STM32F103-Minimum
        board.  From Alan Carvalho de Assis.

    * C Library/Header Files:

      - compiler.h: packed_struct replaced by begin_packed_struct and
        end_packed_struct. Now support IAR style packed structures.  From
        Aleksandr Vyhovanec.
      - Math library: Leverage optimized ARMv8-M functions from BSD license
        ARM file.
      - Shared libraries:  Add a non-standard dllfnc.h function to set the
        symbol table.
      - C Library: Add a support for setvbuf(). This is a collaborative
        effort.  Alan Carvalho de Assis did the initial prototype.
      - C Library: Add setbuf() which is a trivial wrapper around setvbuf().
      - C library:  Add swab().
      - C library: Add strtoimax and strtoumax.
      - C library:  Add ffs(), rindex(), an index().  Add strings.h.  Move
        strcasecmp, strncasecmp, bzero, bcmp, and bcopy to where they
        belong in strings.h.h, not string.h.  bzero, bcmp, and bcopy are
        legacy functions; the contemporary counterparts should be used
        instead.
      - C library: Add fstatfs().
      - Update cwchar.  Add cwctype.

    * Build/Configuration System:

      - Add configuration support for builds with Ubuntu under Windows 10.

    * Tools:

      - tools/noteinfo.c: A hack tool that I use to analyze some sched_note
        output.  Needs a home and may be useful to others.
      - tools/mkconfig.c: Add logic to keep all of the buffering options in
        sync.

    * NSH: apps/nshlib:

      - NSH: Add support for the 'ln' command.
      - NSH ls command: if node is a symobolic link, use readlink() to get
        and the display the target of the symbolic link.
      - NSH: Add readlink command.

    * Applications: apps/examples:

      - apps/examples/nxtext: Make line spacing configurable.
      - apps/system/zmodem/host/nuttx/compiler.h synchronized with
        nuttx/nuttx/include/nuttx/compiler.h.  From Aleksandr Vyhovanec.
      - apps/examples/sotest:  Add a test for shared libraries.
      - apps/examples/ostest:  Add a test of setvbuf().
      - apps/examples/stat:  Add a simple test for stat(), fstat(),
        statfs(), and fstatfs().

Works-In-Progress:

    * IEEE802.14.5/6LowPAN.  Hooks and framework for this effort were
      introduced in NuttX-7.15.  Work has continued on this effort on
      forks from the main repositories, albeit with many interruptions.
      The completion of this wireless feature will postponed until at
      least NuttX-7.21.

Bugfixes.  Only the most critical bugfixes are listed here (see the
ChangeLog for the complete list of bugfixes and for additional, more
detailed bugfix information):

    * Core OS:

      - SMP: There were certain conditions that we must avoid by preventing
        the release of the pending tasks while withn a critical section.
        But this logic was incomplete; there was no logic to prevent other
        CPUs from adding new, running tasks while on CPU is in a critical
        section.  This commit corrects this.  This is matching logic in
        sched_addreadytorun to avoid starting new tasks within the critical
        section (unless the CPU is the holder of the lock).  The holder of
        the IRQ lock must be permitted to do whatever it needs to do.
      - SMP: Make checks for CPU lock set more robust.  There are certain
        conditions early in initialization on during interrupt handling
        where things need to be done a little differently.
      - sched_cpulocked:  Avoid use of spinlock.  That has been reported to
        cause a deadlock (2016-12-28).
      - SMP: Fix a gap where we may try to make modifications to the task
        lists without being in a critical sections.  That permits
        concurrent access to the tasks lists and many subtle problems.
        This fix just remains in the critical section throughout the
        operation (and possible until the task is restore in the event of a
        context switch).  Makes a big difference in stability.
      - SMP: Fix an error in critical section logic when performing a
        context switch from an interrupt handler.  The g_cpu_irqset bit was
        not being set for the CPU so other CPUs did not know about the
        critical section.
      - SMP Signals: Fix some SMP signal delivery logic. Was not handling
        some critical sections correctly and was missing logic to signal
        tasks running on other CPUs.
      - SMP:  Fix timer related issues:  Round robin and sporadic
        scheduling were only being performed for tasks running on the CPU
        that processes the system timer interrupt.  Similarly, CPU load
        measurements were only be processed for running on the CPU that
        receives the sampling interrupt.
      - sched_note: Fix spinlock instrumentation.  From Masayuki Ishikawa.
      - In all implementations of _exit(), use enter_critical_section() vs.
        disabling local interrupts.
      - sigtimedwait:  When timer expires, up_unblock_task() is called.
        This is okay in the single CPU case because interrupts are disable
        in the timer interrupt handler.  But it is insufficient in the SMP
        case.  enter_ and leave_critical_section() must be called in order
        to manage spinlocks correctly.
      - Fix a compile error: in sched_cpuload.c:Line136, the variables ts
        and secs are not defined if CONFIG_CPULOAD_ONESHOT_ENTROPY = 0.
        However, these variables are used regardless of
        CONFIG_CPULOAD_ONESHOT_ENTROPY at lines~180:onwards.  From Rajan Gill.
      - CPU load: Correct computation of the nominal period to use when the
        source is a oneshot timer.
      - Cancellation points:  Fix some backward logic in conditional
        compilation.
      - Remove an unused variable when calling sigwaitinfo() and
        sigtimedwait().  From Masayuki Ishikawa.

    * File System/Block and MTD Drivers:

      - procfs:  Correct to snprintf-related errors in fs_procfsproc.c.
        Resolves issue #24.
      - Add logic to VFS rename:  If target of rename exists and is a
        directory, then the source file should be moved 'under' the target
        directory. POSIX also requires that if the target is a file, then
        that old file must be deleted.
      - Fix open() a block device with
        CONFIG_DISABLE_PSEUDOFS_OPERATIONS=y. From Masayuki Ishikawa.
      - File System: Don't build block driver proxy if PSEUDOFS_OPERATIONS
        are disabled.
      - sendfile():  Fix error introduced with commit
        ff73be870e38959b0aaee5961dc47b4b58dc2d86.  Noted by Maciej Wójcik.

    * Graphics/Graphic Drivers:

      - NxWM configurations.  If using a 7-bit character set, then the
        cursor character cannot be 137 (graphic block).  Use 95
        (underscore) instead.
      - NX server: Correct message queue names.  Should not be at /dev,
        but rather relative to /var/mqueue.

    * Common Drivers:

      - MMCSD_SDIO: Only wait for card ejected if card detection is
        supported. From Alan Carvalho de Assis.
      - Typos withim mtd/ with Macronix MX25L.  In
        NuttX/drivers/mtd/Make.defs letters X between M and 25 are
        missing.  Noted by Oleg Evseev.
      - USBMSC: Always set LUN readonly flag.  From Wolfgang Reißnegger.
      - drivers/lcd:  ssd1306_configspi() must have global scope.
      - MMC/SD SDIO:  Some drivers need to start DMA before sending CMD24
        and some AFTER.  From Alan Carvalho de Assis.
      - drivers/tone.c:  Handle configuration with multiple PWM channels.
        This resolves issue #30: Audio Tone Generator and PWM Multiple
        Output Channel options.
      - drivers/tone.c:  50% duty needs to be expressed a a fixed precision
        number.
      - drivers/spi/Kconfig:  There is too much SPI in the configuration
        menu; SPI Driver Support menu is empty.  From Maciej Wójcik.
      - option to enable Memory Card debug output was hidden with SD cards
        connected through SPI.   From Maciej Wójcik.
      - usbhost_cdcacm: fix tx outbuffer overflow and remove now invalid
        assert.  From Janne Rosberg.

    * Networking/Network Drivers:

      - Networking: Fixed some issues that prevented IPv6 from working with
        IPv4 enabled.  From Pascal Speck.
      - Networking: fixed a nullptr-dereference on iob_clone.  From Pascal
        Speck.
      - Ethernet: Need two work structures (minimum) in all Ethernet
        drivers so that pending poll work is not lost when an interrupt
        occurs.

    * ARMv7-R:

      - I found an issue inside the cp15_coherent_dcache function:  The
        "mcr CP15_BPIALLIS(r0)" should only be used with SMP
        configurationa. In non-SMP configuration this instruction could
        become undefined.  From Manohara HK.

    * Atmel SAM3/4 Drivers:

      - SAM3/4: GPIO bit numbering typo fixes.  From Wolfgang Reißnegger.

    * Atmel SAM3/4 Boards:

      - Add missing sched_note_*() calls in sam4cm SMP functions.

    * NXP/Freescale Kinetis:

      - Kinetis: Fixed wrong MCG VDIV calculation on new NXP K60.  From
        Maciej Skrzypek.
      - Kinetis: Need to set HAVE_UART_DEVICE when UART4 is selected.  From
        Maciej Skrzypek.
      - Kinetis MCG: Wrong FRDIV set in MCG_C1.  From Maciej Skrzypek.

    * NXP/Freescale Kinetis Drivers:

      - Kinetis Serial: Fixed compile error when UART5 is selected.  From
        Maciej Skrzypek.
      - Kinetis SDHC - Enable clock after selected.  From David Sidrane.
      - Kinetis:  Correct some SPI and I2C configuration issues.  From
        David Sidrane.
      - Kinetis Ethernet:  Add #define for number of loops for auto
        negotiation to complete.  From Marc Rechté.
      - Kinetis Werial:  Fixed up_rxint - did not disable the RX
        interuppts. There was an OR where and AND NOT was needed.  From
        David Sidrane.

    * NXP/Freescale LPC43xx:

      - LPC43 pinset definitions:  Add more 1 bit to pinset to reach
        SFSCLK0-SFSCLK3. Remove PINCONFIG_DIGITAL.  From Alan Carvalho de
        Assis.

    * NXP/Freescale LPC43xx Drivers:

      - LPC43 serial:  Correct conditional logic that selects /dev/ttySN.
        Problem noted by Alan Carvalho de Assis.

    * NXP/Freescale i.MX6:

      - i.MX6: Fix clearing GPT status register.  From Masayuki Ishikawa.

    * STMicro STM32:

      - STM32, STM32L4 Oneshot: Fix logic so that it can support multiple
        oneshot timers.
      - STM32 F7: Added missing ARCH_HAVE_RESET for F7.  From David Sidrane.
      - STM32:  Add missing STM32_BKP_BASE.  From David Sidrane.
      - STM32 and STM32F7: Fixes the BKP reference counter issue.  From
        David Sidrane.

    * STMicro STM32 Drivers:

      - Fix for SAMv7 SPI: DLYBS value was calculated, but never written to
        any registers. This led to incorrect timings on the bus.  From
        Michael Spahlinger.
      - STM32 QEncoder: Fix QEncoder driver, based on STM32L4 driver.  From
        Alan Carvalho de Assis.
      - STM32 QEncoder:  Enable clocking to the timer on QE setup; disable
        clock on QE teardown.
      - STM32 Ethernet: Need two work structures so that pending poll work
        is not lost when an interrupt occurs.  This change has also been
        ported to all all other effected Ethernet drivers.
      - STM32 OTGHS host:  stm32_in_transfer() fails and returns NAK if a
        short transfer is received.  This causes problems from class
        drivers like CDC/ACM where short packets are expected.  In those
        protocols, any transfer may be terminated by sending short or NUL
        packet.  From Janne Rosberg.  Adapted Janne Rosberg's patch to
        STM32 OTGHS host to OTGFS host, and to similar USB host
        implementations for STM32 L4 and F7.

    * STMicro STM32 Boards:

      - STM32F4 Discovery: Fix issues with QEncoder support.  From Alan
        Carvalho de Assis.

    * C Library/Header Files:

      - Add debug assertion in libdtoa to catch attempts to use floating
        point output formats from within an interrupt handler.  That will
        cause assertions or crashes downstream because __dtoa will attempt
        to allocate memory.  From Pierre-noel Bouteville.
      - libc: Fix ARMv7-A/R memcpy assembly.
      - Fix return value if x is NaN.  From Aleksandr Vyhovanec.

    * apps/nshlib:

      - NSH: Eliminate a warning when all memory inspection commands are disabled.

    * apps/graphics:

      - apps/graphics/traveler/tools: Fix linkage issue. The -lm should
        come after -o binname.  From Alan Carvalho de Assis.

    * apps/netutils:

      - The CONFIG_NETUTILS_HTTPD_PATH constant is used by httpd_mmap.c and
        httpd_sendfile.c but It was not present in Kconfig menu.  From
        Maciej Wójcik.

    * apps/examples:

      - Configurations that enable OSTEST must not disable signals.
      - apps/examples/ostest:  Was ignoring
        CONFIG_EXAMPLES_OSTEST_FPUTESTDISABLE.
      - In apps/examples/mtdpart/mtdpart_main.c where
        CONFIG_EXAMPLES_MTDPART_NPARTITIONS defining is checked should be
        #ifndef instead of #ifdef.  Noted by Oleg Evseev.

NuttX-7.21 Release Notes
------------------------

The 121st release of NuttX, Version 7.21, was made on June 6, 2017,
and is available for download from the Bitbucket.org website.  Note
that release consists of two tarballs:  nuttx-7.21.tar.gz and
apps-7.21.tar.gz.  These are available from:

    https://bitbucket.org/nuttx/nuttx/downloads
    https://bitbucket.org/nuttx/apps/downloads

Both may be needed (see the top-level nuttx/README.txt file for build
information).

Additional new features and extended functionality:

    * Core OS:

      - pthread rwlocks:  Add an implementation for read/write locks
        (rwlocks) into the pthread library.  These locks are writer
        priority, such that if any writers come in they are given priority
        for writing.  From Mark Schulte.
      - pthread robust mutexes:  Implement robust mutex support:
        pthread_mutex_lock() and trylock() will return EOWNERDEAD if the
        mutex is locked by a thread that no longer exists.  Add
        pthread_mutex_consistent() to recover from this situation.  Keep
        list of all mutexes held by a thread in a list in the pthread's TCB.
        When pthread exits or is cancelled, mutexes held by thread are
        marked inconsistent and the highest priority thread waiting for the
        mutex is awakened.  There is a configuration option to (a) support
        only robust mutexes, (b) support only traditional unsafe mutexes,
        or (c) Support both unsafe and robust mutexes via
        pthread_mutexattr_get/setrobust().
      - pthread cancellation points:  Add logic to disable cancellation
        points within the OS.  This is useful when an internal OS function
        that is NOT a cancellation point calls an OS function which is a
        cancellation point.  In that case, irrecoverable states may occur if
        the cancellation is within the OS. From Juha Niskanen.
      - clock:  Add clock_resynchronize and use subseconds RTC.  Add
        clock_resynchronize for better synchronization of CLOCK_REALTIME and
        CLOCK_MONOTONIC to match RTC after resume from low-power state.  Add
        up_rtc_getdatetime_with_subseconds under
        CONFIG_ARCH_HAVE_RTC_SUBSECONDS to allow initializing (and
        resynchronizing) system clock with subseconds accuracy RTC.  From
        Jussi Kivilinna.
      - clock:  Add new type ssystime_t for relative 64-bit ticks, change
        ticks<->time conversion functions to use ssystime_t.  From Jussi
        Kivilinna.
      - clock:  Add testing for 32-bit overflow of 64-bit system timer.  From
        Jussi Kivilinna.

    * File Systems/Block and MTD Drivers

      - drivers/mtd/w25.c:  Erase sector only if it is not in erased state.
        From Jussi Kivilinna.

    * Graphics/Display Drivers:

      - drivers/lcd:  Extend st7565 driver to include support for the
        AQM_1248A.  From Masayuki Ishikawa.
      - drivers/lcd:  Add driver for Nokia 5110 (Philips PCD8544).  From Alan
        Carvalho de Assis.

    * Networking/Network Drivers:

      - Extensive modifications to support wireless network (see below).
      - TUN driver:  Implement TAP (OSI layer 2) mode. Enable by setting the
        IFF_TAP flag instead of the IFF_TUN flag in ifr_flags.  From Thomas
        Keh.
      - Add user-space networking stack API (usrsock).  User-space
        networking stack API allows user-space daemon to provide TCP/IP
        stack implementation for NuttX network.  Main use for this is to
        allow use and seamless integration of HW-provided TCP/IP stacks to
        NuttX.  For example, user-space daemon can translate /dev/usrsock
        API requests to HW TCP/IP API requests while rest of the user-space
        can access standard socket API, with socket descriptors that can be
        used with NuttX system calls.  From Jussi Kivilinna.
      - net/:  Network driver now retains Ethernet MAC address in a union so
        that other link layer addresses may be used in a MULTILINK
        environment.

    * Wireless Networking/Wireless Drivers:

      - BCM43362:  Support for Broadcom's BCM43362 WiFi chip was contributed
        by Simon Piriou as part of the port of the Particle Photon board.
        Only station functionality is available at present.  This work
        includes not on the WiFi driver, but the support Particle Photon
        board, the infrasture for IEEE 802.11 FullMAC networking including
        the network device interface, WiFi configuration, AP scanning and
        authentication and association with an AP.
      - IEEE 802.11 networking tools and support.
      - IEEE 802.15.4 MAC support.  This is an effort that was started some
        time back by Sebastien Lorquet (with some help from Matte Poppe).
        Recently, Anthony Merlino has taken on this effort and has made
        some significant progress.  Using the Microchip MRF24J40 module with
        the Mikroe Clicker2-STM32 board along with a PC-based IEEE 802.15.4
        sniffer, Anthonly has verified correct transmission and receipt of
        basic frames.
      - Microchip MRF24J40: As mentioned above, this IEEE 802.15.4 radio
        driver is now basically functional.
      - IEEE 802.15.4 Network Driver:  A driver that interfaces the NuttX
        network with the IEEE 802.15.4 MAC has been developed but is still
        incomplete and has not been verified.
      - IEEE 802.15.4 Network Loopback Driver:  A simple IEEE 802.15.4 MAC
        loopback driver was developed.  This driver allowed for parallel
        development of the IEEE 802.15.4 MAC and 6LoWPAN.
      - 6LoWPAN:  The Contiki 6LoWPAN stack has been ported so that works
        within the NuttX networking framework and interfaces with the new
        IEEE 802.15.4 MAC via the network driver.  Live testing with
        IEEE 802.15.4 radios has not yet been done; all testing has used
        the loopback driver.  There are no known problems and the stack
        is ready for additional testing.
      - Add option to enable wireless debug output.

    * Other Common Device Drivers:

      - Add entropy pool and strong random number generator.   Entropy pool
        gathers environmental noise from device drivers, user-space, etc.,
        and returns good random numbers, suitable for cryptographic use.
        Based on entropy pool design from *BSDs and uses BLAKE2Xs algorithm
        for CSPRNG output.  Patch also adds /dev/urandom support for using
        entropy pool RNG and new 'getrandom' system call for getting
        randomness without file-descriptor usage (thus avoiding file-
        descriptor exhaustion attacks). The 'getrandom' interface is similar
        as 'getentropy' and 'getrandom' available on OpenBSD and Linux
        respectively.  From Jussi Kivilinna.
      - XBox One controller:  Adds USB host driver support for the XBox One
        controller.  Currently only the latest version (XBox One X)
        controller works.  The older XBox One controllers do not enumerate
        correctly.  From Brian Webb.
      - drivers/analog:  Add basic COMP driver.  From Mateusz Szafoni.
      - drivers/analog:  Add driver for the LTC1767L ADC.  From Martin
        Lederhilger.
      - drivers/analog:  Add basic OPAMP driver.  From Mateusz Szafoni.
      - drivers/sensors:  Add driver for ST HTS221 humidity sensor.  From
        Juha Niskanen.
      - drivers/sensors:  Add driver for ST LPS25H pressure sensor.  From
        Juha Niskanen.
      - drivers/sensors:  Add driver for ST LIS2DH accelerometer.  From Timo
        Voutilainen.
      - drivers/usbmisc:  Add driver for Fairchild FUSB301 USB type-C
        controller.  From Harri Luhtala.
      - RTC:  Add interface for check if RTC time has been set.  New
        interface allows checking if RTC time has been set.  This allows to
        application to detect if RTC has valid time (after reset) or should
        application attempt to get real time by other means (for example, by
        launching ntpclient or GPS).  From Jussi Kivilinna.
      - Buttons:  Change return value of board_buttons() and the type of
        btn_buttonset_t to uint32_t so that more than 8 buttons can be
        supported.
      - drivers/syslog:  Use monotonic clock for timestamp when available.
        From Jussi Kivilinna.
      - SPI:  Add an instance argument to the SPIDEV definitions.  Thus,
        instead of specifying a FLASH device, for example, as SPI_FLASH, you
        would now use SPI_FLASH(0) where the "instance" argument now
        distinguishes multiple FLASH devices on the same SPI bus.  From
        Sebastien Lorquet.
      - IOBs:  Move from net/iob to a better location in mm/iob where they
        can be shared outside of the networking logic.  Current also used
        by IEEE 802.15.4 MAC and by syslog (when buffering enabled).
      - syslog:  Add option to buffer SYSLOG output to avoid interleaving.
        Uses new shareable IOBs.  Additional logic to assure that the the
        write from the buffer is a single atomic write in normal debug
        output.
      - drivers/can:  Move CAN subsystem to its own directory and put device
        drivers there.  From Alan Carvalho de Assis.
      - drivers/can:  Add Microchip MCP2515 CAN Bus controller driver.  From
        Alan Carvalho de Assis.
      - drivers/audio:  Add cs43l22 audio driver.  From Taras Drozdovsky.
      - drivers/input:  Add Cypress MBR3108 CapSense touch button driver.
        From Juha Niskanen.

    * Simulation

      - configs/sim/sixlowpan:  Configuration for testing the 6LoWPAN with
        the IEEE 802.15.4 loopback network driver.

    * Infineon XMC4xxx:

      - arch/arm/src/xmc4:  Initial, partial support for Infineon XMC4xxx.

    * Infineon XMC4xxx Boards:

      - XMC4500 Relax:  Add basic board support infrastructure of Infineon
        XMC4500 Relax Lite v1.  Basic serial, LED, and button button support
        for a simple NSH configuration.  There are still stome remaining
        issues with serial communications.

    * MicroChip PIC32MX Boards:

      - pic32mx7mmb:  Add support for the Pinquino toolchain.
      - pic32mx7mmb:  Add support for PROCFS file system.

    * NXP Freescale Kinetis:

      - Kinetis:  Allow board to add pullups on SDHC lines.  From David
        Sidrane.
      - Kinetis:  Use optional BOARD_OSC_CR and BOARD_OSC_DIV in clock
        configuration.  From David Sidrane.

    * NXP Freescale Kinetis Drivers:

      - Kinetis:  Add Timer PWM Module (TPM) to K66 chip.  From David
        Sidrane.
      - Kinetis:  Added HW flow control and termios.  From David Sidrane.
      - Kinetis:  Add ARCH_HAVE_I2CRESET.  From David Sidrane.

    * NXP Freescale LPC43xx:

      - Add support for LPC4337FET256.  From Andreas Bihlmaier.

    * STMicro STM32:

      - Change STM32 tickless to use only one timer.  From Konstantin
        Berezenko.
      - STM32 F7:  Add support for LSE RTC and enable RTC subseconds.  From
        Jussi Kivilinna.
      - STM32 L1: stm32l15xx_rcc:  Add support for using MSI as system
        clock. From Juha Niskanen.
      - STM32 L1:  stm32l15xxx_rcc: configure medium performance voltage
        range and zero wait-state when allowed by SYSCLK setting.  Zero
        wait-state for flash can be configured when:  (1) Range 1 and
        SYSCLK <= 16 MHz, (2) Range 2 and SYSCLK <= 8 MHz, or (3) Range 3
        and SYSCLK <= 4.2 MHz.  Medium performance voltage range (1.5V)
        can be configured when SYSCLK is up to 16 MHz and PLLVCO up to
        48 MHz.  From Juha Niskanen.
      - STM32 F0: Add basic support for STM32F0.  From Alan Carvalho de
        Assis.
      - STM32 F0:  Add basic support for STM32F07x family.
      - STM32 L1: stm32l15xx_rcc: Allow board to configure HSE clock in
        bypass-mode.  Allows using MCO output from ST-link chip (on Nucleo
        and Discovery boards) as HSE input.  From Juha Niskanen.
      - STM32 L1: Add support for STM32L152CC, STM32L152RC and STM32L152VC.
        From Juha Niskanen.
      - STM32 F0:  Add support for HSI48.
      - STM32 L4:  Add support for the STM32L496XX family.  From Juha
        Niskanen.
      - STM32 L4: modularize Kconfig to support different product
        lines/families.  This is modeled after STM32F7. Idea is to declare
        each chip in Kconfig but allow for flash size override.  Commit adds
        many STM32L4_HAVE_XXX feature test macros.  From Juha Niskanen.
      - STM32 L4:  Separate SYSCFG into product line specific files for
        clarity.  From Juha Niskanen.
      - STM32 L4:  Add support for many new MCUs from the STM32L4X3XX
        product line.  From Juha Niskanen.
      - STM32 L4:  Add dbgmcu header files.  From Juha Niskanen.
      - STM32 F410:  Add support for STM32F410.  STM32F410 is a version of
        STM32F4 with 32 KB of RAM and 62 or 128 KB of flash.  From Gwenhael
        Goavec-Merou.

    * STMicro STM32 Drivers:

      - SDIO:  Extensions to support the SDIO interface to the BCM43362 from
        Simon Piriou.
      - STM32 F2:  Add USB OTG HS support for stm32f20xxx cores.  From Simon
        Piriou.
      - STM32 F2, F4, and F7:  Add BOARD_DISABLE_USBOTG_HSULPI flag.  From
        Simon Piriou.
      - STM32 F33:  Move DMA logic to a separate files + add ADC support.
        From Mateusz Szafoni.
      - STM32 F3:  Add COMP support.  From Mateusz Szafoni.
      - STM32 F33:  Support for COMP character driver.  From Mateusz Szafoni.
      - STM32 F4:  Implement DMA support for the STM32F4 I2C.  From Rajan Gill.
      - STM32 F7:  Add stm32 RNG support.  This is copied from stm32l4.
        Tested on STM32F746ZG board.  From Juha Niskanen.
      - STM32 L1:  Add STM32L162VE to chip.h.  From Juha Niskanen.
      - STM32 F4:  Add I2C3 SDA pin mapping for STM32F411.  From no1wudi.
      - STM32 L1:  stm32_flash:  Add EEPROM writing for STM32L15XX.  From
        Juha Niskanen.
      - STM32 F7:  Serial:  Add interface to get uart_dev_t by USART number,
        stm32_serial_get_uart.  From Jussi Kivilinna.
      - STM32 F4:  Provide TIM5 definition for STM32F429.  From Matias v01d.
      - STM32 F0:  Add an untested port of the F1 USB device to the STM32F0.
      - STM32 F0:  Add support for the STM32F09X family.  From Juha
        Niskanen.
      - STM32 F0:  Initial cut at I2C driver.  Still a work in progress.
        From Alan Carvalho de Assis.
      - STM32 F33:  Add OPAMP support.  From Mateusz Szafoni.
      - STM32 L4: stm32l4_i2c:  Add I2C4 code.  From Juha Niskanen.
      - STM32 L4:  Add GPIO_PORTI definition.  From Juha Niskanen.
      - STM32 F7 Serial:  Allow configuring Rx DMA buffer size.  From Jussi
        Kivilinna.
      - STM32 L4:  Firewall for stm32l4x3xx.  Not tested for any product
        family, but now it at least compiles.  L496 devices can have one bit
        wider Volatile Data Segment.  From Juha Niskanen.
      - STM32 TIM:  Add method to get timer width.  Freerun timer: Use timer
        width to get the correct clock rollover point.
      - STM32 L4:  Add internal flash write support.  From Juha Niskanen.
      - STM32 L4:  Port stm32l4_serial_get_uart function from STM32F7.  From
        Juha Niskanen.
      - STM32 Ethernet:  Add support for KSZ8081 PHY interrupts.  From
        Sebastien Lorquet.
      - STM32 F4:  Add I2S driver.  From Taras Drozdovsky.
      - STM32 L4:  Add IWDG peripheral.  This is the same as for STM32
        except that prescale and reload can be changed after watchdog has
        been started, as this seems to work on L4.  From Juha Niskanen.
      - STM32 F7:  Add SPI DMA support.  From Jussi Kivilinna.

    * STMicro STM32 Boards:

      - Support for the Particle Photon board was contributed by Simon
        Piriou.  The Photon board is based on a STM32F205G MCU with and on-
        board BCM43362 WiFi chip that interfaces via the STM32's SDIO
        interface.  Board configuration support includes, in addition,
        buttons, LEDS, IWDG, USB OTG HS, and procfs support.  Configurations
        available for nsh, usbnsh, and wlan configurations.
      - Clicker2-STM32:  Support for the Mikroelektronika Clicker 2 for
        STM32 was added by Anthony Merlino.  This board, along with the
        MRF24J40 Click board is the platform used to deveop the IEEE
        802.15.4 support.  The boad configuration includes the MRF24J40
        initialization logic and SPI support.  Configurations exist for nsh,
        knsh, usbnsh, and mrf24j40-radio.
      - Nucleo_F334R8:  Add ADC example.  From Mateusz Szafoni.
      - Nucleo-F334R8:  Add COMP support.  From Mateusz Szafoni.
      - Nucleo-F334R8:  Use new COMP driver.  From Mateusz Szafoni.
      - Adds USB host support to stm32f411-disco board.  From Brian Webb.
      - Add stm32f0discovery board support.  From Alan Carvalho de Assis.
      - Nucleo-F072RB:  Add board configuration.
      - Nucleo-F334R8:  Add OPAMP support.  From Mateusz Szafoni.
      - Nucleo-F072RB:  Add support for the I2C driver used by I2C tools.
      - Nucleo-L496ZG:  Add nucleo-l496zg board files.  From Juha Niskanen.
      - Nucleo-F091RC:  Add nucleo-f091rc board files.  From Juha Niskanen.
      - Nucleo-L432KC:  Add nucleo-l432kc board files.  From Sebastien
        Lorquet.
      - Nucleo-L452RE:  Add nucleo-l452re board files.  From Juha Niskanen.
      - stm32f103-miniumum:  Add board support to use the Nokia 5110
        LCD display driver.  From Alan Carvalho de Assis.

    * C Library/Header Files:

      - C library:  Add strerror_r().
      - C Library:  Add wcstoull(), swprintf(), wcstod(), wcstof(), wcstol(),
        wcstold(), wcstoul(), wcstoll() functions.  Add mbsnrtowcs() and
        wcsnrtombs() (just returning success).  Add mbtowc() and wctomb() to
        C++ std namespace.  From Alan Carvalho de Assis.
      - C Library:  Add ffsl(), ffsll(), fls(), flsl(), flsll() and use
        GCC's __builtin_ctz/__builtin_clz for faster implementation of these.
        From Jussi Kivilinna.
      - fixedmath:  Add square root and b32_t conversion operators.  From
        Jussi Kivilinna.
      - locale.h:  Add a bogus definition of locale_t.
      - C library:  Versions mbrlen and mbsrtowcs taken and adapted from
        FreeBSD code (at https://github.com/freebsd/freebsd/).  From Matias
        v01d.

    * Build/Configuration System:

      - Include C++ library in 'make export'.  From Alan Carvalho de Assis.
      - configs:  Remove all setenv.sh and setenv.bat files.  Remove all
        references to setenv.sh and setenv.bat from all config README files.
      - Kconfig/deconfigs:  Add CONFIG_ARCH_TOOLCHAIN_GNU to indicate that
        the toolchain is based on GNU gcc/as/ld.  This is in addition to the
        CPU-specific versions of the same definition.
      - Move prototype for up_cxxinitialize() from nuttx/include/nuttx/arch.h
        to apps/include/platform/cxxinitialize.h.

    * Tools:

      - Add initialconfig.c so that perhaps in the future we will be able to
        use this to generate a new configuration from scratch (rather than
        having to derive new configurations from existing configurations).
        NOTE: Not yet intregated into the build system.

    * NSH: apps/nshlib:

      - Added support for set [{+|-}{e|x|xe|ex}] [<name> <value>].  Set the
        'exit on error control' and/or 'print a trace' of commands when
        parsing scripts in NSH.  The settings are in effect from the point
        of execution, until they are changed again, or in the case of the init
        script, the settings are returned to the default settings when it
        exits.  Included child scripts will run with the parents settings and
        changes made in the child script will effect the parent on return.
        Use 'set -e' to enable and 'set +e' to disable (ignore) the exit
        condition on commands. The default is -e. Errors cause script to
        exit.  Use 'set -x' to enable and 'set +x' to disable (silence)
        printing a trace of the script commands as they are ececuted. The
        default is +x. No printing of a trace of script commands as they are
        executed.  From David Sidrane.
      - Print expanded variables if -x.  From David Sidrane.
      - ifconfig command:  Extend ifconfig to support 6LoWPAN.  Adapt to
        some changes in configuration variable usage.
      - Network initialization:  If IEEE802.11 selected use wlan0 instead of
        eth0 for network device name.
      - Network initialization:  NSH now has configuration options to select
        the wireless properties.  It builds the configuration structure and
        passes this to wpa_driver_wext_associate() so that it will set the
        network as configured.
      - Network initialization:  Add a new option CONFIG_NSH_NETLOCAL that
        will suppress some built in operations and will support manual
        configuration of a wireless network through command line tools.

    * Examples/Tests: apps/examples:

      - examples/xbc_text: Adds a test program for the XBox One controller
        driver.  From Brian Webb.
      - examples/ostest:  Add a test of robust mutexes.
      - examples/ostest: Add tests for pthread_rwlock.  Adding tests to be
        used to verify the pthread_rwlock lock works.  From Mark Schulte.
      - examples/ostest:  Additional test for rwlock and one for cancel
        cleanup handlers.  From Juha Niskanen.
      - examples/usrsocktest:  Add application for USRSOCK testing.  From
        Jussi Kivilinna.
      - examples/nettest:  Adapt for use in testing 6LoWPAN.
      - examples/nettest:  If doing loopback, but not using the official
        loopback device, then use the server should use the configured client
        IP address.
      - examples/udpblaster:  Several fixes to work with 6LoWPAN.
      - examples/udpblaster:  Add logic to bind the local UDP socket to a
        well-known address.
      - examples/configdata:  Add stacksize and priority.  From Juha Niskanen.

    * Network Utilities: apps/netutils:

      - netutils/netlib:  Add IEEE 802.11 wireless IOCTL wrappers.
      - netutils/netlib: Add a helper function to convert a string to a
        6LoWPAN node address.
      - netlib and NSH: Add logic to get/set the IEEE802.15.4 PAN ID.
      - netutils/dhcpc:  Make the network device name a configuration
        option.  Was hardcoded to eth0 but may, instead, need to be wlan0.
      - netutils/dhcpc:  Remove hard-coded interface device.  Now passed as
        a parameter to dhcpc_open().  From Sebastien Lorquet.

    * Wireless Utilities: apps/wireless:

      - wireless/wapi:   Port of Wapi wireless services.  The original
        depended on features not supported by NuttX:  Removed logic that
        depends on Linux netlink.  Removed functionality that depended on
        the Linux procfs:  This includes only 1) listing of available
        interfaces and 2) listing of all routes.
      - wireless/wapi:  Create command line Wapi application based on
        Wapi sample code.
      - wireless/wapi:  wpa_driver_wext_associate() now accepts a
        configuration parameter that can be used to specify the wireless
        properties.
      - wireless/wapi:  Add basic wapi_event_stream_extract implementation.
        From Simon Piriou.
      - wireless/ieee802154:  Add iwpan and i8sak tools.  iwpan is similar
        in concept to wapi.  From Anthony Merlino (i8sak was originally
        by Sebastien Lorquet).
      - wireless/ieee802154/libmac:  IEEE 802.15.4 MAC library.
      - wireless/wext:  Add drivers_wext from the WPA supplicant; Integrate
        into NSH.  From Simon Piriou.

    * System Utilities (apps/system)

      - apps/system/dhcpc:  Add a command to renew or establish a lease on an
        IPv4 address.
      - apps/system/ntpc:  Add a command to start or stop the NTPC daemon.
      - apps/system/ramtest: Make stacksize and priority conigurable.

    * Platform-Specific Support (apps/platform)

      - apps/platform:  Create gnu/ subdirectory that contains the one and
        only GNU C++ initialization function.  Remove all other C++
        initialization functions.

Bugfixes.  Only the most critical bugfixes are listed here (see the
ChangeLog for the complete list of bugfixes and for additional, more
detailed bugfix information):

    * Core OS:

      - Priority inheritance:  When CONFIG_SEM_PREALLOCHOLDERS==0, there is
        only a single, hard-allocated holder structure.  This is problem
        because in sem_wait() the holder is released, but needs to remain in
        the holder container until sem_restorebaseprio() is called.  The call
        to sem_restorebaseprio() must be one of the last things the
        sem_wait() does because it can cause the task to be suspended. If in
        sem_wait(), a new task gets the semaphore count then it will fail to
        allocate the holder and will not participate in priority
        inheritance.  This fix is to add two hard-allocated holders in the
        sem_t structure:  One of the old holder and one for the new holder.
      - Priority inheritance:  sem_holder sem_findholder missing
        inintalization of pholder.  sem_findholder would fail and code
        optimization covered this up.  From David Sidrane.
      - Partial Fix priority inheritance CONFIG_SEM_PREALLOCHOLDERS=0.  From
        David Sidrane.
      - Priority inheritance:  sem_boostholderprio prevent overrun of
        pend_reprios.  The second case rtcb->sched_priority <=
        htcb->sched_priority did not check if there is sufficient space in
        the pend_reprios array.  From David Sidrane.
      - lp_worker:  Guard from pend_reprios overflow.  From David Sidrane.
      - Priority inheritance: Fixes improper restoration of base_priority in
        the case of CONFIG_SEM_PREALLOCHOLDERS=0.  The call to
        sem_restorebaseprio_task context switches in the
        sem_foreachholder(sem, sem_restoreholderprioB, stcb); call prior to
        releasing the holder. So the running task is left as a holder as is
        the started task. Leaving both slots filled thus failing to perform
        the boost/or restoration on the correct tcb.  This PR fixes this by
        releasing the running task slot prior to reprioritization that can
        lead to the context switch.  To faclitate this, the interface to
        sem_restorebaseprio needed to take the tcb from the holder prior to
        the holder being freed. In the failure case where sched_verifytcb
        fails it added the overhead of looking up the holder.  There is also
        the additional thunking on the foreach to get from holer to
        holder->tcb.  An alternate approach could be to leve the interface
        the same and allocate a holder on the stack of sem_restoreholderprioB
        copy the sem's holder to it, free it as is done in this pr and
        then pass that address sem_restoreholderprio as the holder. It could
        then get the holder's tcb but we would keep the same sem_findholder
        in sched_verifytcb.  From David Sidrane.
      - Priority inheritance:  Fixes improper restoration of base_priority.
        From David Sidrane.
      - sem_holder:  Indexing error.  From David Sidrane.

          if (sem->holder[0].htcb != NULL || sem->holder[**1**].htcb != NULL)
      - realloc():  When realloc() has to fall back to calling malloc(), size
        including overhead was being provided to malloc(), causing a slightly
        larger allocation than needed.  Noted by initialkjc@yahoo.com.
      - scheduler:  Fix tg_flags check with GROUP_FLAG_NOCLDWAIT.  From Masayuki
        Ishikawa.
      - scheduler:  Fix CHILD_FLAG_EXITED in include/nuttx/sched.h.  From
        Masayuki Ishikawa.
      - binfmt/elf:  Fix offset value when calling elf_read() in
        elf_symname().  From Masayuki Ishikawa.
      - binfmt/elf:  Fix offset value when calling elf_read() in
        elf_sectname().  From Masayuki Ishikawa.
      - There can be a failure in IOB allocation to some asynchronous
        behavior caused by the use of sem_post().  Consider this scenario:
        (1) Task A holds an IOB. There are no further IOBs. The value of
        semcount is zero. Task B calls iob_alloc(). Since there are not
        IOBs, it calls sem_wait(). The value of semcount is now -1.  (2)
        Task A frees the IOB. iob_free() adds the IOB to the free list and
        calls sem_post() this makes Task B ready to run and sets semcount to
        zero NOT 1. There is one IOB in the free list and semcount is zero.
        When Task B wakes up it would increment the sem_count back to the
        correct value.  (3) But an interrupt or another task runs occurs
        before Task B executes. The interrupt or other tak takes the IOB off
        of the free list and decrements the semcount. But since semcount is
        then < 0, this causes the assertion because that is an invalid state
        in the interrupt handler. So I think that the root cause is that
        there the asynchrony between incrementing the semcount.  This change
        separates the list of IOBs:  Currently there is only a free list of
        IOBs.  The problem, I believe, is because of asynchronies due
        sem_post() post cause the semcount and the list content to become out
        of sync.  This change adds a new 'committed' list:  When there is a
        task waiting for an IOB, it will go into the committed list rather
        than the free list before the semaphore is posted.  On the waiting
        side, when awakened from the semaphore wait, it will expect to find
        its IOB in the committed list, rather than free list.  In this way,
        the content of the free list and the value of the semaphore count
        always remain in sync.
      - binfmt:  Fix .dtor memory allocation.  From Masayuki Ishikawa.

    * File System/Block and MTD Drivers:

      - SmartFS:  If whence is SEEK_END, the file offset shall be set to the
        size of the file plus offset. Noted by eunb.song@samsung.com.
      - mtd/progmem:  Fix incorrect target address calculation.
        progmem_read/write() is incorrectly calculating the target address,
        expecting the offset argument is given in a block number. This is
        completely wrong and as a result invalid flash region is accessed.
        Byte-oriented read/write interfaces of mtd device accept the target
        address in a byte offset, not a block number.  From Heesub Shin.
      - procfs:  Fix wrong member IDs are displayed when 'cat
        /proc/<pid>/group/status'.  From Nobutaka Toyoshima.
      - procfs:  Fix incorrect uptime with CONFIG_SYSTEM_TIME64.  From
        Masayuki Ishikawa.
      - vfs/poll: round timeout up to next full tick.  Calling poll() with
        timeout less than half tick (thus MSEC2TICK(timeout) => 0) caused
        returning error with EAGAIN. Instead of rounding timeout down, value
        should be rounded up. Open Group spec for poll says:
        "Implementations may place limitations on the granularity of timeout
        intervals. If the requested timeout interval requires a finer
        granularity than the implementation supports, the actual timeout
        interval will be rounded up to the next supported value."  From Jussi
        Kivilinna.
      - mtd/config:  erase block between block read and write.  From Juha
        Niskanen.
      - mtd:  Build RAMTRON and AT45DB drivers only if selected.  From Juha
        Niskanen.
      - mtd/config:  Fix byte read interface test.  From Juha Niskanen.
      - mtd:  Fix some unallocated and NULL pointer issues.  rwb->wrflush and
        rwb->wrmaxblocks in rwbuffer could get unallocated values from
        ftl_initialize() in some configurations.  Also fixes related assert:

          up_assert: Assertion failed at file:rwbuffer.c line: 643

        that can happen with the following configuration:

          CONFIG_FTL_WRITEBUFFER=y
          CONFIG_DRVR_WRITEBUFFER=y
          # CONFIG_FS_WRITABLE is not set

        These problems are caused by CONFIG variable differences between the
        buffer layers. TODO: This is not a perfect solution. readahead
        support has similar issues.  From Juha Niskanen.
      - net procfs:  Fix buffer corruption and refactor netdev_statistics.c.
        From Masayuki Ishikawa.
      - FAT:  Fix 'Missing unlock' in fs_fat32.c.  From Masayuki Ishikawa.
      - VFS fdopen:  Add missing file stream flags clearing.  Clear file
        stream structure regardless of config options. Structure clearing is
        needed as previous use of stream list entry might leave fs_flags
        set.  From Harri Luhtala.
      - mtd/smart: Fix use of uninitialized variable.  From Jussi Kivilinna.
      - mtd/w25.c:  Enable short delay after sector/chip erase.  From Jussi
        Kivilinna.
      - mtd/config:  Add some error checks for I/O errors.  From Juha
        Niskanen.

    * Graphics/Graphic Drivers:

      - net procfs:  Some long lines were being generated that cause buffer-
        related problems and corrupted output.

    * Networking/Network Drivers:

      - Fixed wrong assert on udp dgram send.  From Pascal Speck.
      - TCP/IPv6: Fix a compile issue when IPv6, but not IPv4 is enabled.
      - net/socket/accept:  Fix building with CONFIG_NET_LOCAL_STREAM.  From
        Jussi Kivilinna.
      - Argument of network device IOCTL should be unsigned long, just as
        will all other IOCTL methods.
      - net/socket:  Fix cloning of local and raw sockets.  From Jussi
        Kivilinna.
      - TCP:  Wait for 3-Way Handshare before accept() returns.  From Simon
        Piriou.
      - TCP:  Send RST if application 'unlistens()' before we complete the
        connection sequence.
      - TCP:  An RST received during the 3-way handshake requires a little
        more clean-up.
      - IPv6:  Fix net_ipv6_pref2mask().  From Masayuki Ishikawa.
      - network IOCTL commands:  The only place in net/netdev/netdev_ioctl.c
        where the interface state should change is for SIOCSIFFLAGS.  The
        other ones .. SIOCSIFADDR, SIOSLIFADDR, SIODIFADDR ..  should not
        change the link state.  From Sebastien Lorquet.
      - TCP:  Fix tcp_findlistner() in dual stack mode.  From Masayuki
        Ishikawa.

    * Common Drivers:

      - Fix as5048b by adding missing frequency parameter.  From Andreas
        Bihlmaier.
      - multiple fixes in nrf24l01 driver:  (1) signal POLLIN if there is
        already data in the FIFO, (2) send ETIMEDOUT to userspace after 2
        seconds if TX IRQ was not received, (3) handle FIFO overflow, (4)
        handle invalid pipes/empty FIFO, and (5) multiple cosmetics (missing
        static, duplicate define, missing \n).  From Leif Jakob.
      - input/mxt:  Prevent overriding i2c transfer return value.
        put_reg/get_reg function was overriding i2c transfer error code with
        i2creset return value, that lead to OK status although actual
        transfer failed.  From Juha Niskanen.
      - drivers/audio/wm8904:  WM8904 has same problem as that fixed by Juha
        Niskanen in the MaxTouch driver.
      - UART 16550:  Missing left parenthesis in function prototype.  This is
        Bitbucket Issue #41.
      - USBMSC:  Fix a wrong lun number issue.  From Masayuki Ishikawa.
      - drivers/i2c:  Fix compile issues if CONFIG_DISABLE_PSEUDOFS_OPERATIONS
        is enabled.
      - drivers/serial: I discovered a problem in the file
        drivers/serial/serial.c concerning the function uart_close. In the
        case that a serial device is opened with the flag O_NONBLOCK the
        function uart_close blocks until all data in the buffer is
        transmitted. The function close called on an handle opened with
        O_NONBLOCK should not block. The problem occurred with a CDC/ACM
        device.  From Stefan Kolb.
      - drivers:  Fix some bad NULL checks.  From Juha Niskanen.
      - drivers:  Rename newly introduced up_i2creset to I2C_RESET.  From
        Juha Niskanen.
      - drivers/bch:  BCH character driver bch_ioctl() always returns -ENOTTY
        for DIOC_GETPRIV command.  It should returns OK if DIOC_GETPRIV
        command succeeds.  From  EunBong Song.
      - Replace sprintf() with snprintf() in pipe.c.  From Nobutaka Toyoshima.
      - drivers/bch:  Fix 'Missing Unlock' in bchdev_driver.c.  From Masayuki
        Ishikawa.
      - button_upper:  Fix interrupt enabling for poll-events.  From Jussi
        Kivilinna.
      - drivers/{sensors,usbmisc}:  Fix uninitialized I2C frequency.  From
        Juha Niskanen.

    * ARM:

      - Set EABI stack alignment for all ARM architectures (remove OABI
        code).  From David Cabecinhas.
      - Remove redundant interrupt stack coloring and OABI code.  From David
        Cabecinhas.
      - Fix off-by-one interrupt stack allocation in 8-byte aligned
        architectures.  From David Cabecinhas.

    * ARMv6-M:

      - CONFIG_DEBUG_HARDFAULT should be available for Cortex-M0 too.

    * Microchip/Atmel SAM3/4 Drivers:

      - SAM3/4:  Fixed configurations for TWI master.  Obviously an
        incomplete port from SAMA5.

    * Microchip/Atmel SAMv7 Drivers:

      - SAMV7: Watchdog:  Fix Forbidden Window Value.  According the Datasheet
        the WDD Value is the lower bound of a so called Forbidden Window and
        to disable this we have to set the WDD Value greater than or equal to
        the WDV Value.  This seems to be a bug in the datasheet. It looks
        like we have to set it to a greater value than the WDV to really
        disable this Thing.  When triggering the Watchdog faster than the
        (very slow) clock source of the Watchdog fires, this Forbidden Window
        Feature resets the System if WDD equals to WDV.  This Changeset
        disables the Forbidden Window by setting the WDD Value to the Maximum
        (0xfff) Value possible.  From Frank Benkert.
      - SAMV7 EMAC:  Add conditional logic to account the fact that the
        SAMV71 has 6 rather than 3 queues after version 1.  From Ian McAfee.

    * NXP/Freescale Kinetis Drivers:

      - Kinetis:  Fixed GPIO _PIN_OUTPUT_LOWDRIVE swapped with
        _PIN_OUTPUT_OPENDRAIN.  From David Sidrane.
      - Ensure interrupts are back on BEFORE running code dependent on
        clock_systimer.  From David Sidrane.
      - Kinetis k66, k64, k60, k40, k20: Pin mux configure all I2C signals as
        Open Drain.  The output structure of the GPIO for I2C needs to be
        open drain.  When left at the default, one can observe on a scope the
        slave contending with the push-pull during the ACK.  From David
        Sidrane.
      - Kinetis K66:  Fixed TMP2_CH1 definition.  From David Sidrane.
      - Kinetis K66:  Define ALT1 to match ref manual.  From David Sidrane.
      - Kinetis K66:  GPIO and pin mux cleanup.  From David Sidrane.
      - Kinetis ADC:  Various corrections and updates.  From David Sidrane.

    * NXP/Freescale LPC43xx:

      - Add missing PINCONF_INBUFFER in several places of
        lpc4310203050_pinconfig.h.  From Andreas Bihlmaier.
      - Fix logic in preprocessor checks and correct arguments to
        lpc43_pin_config initialization.  From Andreas Bihlmaier.

    * NXP/Freescale LPC43xx Drivers:

      - Fix logic error in lpc43_adc.  From Andreas Bihlmaier.
      - Use correct macro for irqid (fortunately both point to
        LPC43_IRQ_EXTINT+18).  From Andreas Bihlmaier.
      - Actually write modified value to register.  From Andreas Bihlmaier.
      - Increase number of supported PWM channels from 4 to 6.  From Andreas
        Bihlmaier.

    * Silicon Labs EFM32 Drivers:

      - EFM32 I2C: Fix timeout calculation.  From Masayuki Ishikawa.

    * STMicro STM32:

      - As discovered by dcabecinhas.  This fix assume the 8 byte alignment
        options for size stack size or this will overwrite the first word
        after TOS.  See
        https://github.com/PX4/Firmware/issues/6613#issuecomment-285869778.
        From David Sidrane.
      - STM32 F7:  In stm32_allocateheap.c There are 5 not 4 configurations.
        From David Sidrane.

    * STMicro STM32 Drivers:

      - STM32, STM32 F7, STM32 L4:  OTG host drivers: Do not do data toggle
        if interrupt transfer is NAKed.  Suggested by webbbn@gmail.com.
      - Save elapsed time before handling I2C in stm32_i2c_sem_waitstop().
        This change follows the same logic as in previous fix to
        stm32_i2c_sem_waitdone().  It is possible that a context switch
        occurs after I2C registers are read but before elapsed time is saved
        in stm32_i2c_sem_waitstop(). It is then possible that the registers
        were read only once with "elapsed time" equal 0. When scheduler
        resumes this thread it is quite possible that now "elapsed time" will
        be well above timeout threshold. In that case the function returns
        and reports a timeout, even though the registers were not read
        "recently". Fix this by inverting the order of operations in the loop
        - save elapsed time before reading registers. This way a context
        switch anywhere in the loop will not cause an erroneous "timeout"
        error.  From Freddie Chopin.
      - STM32, STM32 F7, and STM32 L4:  Clone Freddie Chopin's I2C change to
        similar STM32 I2C drivers.  From David Sidrane.
      - STM32:  OTG host implementations of stm32_in_transfer() must obey the
        polling interval for the case of isochronous and interrupt endpoints.
      - STM32:  Fix erase sector number for microcontrolers with more than 11
        sectors.  Erase a sector from the second bank cause the bit 4 of SNB
        being set but never unused, so trying to erase a sector from the first
        bank was actually eraseing a sector from the second bank.  From José
        Roberto de Souza.
      - STM32:  Make up_progmem thread safe.  Writing to a flash sector while
        starting the erase of other sector have a undefined behavior so lets
        add a semaphore and synchronize access to Flash registers.  But for
        the semaphore to work it needs to be initialized so each board needs
        call stm32_flash_initialize() on initialization, so to avoid runtime
        problems it is only using semaphore and making it thread safe if
        initialized, after all boards starts to call stm32_flash_initialize()
        we can remove the boolean and the check.  From José Roberto de Souza.
      - STM32:  Add workaround for flash data cache corruption on
        read-while-write.  This is a known hardware issue on some STM32 see
        the errata of your model and if you make use of both memory banks you
        should enable it.  From José Roberto de Souza.
      - STM32 Flash fixes.  From José Roberto de Souza.
      - STM32 Flash:  Missing unlock on F1 HSI off path.  From David Sidrane.
      - STM32 F4 I2C: I needed to use DS3231, I remember that in past it
        worked ok, but now for stm32f4xx is used another driver (chip
        specific, stm32f40xxx_i2c.c) and DS3231 driver doesn't work.  After
        investigating a problem I found that I2C driver (isr routine) has a
        few places there it sends stop bit even if not all messages are
        managed. So, e.g., removing stm32_i2c_sendstop (#1744) and adding
        stm32_i2c_sendstart after data reading helps to make DS3231 working.
        From  Alexander Oryshchenko; verified by David Sidrane.
      - STM32 F7 Serial:  Serial fix for dropped data:  (1) Revert the
        inherited dma bug from the stm32.  see
        https://bitbucket.org/nuttx/nuttx/commits/df9ae3c13fc2fff2c21ebdb098c520b11f43280d
        for details.  And (2) Most all CR1-CR3 settings can not be configured
        while UE is true. Threfore we make all operation atomic and disable
        UE and restore it's originalstate on exit.  From David Sidrane.
      - STM32 L1:  Fix IWDG and WWDG debug mode stop for STM32L15XX.  From
        Juha Niskanen.
      - STM32 F7:  Fix UART7 and UART8 IFLOWCONTROL options.  From Jussi
        Kivilinna.
      - STM32 F7:  Add warning for RXDMA + IFLOWCONTROL combination.
        Combination of RXDMA + IFLOWCONTROL does not work as one might
        expect.  Since RXDMA uses circular DMA-buffer, DMA will always keep
        reading new data from USART peripheral even if DMA buffer underruns.
        Thus this combination only does following: RTS is asserted on USART
        setup and deasserted on shutdown and does not perform actual RTS
        flow-control.  Data loss can be demonstrated by doing long up_mdelay
        inside IRQ critical section and feeding data to RXDMA+IFLOWCONTROL
        UART.  From Jussi Kivilinna.
      - STM32 F7 Serial:  Do not stop processing input in SW flow-control
        mode.  From Jussi Kivilinna.
      - STM32 L4 DMA: Correct bad channel definition.  From Sebastien Lorquet.
      - STM32 F7:  Warn if no DMA2 configured when using ADC with DMA.  Also
        correct ADC channel numbers that DMA callback passes to upper half
        driver.  From Juha Niskanen.
      - STM32 F7 ADC:  Do not override ADCPRE_DIV when measuring
        internal voltage.  From Juha Niskanen.
      - STM32 L4:  Don't think these chips have DPFPU, DTCM or ITCM.  From
        Juha Niskanen.
      - STM32 F7 Flash:  macro naming errors, there is no FLASH_CONFIG_F for
        F7.  From Juha Niskanen.
      - STM32 L4: stm32l4x6xx_pinmap:  Update I2C4 and DCMI pins.  From Juha
        Niskanen.
      - STM32 L4: stm32l4_i2c: change wrong macro to CONFIG_I2C_POLLED.  From
        Juha Niskanen.
      - Fix STM32F7 I2C interrupt handler.  From Jussi Kivilinna.
      - STM32:  Serial Allow configuring Rx DMA buffer size.  From David
        Sidrane.
      - STM32 CAN: I had the problem that the transmit FIFO size (= actual
        elements in FIFO) was slowly increasing over time, and was full after
        a few hours.  The reason was that the code hit the line
        "canerr("ERROR: No available mailbox\n");" in stm32_cansend, so
        can_xmit thinks it has sent the packet to the hardware, but actually
        has not. Therefore the transmit interrupt never happens which would
        call can_txdone, and so the size of the FIFO size does not decrease.
        The reason why the code actually hit the mentioned line above, is
        because stm32can_txready uses a different (incomplete) condition than
        stm32can_send to determine if the mailbox can be used for sending,
        and thus can_xmit forwards the packet to stm32can_send.
        stm32can_txready considered mailboxes OK for sending if the mailbox
        was empty, but did not consider that mailboxes may not yet be used if
        the request completed bit is set - stm32can_txinterrupt has to
        process these mailboxes first.  Note that I have also modified
        stm32can_txinterrupt - I removed the if condition, because the CAN
        controller retries to send the packet until it succeeds. Also if the
        condition would not evaluate to true, can_txdone would not be called
        and the FIFO size would not decrease also.  From Lederhilger Martin.
      - STM32 Serial:  Fix freezing serial port.  Serial interrupt
        enable/disable functions do not disable interrupts and can freeze
        device when serial interrupt is received while execution is at those
        functions. Trivially triggered with two or more threads write to
        regular syslog stream and to emergency stream. In this case, freeze
        happens because of mismatch of priv->ie (TXEIE == 0) and actually
        enabled interrupts in USART registers (TXEIE == 1), which leads to
        unhandled TXE interrupt and causes interrupt storm for USART.  From
        Jussi Kivilinna.
      - STM32 I2C:  Make private symbols static.  From Juha Niskanen.
      - STM32 L4 GPIO:  Put back EXTI line source selection.  From Juha
        Niskanen.
      - STM32 L4 RTC:  Store RTC MAGIC to backup reg, not to address zero.
        From Juha Niskanen.

    * STMicro STM32 Boards:

      - Disable serial console on stm32f103-minimum usbnsh example project
        config. Devices enumerate after this change.  From Bob Ryan.
      - Nucleo-144:  Default for choice in Kconfig was not one of the
        possible choices.
      - Nucleo-F4X1RE User LEDS: Issue #51 reports compilation problems with
        stm32_userled.c.  Reported by Gappi92.

    * TI Tiva Drivers:

      - Tiva I2C:  Correct an error in conditional compilation.
      - Tiva SSI:  Resolves issue 52 'Copy-Paste error in
        tiva_ssibus_initialize()' submitted by Aleksandr Kazantsev.

    * C Library/Header Files:

      - C Library vsnprintf():  Fix precision for string formatting.  Fixes
        use of format precision to truncate input string.  From Jussi
        Kivilinna.
      - C Library vsnprintf():  If size is zero, then vsnprintf() should
        return the size of the required buffer without writing anything.
        From Jussi Kivilinna.
      - C Library netdb: in dns_query_callback, ret != -EADDRNOTAVAIL
        condition consumes error returns including EAGAIN in this case,
        dns query retransmission doesn't work.  From Ritajina.
      - C Library netdb:  Fix time info in lib_dnscache.c.  From Masayuki
        Ishikawa.
      - C Library netdb: Fix bugs in lib_gethostbynamer.c. This fix sets
        h_name in struct hostent returned by gethostbyname().  From Masayuki
        Ishikawa.
      - C Library Defect Workaround: replace '%6.6u' format with an
        equivalent '%06u'.  From Tomasz Wozniak.

    * Tools

      - Fix mksyscall host binary name.  From Alan Carvalho de Assis.

    * Applications (apps/)

      - Fix some calls to task_create():  argv[0] is the first parameter, not
        the name of the task.
      - Bitbucket Issue 5:  I found an unexpected behavior in apps/
        configuration generation. Adding external symbolic link in apps/
        directory and using Make.defs for Kconfig generation, Kconfig file
        has a wrong path in the source argument. It contains original dir
        path outside of the source tree instead path to sub-directory in
        apps/.  The problem is connected with make/system symbolic link path
        resolution.  Corrected by a patch submitted by Artur Madrzak with
        Issue 5.
      - apps/: Make more globals static to avoid name clashes.  From Juha
        Niskanen.

    * NSH: apps/nshlib:

      - NSH library:  In nsh_argexand(), if CONFIG_NSH_ARGCAT is defined but
        CONFIG_NSH_CMDPARMS defined and/or CONFIG_DISABLE_ENVIRON not
        defined, then there is a situation that causes an infinite loop in
        the parser.  Noted by Freddie Chopin.
      - NSH library:  Fix building when CONFIG_NET_USRSOCK enabled with other
        link-layers.  From Jussi Kivilinna.
      - NSH library:  Fix some warnings about integer/pointer casts of
        different sizes (probably only effects 64-bit simulation).
      - NSH library:  Fix open flags in nsh_codeccmd.c.  From Masayuki
        Ishikawa.
      - I need to look at the registers that are at or around 0xe000ef90.
        Using mw and xd, I see that nsh does not support pointers greater
        than 0x7fffffff.  A quick look at the source shows that the pointers
        for those two commands are set with calls to strtol() rather than
        strtoul().  Changing the two pointer-setting instances to strtoul()
        fixes the problem, at least for my architecture/config.  From Ian
        McAfee.
      - NSH library: Fix a resource leak in cmd_hexdump().  From Nobutaka
        Toyoshima.

    * Examples/Tests: apps/examples:

      - apps/examples/hidkbd:  Remove call to arch_usbhost_initialize().
        That is violation of the OS interfacing rules and will no longer be
        supported.  USB host should be initialized as part of the normal
        board bring-up logic as with any other devices and should not involve
        illegal calls from applications into the OS.
      - apps/examples/usbterm:  Removed because it is not very useful and
        because it can be configured to use an illegal call into the OS.
      - examples/mm: Fix Makefile.  Built-in was not being registered.
      - examples/hidkbd:  Add some missing configuration settings.
      - examples/random:  Avoid stack overflows.  From Juha Niskanen.
      - examples/nettest:  Fix an error in pre-processor expression.
      - examples/mtdpart:  Prevent part array overflow.  mtdpart examples
        create partitions and allocate from 1 index not a 0 index to part[]
        array. This cause buffer overflow for part array.  This change fixes
        this problem.  From  EunBong Song.
      - examples/can:  Fix can example app to print data when
        CONFIG_EXAMPLES_CAN_READ is defined.  From Alan Carvalho de Assis.

    * Network Utilities: apps/netutils:

      - Not a clean fix, but at least makes DHCP working with
        CONFIG_NETDEV_MULTINIC.  From Andreas Bihlmaier.
      - Ensure netlib will not be broken when setip will not bring the
        network up anymore.  From Sebastien Lorquet.

    * CAN Utilities: apps/canutils:

      - Fix libcanard github download link to get it compiling correctly.
        From Alan Carvalho de Assis.
      - Fix to use the new canardInit() function.  From Alan Carvalho de
        Assis.

    * System Utilities (apps/system)

      - system/dhcpc:  Add missing argument of fprintf.

    * Tools (apps/tools):

      - The dedicated windows tool at tools/mkkconfig.bat uses $APPSDIR,
        which is not a windows shell variable, and is left uninitialized, but
        in fact should be the current directory.  From Sebastien Lorquet.

NuttX-7.22 Release Notes
------------------------

The 122nd release of NuttX, Version 7.22, was made on September 9, 2017,
and is available for download from the Bitbucket.org website.  Note
that release consists of two tarballs:  nuttx-7.22.tar.gz and
apps-7.22.tar.gz.  These are available from:

    https://bitbucket.org/nuttx/nuttx/downloads
    https://bitbucket.org/nuttx/apps/downloads

Both may be needed (see the top-level nuttx/README.txt file for build
information).

Additional new features and extended functionality:

    * Core OS:

      - pthreads:  Move functions from sched/pthreads to libc/pthreads.  These
        functions just coordinate other OS interface calls but are not a
        fundamental OS interfaces and, hence, do not belong within the OS:
        pthread_yield(), pthread_once(), pthread_cond_init(),
        pthread_cond_destroy(), pthread_barrier_init(),
        pthread_barrier_destroy(), and pthread_barrier_wait().
      - Add power-related debug output.

    * File Systems/Block and MTD Drivers

      - RAMTRON:  Add support for splitting block writes in chunks.  Some
        Re-RAMs like MB85AS4MT have a write buffer size limitation.  From
        Boris Astardzhiev.
      - MTD: Add driver for Macronix QuadSPI flash memory.  From Simon Piriou.

    * Graphics/Display Drivers:

      - SSD1306 LCD Driver:  (1) Separate lcd_dev_s setup to separate object.
        g_oleddev takes 1 KiB because framebuffer and was allocated to .data
        section because of lcd_dev_s function pointer setup. Move lcd_dev_s
        setup out, so that g_oleddev goes to .bss and avoid wasting ROM. (2)
        Fix memory corruption caused by ssd1306_getrun(). ssd1306_getrun was
        writing one extra byte (with value 0) past target buffer when pixlen
        is multiple of 8. When pixlen was not multiple of 8, last byte of
        buffer was fully cleared, instead of modifying only the (pixlen % 8)
        bits of last byte.  (3) Add support for board power control.
        ThingseeOne has regulator for controlling display power on/off.  Patch
        adds support for board based power control to SSD1306 driver. (4) Add
        DD-12864WO-4A/SSD1309 support to SSD1306 driver. From Jussi Kivilinna.

    * Networking/Network Drivers:

      - Sockets: Support listening sockets in the getsockname() function.
        From Roland Takacs.
      - IP Forwarding:  At the IP level, network may be configured to forward
        IP packets that are not destined for the target through a different
        network device, decrementing the packet TTL.
      - IP forwarding:  Add optional support to forward broadcast and
        multicast packets.  Add missing ICMP support.
      - ICMPv6:  Add 6LoWPAN and IP forwarding support.
      - ICMPv6:  Support source link-layer address option in RA.  From
        Masayuki Ishikawa.
      - TUN Driver: Add definitions that will permit TUN-only networking.
      - Socket I/F:  Created a socket interface used to provide socket support.
        Each address family has an interface that describes how to perform
        socket operations on that address family.  Currently only a couple of
        methods are defined in the socket interface call table
      - Remove CONFIG_NET_MULTILINK.  This increases code size by a little,
        but greatly reduces the complexity of the network code.
      - Network procfs:  Add support for routing tables at proc/net/route.
      - Network procfs:  Add support for network procfs statistics for the
        PF_IEEE802154 address family.
      - Network Driver Backlog:  Remove driver based backlog support.  This
        affects the entire network, but is used by only one driver.  The only
        supported RX backlog is now via common read-ahead buffering.

    * Wireless Networking/Wireless Drivers:

      - IEEE 802.15.4 MAC / MRF24J60 Driver:  Extensive updates for
        association/beacon-enabled networks.  From Anthony Merlino.
      - IEEE 802.15.4 MAC / MRF24J60 Driver:  Hook in setdevmode from newly
        added radio attribute setting.  From Anthony Merlino.
      - IEEE 802.15.4 MAC: Supports get request for coordinator address.  From
        Anthony Merlino.
      - IEEE 802.15.4 MAC: Notify radio layer of changes in devmode.  From
        Anthony Merlino.
      - IEEE 802.15.4:  Add special attribute that can be used to perform a
        regdump of the radio.  From Anthony Merlino.
      - IEEE 802.15.4 loopback driver:  Better simulation addressing: short
        and extended addresses, panid, and IP address conversion.
      - IEEE 802.15.4 Network Driver:  Add logic to setup the network mask,
        update the MAC-based IPv6 addressing when the network is brought up.
        The idea is that addressing changes are supposed to occur only while
        the network is down but won't take effect until the network is up
        again.
      - PktRadio:  Add an infrastructure to support networking on generic
        (non-IEEE 802.15.4) packet radios.
      - PktRadio Loopback Driver:  Add a PktRadio loopback network driver to
        testing testing with 6LoWPAN and PktRadios on the simulator.
      - Spirit Network Driver:  The Spirit1 radio (SPSGRF-915) is the first
        generic PktRadio Network driver.  Based on STMicros STack packets
        with 8-bit addressing.  We need to use the STack packets in order to
        provide the source address and automatic ACKing.
      - Network procfs:  Fix so that PktRadio address are shown correctly.
      - Networking:  Add support for some packet radio IOCTL commands.
      - 6LoWPAN:  Added handling for TCP and ICMPv6 packets.
      - 6LoWPAN:  Add configurable support for 6LoWPAN star topology.  With
        this change, the endpoints which are the 'points' of the star will
        forward all traffic to the coordinator.  The coordinator is assumed to
        be the 'hub' of the star.  This function also used IPv6 forwarding.
      - 6LoWPAN:  The original, Contiki-based design used only a single buffer
        for reassemblying larger packets.  This could be a problem issue for
        hub configurations which really need the capability concurrently
        reassemble multiple incoming streams concurrently. These was also a
        design issue in that the reassembly buffer could be corrupted by
        outgoing packets.  The design was extended to support multiple
        reassembly buffers, each associated with the reassembly tag and source
        address.  This assures that there can be be no corruption of the
        reassembly once it has started.
      - 6LoWPAN PktRadio:  Now radio agnostic.  All IEEE 802.15.4 dependencies
        have been removed or isolated so that 6LoWPAN can be used with any
        kind of packet radio.  This involved things like:  (1) generalizing
        the representation of radio MAC meta-data,  (2) changes to handle
        variable-length radio addresses,  (3) removal of all explicit IEEE
        802.15.4 types, references, and interfaces, (4) a new radio driver
        interface to return 'capabilities' of the driver.
      - ICMPv6:  Update so that ICMPv6 can be used with 6LoWPAN.
      - IPv6 Neighbor:  Update table format to support IEEE 802.15.4 MAC
        addresses.
      - PF_IEEE802154 Address Family:  Add support for the PF_IEEE802154
        address family socket type. This socket is similar to the PF_PACKET,
        "raw" packet address family except that:  (1) it supports only
        SOCK_DRAM, not SOCK_RAW, and (2) works only with IEEE 802.15.4
        MAC-based radios.  This address family permits simple access to IEEE
        802.15.4 IOCTLs and frame-level network transfers.

    * Other Common Device Drivers:

      - Dynamically configurable USB composite devices:  We developed a huge
        Changeset over a year ago to make USB Composite configuration
        dynamical and be able to instantiate the CDC/ACM multiple times inside
        this device.  We use this feature to switch between one in typical USB MSC + CDC/ACM configuration and up to three CDCACMs dynamically.
        I've changed the interface for some USB-Functions to receive also the
        dynamic configuration.  From Frank Benkert.
      - Franks' change remained on a branch until all issues were resolved.
        the current version in Master is complete and ready for use.
      - power:  battery_charger:  Add ioctl for charging input current.  From
        Juha Niskanen.
      - SMPS driver:  Add generic upper-half driver for SMPS.  From Mateusz
        Szafoni.
      - LED Driver:  Add support for inverted LEDS.  From Jeff.
      - LED Driver:  Add lightness correction for RGB LED driver.  From Jeff.
      - LTC4151 Driver:  Add driver for LTC4151 current and voltage monitor.
        From Giorgio Groß.
      - Serial TERMIOS:  tcdrain() implementation based on a new term ioctl.
        From Sebastien Lorquet.
      - Serial TERMIOS:  Add support for TCFLUSH.  From Sebastien Lorquet.
      - syslog:  Add option to use the CLOCK_MONOTONIC for time stamping. From
        Jussi Kivilinna.
      - HC-SR04 Driver:  Add support to HC-SR04 distance sensor.  From Alan
        Carvalho de Assis.
      - COMP Driver:  Add poll support.  From Pekka Ervasti.
      - BQ2429X Driver:  Add driver for TI BQ2429X battery charger.  From Juha
        Niskanen.
      - ADC Driver:  Add poll support.  From Juha Niskanen.
      - BCH Driver:  Add poll support.  From Jussi Kivilinna.
      - RTC Driver:  Extend the RTC framework with an alarm read ioctl
        (RTC_RD_ALARM).  Through it consumer could get configuration settings
        about previously scheduled hardware alarms (active status, hours,
        minutes, seconds).  From Boris Astardzhiev.

    * Simulation

      - sim/ipforward:  Add an IP forwarding configuration using TUN devices
        and apps/examples/tun.
      - Console:  Add non blocking read to devconsole driver.  From Simon
        Piriou.
      - Networking:  Poll for TX frames to speed up driver.  From Simon Piriou.
      - pf_ieee802154:  Add configuration for testing PF_IEEE802154 address
        family sockets.
      - ARM Simulator:  Adds necessary functionality to build Simulator under
        ARM Linux. Tested only on Raspberry3. Currently setjmp/longjmp do not
        save/restore floating point registers.  From Nickolay Semyonov.

    * MicroChip/Atmel SAML21 Drivers:

      - SAML21 I2C driver.  Developed for and contributed with permissin from
        Filament company.  From Alan Carvalho de Assis.
      - SAMD/L21 USB Driver:  Add a USB driver.  Developed for Filament Inc.
        by Offcode, LTD.  From Janne Rosberg.

    * MicroChip/Atmel SAMv7 Boards:

      - SAMV71-XULT:  Add support for the MRF24J40 radio and create a
        mrf24j40-starhub configuration.
      - SAME70-Xplained:  Add MRF24J40 support.

    * NXP Freescale Kinetis Drivers:

      - Kinetis USB Improvements:  usbdev clean up ensuring proper use of HW.
        Rework suspend and resume logic so they perform properly.  Made attach
        and detach functions optional. As they do not make sense for a bus
        powered device.  From David Sidrane.
      - Kinetis SPI driver:  From David Sidrane.
      - Kinetis:  I2C driver added I2C3, reference counting and reset.
        Refactored the driver to support reference counting and reset added
        I2C3. From David Sidrane.
      - Kinetis RTC:  Implementation of the alarm read function.

    * NXP Freescale Kinetis Boards:

      - configs/teensy-3.x USB:  Define USBOTG-FS Read from FLASH access in
        board config.  Allow the board config to define the USBOTG-FS to have
        Read access to FLASH.  From David Sidrane.
      - configs/teensy-3.x:  Removed call to khci_usbattach.  The call is not
        need by the driver if CONFIG_USBDEV_BUSPOWERED=y.  On a USB powered device if we are running we are attached.  From David Sidrane.
      - freedom-k66f:  Use SPI driver.  Initialize SPI1 on connector J6. No
        real use, as of yet.  From David Sidrane.

    * NXP Freescale LPC43xx:

      - LPC43xx:  Modify up_allocate_(k)heap() to support PROTECTED mode. From
        Alan Carvalho de Assis.

    * NXP Freescale LPC4xx Boards:

      - configs/Bambino:  Add protected mode configuration to Bambino board.
        From Alan Carvalho de Assis.

    * On Semiconductor LC823450

      - LC823450: Initial support for ON Semiconductor LC823450. From Masayuki
        Ishikawa.
      - LC823450: eMMC/SD and USB support for LC823450.  From Masayuki Ishikawa.

    * On Semiconductor LC823450 Boards

      - LC823450-XGEVK:  LC823450-XGEVK board support.  From Masayuki
        Ishikawa.
      - LC823450-XGEVK:  Add eMMC/SD and USB support.  From Masayuki Ishikawa.

      * STMicro STM32:

      - STM32 L4:  Add support for the STM32L475 family.
      - STM32 L4 RCC:  Enable ADC clock source.  From Juha Niskanen.
      - STM32:  Allow clock frequencies > 168 MHz on stm32f427/429.  We need
        to enable the power overdrive for this case.  This change allows the
        required bits to be set in proper sequence.  It also modifies the
        local register access operations to allow more than 16-bit registers.
        From Sebastien Lorquet .
      - STM32 F4:  Add support for STM32F433RC.  From Alan Carvalho de Assis.
      - STM32 F7:  Add new configuration option for enabling flash ART
        Accelerator and flash prefetcher.  From Jussi Kivilinna.

    * STMicro STM32 Drivers:

      - STM32 TIM:  Add the set counter function for stm32 timers.  From
        Sergey Ustinov.
      - STM32 HRTIM:  Update HRTIM definitions. Add HRTIM driver.  From
        Mateusz Szafoni.
      - STM32 HRTIM:  Add HRTIM character driver.  From Mateusz Szafoni.
      - STM32 HRTIM:  Fix DAC triggers configuration, Add missing master timer
        logic, enable DAC triggering.  From Mateusz Szafoni.
      - STM32 HRTIM:  Add DMA configuration. From Mateusz Szafoni.
      - STM32 HRTIM:  Add burst mode configuration.  From Mateusz Szafoni.
      - STM32 RTC:  Port Boris Astardzhiev's RTC change for STM32L4 to STM32.
      - STM32 DAC:  Add support for HRTIM triggering.  Separate dma buffer
        configuration for channels.  From Mateusz Szafoni.
      - STM32 DAC:  Conditional logic for timer triggering, fix TSEL
        configuration when HRTIM, DMA request remapping, Add DMA buffers
        initialization logic.  From Mateusz Szafoni.
      - STM32 DAC:  Support external triggering for DMA transfer.  From Mateusz
        Szafoni.
      - STM32 L1 TIM:  Add base address for TIM11.  From Juha Niskanen.
      - STM32 F4 FLASH:  Enable/disable the flash write protection on any
        sector.  I have verified it to work on the STM32 F427.  From Sebastien
        Lorquet.
      - STM32 F4 Clocking:  To use an external oscillator module (not just a
        crystal) with the STM32F4, one needs to enable the HSEBYP bit in the
        RCC_CR register. This change allows an integrator to define
        STM32_RCC_CR_HSEBYP in their board.h file if they want this
        configuration.  From Jeff.
      - STM32 F4 USB:  I'm working on bringing up USB full-speed support on
        STM32F405. My board does not include a USB power switch, VBus
        sensing, over current detection, or ID pin.  This commit add a
        config STM32_OTGFS_VBUS_ CONTROL which lets us selectively disable
        VBus sensing and control.  I also sneaked in a change to disable the
        configgpio call for the ID pin, which is only used in OTG mode which
        isn't supported yet.  The only pins that need to be initialized should
        be OTGFS_DP and OTGFS_DM.  From Jeff.
      - STM32 FLASH:  Add CONFIG_STM32_STM32F469 support. From David Sidrane.
      - STM32 COMP:  Add default INM configuration and some missing COMP
        1,3,5,7 code.  From Mateusz Szafoni.
      - STM32 F33:  Add missing SYSCFG CFGR3 definitions.  From Mateusz Szafoni.
      - STM32 L4 Serial: Allow configuring Rx DMA buffer size.  From Juha
        Niskanen.
      - STM32 L4 COMP:  Input minus pin extended selection.  From Juha Niskanen.
      - STM32 L4 COMP:  Bind to upper half comp driver.  From Pekka Ervasti.
      - STM32 L4 DAC:  Port from STM32.  Add ADC register definitions.  From
        Juha Niskanen.
      - STM32 L4 DAC:  Add option for routing DAC output to ADC.  Actually
        write something to the DAC DMA buffer.  From Juha Niskanen.
      - STM32 L4 DAC:  Separate DMA buffer configuration for channels. From
        Juha Niskanen.
      - STM32 L4 ADC:  Implement peripheral.  From Juha Niskanen.
      - STM32 F7:  Definitions for I2C4, SDMMC2.  Adapted RAM start / size to
        internal SRAM.  From Titus von Boxberg.
      - STM32 F7 I2C4:  I2C4_SDA can also be on GPIO PB7.  From Titus von
        Boxberg.
      - STM32 F7 LTDC:  Option for DSI output, inconsistency: the stm32f746
        does not feature a DSI interface.  compilable with LTDC_INTERFACE and
        LTDC_USE_DSI.  From Titus von Boxberg.
      - STM32 F7 Clocking:  Added functions for DSI clock source selection.
        From Titus von Boxberg.
      - STM32 F7 Clocking:  Enable APB2 DSI clock.  From Titus von Boxberg.
      - STM32 F7 LTDC:  No board specific dithering values used; corrected
        dithering init.  Corrected LIPOS/LIPCR calculation.  Change only
        polarity bits in LTDC_GCR.  From Titus von Boxberg.
      - STM32 F7 Reset:  Added function for reset.  From Titus von Boxberg.
      - STM32 F7 DMA:  DMA add dcache alignment check in stm32_dmacapable.  In
        the case dcache write-buffed mode is used (not write-through) buffer
        alignment is required for DMA transfers because  a)
        arch_invalidate_dcache could lose buffered writes data and b)
        arch_flush_dcache could corrupt adjacent memory if the maddr and the
        mend+1, the next next address are not on ARMV7M_DCACHE_LINESIZE
        boundaries.  From David Sidrane.
      - STM32 F7 SDMMC: SDMMC remove widebus limitation on DMA.  There is no
        documentation for the STM32F7 that limits DMA on 1 bit vrs 4 bit
        mode.  From David Sidrane.
      - STM32 F7 SDMMC: SDMMC add dcache alignment check in
        dma{recv|send}setup. In the case where CONFIG_SDIO_PREFLIGHT is not
        used.
      - STM32 F7 RTC: Port Boris Astardzhiev's RTC change for STM32L4 to
        STM32F7.

    * STMicro STM32 Boards:

      - STM32F103-Minimum:  Add GPIO device driver example.  From Alan
        Carvalho de Assis.
      - STM32F103-Minimum: Add small hello example for  STM32F103-Minimum
        board.  From Alan Carvalho de Assis.
      - STM32F103-Minimum: Add support for SmartFS on Winbond W25 SPI NOR
        Flash.  From Alan Carvalho de Assis.
      - STM32F103-Minimum: (1) Enable CONFIG_MTD_PARTITION in Kconfig if flash
        partition is enabled and (2) Update the README.txt file with info
        needed to get SmartFS working.  From Alan Carvalho de Assis.
      - Nucleo-F334R8:  Add HRTIM initialization.  From Mateusz Szafoni.
      - Nucleo-F334R8:  UART2 is default serial port (STLINK Virtual Port).
        From Mateusz Szafoni.
      - Clicker2-STM32:  Add a configuration that was used with the MRF24J60
        for 6loWPAN testing.
      - Clicker2-STM32:  Allow both IEEE 802.15.4 MAC character and network
        devices to be registered.
      - Clicker2-STM32:  Add configurations to support the endpoint and hub
        roles in a star topology.
      - Clicker2-STM32:  Add support for per-function-call stack checking.
        From Anthony Merlino.
      - Clicker2-STM32:  Configure EDBG SPI CS just to make that it is
        disabled.
      - STM32F4 Discovery: Add logic to register the button driver and the
        user led driver if so configured.  From Jan Pobrislo.
      - STM32F4-Discovery:  Add a configuration for testing libc++.  From Alan
        Carvalho de Assis.
      - B-L475E-IOT01A:  Add support for the STMicro B-L475E-IOT01A board.
        From Simon Piriou.
      - B-L475E-IOT01A: Add support for the SPSRGF/Spirit1 radio module.  Add
        a configuration for testing sprit radio.
      - B-L475E-IOT01A:  Add configurations to support a star topology.
      - B-L475E-IOT01A:  Add basic support for external Macronix QuadSPI flash
        memory.  From Simon Piriou.
      - B-L475E-IOT01A:  Enable UDP broadcast test in the spirit-starhub
        configuration.
      - STM32F334-DISCO:  Add STM32F334-DISCO basic support.  From Mateusz
        Szafoni.
      - STM32F746-Disco:  Add ADC3 support.  From Ivan Ucherdzhiev.
      - STM32L476-Disco:  Add a knsh configuration that may be used to test
        the PROTECTED build mode.
      - STM32F769I-DISCO:  Initial port to STM32F769I-DISCO.  From Titus von
        Boxberg.

    * C Library/Header Files:

      - Move TUN ioctl command to include/nuttx/net/ioctl.h so that it will
        always be unique.
      - Math Library:  Port gamma() and lgamma() from FreeBSD to NuttX.  From
        Alan Carvalho de Assis.
      - C++: Compilation with recent C++ compiler needs an overloaded delete
        operator that includes a size_t size argument.  New sized delete
        operators are only for C++14 and above.

    * Build/Configuration System:

      - Initial clang compile.  From Goran Mekic.
      - Add CLANG definitions in Kconfig and Toolchain.defs.
      - drivers/wireless/ieee802154:  Moved radios to individual
        sub-directories.  From Anthony Merlino.
      - Makefile.unix: Add savedefconfig target.  From Gwenhael Goavec-Merou.
      - Add Gwenhael's change to Makefile.win and update README.txt to
        described the new make target.
      - All defconfig files are now in the compressed format created with
        'make savedefconfig.'  The original .config file can be reconstituted
        using 'make olddefconfig.'
      - Build System:  It is no longer necessary to have a unique Make.defs
        file for each configuration.  A board may share a common Make.defs
        file in the scripts directory.  Duplicate Make.defs files removed;
        common Make.defs file moved to the scripts/ sub-directory for each
        board.
      - Networking: Move INET socket interface out of net/sockets to its own
        directory net/inet.

    * Tools:

      - testbuild.sh:  Added -x to fail build on errors for continuous
        integration (CI).  On CI we want to know ASAP of a failure.  From
        David Sidrane.
      - Improve configure.sh behavior:  (1) enable to call from top directory.
        (2) enable to designate direct path for config.  (3) install .gdbinit
        if the target has.  From Hidetaka Takano.
      - Update tools/configure.c to same functionality as configure.sh.  Add
        an array of optional file names.  Currently, .gdbinit is the only
        optional file but other things like IDE-specific project files might
        need to be copied as well.
      - tools/configure.sh will now copy Eclipse project files if they are
        present in the board directory file.
      - Update configure.sh, configure.bat, configure.c:  With compressed
        format, part of the installation requires that we run 'make
        olddefconfig' to restore the uncompressed defconfig format.  Also,
        while I was at it, I also added options to select host platform on
        configure command line.
      - tools/refresh.sh:  Now runs make savedefconfig before copying the new
        defconfig file in place;  Also, added a new option --defaults.  Since
        the number of defaults that you now have to answer is so large, the
        option lets you just accept the default values.  So it works just like
        --silent but still prompts you for the decision to save or discard the
        new defconfig file.
      - tools/refresh.sh:  Update so that it can find the Make.defs file in
        the new location.

    * NSH: apps/nshlib:

      - NSH Library:  Add a Telnetd command.  This is needed when network
        initialization is deferred.  In that case, telnet daemon cannot be
        started until the network is finally initialized.  The telnetd command
        was added just for that case:  So that the telnet daemon can be
        started from the NSH command line after the network is configured.
      - NSH Library:  Misc changes needed for PktRadio support.
      - NSH Library:  Extend ifconfig command so that it can set variable
        length packet radio address.
      - NSH Library:  Update addroute and delroute command.  The would support either
        IPv4 or IPv6, but not both.  Allow expression of the netmask in IPv4 CIDR or
        IPv6 slash notation.  This really reduces the pain of using the commands,
        especially for IPv6.
      - NSH Library: Add a route command that will dump the content of routing table.

    * Examples/Tests: apps/examples:

      - examples/udp: Add configurable network device name; Add option to
        suppress network initialization which is not needed if started by NSH
        or for 6LoWPAN.
      - examples/udp:  Fix registration as a built-in program; Change some
        naming to make room for a second target.  Current one endpoint is the
        target and one is the host.  This will (eventually) allow two targets
        to be both endpoints of the test.  Change build so that both server
        and client can be on a target, rather than one on the target one on
        the host PC.  Server IP address may not be provided on the command line.
      - examples/udp:  Port numbers need to be configurable to work with
        6LoWPAN.  Need to bind the client socket to a port number.  This was
        not required before so is a apparently a change in the UDP packet
        dispatch logic.
      - examples/udp:  Enable testing with the broadcast address.
      - examples/nettest:  Support target boards on both ends of the test.
        Separate out network initialization so that it may be used by both a
        target server and a target client.  Fix client/server naming
        confusion; Add command line option to select the server address on the
        target.  Add support for both endpoints on target boards vs. one on a
        target and one on the host PC.
      - examples/nettest:  The send buffer size is now a configuration option.
      - examples/nettest:  Loopback option should be available in Kconfig for
        PktRadio.
      - examples/keypadtest: REMOVED and warehoused in the Obsoleted
        repository.  This was just a bad clone of apps/examples/hidkbd for a
        keypad driver that was removed years ago.  It also uses illegal
        function calls into the OS.  So it has no purpose:  It is redundant, it
        uses illegal interfaces, and is a test for non-existent code.
      - examples/ipforward: Add an IP forwarding example using only TUN
        devices.  Test extended to test forwarding of ICMPv6 multicast messages.
      - Implement powermonitor example for ltc4151 current and voltage
        monitor.  From Giorgio Groß.
      - examples/pf_ieee802154:  Add for testing PF_IEEE802154 sockets.  Add
        PANID to command line options; Cannot bind to address zero... There is
        no counterpart to INADDR_ANY for these radios (not now at least).
      - examples/dac:  Add DAC example.  From Juha Niskanen.

    * Network Utilities: apps/netutils:

      - netutils/telnetc:  This a port of libtelnet to NuttX.
      - netutils/telnetd and users of telnetd:  Add support for IPv6.
      - netutils/thttpd:  Remove the netstats demo.  This depends on an
        illegal function call and cannot be supported.  That example could be
        replaced with logic that uses the procfs network entries as was done
        for NSH which had the same issue.  But I am too lazy to implement that.
      - netutils/netlib:  Add support for PktRadio IOCTL commands.
      - netutils/netlib:  Add a helper to decode short addresses.

    * Wireless Utilities: apps/wireless:

      - wireless/ieee802154/i8sak:  Rewrote i8sak to be test CLI for IEEE
        802.15.4 MAC layer.  From Anthony Merlino.
      - wireless/ieee802154/i8sak:  Updates to i8sak for
        association/beacon-enabled changes to IEEE 802.15.4.  From Anthony
        Merlino.
      - wireless/ieee802154/i8sak:  Add option to make it easy to send large
        frame for testing purposes.  From Anthony Merlino.
      - wireless/ieee802154/i8sak:  Add scan command.  From Anthony Merlino.
      - wireless/ieee802154/i8sak:  Add coordinfo command allowing you to
        poll various attributes related to the coordinator.  From Anthony
        Merlino.
      - wireless/ieee802154/i8sak:  Add a option to retry on failures to the
        assoc command (usually meaning tht the coordinator is not yet up).
      - iwireless/ieee802154/8sak:  Add reset command to reset the MAC layer.
        Adds option to assoc command -t to specify how long to wait for a
        response from the Coordinator.  From Anthony Merlino.
      - ieee802154/i8sak:  Adds command to trigger regdump of radio.  From
        Anthony Merlino.

    * System Utilities (apps/system)

      - apps/system/composite: Update to apps/system/composite associated with
        big changes to the composite device logic.  From Frank Benkert.
      - apps/system/composite:  Remove CDC/ACM and MSC configuration logic.
        This belongs in the OS composite initialization.  Add and argument so
        that you can select the USB composite configuration to be attached.
        Restore USB tracing; remove unused field in a structure.  Remove
        configuration settings that are no longer used.  Fix configuration
        selecting.. was setting the port number, not the configure ID.  Also
        add a configuration option to select the default configuration.
      - apps/system/composite: Add a configuration option to the boardctl()
        calls to support multiple composite device configurations dynamically.
      - apps/system/composite:  Remove references to USBMSC.  There still
        dependencies on CDC/ACM in the serial USB trace output.
      - apps/system/telnet:  Add Telnet Chat daemon and client from
        libtelent.

    * Platform-Specific Support (apps/platform)

Bugfixes.  Only the most critical bugfixes are listed here (see the
ChangeLog for the complete list of bugfixes and for additional, more
detailed bugfix information):

    * Core OS:

      - Fix ELF loader up_checkarch on ARM arch.  From Cristian Condurache.
      - pthread_mutex_unlock():  Missing check for the case where
        pthread_mutex_lock() is called when the mutex is not locked.  In that
        case, it would increment the underlying semaphore above 1.  This is
        the fix for a problem noted by initialkjc@yahoo.com.
      - sig_timedwait():  Pending signal structure used after it has been
        releasd.  From anonymous Bitbucket Issue 59.
      - mm_mallinfo:  do heap end debug assert check with heap semaphore held.
        From Jussi Kivilinna.
      - sched/:  Fix return value in sched_setaffinity().  From Masayuki
        Ishikawa.
      - Work Queues:  work_queue() must cancel existing work prior to queuing
        new work, otherwise the work queue list structure can become
        corrupted. Problem noted by Pascal Speck.
      - waitpid():  Corrects two problems when CONFIG_SCHED_HAVE_PARENT +
        CONFIG_SCHED_CHILD_STATUS are enabled:  (1) Was erroring out if the
        waited for task had already exited, and (2) was not freeing resources
        when a wait was completed.  From Boris Astardzhiev.

    * File System/Block and MTD Drivers:

      - VFS poll():  Fix timeout calculation.  From Jim Paris.
      - VFS poll():  Fix poll for regular files and block devices.  Open Group
        documentation says that poll (and select) support regular files and
        that 'Regular files shall always poll TRUE for reading and writing'.
        From Jussi Kivilinna.
      - VFS epoll():  Fix epoll_wait function.  From Simon Piriou.
      - Smart FS:  Fix wrong freeing of device structure and use-after-free
        issues on error paths.  From Jussi Kivilinna.
      - MTD FLASH drivers:  The byte write method of several drivers had a
        cloned error:  It was not locking the bus while performing byte write
        operations.
      - MTD M2PX: If we READ while a write/erase is pending, the command is
        ignored and the write/erase continues. If we don't catch this situation
        we will return garbage to the user because the flash will not execute
        the command.  So READ MUST wait for write completion, and before that,
        the bus must be locked since it's a precondition to calling
        waitwritecomplete().  From Sebastien Lorquet.
      - MTD FLASH drivers: Clone Sebastien Lorquet's m25px change to at25,
        is25xp, ramtron, and sst25xx.
      - MTD W25:  Add missing locking and fix SPI_SELECT usage for
        w25_unprotect.  From Jussi Kivilinna.
      - MTD W25:  Wait for BUSY flag to clear in w25_readid and
        w25_unprotect.  W25Q128 datasheet says that all instructions expect
        'Read Status Register' and 'Erase/Program Suspend' are ignored when
        BUSY flag in status register is '1'. Therefore wait for busy flag to
        clear in w25_readid() and w25_unprotect().  From Jussi Kivilinna.
      - Automounter: FS_AUTOMOUNTER should depend on SCHED_LPWORK.  From
        Nickolay Semyonov.

    * Networking/Network Drivers:

      - TCP Listen: Throw error when error happens in the tcp_listen
        function.  From Roland Takacs.
      - Network Device Management:  Do not search net device when all-zeros
        address is used.  From Roland Takacs.
      - Network Device Management:  Fix a error in netdev_register(); it was
        not handling device names properly when TUN is the only network device.
      - Network Device Management:  Fix netdev_dev_lladdrsize().  In some
        configurations, it could return the wrong size for the address of a
        packet radio.
      - Network Device Management:  Fix typo for 802.11 devices in
        netdev_register().  Was being masked before because depended on
        CONFIG_NET_MULTLINK.
      - TUN Driver:  Use critical section instead of semaphore in
        tun_ifdown().  From Masayuki Ishikawa.
      - TUN Driver:  Do all polling on worker thread.  Otherwise, the stack
        gets very deep.
      - TUN Driver:  Currently cannot support TAP mode unless Ethenet is
        enabled.
      - netdb:  Fixed buffer size used for sending DNS queries should depend
        on the configured DNS name size.  From Ritjaina.
      - UDP networking:  The TTL (time to live) was not being set in the IPv4
        or IPv6 header unless the UDP socket was bound.
      - UDP Networking:  Fix a copy-paste error that could effect networking
        when both IPv4 and IPv6 are enabled.
      - UDP Networking:  When upd_input() cannot process a packet, it returns
        ERROR so that network drivers may try calling ipv4_input() later.  In
        this case, it must also set d_len to zero.  Otherwise, all network
        drivers will assume tht there is also an outgoing packet.  This
        results in a gratuitous ARP.
      - TCP Networking:  Correct some issues that prevent TCP from working
        correctly when both IPv4 and IPv6 are enabled.
      - TCP Networking:  TCP disconnection callbacks are not retained in a
        list.  This will support multiple callbacks per lower-level TCP
        connection structure.  That is necessary for the cae where a socket is
        dup'ed and shares the same lower-level connection structure.  NOTE:
        There still needs to be a call to tcp_start_monitor() when the socket
        is dup'ed.
      - TCP Networking:  Start the network monitor for a socket when a TCP
        socket is dup'ed.
      - TCP Networking:  If one of the dup'ed socket's is closed, then network
        monitor resources associated with that one socket must be recovered.
        Also, in the event that socket is being used on one thread, but then
        closed on another, any threads waiting for events from the socket
        should be informed of the closure.  That latter requirement is not
        implemented because current data structures do not support it.
      - TCP Networking:   Fix a race condition.  The accept() operation is
        performed with the network locked.  However, the network is unlocked
        BEFORE the connected state is set.  Therefore, a context switch may
        occur and the socket may no longer be connected when it is marked so.
        Noted by Pascal Speck.
      - Network routing tables:  Fix a compilation error when IPv6 and
        routing are enabled.
      - Network procfs:  Fix some spacing when both IPv6 and IPv4 are enabled.
      - Network Local Sockets:  Fix accept for local stream sockets.  From
        Jussi Kivilinna.
      - Network Local Sockets:  Fix server lc_waitsem overflow.  From Jussi
        Kivilinna.
      - IPv6 Networking:  Remove comparisons to the address with all ones
        set.  IPv6 does not support broadcast addresses and certainly not in
        that form.  Replace with multicast addresses beginning with 0xff02.
      - ICMPv6 Networking:  Fix a compilation issue with
        CONFIG_NET_ICMPv6_AUTOCONF=y.  From  Masayuki Ishikawa.
      - Networking:  Fix net_lock returning ERROR when instead of real error
        code on failure.  From Jussi Kivilinna.
      - IGMPv2 Networking:  Remove special support for interrupt level
        processing (there is none) and fix some timer cancellation logic.  In
        many files, correct comments.  There is no interrupt level processing
        in the networking layer.

    * Wireless/Wireless Drivers:

      - IEEE 802.15.4 MAC:  Need counting protection on the logic that
        releases the notification resources.  Otherwise, notification handlers
        may be operating with a stale pointer.
      - IEEE 802.15.4 MAC: Improves internal timer logic to handle work
        serially.  Before, the MAC timer used a watchdog to schedule work with
        the high priority worker queue.  However, since everything in the MAC
        is supposed to be serialized through the use of the high priority work
        queue, but the timer uses a watchdog, there are some unintended
        consequences. To simplify, we now use the delayed work feature of the
        work queue.  From Anthony Merlino.
      - IEEE 802.15.4 Network Driver: Update RX statistics in network driver.
      - IEEE 802.15.4 MRF24J40 Driver:  Minor timing fix. Matches recommended
        value in datasheet.  Splits up driver into multiple files to make it
        easier to navigate.  Fixes issue with non-beacon enabled mode.  From
        Anthony Merlino.
      - IEEE 802.15.4 MRF24J40 Driver:  Fix a bug causing radio to cease
        transmitting.  From Anthony Merlino.
      - IEEE 802.15.4 MRF24J40 Driver:  Fixes issues with sleeping for beacon
        enabled networking.  From Anthony Merlino.
      - EEE 802.15.4 MRF24J40 Driver:  Fix math error for calculating sleep
        count values.  From Anthony Merlino.
      - IEEE 802.15.4: Fix timing issues for beacon enabled coordinators and
        endpoints. From Anthony Merlino.
      - iIEEE 802.15.4: Fix issue with association on beacon-enabled
        networking.  From Anthony Merlino.
      - 6LoWPAN:  Correct a few addressing issues.  Also reserve two bytes at
        the end of the frame for the FCS.
      - 6LoWPAN:  Fixes needed when extended addressing is enabled; broke short
        addressing.  Loopback driver needs to initialize the MAC meta data;
        Address decompression logic must have the MAC address to handle the
        most common compression cases.  Fix a src/dest address confusion and
        other addressing problems.
      - 6LoWPAN:  Add missing IPv6 address creation to HC1 decode logic. Fix a
        typo in an index that prevented use with HC1 and extended addresses.
      - 6LoWPAN:  TCP logic was not obeying MTU packet size limitations.
      - 6LoWPAN:  Major re-architecting of TCP logic to properly handle TCP
        stuff like ACKs and TDP windowing which were not properly covered in
        the initial design.
      - 6LoWPAN:  HC06, copy TCP header as though it were data.  TCP packet
        reassembly now seems to work OK.
      - 6LoWPAN:  Fix duplicate and bad memcpy in loopback driver.
      - 6LoWPAN:  Fix a misconception about HC06 16-bit IPv6 address
        compression.
      - 6LoWPAN:  TCP send logic was returning a failure in one case when, in
        fact, the send was successful.

    * Common Drivers:

      - USB MSC:  Use struct instead of pointer to the struct as sizeof
        argument in memset in usbmsc.c.  Otherwise it leads to error: argument
        to sizeof in memset call is the same pointer type struct usbmsc_lun_s
        * as the destination.  From Oleg Evseev.
      - USB MSC:  Add missing logic to define endpoints.  The composite
        changes broke the the non-composite, USB MSC only case because it omitted the critical setup when USB MSC was not part of the composite.
      - USB CDC/ACM.  Fix several known problems resulting from merge of USB
        composite device.  That merge now breaks some of the non-composite USB
        devices.
      - Button Driver:  Interrupts weren't enabled since nothing updates them
        after btn_poll() marks the file descriptor structure as being polling.
        From Jan Pobrislo.
      - ADC Driver:  Fix some data alignment issues in the ADC driver.
      - I2C Drivers:  Handle I2C_TRANSFER return value consistently.  Some I2C
        peripherals transfers return zero on success, others number of
        completed transfers.  Make drivers robust against this.  From Juha
        Niskanen.
      - COMP Driver:  Fix compilation errors when poll disabled.  From Mateusz
        Szafoni.

    * Simulation:

      - Simulation:  Fix mkdir issue in GNU target.  From Simon Piriou.
      - Simulation:  x86 stack needs to be aligned to 16-byte boundaries.
      - Simulation:  Fix building 32-bit simulation on 32-bit X86.  From Jussi
        Kivilinna.

    * ARM:

      - ARM: The older ARM7 and ARM9 configurations were determining CFLAGS
        based on the GCC version 4.x.x or not.  That needx to be extended for
        5.x.x and 6.x.x which also behave like 4.x.x.

    * ARMv7-M:

      - Fixed ARMv7-M Toolchain setting.  Cortex-M4 only have Single
        Precision FPU.  From Hidetaka Takano.
      - ARMv7-M syscall logic:  Clear bit 0 in PC settings.  Bit 0 is the
        thumb mode indication and should not be set in the PC.  This extra bit
        has not caused problems in the past, but seeing it set in the PC is
        unnerving.

    * Espressif ESP32:

      - Fix ESP32 gpio enable reg and default UART pin. Modify default UART
        pin for ESP-WROOM-32. Fix gpio enable reg.  From Sungki Kim.

    * Microchip/Atmel SAMD21 Drivers:

      - SAMD21:  Fix some SPI-related issues.  From Matt Thompson.
      - SAMD21 SPI: I was having issues with the bus freezing up .. slaves
        holding SDL low.. so I rewrote a good portion of the interrupt logic
        based on the application notes from Atmel.  One major improvement is
        using the RXNACK flag in the STATUS register, which indicates that no
        device responded to an address packet. Assuming that the chip will
        always give an interrupt status, I believe it's possible to eliminate
        the timer as well.  From Matt Thompson.
      - SAMD/L21:  Need to preserve errno value across syslog() call.
      - SAMD21:  Changes needed to get USB working.  From Matt Thompson.

    * Microchip/Atmel SAMv7 Drivers:

      - SAMv7 TWIHS:  TWIHS driver add reference counting. From David Sidrane.
      - SAMv7 CAN:  We discovered a problem with the samv7 mcan driver which
        results, under some circumstances, in a very high CPU load.  The
        problem occurs, and is easily reproducible, if the device is connected
        to a CAN network with a wrongly configured CAN speed (baud rate). In
        our tests we set the CAN speed of the device to 1000000 and the speed
        of the other CAN nodes to 500000. The device is restarted and sends a
        CANopen "bootup message" to the CAN network. This results in huge
        amount of errors messages on the CAN bus, probably because of the CAN
        feature for acknowledging error messages. The error messages can't be
        read by the device because of the misconfigured CAN speed, instead the
        CAN chip reports lots of errors, which are reported to the application
        which uses the CAN driver (CONFIG_CAN_ERRORS is enabled).  The CAN
        errors are reported from the CAN chip via interrupts and thus the
        interrupt load is very high in this scenario. To fix the problem the
        driver now disables each RX error interrupt after it is occurred.  The
        RX error interrupts are turned back on if at least one CAN message is
        received successfully.  From Stefan Kolb.
      - SAMv7 CAN:  I discovered while working on the SAMV7 mcan driver that
        the implementation of the CAN error handling is suboptimal. In the
        current implementation the many errors are implemented as pending
        errors.  But those errors are not pending, the errors occurred and are
        gone directly afterwards. This commit changes the described behavior
        and simplifies the handling of CAN errors.  From Stefan Kolb.

    * Microchip/Atmel SAMv7 Boards:

      - SAMv71-XULT:  Fix MRF24J40 interrupt GPIO number.

    * NXP/Freescale Kinetis:

      - Kinetis MPU:  Disable MPU when not in protected mode.  The hardware
        reset state of the the MPU precludes any bus masters other than DMA
        access to memory. Unfortunately USB and SDHC have their own DMA and
        will not have access to memory in the default reset state.  This change
        disabled the MPU if present on system startup.  From David Sidrane.
      - Kinetis MPU:  Fixed warning for kinetis_mpudisable. Missing header
        file added.  From David Sidrane.
      - Kinetis SIM:  Ensure isolation of clock dividers for 0 value case.
        This fixes a bug were a SoC does not have a clockdivN register and
        passes a 0 for the init value.  This prevents overflow of the 0
        decremented to -1 (0xffffffff) spilling over to other clockdivN
        fields.  From David Sidrane.

    * NXP/Freescale i.MX6 Drivers:

      - i.MX6: Fix a wrong parameter passed when calling irq_attach() in
        imx_serial.c.  From Masayuki Ishikawa.
      - Based on Masayuki's change, I review all serial driver vector
        attachment.  I Found one additional error and updated all relevant
        drivers to current interrupt parameter passing.

    * STMicro STM32:

      - STM32 F410 Kconfig:  Fix peripherals available on the STM32 F410.
        This also adds a select for STM32_HAVE_DAC1 present on this STM32
        flavor.  From Gwenhael Goavec-Merou.
      - STM32 L4 DMA: Correct USART3_RX bad channel definition.  From Juha
        Niskanen.
      - STM32 L4 PWR:  Correct PWR_SR2 REGLPS and REGLPF bits, add port I
        registers.  Also remove duplicate section from Kconfig.  From Juha
        Niskanen.
      - STM32 F7: do not enable read-modify-write on DTCM.  "AN 4667 - STM32F7
        Series system architecture and performance" recommends to disable
        read-modify-write on DTCM: "If the DTCM-RAM is used as data location
        and the variables used are byte or/and halfword types, since there is
        no ECC management in this RAM on the STM32F7 Series, it is recommended
        to disable the read-modify-write of the DTCM-RAM in the DTCM interface
        (in the DTCMCR register) to increase the performance." From Jussi
        Kivilinna.

    * STMicro STM32 Drivers:

      - STM32 TIM3/4 are always 16-bits; never 32-bits.  Noted by Eetu
        Nevalainen..
      - STM32 ADC:  Invalidate dma buffer before use.  Missing invalidation
        caused old samples being fetched from cache.  From Jussi Kivilinna.
      - STM32, STM32L4, STM32F7 ADC:  Fix channel 18 sample time.  From Juha
        Niskanen.
      - STM32 DAC:  Fix some configuration logic. When STM32_NDAC is greater
        than 1, then second channel is always DAC1OUT2.  From Mateusz Szafoni.
      - STM32 DAC:  Fix compilation when DMA disabled for channel.  From
        Mateusz Szafoni.
      - STM32 F0:  Fix some funny shifts in DAC header files.  From Juha
        Niskanen.
      - STM32 F1 RTC fixes:  (1) Compile issues because of missing RTC_MAGIC
        #defines, (2) missing functionality based on RTC_MAGIC in RTC based on
        stm32_rtcounter.c, (3) IRQ setup from up_rtc_initialize was later
        reset in up_irqinitialize, (4) write access to backup registers
        without enabling access to backup domain, (5) possible races in
        set/cancel alarm.  tested with STM32F103C8 only.  device now wakes up
        from forced STANDBY mode by alarm.  From Leif Jakob.
      - STM32/STM32 L4 PWM:  While attempting to output a 70 MHz square wave
        from the timer output of a STM32 clocked at 140 MHz, found that the
        reload calculation was off by one.  This correction does allow the
        output up to 70 MHz.  I am not sure this affects most users
        generating slow PWM but for frequencies close to the PCLK, the
        difference becomes significant.  From JM.
      - STM32 L4 I2C: Set I2C SDA and SCL pins to open drain mode.  From Pekka
        Ervasti.
      - STM32 L4 I2C: I2C4 was writing to wrong RCC registers.  From Juha
        Niskanen.
      - STM32 L4 DAC:  Report transfer as completed in DMA callback.  Without
        this even O_NONBLOCK writes block the calling task if DAC was using
        DMA.  From Juha Niskanen.
      - STM32 L4 COMP: comparators share RCC enable bit with SYSCFG.  From
        Juha Niskanen.
      - STM32 L4 ADC:  Correct EXTSEL macros.  From Juha Niskanen.
      - STM32 L4 TIM: TIM15,16,17 are always in APB2.  From Juha Niskanen.
      - STM32 F7 I2C: Set I2C4 SDA and SCL pins to open drain mode.  From Juha
        Niskanen.
      - STM32 F4 RTCC: ISR register and write protection fix.  From Eetu
        Nevalainen.
      - STM32 F7 Ethernet:  Fix typo in header; Add memory sync barrier
        between writing to DMA TX descriptor and restarting DMA TX. Avoid
        calling work_queue on pollwork if it's already queued, just skip a
        poll cycle instead.  Nucleo-144: Fix RMII TXD1 signal, connected to
        PB13 not to PG14.  From savinz.
      - STM32 F7:  Added missing config option for register value debugging.
        From Titus von Boxberg.
      - STM32 F7:  No FSMC, only FMC for STM32F7.  From Titus von Boxberg.
      - STM32 F7:  HEAP2 depends on CONFIG_ARCH_HAVE_HEAP2, not on particular
        FMC RAM type.  From Titus von Boxberg.
      - STM32 F7:  STM32_RCC_DCKCFGR2 has nothing to do with PLLI2S; PLLI2S is
        not dependent on LTDC, instead on SAICLK1/2 generated from PLLI2S.
        From Titus von Boxberg.
      - STM32F7: Some STM32F7 builds failed in build testing due to undefined
        STM32_SRAM1_BASE.  I think that is because stm32_allocateheap.c was
        not including chip/stm32_memorymap.h.
      - STM32 F7: dcache write-buffed mode is used (not write-through) buffer
        alignment is required for DMA transfers because a)
        arch_invalidate_dcache could lose buffered writes data and b)
        arch_flush_dcache could corrupt adjacent memory if the buffer and the
        bufflen, are not on ARMV7M_DCACHE_LINESIZE boundaries.  From David
        Sidrane.

    * STMicro STM32 Boards:

      - STM32F103-Minumum SPI: SPIDEV_WIRELESS used when this has
        changed to SPIDEV_CONTACTLESS. From Nicolas Estibals.
      - configs/:  a few more places where SPIDEV_WIRELELSS should be
        SPIDEV_CONTACTLESS.
      - STM32F103-Minumum:  Fix a BUG when reading from output pin.  We need
        a different read_ops to read from output pin. This patch fixes the
        issue.  From Alan Carvalho de Assis.
      - STM32F103-Minumum: Use separated read_ops for GPIO interrupt pins.
        From Alan Carvalho de Assis.
      - STM32F103-Minumum: Fix compiler error in MCP2415 logic.
      - STM32F746G-DISCO:  Fix for compilation of STM32F746G-DISCO.  From Ivan
        Ucherdzhiev.
      - STM32F746G-DISCO:  Fix for stm32f746g-disco board for button support
        with interrupt.  This change is tested with buttons app example and it
        is working with interrupts (signals). I tried the test with polling
        but at this point it doesn't work.  From Ivan Ucherdzhiev.

    * Build System

      - Fix -Werror=implicit-fallthrough on gcc7.  From Julien Lecoeur.
      - configs/Board.mk:  Remove comment form end of line. In windows native
        build, it appears to be trying to make that an extra parameter to the
        AR command.  From Jeff.
      - configs/Board.mk:  Remove quotes from CONFIG_ARCH_FAMILY.  Causes
        problems with Windows native build.  From Jeff.
      - Makefile.win would only create uboot images for ARM.  MIPS support
        also needed.  From Lwazi Dube.

    * C Library/Header Files:

      - C++:  Fix C++ __guard implementation for ARM.  The standard C++ ABI
        that most platforms follow defines __guard to be 64 bits.  The existing
        implementation of libxx_cxa_guard.cxx follows this.  However, the
        32-bit ARM C++ ABI defines it as 32 bits instead, and changes the
        meaning slightly so only the lowest bit is used. This matters because
        GCC creates guard symbols without regards to what libxx_cxa_guard.cxx
        says.  So on ARM, gcc allocates 4 bytes, but __cxa_guard_release
        writes 8 bytes, zeroing out another unlucky variable nearby. Fix it
        by special-casing 32-bit ARM in libxx_cxa_guard.  From Jim Paris.
      - C++:  In cwchar it uses CONFIG_LIBC_WCHAR to only export the wc/mb
        functions.  When a build does not want to use wide or multibyte char
        CONFIG_LIBC_WCHAR is not set. Therefore we should to only export the
        wc/mb functions when defined.  Regardless of the stat of
        CONFIG_LIBC_WCHAR the non mb/wc  definitions such as mbstate_t,
        wint_t, wctype_t need to be exported.  From David Sidrane.
      - C Library:  Fix an error in mkstemp() the could result in an infinite
        loop.  From Alan Carvalho de Assis.
      - C Library:  (1) Fix an error in mkstemp() the could result in an
        infinite loop.  (2)  Fix for wrong output in some cases.  For Example:
        (a) input: "FILEXX", output: "FILE00" and repeats same output for
        further invocations of mkstemp(). But, the output has to be FILE01,
        FILE02, ...., FILEZZ. (b) input: "FILEXXXXXX", output: "FILE100000",
        for next invocation "FILE200000" and so on.  But it's good, if the
        output goes like FILE000001, FILE000002, ..., FILE000101, ...  From
        Lokesh B V.
      - C Library:  gethostbyname_r: Fix check for space in buffer.
      - C Library:  inet_ntop() was printing negative values for fields >127.
      - Math Library:  Fix wrong output in modf() API.  The sign of integral
        part given by the modf() should be same as sign of input.  But for
        inputs between 0 and 1, the sign of integral part was not same as
        sign of input.  From Lokesh B V.
      - Math Library:  Fix wrong output in ceil() API.  Ex:for input x = 1.0,
        the output should be 1.0, but the output was 2.0.  From Lokesh B V.

    * Tools

      - tools/testbuild.sh: Fix missing $ before variable name.
      - tools/mkdeps.c:  Eliminate a warning. MAX_PATH may already be defined
        in included system files.  From Jeff.

    * Applications: apps/

      - All apps/ Makefiles:  Add .PRECIOUS: apps/libapps.a to every
        Makefile.  Hopefully this will end awkward problems when you Control-C
        out of a build and libapps.a is deleted.
      - platform/Makefile: More attempts to fix for Windows native build.
        Backslash as a delimiter causes problems in pattern subsitutions.

    * NSH: apps/nshlib:

      - NSH network initialization: Fix some ieee 802.15.4 initialization
        logic.  It should not set the saddr or panid; those cannot be
        hard-coded but must come from the coordinator.  Re-factor a function
        that has gotten too big and too complex.  Do not set the IP address
        for 6loWPAN.  The 6loWPAN stack uses IP address that derive from the
        ieee 802.15.4 addressing and cannot be (safely) configured by the user.
      - NSH Library: Fix copy-paste typo in nsh_usbconsole.c.  From Oleg
        Evseev.
      - NSH Library: fix size of 6LoWPAN extended address.
      - NSH Library: Fix build break in nsh_command.c with IPv4/IPv6 dual
        stack.  From Masayuki Ishikawa.
      - NSH Library: Correct parsing of ifconfig so that you can specify the
        HW address without specifying the IP address.

    * Examples/Tests: apps/examples:

      - examples/smart: Fix some compilation errors.  Obviously this test has
        not been used in a LONG time.
      - examples/udp:  Renaming some files to prevent name collision in
        libapps.a.  Fix naming of a configuration setting.
      - examples/nettest:  Renaming some files to prevent name collision in
        libapps.a
      - examples/nximage:  Remove unused global variable.
      - examples/nsh:  Remove APPNAME, PRIORITY, and STACKSIZE settings from
        Makefile to avoid showing nsh in Builtin Apps.  From Masayuki Ishikawa.

    * Network Utilities: apps/netutils:

      - netutils/tftpc:  Missing header file causes errors in some
        configurations.
      - netutils/tftpc:  TFTPC depends on CONFIG_NET_IPv4.
      - netutils/netlib:  Fixes to work when only USRSOCK is enabled.
      - netutils/netlib: Fix netlib_nodaddrconv() so that its return type is
        the same as other address conversion functions.
      - netutils/netlib: If only PF_IEEE802154 socket family is enabled, then
        must use SOCK_DGRAM.
      - netutils/ftpc:  Fix some memory leaks.  From Boris Astardzhiev.
      - netutils/thttpd: Fix a malformed if condition detected by GCC 6.x.x.
      - netutils/dhcpd: Prevent buffer overflow in dhcpd_addoption.  offset
        represents distance from start of option buffer.  So this should be
        changed current option pointer minus start of buffer.  From EunBong
        Song.

    * Wireless Utilities: apps/wireless:

      - wireless/ieee802154/i8sak:  Need to increment the next_saddr after
        each successful association.

    * System Utilities (apps/system)

      - correct copy-paste typo in comments in composite_main.c  From Oleg
        Evseev.
      - system/dhcpc:  The DHCPC renew command did not build correctly due to
        naming problems.  Noted by Masayuki Ishikawa.
      - system/dhcpc: Fix warning about renew_main.o appear twice in rule.

    * Tools (apps/tools):

      - tools/mkkconfig.bat: Use %cd% instead of %~dp0 for usage of APPSDIR
        in this batch file.
      - tools/mkkconfig.bat:  Remove quotes in echo.  These were begin
        Echo'ed and generating double quots in the output.  From Jeff.
      - Windows build fixes:  tools/mkkconfig.bat - switch APPSDIR path to
        use forward slashes for kconfig-frontends. interpreters/ficl -
        Reorder some targets that causes GNUwin32 make to behave badly.  From
        Jeff.

NuttX-7.23 Release Notes
------------------------

The 123rd release of NuttX, Version 7.23, was made on December 4, 2017,
and is available for download from the Bitbucket.org website.  Note
that release consists of two tarballs:  nuttx-7.23.tar.gz and
apps-7.23.tar.gz.  These are available from:

    https://bitbucket.org/nuttx/nuttx/downloads
    https://bitbucket.org/nuttx/apps/downloads

Both may be needed (see the top-level nuttx/README.txt file for build
information).

Additional new features and extended functionality:

    * Core OS:

      - sem_open() should return SEM_FAILED on any failures.  This is change
        in the POSIX specification since the original sem_open() was written
        so many years ago.
      - exec():  The non-standard interface exec() is now enshrined as a
        official NuttX API.  I really dislike doing this but I think that
        this is probably the only want to load programs in the protected
        mode.  It is currently used by some example code under apps/ that
        generate their own symbol tables for linking.  Other file execution
        APIs relay on a symbol table provided by the OS.  In the protected
        mode, the OS cannot provide any meaning symbol table for execution
        of code in the user-space blob so that is they exec() is really
        needed in that build case.  And, finally, the interface is
        completely useless and will not be supported in the KERNEL build
        mode where the contrary is true:  An application process cannot
        provide any meaning symbolic information for use in linking a
        different process.
      - OS Internal Functions:  Rename many OS internal functions so it is
        clear that they are not part of the application interface.  All
        internal functions with the sem_* prefix became nxsem_*, sig* become
        nxsig_*, mq_* become nxmq_*, etc.
      - Cancellation Points:  Add new cancellation point interface,
        check_cancellation_point().
      - Signals:  Add logic to wake up a thread that is waiting on a signal
        if it is canceled.
      - sigtimedwait():  Add logic to suppress the wait if there is a
        pending cancellation.
      - clock_nanosleep():  Implement clock_nanosleep().  nanosleep() is now
        reduced to a libc wrapper around clock_nanosleep().
      - task_delete():  Do not permit user applications to delete kernel
        threads.
      - kthread_create():  Rename kernel_thread() to kthread_create() for
        better naming consistency with task_create() and kthread_delete().
      - boardctl():  Remove the BOARDIOC_GRAPHICS_SETUP command.
      - TCB:  Move POSIX thread specific data from pthread TCB to common TCB
        structure.  This change allows using pthread_getspecific and
        pthread_setspecific from main thread. Patch also enables using
        pthread data with config option CONFIG_DISABLE_PTHREAD=y. From Jussi
        Kivilinna.
      - mm:  Remove the CONFIG_GRAN_SINGLE configuration option.  It adds no
        technical benefit (other than some minor reduction in the number of
        interface arguments) but adds a lot of code complexity.  Better
        without it.
      - mm:  Add a function to get information about the state of the
        granule allocator.  This is the moral equivalent of mallinfo().

    * File Systems/Block and MTD Drivers

      - MT25Q Serial FLASH:  Add support for Micron MT25Q series MT25Q128.
        From Sebastien Lorquet.
      - MX35LFxGE4AB:  Add an MTD driver for Macronix MX35LFxGE4AB serial
        NAND flash.  From Ekaterina Kovylova.
      - FileMTD:  Add block device MTD interface.  Block MTD interface
        allows using block device directly as MTD instead of having to use
        file-system in between.  NOTE that this provides the opposite
        capability of FTL which will let you use an MTD interface directly
        as a block device.  From Jussi Kivilinna.
      - BCH:  The character driver to block device access now supports an
        IOCTL to get the geometry of the underlying block device.
      - mkfatfs:  Remove mkfatfs from the OS.  This is a user-space
        application and belongs in apps, not in the OS.
      - procfs:  Implements procfs /proc/fs/blocks and /proc/fs/usage files,
        replacing the NSH df command.  Also implements procfs /proc/fs/mount
        file, replacing the NSH mount command when there are no arguments.
      - procfs:  Add /proc/meminfo.  This is an alternative way to get the
        information that was previoulsy available in apps/system/free.
        apps/system/free was removed because it made illegal calls into the
        OS violating the portable interface.  This new procfs entry provides
        the same information with no such violation.  it also provides
        information about the kernel heap (formerly /proc/kmm), about the
        use of program memory(formerly /proc/progmem).  And also information
        for the page table usage in the KERNEL build.
      - UserFS:  Adds the UserFS client and of the UserFS feature in
        general.  Initially used Unix domain local sockets instead of
        message queues.  Easier to transfer big data in local sockets than
        message queues.  However, that lead to certain inescapable deadlock
        conditions So the IPC was converted to UDP LocalHost loopback
        sockets.  The problem with the local sockets is that they do require
        operations on the top level pseudo-file system inode tree.  That
        tree must be locked during certain traversals such as enumerate
        mountpoints or enumerating directory entries.  This conversion is
        unfortunate in the sense that Unix local domain sockets are
        relatively lightweight.  LocalHost UDP sockets are much heavier
        weight since they rely on the full UDP stack.

    * Graphics/Display Drivers:

      - Framebuffer character driver:  Add framebuffer character device driver.
      - LCD Framebuffer:  Add support for a generic front-end that will
        convert any LCD driver into a framebuffer driver.
      - Framebuffer character driver:  Include support for LCD drivers that
        use a simulated framebuffer and must receive explicit notification
        when there is an update to a region in the framebuffer.
      - LCD:  Make LCD driver configuration independently selected from NX
        graphics configuration.  This makes things awkward and loses some
        error checking but is a necessary step in order to make LCD drivers
        usable when the NX graphics system is disabled.

    * Networking/Network Drivers:

      - Networking:   Add implementation of logic for SIOCGIFCONF and
        SIOCGLIFCOF IOCTL commands.
      - Network IOCTLs:  Add support for the SIOCGIFBRDADDR ioctl() command.
      - Routing Tables:  Permit IPv4 and IPv6 routing tables to be of
        different sizes.
      - Routing Tables:  Adds support for read-only routing tables.  Prior
        to this change, routing tables were only support in RAM and had to
        be initialized with explicit logic to add the necessary routes to
        the routing table.  With this change, routes may be defined in the
        pre-initialized, read-only routing table provided by the
        board-specific logic.
        This would be particularly useful, for example, in the case where
        there is only a single network adaptor and you want all output
        packets to go to the single adaptor in all cases.  So for that
        behavior you could add a read-only routing table to the
        board-specific long that contains a single entry, the default route:
        0.0.0.0/0.
      - Routing Tables.  Added support for routing tables in files in a file
        system.  This might be useful for customized, per-unit routing
        tables. There are two issues with it however:
         1. Reading from file system on a per packet basis could be slow.  I
            think it probably should have a small, in-memory cache of most
            frequently used routes for good problem.
         2. Currently the delroute logic is disabled due to a problem with
            the design.  NuttX does not currently support truncate().
            Therefore, it is not possible to delete entries from the routing
            table file. In this current implementation, that leaves the last
            entry intact at the end of the file.  An alternative design
            might include a tag on each record to indicate if the record is
            valid or not.  That would work but would add complexity to the
            other routing table functions.
      - Routing Tables:  Add support for an in-memory routing table cache in
        order to improve performance when the routing table is retained in a
        file. The cache holds the most recently used routing table entries
        and so can eliminate some file access.  Flush the in-memory cache
        when any entry is deleted from the routing table.  When a router
        matching an IP address is found, add the routing table entry to the
        cache.
      - Routing Tables:  Add logic to mark a route as most-recently-used in
        the route cache.
      - ICMP:  This change adds support for semi-standard IPPROTO_ICMP
        AF_INET datagram sockets.  This replaces the old ad hoc, nonstandard
        way of implementing ping with a more standard, socket interface.
      - ICMPV6: This commit adds support for semi-standard IPPROTO_ICMP6
        sockets.  This is a replacement for the non-standard ICMPv6 ping
        support that violated the portable POSIX OS interface.
      - ICMPv6:  Add option to manually specify router prefix in router
        advertisement message.  From Sakari Kapanen.
      - Local Sockets:  This commit modifies the Unix domain local socket
        design. Local sockets are built on top of pipes.  The Local socket
        implementation maintained file descriptors to interrupt with the
        pipes. File descriptors have the bad property that they are valid
        only while running on the thread within the task that created the
        local socket.
        As a policy, all internal OS implementations must use "detached"
        files which are valid in any context and do not depend on the
        validity of a file descriptor at any point in time.  This commit
        converts the usage of file descriptors to detached files throughout
        the local socket implementation.

    * Wireless Networking/Wireless Drivers:

      - IEEE-802154:  Adds support for receiving MAC events via IOCTL through
        socket interface.  From Anthony Merlino.
      - IEEE-802154:  Simplifies notify() and rxframe() calls to a single
        notify() call. dataind's and all other "notifs" are now "primitives"
        which aligns with standard terminology  From Anthony Merlino.
      - MAC802154:  Add support for getting promiscuous mode state From
        Anthony Merlino.
      - MAC802154 Character Driver: When in promiscuous mode, the char
        driver sends the entire frame, including the MAC header.  This
        change adds an offset field indicating the header-payload boundary.
        It is set to 0 when not in promiscuous mode as the header is not
        passed to the application
      - 6LoWPAN: Remove CONFIG_NET_6LOWPAN_FRAMELEN.  In this case where
        multiple radios are supported, this may not be a constant.  6LoWPAN
        now always queries the driver to get the maximum frame length.
      - 6LoWPAN:  Support sending to a router that is on-link and may be
        able to forward the packet for us if the destination is not
        reachable directly.  From Anthony Merlino.
      - XBee:  Adds XBee S2C (802.15.4 firmware) support. XBee driver
        emulates mac802154 interface.  From Anthony Merlino.

    * Other Common Device Drivers:

      - PowerLED:  Add upper-half driver for high power LED driver (powerled)
        From Mateusz Szafoni.
      - RTC Driver:  Add periodic alarms to upper and lower halves.  From
        Juha Niskanen.
      - Pipes:  Fix writing large buffers not triggering POLLIN for reader
        poll.  From Jussi Kivilinna.
      - USB CDC/ACM Device:  Add support for RX flow control to the CDC/ACM
        driver.
      - USB CDC/ACM Device:  Add support for flow control TERMIOs in CDC/ACM
        driver.
      - USB RNDIS Device:  Add RNDIS-over-USB driver.  From Sakari Kapanen
        with added Hi-Speed support from Masayuki Ishikawa.
      - Loop Driver:  Don't use file descriptors... Use the internal file
        system interfaces so that the loop device can be shared across
        threads.
      - APA102 LED controller:  Add driver for APA102 LED controller.  These
        LEDs are used on LED Strips and are controlled over SPI.
      - INA219.  Add INA219 Driver.  The INA219 is a combined voltage and
        current sensor that can measure up to 26 volts and a current that
        depends on an external shunt resistor.  Connection happens via
        i2c/smbus and the chip features a power supply rail that is
        independent from the measured voltage, so it can measure low
        voltages.  Right now it measures bus voltage and current, and does
        not use the internal calibrated current reading, nor the available
        power measurement.  From Sebastien Lorquet.
      - PCA9555:  The IRQ subsystem now supports passing a void * parameter
        to IRQ handlers.  Use that method to support multiple PCA9555
        devices, by passing a pointer to the device to the board defined IRQ
        handler.  Now the CONFIG_ for multiple PCA devices just allocates
        device structures dynamically instead of statically when not enabled.
        The same interrupt handler is entered with the device structure
        parameter in all situations, multiple or single PCA. One should
        still be careful if multiple PCA devices share the same IRQ.  From
        Sebastien Lorquet.
      - APDS-9960: Add driver for the APDS-9960 gesture sensor.  From Alan
        Carvalho de Assis.
      - MAX7219:  Add support to MAX7219 LED Matrix as LCD interface.  From
        Alan Carvalho de Assis.
      - WM8774:  Add WM8774 audio DAC support.  From Masayuki Ishikawa.
      - Nunchuck: Add Nintendo Wii Nunchuck driver.  From Alan Carvalho de
        Assis.

    * Simulation

      - Simulation:  Add a configuration for non-graphical testing of the
        framebuffer character driver using apps/example/fb.
      - Simulation:  Add a configuration for testing the UserFS using
        apps/examples/userfs.

    * Broadcom BCM2708:

      - BCM2708:  Add enough infrastructrue (more stubs) to get a clean
        compilation of the Pi Zero configuration (with many undefined things
        at link time).   This includes several register definition header
        files (some from Alan Carvalho de Assis), basic interrupt handling
        logic, boot-up files, GPIO support, tickless timer, build and
        configuration logic

    * Broadcom BCM2708 Boards:

      - Raspberry Pi Zero.  Basic board support at configs/pizero.  Untested
        in this release and still some remaining issues.

    * Infineon XMC4xxx Boards:

      - XMC4500-Relax:  Add config for UART3 on RXD P0.0 and TXD P0.1 pins.
        From Alan Carvalho de Assis.

    * NXP Freescale LPC17xx Boards:

      - Open1788:  Add initialization of Framebuffer driver.  Add
        configuration for testing the framebuffer driver.

    * NXP Freescale LPC43xx Drivers:

      - LPC43xx:  Add LPC43xx CAN driver.  From Alexander Vasiljev.

    * NXP Freescale LPC43xx Boards:

      - MCB1700:  Add support for Keil MCB1700 board.  From Alan Carvalho de
        Assis.
      - Open1788:  Add support for the discrete joystick driver.
      - Open1788:  Add a configuration for testing pdcurses with discrete
        joystick.

    * On Semiconductor LC823450

      - LC823450:  Add ADC driver and watchdog drivers.  From Masayuki
        Ishikawa.
      - LC823450:  Add IPL2 support.  From Masayuki Ishikawa.
      - LC823450:  Add I2S support. From Masayuki Ishikawa.
      - LC823450:  Add auto LED for CPU activity.  From Masayuki Ishikawa.

    * On Semiconductor LC823450 Boards

      - LC823450-XGEVK:  Enable ADC and watchdog driver.  From Masayuki
        Ishikawa.
      - LC823450-XGEVK:  Add IPL2 support.  From Masayuki Ishikawa.
      - LC823450-XGEVK:  Add WM8774 support. From Masayuki Ishikawa.
      - LC823450-XGEVK:  Add auto LED support.  From Masayuki Ishikawa.
      - LC823450-XGEVK:  Enable CONFIG_SMP for audio. From Masayuki Ishikawa.
      - LC823450-XGEVK:  Add rndis configuration.  From Masayuki Ishikawa.

    * STMicro STM32:

      - ARM Kconfig:  Add support for classic ARM11 architecture selections.
      - STM32 Tickless:  Removes the restriction to 16-bit counts when a
        32-bit timer is used for tickless operation on the stm32.  As it
        was, the restriction is very limiting, especially if one wants high
        granularity and large achievable intervals and has the hardware
        (namely the 32bit timers) available.  From Rajan Gill.
      - STM32 L4 Kconfig:  Add some L486 and L496 chips.  From Juha Niskanen
      - STM32 F7:  Adds architecture support for the STM32 F72x and F73x
        families.  From Bob Feretich.
      - STM32 F7:  Allow changing voltage output scaling setting and
        prevents enabling over-drive mode for low frequencies (STM32 F74xx,
        75xx, 76xx, 77xx). From Jussi Kivilinna.  Changes replicated for
        the 72xx and 73xx families.

    * STMicro STM32 Drivers:

      - STM32 ADC:  Added support for ADC's IO_ENABLE_TEMPER_VOLT_CH ioctl
        on STM32F10XX and STM32F20XX.  From Dmitriy Linikov.
      - STM32 Wakeup: Add logic for enabling wakeup pins.  From Oleg Evseev.
      - STM32 PWR:  Adds stm32_pwr_getsbf and stm32_pwr_getwuf functions
        that return the standby flag and the wakeup flag PWR power
        control/status register.  From Oleg Evseev.
      - STM32 HRTIM:  Sdd support for capture, chopper, deadtime and dump
        registers.  From Mateusz Szafoni.
      - STM32 RTC:  Canceling an alarm marks it as inactive.  From Juha
        Niskanen
      - STM32 Serial:  Add interface to get uart_dev_t by USART number,
        stm32_serial_get_uart().  From Juha Niskanen.
      - STM32 F33xx ADC:  Initial ADC support for the STM32F33XX.  From
        Mateusz Szafoni.
      - STM32 F33xx ADC:  Add ADC DMA support to STM32F33 configuration.  From
        Mateusz Szafoni.
      - STM32 L4 ADC:  Port analog watchdog ioctl commands from the Motorola
        MDK.  From Juha Niskanen
      - STM32 L4 ADC:  Add option for routing ADC data to DFSDM, fix DFSDM
        DMA. From Juha Niskanen
      - STM32 L4 ADC:  Add PM hooks from Motorola MDK
      - STM32 L4 FLASH:  Add function for modifying device option bytes,
        From Juha Niskanen.
      - STM32 L4 DFSDM:  Add peripheral support for digital filters for
        sigma-delta ADCs.  Initial version.  Timer trigger support is not
        completed and there is some issue with DMA.  From Juha Niskanen.
      - STM32 L4 I2C:  Port then STM32 F7 I2C driver to STM32 L4.  STM32L4 I2C
        driver is in work-in-progress state (plentiful of TODOs and
        #warnings) and lags many features found in more up-to-date STM32 I2C
        drivers.  The peripheral on STM32F7 and STM32L4 are identical except
        for L4's 'wakeup from stop mode' flag and STM32F7's I2C driver is in
        more 'ready to use' state.  The I2C clock configuration is kept the
        same as before (I2CCLK = PCLK1 80 MHz) instead of switching to
        STM32F7 arch default that is I2CCLK=HSI. Further work would be to
        add configuration option for choosing I2C clock source instead of
        current hard-coded default.  From Jussi Kivilinna.
      - STM32 L4 RTC:  Add up_rtc_getdatetime_with_subseconds
      - STM32 L4 RTC:  Change maximum alarm time from 24h to one month.  From
        Juha Niskanen.
      - STM32 L4 RTC:  Add support for periodic interrupts with
        (experimental) CONFIG_RTC_PERIODIC.   From Juha Niskanen.
      - STM32 L4 SDMMC:  Add support for an SDMMC driver.  From Miha Vrhovnik.
      - STM32 L4 Serial:  Suspend serial for Stop mode.  From Juha Niskanen.
      - STM32 L4 Serial/PM:  STM32L4 serial PM interface improvements:
        Check rx/tx buffers for pending data in pmprepare.  Remove adhoc PM
        interfaces and move serial suspend functionality behind CONFIG_PM.
        From Jussi Kivilinna.

    * STMicro STM32 Boards:

      - STM32F103-Minimum:  Add board support for APA102 driver.  From Alan
        Carvalho de Assis.
      - STM32F103-Minimum:  Add ADC support on stm32f103-minimum board.
        From Alan Carvalho de Assis.
      - STM32F103-Minimum:  Add support for LM75 in the stm32f103-minimum
        board.  From Alan Carvalho de Assis.
      - STM32F103-Minimum:  Add an ADPS-9960 example configuration.  From
        Alan Carvalho de Assis.
      - STM32F103-Minimum:  Add board support for MAX7219 LED Matrix
        controller.  From Alan Carvalho de Assis.
      - STM32F103-Minimum:  Add USB MSC device initialization to
        stm32f103-minimum.  From Alan Carvalho de Assis.
      - STM32F103-Minimum:  Add framebuffer driver initialization for
        stm32f103-minimum board.  From Alan Carvalho de Assis.
      - STM32F103-Minimum:  Add Nunchuck board support for
        stm32f103-minimum board.  From Alan Carvalho de Assis.
      - STM32F4 Discovery:  Add support for JLX12864G display on STM32F4
        Discovery board.  From Alan Carvalho de Assis.
      - Viewtool-STM32F107:  Add support to auto-mount the procfs file system.
      - Photon:  Support SPI1 and SPI3.  From Anthony Merlino.
      - STM32F334-DISCO:  Add lower half driver for high power LED
        (powerled).  From Mateusz Szafoni.
      - STM32F334-DISCO:  Add flash mode support for powerled driver. From
        Mateusz Szafoni.
      - STM32F334-DISCO:  Add powerled example configuration.  From Mateusz
        Szafoni.
      - STM32F334-DISCO:  Add lower-half driver for SMPS (buck-boost onboard
        converter).  From Mateusz Szafoni
      - Nucleo-F334R8:  Add logic for zero latency high priority interrupts
        example.  From Mateusz Szafoni.
      - Nucleo-F334R8:  Add highpri example configuration.  From Mateusz
        Szafoni.
      - STM32 F4 Discovery:  Added support for the LIS3DSH accelerometer on
        the STM32F4 Discovery rev. C boards.  From Florian Olbrich.
      - STM32 F4 Discovery: ROMFS for STM32F4 Discovery board.  From Tomasz
        Wozniak.
      - STM32 F4 Discovery:  Add a USB MSC configuration.  From Alan Carvalho
        de Assis.
      - STM32 F4 Discovery:  RNDIS support on STM32F4Discovery + DM-STF4BB.
        NOTE: MAC address for the host side starts 0xaa.  This assignment
        scheme should be fixed later.  From Masayuki Ishikawa.
      - STM32 F4 Discovery:  Add STM32F4 Discovery board support for
        Nunchuck joystick.  From Alan Carvalho de Assis.
      - STM3240G-EVAL:  Add a configuration for testing the Framebuffer
        character driver using the LCD framebuffer front.
      - STM3240G-EVAL:  Mount procfs if enabled.
      - STM3240G-EVAL:  Add support for pdcurses and the pdcurses demo
        programs in the 'fb' configuration.
      - Clicker2-STM32:  Adds SD card, automount, and syslog file
        support and fixes a few minor issues.  From Anthony Merlino.
      - Clicker2-STM32:  Adds support for USB RNDIS device.  From Anthony
        Merlino.
      - Olimex STM32-H407:  Add serial support on the on-board UEXT
        connector.  Add USART6 for UEXT connector.   Add nsh_uext
        configuration and README update.  From Jan Pobříslo.
      - Nucleo-F410RB:  Add support for the nucleo-F410RB board.  From
        Gwenhael Goavec-Merou.
      - STM32F429i-DISCO:  Add framebuffer driver initialization.  Add a
        framebuffer (fb) configuration.
      - STM32F429i-DISCO:  Add logic to auto-mount procfs.  Enable procfs in
        all configurations that use NSH.
      - STM32F429i-DISCO:  Enable support for the STMPE811 touchscreen
        controller.  Enable touchscreen and also the touchscreen testa at
        apps/examples/touchscreen in the fb configuration.
      - STM32F429i-DISCO:  Convert NxWM configuration to use LTDC
        framebuffer driver instead of SPI serial.  Also reduce number of
        layers from 4 to 1 in fb configuration.  Only one layer is used.
      - STM32L476-MDK:  Add support for the on-board LEDs.
      - Nucleo-L496ZG:  Add DFSDM initialization.  From Juha Niskanen
      - Nucleo-L496ZG:  Add support for SDMMC driver.  From Miha Vrhovnik.
      - Nucleo-L496ZG:  Enable I2C4 bus with i2ctool in NSH configuration.
        From Jussi Kivilinna.
      - Nucleo-L496ZG:  Make HSE on Nucleo-L496ZG default to enable USB.
        From Miha Vrhovnik.
      - Nucleo-F746ZG:  Use the serial console over /dev/ttyACM0 by default.
        The Nucleo-F746ZG doesn't come with Arduio RS-232 shield, then it is
        better to use the serial over the /dev/ttyACM0 that is created
        automatically when the board is plugged in the computer.  From Alan
        Carvalho de Assis.
      - Nucleo-144:  Adds support for the Nucleo-144 boards with
        STM32F722ZE.  From Bob Feretich.

    * ZiLOG Z80

      - z80/include: compiler.h, limits.h, types.h:  Update SDCC/z80 files
        to include support for long long, inline, __FILE__, and __func__.

    * C Library/Header Files:

      - include/:  Add stdnoreturn.h.  Holds definitions for the C11
        noreturn keyword.  Applies to C too.
      - include/netinet/tcp.h:  Add trivial standard tcp.h header file.
      - libc:  Add support for readv() and writev().
      - libc:  Adds tcflow().
      - libc:  Add support for sigwait().
      - libnx:  Changes to allow the font subsystem to be built without
        enabling the entire graphics system (CONFIG_NX).  Adds
        CONFIG_NXFONTS and CONFIG_NXGLIB.  Needed to duplicate some Kconfig
        setting for NXFONTs if it can be configured and built independently
        of NX.

    * Tools:

      - tools/configure.sh:  Add special support so that you can start with a
        windows native configuration and install on a different host (and
        vice versa).
      - tools/configure.c:  Duplicate new functionaity added to configure.sh.
      - tools/configure.sh:  This commit adds a -m option for macOS. For
        anyone not aware, Apple renamed OSX to macOS recently; thus the 'm'
        instead of 'o'. This does not change the other uses of *_OSX to
        macOS. From jeditekunum.
      - tools/configure.c:  Update functionality to match last change to
        tools/configure.sh.

    * NSH: apps/nshlib:

      - apps/nshlib:  mount command no long uses the non-standard OS
        interface foreach_mountpoint().  Now simply cats /proc/fs/mount
        when there are no arguments to the mount command.
      - apps/nshlib:  df command no long uses the non-standard OS interface
        foreach_mountpoint().  Now simply cats /proc/fs/blocks or
        /proc/fs/usage.
      - apps/nshlib:  The free commands no longer used mallinfo() to get
        the state of the use heap.  Two reasons:  That is not useful
        information in the kernel build.  And (2) there are other memory
        resources of interest in other configurations such as the Kernel
        heap in PROTECTED and KERNEL builds, and the prog mem uses when
        FLASH is used to hold modifiable data.  The free command has been
        extended to just dump the content of procfs entries and to include
        all of these other memory resources of the procfs entries are
        available.

    * Examples/Tests: apps/examples:

      - apps/examples/fb:  Add a simple test for the framebuffer character
        driver..
      - apps/examples/ostest: sem_open() now returns SEM_FAILED in the
        event of a failure.
      - examples/ostest:  Extend cancellation test to make sure that
        cancelable threads waiting on a message queue or on a signal can be
        canceled.
      - Added a simple reader example for the LIS3DSH acceleration sensor
        on STM32F4Discovery.  From Florian Olbrich.
      - apps/examples/apa102:  Add a Rainbow example for APA102 LED Strip.
        From Alan Carvalho de Assis.
      - apps/examples/flowc:  Add a simple test of serial hardware flow
        control.
      - Add powerled driver example.  From Mateusz Szafoni.
      - apps/examples/ina219: A simple infinite loop that polls the INA219
        sensor and displays the measurements.  From Sebastien Lorquet.
      - apps/examples/alarm:  Add options for reading alarm value and
        canceling it.  From Juha Niskanen.
      - Add -n samples to lm75 app and replace Centigrade with Celsius.
        From Alan Carvalho de Assis.
      - apps/examples/adps9960:  Add ADPS-9960 example.  From Alan Carvalho
        de Assis.
      - apps/examples/obd2:  Add OBD2 example application.  From Alan
        Carvalho de Assis.
      - apps/examples/userfs:  Add a test case for verifying UserFS.
      - apps/examples/smps:  Add SMPS driver example.  From Mateusz Szafoni.
      - apps/examples/pdcurses:  Bring in pdcurses demos and make them
        conform to the NuttX coding style.
      - apps/examples/pdcurses:  Add a very simple example that just shows
        the entire character set (7-bit only).  It adapts to the size of
        the framebuffer and, hence, can be used with very tiny displays.
        In fact it looks really dumb on big displays.
      - apps/examples/nunchuck:  Add Nunchuck example application.  From
        Alan Carvalho de Assis.

    * File System Utilities: apps/fsutils:

      - apps/fsutils/mkfatfs:  Move mkfatfs from the OS to here.

    * Network Utilities: apps/netutils:

      - apps/netutils/netlib:  Add netlib_ipv6adaptor() and
        netlib_ipv4adaptor().
      - apps/netutils/netlib:  Add helpers for reading the routing table:
        netlib_read_ipv4route() and netlib_read_ipv6route().
      - apps/netutils/netlib:  Add new utilities netlib_ipv[4|6]router()
        that can be used to determine the IP address of a router that would
        be used some some destination IP address that is not locally
        accessible.
      - apps/netutils/ftpc:  Adds support for IPv6 and fixes various
        transfer issues.   From Anthony Merlino.

    * CANUtilities: apps/canutils:

      - apps/canutils/libobd2:  Add libobd2 for NuttX.  From Alan Carvalho
        de Assis.

    * Graphics: apps/graphics:

      - graphics/traveler:  Convert to use the framebuffer driver.
      - apps/graphics/pdcurs34:  This commit brings the public domain
        pdcurses library into NuttX.  NuttX graphics support based on the
        framebuffer character drivers has been integrated.  Input is
        currently limited to a discrete joystick driver.

    * Wireless Utilities: apps/wireless:

      - apps/wireless/ieee802154/i8sak:  Adds socket interface support. You
        can now use both socket or char driver to control the MAC layer.
        From Anthony Merlino.
      - apps/wireless/ieee802154/i8sak:  Adds sniffer port option and a few
        other get/set parameters.  From Anthony Merlino.
      - apps/wireless/ieee802154/i8sak: Changes 'notif' to 'primitive'
        corresponding to the changes in the Kernel.  From Anthony Merlino.
      - apps/wireless/ieee802154/i8sak: Channel setting is now saved
        locally, so when performing a startpan or assoc, the channel
        previously set is still used, even though the MAC layer gets reset.
        From Anthony Merlino.
      - apps/wireless/ieee802154/i8sak:  Adds ability to get/set rxonidle
        setting for MAC layer. From Anthony Merlino.
      - apps/wireless/ieee802154/i8shark:  Adds i8shark, a sniffer "adapter"
        that captures all 802.15.4 traffic, packages it into a Wireshark ZEP
        packet, and sends it to a host running Wireshark  From Anthony
        Merlino.

    * System Utilities (apps/system)

      - apps/system/ping and ping6:  This commit removes the ping and ping6
        commands from NSH and replaces then with the apps/system/ping and
        apps/system/ping6 built-in commands.  The NSH ping[6] commands had
        to be removed because they violated the portable POSIX OS interface.
        The apps/system/png and ping6 command uses the sem-standard
        IPPROTO_ICMP and IPPROTO_ICMP6 socket interfaces.

    * Platform-Specific Support (apps/platform)

Bugfixes.  Only the most critical bugfixes are listed here (see the
ChangeLog for the complete list of bugfixes and for additional, more
detailed bugfix information):

    * Core OS:

      - Task Environment Creation:  Fix an error in the duplication of the
        child tasks environment in the special case where the parent's
        environment was created, but then all of the variables were unset.
        In that case, there is still an allocation in place but the size of
        the allocation is zero. This case was not being handled correctly
        when a child task attempts to create its environment and inherit the
        zero-size partent environment. Noted by Anthony Merlino.
      - timer_create():  Fix watchdog resource leak if cannot allocate a new
        timer. From Bruno Herrera.
      - OS Internal Functions: Internal OS functions should not return error
        information via the user errno variable:  This includes functions
        like file_seek(), file_read(), file_write(), etc.  The complete list
        is too long to duplicate here (please refer to the ChangeLog for
        details).
      - OS Internal Functions:  Not only should internal OS functions not
        modify the errno variable, they should never introduce cancellation
        points:  psock_connect(), psock_listen(), psock_getsockopt(), etc.
        The list is too long to duplicate here (please refer to the
        ChangeLog for details).
      - OS Internal Functions:  Create OS internal versions of many
        applications functions that were used by the OS.  The new versions
        differ from the application interfaces in that (1) they do not
        return error information via the errno variable, and (2) they never
        create cancellation points.  This includes new internal interfaces
        like nxsem_init() that is like sem_init(), etc.  There are too many
        to list here (see the ChangeLog for details).
      - Task Exit:  task_exithook.c fails to link if signals are disabled
        because was unconditionally trying to send the SIGCHLD signal to the
        parent in certain configurations.  Noted by Jeongchan Kim.
      - memalign():  Fix heap corruption caused by using unaligned chunk
        size.  Unaligned nodes generated by memalign later cause heap
        corruptions when nodes are shrink further (for example, 24 bytes ->
        8 bytes, when alignment is 16 bytes).  From Jussi Kivilinna.
      - SMP:  In sched/sched/sched_cpuselect.c, in order to find the cpu
        with the lowest priority thread, we have to remember the already
        found lowest priority.  Noted by Anonymous in Issue #75.
      - spinlocks:  Disable local interrupts in spin_setbit() and
        spin_clrbit() in order to avoid a deadlock condition.  From Masayuki
        Ishikawa.
      - atexit()/on_exit():  Clear atexit()/on_exit() function pointer
        before calling it.  On most archs, up_assert() calls exit() so
        without this change, if atexit() function triggers an assertion we
        are in endless loop.  From Juha Niskanen.

    * File System/Block and MTD Drivers:

      - tmpfs:  Fixed directory unlocking in tmpfs_opendir.   From Dmitriy
        Linikov.
      - fcntl():  fcntl() did not return success fail for F_SETFL.  Reported
        by Jussi Kivilinna.
      - tcdrain():  tcdrain() was recently added to the NuttX C library.
        But there is a problem.  The specification of tcdrain() requires
        that it be a cancellation point.  In order to do this, tcdrain was
        moved from the C library into the OS and the addition cancellation
        point hooks were added.  In non-FLAT builds, access via system calls
        is also now supported.
      - FS FAT:  Fix hard-fault when listing contents of FAT root.  From
        Jussi Kivilinna.
      - procfs: Correct a problem that was causing an apparent directory to
        be reported as a file instead of a directory by opendir.  This
        happened after adding these three new procfs entries: fs/block,
        fs/mount, and fs/usage.  Of course, there is no directory fs in this
        case, only three files that have fs/ in their relative pathnames.
        The logic was detecting that fs was the name of the enty to report,
        but it was then declaring that fs was a file (because fs/block is of
        type file).  This was fixed by adding a check for matching lengths.
        i.e., if strlen(fs) != strlen(fs/block), then report fs as a
        directory instead of a file.
      - procfs:  Fix uptime being clse to maximum 32-bit value in certain
        config.  From Juha Niskanen.

    * Binary Loader:

      - binfmt/:  Don't schedule starthook if there are no constructors.

    * Graphics/Display Drivers:

      - LCD: ILI9341 initialize method not permitted to set errno.

    * Networking/Network Drivers:

      - Networking:  net/netdev/netdev_ifconfig.c: Was not returning all of
        the address info.
      - Networking: In some cases, packets are still not sent behind the
        router. I found that NuttX sends the ARP requests not to the router
        but to the target. Mistake in file net/route/netdev_router.c.  From
        Aleksandr Kazantsev.
      - SIOCGIFCONF and SIOCGLIFCONF IOCTL commands should only report on
        network adatpors in the UP state.
      - recvfrom():  Fix double leave_cancellation_point on error path.
        From Jussi Kivilinna.
      - send():  Verify that sock descriptor is valid.  Fixes assertion when
        using send on closed socket.  From Jussi Kivilinna.
      - sendto():  Remove assert check for null psock and buf input
        pointers.  Removes check as 'psock == NULL' altogether because that
        checked for later in psock_send and psock_sendto. Change null check
        for 'buf' so that it is handled same as in recvfrom.c (return
        -EINVAL instead of assert).  From Jussi Kivilinna.
      - sockgetname() files need to include udp/udp.h and tcp/tcp.h or
        otherwise NET_UDP_HAVE_STACK and NET_TCP_HAVE_STACK are undefined
        and the logic is never compiled.  Noted by Anthony Merlino.
      - dup()/dup2():  There was a reference counting problem in the TCP
        logic of net_clone().  net_clone() which is the common logic
        underlying dup() and dup2() for sockets.  When net_clone() calls
        net_start_monitor() and net_start_monitor() returns a failure
        (because the underlying TCP connection) then net_clone() must back
        out the reference count on the structure.  Problem noted by Pascal
        Speck and this implementation of the solution is based on his
        suggestion.
      - close():  There was a possible recursion that could eventually
        overflow the stack.  The error occurred when closing the socket with
        inet_close() while a socket callback was still queued.  When the
        socket callback was executed by devif_conn_event(), this resulted in
        a call to psock_send_eventhandler() with TCP_CLOSE flag set which
        then called tcp_lost_connection().  tcp_shutdown_monitor() then
        called tcp_callback() again, which again called
        psock_send_eventhandler(), and so on....  Noted by Pascal Speck.
        Solution is also similar to a solution proposed by Pascal Speck.
      - inet:  Add check for protocol before handing out TCP and UDP sockets.
      - IP Forwarding:  Fixes typo that caused build error when IP
        forwarding was enabled with CONFIG_NET_ICMPv6_NEIGHBOR enabled as
        well.  From Anthony Merlino.
      - IP Forwarding:  Do not add link layer header size to d_len inside
        devif_forward().  From Anthony Merlino.
      - TCP Networking:  When CONFIG_NET_TCP_WRITE_BUFF=y there is a
        situation where a NULL pointer may be dereferenced.  In this
        configuration, the TCP connection's 'semi-permanent' callback,
        s_sndcb was nullified in tcp_close_disconnect.  However, other logic
        in tcp_lost_connection() attempt to use that callback reference
        after it was nullifed.  Fixed in tcp_lost_connectino() by adding a
        NULL pointer change before the access.  This was reported by Dmitriy
        Linikov in Bitbucket Issue 72.
      - UDP Broadcast:  Fix some issues with regard to UDP broadcast
        handling.  This is Bitbucket Issue #77.
      - ICMP:  Fix an error in the poll logic.  It was assumed that the
        input parameter pvconn was valid.  It was not.  Instead, the poll
        logic must work like the sendto() and recvfrom() logic:  It must
        keep a copy of the conn structure in the private data.
      - ICMPv6: Fixes several errors preventing icmpv6_radvertise.c from
        being compiled. Fixes conversions to network byte order (namely
        vlifetime, plifetime, mtu).  IPv6 source address is set to
        link-local IP address instead of the address in the netdev
        structure. This is in compliance to RFC 4861. RA didn't work on
        Linux before this change.  Finally, router prefix and prefix length
        are derived from the IPv6 address and netmask in the netdev
        structure. This seems to make more sense than using a predefined,
        separate prefix from the config.  From Sakari Kapanen.
      - ICMPV6:  icmpv6_input() needs to set d_len to 0 after consuming echo
        reply, otherwise, garbage will get sent out.  From Anthony Merlino.
      - ICMPV6:  Fix an error in the poll logic.  It was assumed that the
        input parameter pvconn was valid.  It was not.  Instead, the poll
        logic must work like the sendto() and recvfrom() logic:  It must
        keep a copy of the conn structure in the private data.
      - IGMPv2 Send:  Fix incoming IGMP checksum calculation.  From Louis
        Mayencourt.
      - ARP:  Fix IGMP Ethernet address computation.  From Louis Mayencourt.

    * Wireless/Wireless Drivers:

      - CC1101:  CC1101 driver not permitted to set errno.
      - 6LoWPAN:  Correct an error in uncompressing multicast address.
      - 6LoWPAN:  Correct a bug in handling uncompressed frames (IPv6
        dispatch).  Adds a separate local variable, protosize, to keep track
        of the size of thep protocol header.
      - 6LoWPAN:  Fix an endian-ness problem in 6LoWPAN address
        decompression.  From Anthony Merlino.
      - 6LoWPAN:  The logic that extracts interface identifier from the IP
        address needs to be generalized to handle cases where the address is
        not a link local address.  From Anthony Merlino.

    * Common Drivers:

      - Serial: 16550 UART driver IOCTL method must not set errno; it must
        return a negated errno value.
      - LIS3DSH:  Added the argument parameter (FAR void *arg) to the
        interrupt handler provided by the LIS3DSH driver to fit the
        definition for ISRs in xcpt_t.  Changed the check for working queue
        availability in lis3dsh interrupt handler to use work_available()
        and not crash in case of an overrun.  From Florian Olbrich.
      - LIS2DH:  Fixes for self-test.  From Jussi Kivilinna.
      - LIS2DH:  Fix use of obsolete dbg macro.  From Jussi Kivilinna.
      - LIS331DL:  LIS331DL driver not permitted to set errno.
      - HTS221:  Power-on sensor for loading calibration data. From Jussi
        Kivilinna.
      - MCP2515:  Fix the MCP2515 Bit Rate Prescale calculation.   Fix BRP
        for SET_BITTIMING ioctl as well.  From Alan Carvalho de Assis.
      - STMPE811: Fix GPIO operation of STMPE811 driver.
        1. STMPE811_GPIO_DIR was defined for register name and later was
          redefined to be the pin direction mask for `stmpe811_gpioconfig`.
          I decided to change register name to be STMPE811_GPIO_DIR_REG, and
          keep pin direction mask STMPE811_GPIO_DIR, so that any external
          code that already use this driver will be unchanged.
        2. The STMPE811 register GPIO_DIR uses bit value 1 for output and 0
          for input, but `stmpe811_gpioconfig` set the opposite.
        3. The call to `stmpe811_gpiowrite` from inside of
          `stmpe811_gpioconfig` leaded to deadlock.
        From Dmitriy Linikov.
      - BQ2429X:  Add BATIO_OPRTN_SYSON for enabling BATFET after SYSOFF.
        From Jussi Kivilinna.

    * Simulation:

      - Simulation:  Serial and console drivers are not permitted to set
        the errno.

    * ARMv7-M:

      - ARM Stack Check:  Fix assert panic when both TLS and interrupt stack
        are enable.  From Jussi Kivilinna.

    * Infineon XMC4xxx Drivers:

      - XMC4 USIC: Kconfig was not selecting XMC4_USIC for USIC1. From Alan
        Carvalho de Assis.
      - XMC4 UART: Fix XMC4xxx USIC UART sginal to be high level when in idle.
        From Alan Carvalho de Assis.
      - XMC4 UART:xmc4_uart_configure() expects the channel# not uartbase as
        an input parameter.  From Alan Carvalho de Assis.
      - XMC4 UART:  Enable RX/TX status.  From Alan Carvalho de Assis.
      - XMC4 UART:  The Alternative Receive Interrupt was not being
        configured.

    * Infineon XMC4xxx Boards:

      - XMC4500-Relax:  Setup max. freq. 120MHz and setup pull-up to UART
        RXD pin.  From Alan Carvalho de Assis.

    * Microchip/Atmel SAMv7 Drivers:

      - SAMv7:  DAC and ADC drivers are not permitted to set the errno.
      - SAMv7:  Correct an error in RX DMA setup.  From Manish Kumar Sharma.
      - SAMv7 USB:  It is necessary to disable pre-emption and interrupts
        around a loop that copies TX data into the hardware in order to
        avoid a TX data underrun condition.  From Anthony Merlino.

    * NXP/Freescale LPC31xx Drivers:

      - LPC31xx:  Serial and console drivers are not permitted to set
        the errno.

    * NXP/Freescale LPC43xx:

      - lpc43xx:  lpc43_adc.c was being selected by the build system when
        DAC was selected.

    * NXP/Freescale LPC43xx Drivers:

      - LPC43xx Ethernet:  Fix some backward logic setting full-duplex and
        100mbps when autoconfiguration is disabled.  Noted by Anonymous in
        Issue #76.
      - lpc43xx: UART_RX pins should be configured with input buffers
        enabled. Otherwise it cannot be read.  From Alexander Vasiljev.

    * STMicro STM32:

      - STM32 F2:  Fixed build for STM32F20XX platforms when
        CONFIG_STM32_DMACAPABLE is enabled.  From Dmitriy Linikov.
      - STM32 F4:  Remove ltdc.h and dma2d.h. Those header files in that
        location permitted inclusion into application space logic and,
        hence, facilitated and encouraged calling into the OS and violating
        the portable POSIX OS interface.  The definitions in those header
        files were move the appropriate location in the counterpart,
        architecture specific files at arch/arm/src/stm32/dma2d.h and ltdc.h.
      - STM32 L4:  Build stm32l4_idle.c only if  CONFIG_ARCH_IDLE_CUSTOM is
        not enabled.  From Jussi Kivilinna.
      - STM32 F7:  Remove ltdc.h and dma2d.h. Those header files in that
        location permitted inclusion into application space logic and,
        hence, facilitated and encouraged calling into the OS and violating
        the portable POSIX OS interface.  The definitions in those header
        files were move the appropriate location in the counterpart,
        architecture specific files at arch/arm/src/stm32f7/dma2d.h and
        ltdc.h.

    * STMicro STM32 Drivers:

      - STM32:  DAC and ADC drivers are not permitted to set the errno.
      - STM32 ADC:  Clear pending interrupts.  From Mateusz Szafoni.
      - STM32 CAN:  Lower part of STM32 CAN driver
        arch/arm/src/stm32/stm32_can.c uses all three hw tx mailboxes and
        clears TXFP bit in the CAN_MCR register (it means transmission order
        is defined by identifier and mailbox number).
        This creates situation when order frames are put in upper part of
        CAN driver (via can_write) and order frames are sent on bus can be
        different (and I experience this in wild).  Since CAN driver API
        pretends to be "file like" I expect data to be read from fd the same
        order it is written. So I consider described behaviour to be a bug.
        Fixed by settin the TXFP bit in the CAN_MCR register (FIFO
        transmit order).  From comments by Alexey T, in Bitbucket Issue 73.
      - STM32 HRTIM:  Fix pclk calculation.  From Mateusz Szafoni.
      - STM32 HRTIM:  Fix burst mode prescaler update. From Mateusz Szafoni.
      - STM32 (alt) I2C:  Ensure proper error handling. Injecting data
        errors would cause the driver to continually reenter the isr with
        BERR an RxNE.  This fix allows the error to be cleared and
        propagated to the waiting task.  From David Sidrane.
      - STM32:  LTDC and DMA2D drivers are not permitted to set the errno.
      - STM32 RTC:  Workaround for potential subseconds race condition.  In
        all recent STM32 chips reading either RTC_SSR or RTC_TR is supposed
        to lock the values in the higher-order calendar shadow registers
        until RTC_DR is read. However many old chips have in their errata
        this silicon bug (at least F401xB/C, F42xx, F43xx, L15xxE, L15xVD
        and likely others):  "When reading the calendar registers with
        BYPSHAD=0, the RTC_TR and RTC_DR registers may not be locked after
        reading the RTC_SSR register. This happens if the read operation is
        initiated one APB clock period before the shadow registers are
        updated. This can result in a non-consistency of the three
        registers. Similarly, RTC_DR register can be updated after reading
        the RTC_TR register instead of being locked."
      - STM32 Serial:  Do not stop processing input in SW flow-control
        mode.  From Juha Niskanen.
      - STM32F33xxx ADC:  Add some publicly visible interfaces and some
        code to support injected channels.  From Mateusz Szafoni.
      - STM32F33xxx DMA:  Add public interface to handle with DMA
        interrupts.  From Mateusz Szafoni.
      - STM32F33xxx RCC:  Fix CAN clock enable.  From Mateusz Szafoni.
      - stm32 F4 I2C:  Ensure proper interrupt handling.  Injecting data
        errors that causes a STOP to be perceived by the driver, will
        continually re-enter the isr with SB not set and BTF and RxNE set.
        This changes allows the interrupts to be cleared and propagates a
        I2C_SR1_TIMEOUT to the waiting task.  From David Sidrane.
      - STM32 L4 Serial:  Do not stop processing input in SW flow-control
        mode.  From Juha Niskanen.
      - STM32 F7:  LTDC and DMA2D drivers are not permitted to set the errno.
      - STM32 L4:  DAC and ADC drivers are not permitted to set the errno.
      - STM32 L4 DAC:  Do not configure output pin if it is not used.  From
        Juha Niskanen.
      - STM32 L4 RTC, PM:  Small fixes to subseconds handling, ADC
        power-management hooks
      - STM32 F4 RTC:  Fix reading alarm value that is more than 24h in
        future.  From Juha Niskanen
      - STM32 L4 RTC:  Fix reading alarm value that is more than 24h in
        future.  From Juha Niskanen
      - STM32 L4 TIM:  Fix compilation of timers with complementary outputs
        when not PWM_MULTICHAN.  From Juha Niskanen.
      - STM32 L4 RCC:  Restore backup-registers after backup-domain reset.
        From Jussi Kivilinna.
      - STM32 L4 RTC:  Correct RTC_SSR and RTC_TR read ordering.  In all
        recent STM32 chips reading either RTC_SSR or RTC_TR is supposed to
        lock the values in the higher-order calendar shadow registers until
        RTC_DR is read. Change the register read ordering to match this and
        don't keep a workaround for a hypothetical race condition (not in
        any L4 errata, lets for once assume ST's silicon works as it is
        documented...)
      - STM32 L4 RTC:  Init mode was never exited because nested locking in
        rtc_synchwait() disabled backup domain access.  From Juha Niskanen.
      - STM32 L4 RTC:  Use backup register magic value instead of INITS
        bit.  The INITS (bit 4) of RTC_ISR register cannot be used to
        reliably detect backup domain reset. This is because we can operate
        our device without ever initializing the year field in the RTC
        calendar if our application does not care about correct date being
        set.  Hardware also clears the bit when RTC date is set back to year
        2000.  From Juha Niskanen.
      - STM32 L4 RTC:  Put back the SSR race condition workaround.  ST has
        confirmed that the issue has not been fixed, and that it applies to
        STM32 L4 too (was not in errata sheets due to documentation bug) See
        discussion: https://community.st.com/thread/43710-issue-with-rtc-maximum-time-resolution .
        From Juha Niskanen.
      - STM32 F7 BBSRAM:  Avoid assert in stm32_bbsram_savepanic. If panic
        happens before stm32_bbsram is initialized, stm32_bbsram_savepanic
        caused additional assert panic. Function has null pointer check, so
        drop DEBUGASSERT.  From Jussi Kivilinna.
      - STM32 F7 I2C: fix I2C_M_NORESTART handling.  From Jussi Kivilinna.
      - STM32 F7 I2C:  Restore bus frequency after I2C reset.  Copy
        frequency restoration fix from STM32L4 I2C driver to STM32F7 I2C
        driver.  From Jussi Kivilinna.
      - STM32 F7 RTC:  Fix reading alarm value that is more than 24h in
        future.  From Juha Niskanen

    * STMicro STM32 Boards:

      - STM32F334-DISCO:  Add missing ram_vectors configuration in linker
        script.  From Mateusz Szafoni.
      - Nucleo-F334R8:  Add missing ram_vectors configuration in linker
        script.  From Mateusz Szafoni.
      - Nucleo-F334R8:  Add Missing ADC trigger configuration to the highpri
        configuration.  From Mateusz Szafoni.
      - STM3240G-EVAL:  The timer frequencies (BOARD_TIMx_FREQUENCY) are
        incorrectly defined in board.h.  Since the APB prescalers are set to
        divide by 4 and 2 respectively, the frequencies should be "2xAPBx"
        as said in the comment. The correct frequencies are already defined
        but as STM32_APBx_TIMx_CLKIN.  From Mattias Edlund.
      - STM32F429i-DISCO:  The ltdc configuration has been deleted because
        it violated the portable POSIX OS interface.  It used
        apps/examples/ltdc and include ltdc.h and dma2d.h which were also
        removed for the same reason.

    * ZiLOG Z80

      - configs/z80sim and xtrs:  Serial driver lower halves ioctl methods
        should return a negated errno value, not set the errno variable.
      - z80 Make.defs:  Fixes dependency generation with newest SDCC
        compiler.
      - configs/z80sim:  Fix a naming problem.  Also, don't try to build the
        serial driver if CONFIG_NFILE_DESCRIPTOR=0.
      - Z80:  Makefile fix for use with current SDCC.

    * Build System

      - configs/:  All defconfig files that include
        CONFIG_NET_ICMPv6_SOCKET=y need to select CONFIG_SYSTEM_PING6=y and
        deselect CONFIG_DISABLE_POLL.
      - configs/:  All NX configuration... Because of recent changes to
        libnx/nxfonts, Supported bit per pixel must be separated specified
        for NXFONTs too and need to match the select BPP for NX.
      - Build system:  Fix CONFIG_BUILD_KERNEL logic directories that have
        ubin and kbin subdirectories.  Conditional logic was fine for
        CONFIG_BUILD_FLAT and CONFIG_BUILD_PROTECTED but generated useless
        dependencies if CONFIG_BUILD_KERNEL.

    * C Library/Header Files:

      - libc/stdio:  Build the lib_noflush() and lib_snoflush() stubs even
        if CONFIG_FILE_DESCRIPTORS=0.  They may still be needed.
      - libc and libnx:  When the libraries are built into two libraries, a
        user space library and a OS space library (as in the PROTECTED and
        KERNEL build).  Then the user space library must not use the OS
        internal interfaces; similarly, the OS must avoid using the
        userspace interfaces so that it does not muck the errno value or
        create spurious cancellation points.
      - libc/match:  Use of exp() vs expf() in logf() caused function to be
        slow.  From Alan Carvalho de Assis.
      - libnx:  Fixes a memory leak that is caused because the client message
        queue is not unlinked after the client disconnects from the NX
        server.  From Masayuki Ishikawa.
      - sscanf():  Fix sscanf() character conversion (%c): do not add '\0' at
        the end as for strings, cause, for example, parsing one character
        will fill two bytes: character itself and zero one '\0' after it, so
        will overflow one byte variable argument and corrupt memory for
        variables allocated after it.  From Oleg Evseev.

    * Tools

      - tools/:  configure.sh and configure.c should redirect stdout to
        /dev/null but should not suppress stderr output.

    * NSH: apps/nshlib:

      - apps/nshlib/:  Avoid truncating the strcmp result in the parser
        into a unsigned char variable.  nshlib/nsh_netcmds.c:  Check for
        valid hostip before using it.   From Bruno Herrera.
      - apps/nshlib/:  Fix resource leak in 'dd' commenad when 'if=' or
        'of=' params are repeated in the command line.  For example:
          dd if=/dev/null if=/dev/zero of=/dev/null or
          dd if=/dev/zero of=/dev/zero of=/dev/null.   From Bruno Herrera.
      - apps/nshlib:  This commit eliminates the ping and ping6 commands
        from NSH and replaces them with 'built-in' commands at
        apps/system/ping and ping6.  The original NSH version of ping[6]
        commands violated the portable POSIX interface and, hence, had to
        be removed. The new system/ping and ping6 built-in commands uses
        the new IPPROTO_ICMP AF_INET and IPPROTO_ICMP6 AF_INET6 datagram
        sockets to implement ping.
      - apps/nshlib: Fix parsing of empty strings when CONFIG_NSH_CMDPARMS
        is not defined. Problem noted by Juha Niskanen.

    * Examples/Tests: apps/examples:

      - All configurations that use NXIMAGE or NXHELLO must select
        NX_MULTIUSER.  All configurations that use examples/nxterm must
        enable CONFIG_LIB_BOARDCTL.
      - All configurations that use NXLINES must select NX_MULTIUSER.  All
        configurations that use the NX server need to have larger POSIX
        messages.
      - apps/examples/adc:  Fix g_adcstate.count initialization.  From
        Masayuki Ishikawa.
      - apps/examples/elf:  Remove low-level interfaces and replace with
        call to exec().
      - apps/examples/nxflat:  Remove low-level interfaces and replace with
        call to exec().
      - examples/ostest:  Works around a bug in printf() when cancellation
        points are enabled.  printf() is a cancellation point because it
        calls write().  This is correct according to OpenGroup.org.
        However, printf holds the stdio library semaphore when it is
        canceled and this leaves the semaphore in a bad state.  No fix for
        the printf bug yet.
      - apps/examples/nx:  The NX example no longer supports single user
        mode.
      - apps/examples/nxtext:  The nxtext example no longer supports single
        user mode.
      - apps/examples/nxhello now supports only multiuser mode.
      - apps/examples/nximage now supports only multiuser mode.
      - examples/nxlines:  Now supports only multiuser mode.

    * Network Utilities: apps/netutils:

      - apps/netutils/ftpc:  Fix some crazy comparisons to determine is a
        file is an absolute path.  Noted by Anthony Merlino.

    * System Utilities (apps/system)

      - apps/system/i2ctool: Fixed i2ctool write operation in `no restart`
        mode (flag `-n`).  It seems that I2C driver has changed a bit since
        i2ctool was written, so now i2ctool sends repeated start even if
        `no restart` flag (-n) was passed to it.  From Dmitriy Linikov.

NuttX-7.24 Release Notes
------------------------

The 124th release of NuttX, Version 7.24, was made on March 2, 2018,
and is available for download from the Bitbucket.org website.  Note
that release consists of two tarballs:  nuttx-7.24.tar.gz and
apps-7.24.tar.gz.  These are available from:

    https://bitbucket.org/nuttx/nuttx/downloads
    https://bitbucket.org/nuttx/apps/downloads

Both may be needed (see the top-level nuttx/README.txt file for build
information).

Additional new features and extended functionality:

    * Core OS:

      - SMP: Introduce spin_lock_irqsave() and spin_unlock_irqrestore().
        These APIs are simplified version of enter_critical_section()
        and leave_critical_section() to protect data (e.g. registers) in
        SMP mode.  By using these APIs inside drivers, performance will
        be improved.  From Masayuki Ishikawa.
      - System Timer:  Replace critical section APIs with spinlock APIs.
        (64bit only).  If SMP=n or SMP=y && SPINLOCK_IRQ=n, this works
        in the same way as before.  If SMP=y && SPINLOCK_IRQ=y, performance
        will be improved.  From Masayuki Ishikawa.
      - POSIX Timers: Replace critical section APIs with spin lock APIs in
        clock_gettime.c.  This change will improve performance for SMP
        systems but nothing changes for non-SMP systems.  In SMP mode,
        the running TCB is not always at the g_readytorun.head.  From
        Masayuki Ishikawa.
      - SMP: Introduce spin_lock_wo_note() and spin_unlock_wo_note().  These
        APIs are used in sched_note.c to protect instrumentation data.  The
        difference between these APIs to existing spin_lock() and
        spin_unlock() is that they do not perform instrumentation to avoid
        recursive call when SCHED_INSTRUMENTATION_SPINLOCKS=y.  From
        Masayuki Ishikawa.
      - Interrupts:  Add a configuration option to show interrupt
        information via a procfs file.

    * File Systems/Block and MTD Drivers

      - VFS:  Add support for truncate() and ftruncate().
      - FAT, SmartFS, UserFS, UnionFS, TmpFS, NFS: Add truncate() support.
      - FAT.  Effectively handles the situation when a new file position is
        within the current sector.  Accelerates the work of the FS with a
        multitude of operations to write small pieces of data within the
        current sector.  From Aleksandr Vyhovanec.

    * Graphics/Display Drivers:

      - HiletGo OLED:  Add configuration support for HiletGo SSD1306 OLED.
      - lcd/ft80x:  This commit adds an FTDI/BridgeTek FT80x GUI driver.  It
        is untested (I don't even have hardware yet) and, hence, it is
        marked as EXPERIMENTAL).

    * Networking/Network Drivers:

      - 6LoWPAN:  Adds configuration options for specifying preloaded
        address contexts for compression  From Anthony Merlino.
      - TCP:  Introduce tcp receive window control based on I/O buffer.
        NOTE:  The algorithm is still experimental but useful for http
        streaming.  From Masayuki Ishikawa.
      - UDP:  Add an implementation of UDP write buffering.
      - Routing Tables:  Adding ftruncate() support eliminates an issue
        in file-based routing table management system.
      - Telnet:  Add support for Telnet character mode  From Masayuki
        Ishikawa.

    * Other Common Device Drivers:

      - drivers/input/ft5x06.c:  Add a driver for the FT5x06 capacitive,
        multi-touch, touchscreen controller.
      - drivers/input/ft5x06:  Add a polled mode of operation for the FT5x06
        in attempt to work around the fact that the LPCXpresso-LPC54628
        chose a non-interrupt pin for the FT5x06 interrupt.  Driver is still
        not yet functional.
      - drivers/power/bq2429x.c:  Add trickle charging mode  From Juha
        Niskanen.
      - drivers/sensors:  Add support to MAX44009 ambient light sensor.
        From Juha Niskanen.
      - drivers/sensors:  Added support for LIS3DH accelerometer sensor.
        From Matt Thompson.
      - drivers/eeprom:  EEPROM driver for AT24xx compatible EEPROMs.
        From Sebastien Lorquet.

    * Simulation

      - sim:  Add support for a RAM MTD driver and initialization for use
        with SmartFS.
      - sim:  Add support for testing NXFFS.

    * ARM:

      - ARMv7-A, ARMv7-R, ARMv7-M:  Add atomic read-add-write and
        read-subtract-write functions.

    * Infineon XMC4xxx:

      - XMC4xxx:  Refactor PLL setup, refactored PLL/CLK config, easier,
        checks for correctness, call go_os_start if STACK_COLORIZED, smarter
        config of EXTCLK output freq.  From David Alessio.

    * Infineon XMC4xxx Boards:

      - Add FPU to xmc4 ostest.  Remove +x from makefiles, preserve
        .gdbinit across make clean, add FPU support to ostest on xmc4,
        add FPU test to ostest on xmc4  From David Alessio.

    * Microchip/Atmel SAMD/L Drivers:

      - SAMD: SAMD External Interrupt Controller (EIC) support  From Matt
        Thompson.
      - SAMD/L:  Added Analog Comparator basic initialization  From Matt
        Thompson.
      - SAMD/L:  Added FDPLL clock support.  Fixed sequence of OSC32K
        calibration setup.  From Matt Thompson.
      - SAMD/L: Added loading factory USB calibration data from NVRAM.
        From Matt Thompson.
      - SAMD/L: Added experimental DMA support to SPI driver.  spi_exchange()
        uses a pair of DMA channels for TX and RX.  From Matt Thompson.

    * Microchip/Atmel SAM3/4 Boards:

      - Flip&Click SAM3X:  Add board support for the Mikroe Flip&Click
        SAM3X.
      - Flip&Click SAM3X:  Adds basic board support for the HiletGo OLED.

    * Microchip PIC32MZ

      - PIC32MZEF:  Add architectural support for the PIC32MZEF family.

    * Microchip PIC32MZ Boards

      - Flip&Click PIC32MZ:  Adds board support for the Mikroe Flip&Click
        PIC32MZ board.
      - Flip&Click PIC32MZ:  Add board support for HiletGo OLED.
      - Flip&Click PIC32MZ:  Add an nxlines configuration for use in
        testing the custom HiletGo Click board.

    * NXP Freescale LPC43xx Drivers:

      - LPC43xx:  Adapt LPC176x RTC driver for the LPC43xx.  From Gintaras
        Drukteinis.
      - LPC43xx:  Add Windowed Watchdog Timer (WWDT) driver.  Tested on
        LPC4357 but should be compatible for all LPC43xx MCUs.
        From Gintaras Drukteinis.
      - Leverage the LPC54xx SD/MMC back to the LPC43xx (where it came from
        originally).

    * NXP Freescale LPC43xx Boards:

      - Bambino-200e:  Add LPC43 SDMMC board support to Bambino-200E.  From
        Alan Carvalho de Assis.

    * NXP Freescale LPC54xx:

      - LPC546xx:  Added basic architectural support for the LPC546xx
        family.

    * NXP Freescale LPC54xx Drivers:

      - LPC546xx:  Basic NSH configuration includes support for UARTs,
        SysTick timer, GPIOs, LEDs, and buttons
      - LPC546xx:  Additional drivers include EMC, I2C, Ethernet
      - LPC546xx:  Implement GPIO interrupt support.
      - LPC546xx:  And unverified SPI driver is included.
      - LPC546xx:  Ported LPC1788 LCD driver to use the LPC54xx pin.
      - LPC546xx:  Bring in LPC43xx SD/MMC driver from
        https://github.com/Smoothieware/smoothie-nuttx/tree/master/nuttx/arch/arm/src/lpc43xx
        and adapt for use with the LPC43xx
      - LPC546xx:  Add DMA driver ported from the LPC43xx GPDMA driver.
      - LPC546xx:  Bring in WWDT driver from LPC43.
      - LPC546xx:  Add an RTC driver and a RTC character driver lower half.
      - LPC546xx:  Add support for a random number generator.
      - LPC546xx:  Add an Ethernet driver.

    * NXP Freescale LP54xx Boards:

      - LCXpresso-LPC54628:  Added support for the LPCXpresso-LPC54628
        board.  The initial bring-up used a basic NSH port.
      - LCXpresso-LPC54628:  On-board SDRAM is also supported
      - LCXpresso-LPC54628:  Add support for I2C2 and for the I2C tool to
        the NSH configuration.
      - LCXpresso-LPC54628:  Add support for the USER button.  Enable the
        apps/examples/button test in the NSH configuration.
      - LCXpresso-LPC54628:  Add the fb configuration for testing the LCD.
      - LCXpresso-LPC54628:  Add support for the the FT5x06 touchscreen
        controller.  Enable the driver as well as the apps/examples
        touchscreen test.
      - LCXpresso-LPC54628:  Add an NxWM configuration.
      - LCXpresso-LPC54628:  Add logic to bring up SDMMC.
      - LCXpresso-LPC54628:  Add logic to register the RTC character driver
        if it is enabled.  Enable the RTC and RTC character driver in the
        NSH configuration.
      - LCXpresso-LPC54628:  Add a netnsh configuration that was be used to
        test the Ethernet driver.
      - LCXpresso-LPC54628:  Add LittlevGL graphics demo configuration.

    * On Semiconductor LC823450

      - LC823450 SMP improvements:  (1) Apply irq_spin APIs to
        modifyregXX, (2) Do not use modifyreg32() to enable Mutex, (3)
        Modify IRQ control for i2s.  Apply irq_spin APIs to
        dma/syscontrol/usbdev.  From Masayuki Ishikawa.
      - LC823450:  LC823450 http streaming improvements: (1) Use spinlock
        APIs in lc823450_gpio.c.  (3) Fix a potential race condition in
        up_enable_irq(), (3) Use spinlock APIs instead of critical section
        APIs, (4) Enable HRT_TIMER in lc823450_timerisr.c. (5) Use spinlock
        APIs instead of critical section APIs. (6) Fix race conditions in
        dma/usbdev.  From Masayuki Ishikawa.
      - LC823450: Introduce DVFS.   This version only supports manual mode
        and Vdd1 is fixed to 1.2V.  From Masayuki Ishikawa.

    * On Semiconductor LC823450 Drivers

      - LC823450:  Refactor timer driver.  Add MTM timer APIs for DVFS.
        Introduce up_rtc_gettime() for CONFIG_RTC_HIRES.  Introduce idle
        time calculation in DVFS.  Also, DVFS autonomous mode based on CPU
        idle time is supported.  NOTE: voltage control is still disabled.
        From Masayuki Ishikawa.

    * On Semiconductor LC823450 Boards

      - LC823450-XGEVK:  I2S interrupt will be handled on CPU0 with this
        change.  Assign CPU1 to lpwork.  This change will improve load
        balancing for networking with RNDIS.  From Masayuki Ishikawa.
      - LC823450-XGEVK: Enable SPINLOCK_IRQ and NXPLAYER in rndis.  From
        Masayuki Ishikawa.
      - LC823450-XGEVK: LC823450 http streaming improvements: (1) In SMP
        mode, H/W interrupts should be handled on CPU0 to avoid deadlocks.
        (2) Call up_enable_irq() to assign CPU0 for IRQ handling.  (3)
        Enable HRT_TIMER, LC823450_MTM0_TICK, SPINLOCK_IRQ, (4) Enable
        NET_TCP_RWND_CONTROL, NXPLAYER_HTTP_STREAMING_SUPPORT (rndis only)
        From Masayuki Ishikawa.
      - LC823450-XGEVK:  Enable DVFS in lc823450_bringup.c.  Enable DVFS
        in audio and rndis. Add Telnet character mode to rndis.  From
        Masayuki Ishikawa.
      - LC823450-XGEVK:  Explicitly assign I2S IRQ handling to CPU0.  From
        Masayuki Ishikawa.
      - LC823450-XGEVK:  Enable RTC_HIRES instead of RTC_DATETIME (audio/
        rndis).  Disable TCP_WRITE_BUFFERS and change SCHED_LPWORKPRIORITY
        (rndis). Update SMP and DVFS related part.  From Masayuki Ishikawa.

    * STMicro STM32:

      - STM32 F7:  Add support for the STM32F72x/73x family. From Bob
        Feretich.

    * STMicro STM32 Drivers:

      - STM32 HRTIM:  Add interface to change outputs SET/RST configuration.
        From Mateusz Szafoni.
      - STM32 HRTIM:  Add interface to get timer clock frequency,
        calculation, add compare/capture registers significant bits
        checking.  From Mateusz Szafoni.
      - STM32 HRTIM:  Add interface to set timer frequency, fix slave timers
        reset configuration, change POWER_INFO to TIMER_INFO  From Mateusz
        Szafoni.
      - STM32 HRTIM:  Add repetition support and fix enum overflow  From
        Mateusz Szafoni.
      - STM32 HRTIM:  Add HRTIM push-pull mode configuration.  From
        raiden00pl.
      - STM32 FLASH:  Add progmem support for STM32L15XX From Juha Niskanen.

    * STMicro STM32 Boards:

      - configs/photon: Adds BOARD_TIMn_FREQUENCY macros  From Anthony
        Merlino.
      - configs/indium-f7:  Adds support for the RAF Research Indium-F7
        board.  From Bob Feretich.
      - Rename the configs/stm32f0discovery board directory to
        configs/stm32f051-discovery.  There are others stm32f0discovery
        boards with different MCUs and different peripherals on the board.
        From Alan Carvalho de Assis.
      - configs/stm32f072b-discovery:  Adds support for stm32f072b-disco
        board. This is the board. I added the LEDs of this board and tested
        the compilation.  From Alan Carvalho de Assis.
      - configs/stm32f103-minimum:  Add AT24 EEPROM support on STM32F103-
        Minimum board  From Alan Carvalho de Assis.
      - configs/stm32f103-minimum:  Add support to BMP180 on BluePill
        (stm32f103-minimum) board.  From Alan Carvalho de Assis.
      - configs/stm32f334-disco:  Add buck converter and boost converter
        logic.  From Mateusz Szafoni.
      - configs/stm32f103-minimum:  Add zerocross support to STM32F103-
        Minimum board  From Alan Carvalho de Assis.
      - configs/stm32f103-minimum:  Add OLED SSD1306 support to
        STM332F103-Minimum  From Alan Carvalho de Assis.
      - configs/stm32f103-minimum: Add board support to MAX6675 Thermocouple
        sensor  From Alan Carvalho de Assis.
      - configs/stm32f746g-disco: Add stm32f746g-disco Ethernet configuration.
        Add USART1 support (connected to the USB virtual serial port)  From
        Louis Mayencourt.
      - configs/viewtool-stm32f107:  Add support for FT80X initialization.
        Add ft80x configuration that will eventually be used for testing the
        ft80x if I ever receive hardware.

    * Tools:

      - tools/logparser:  Add a tool which will help me to convert git logs
        to ChangeLog format.

    * NSH: apps/nshlib:

      - apps/nshlib:  Add support for a truncate command.  This will be used
        to test the new ftruncate file system support.
      - apps/nshlib:  Add support for Telnet character mode.  From Masayuki
        Ishikawa.
      - apps/nshlib: Add support for '-n' option to the echo command.  From
        Masayuki Ishikawa.
      - apps/nshlib:  Add irqinfo command.

    * Examples/Tests: apps/examples:

      - apps/examples/userfs:  Add truncate() support for userfs.
      - apps/examples/lvgldemo:  Add lvgldemo example for LittlevGL.
      - apps/examples/veml6070:  Add VEML6070 Application Example.  From
        Alan Carvalho de Assis.
      - apps/examples/bmp180: Add BMP180 application example.  From Alan
        Carvalho de Assis.
      - apps/examples/ft80x:  Add a test of the FT80x based on FTDI
        SampleApp.  Includes tests of GPU primitives and graphics co-
        processor commands.

    * Network Utilities: apps/netutils:

      - apps/netutils/netlib: Add default route in netlib_set_dripv4addr().
        From Masayuki Ishikawa.

    * Graphics: apps/graphics:

      - apps/graphics/littlevgl:  Add littlevgl library.  From Alan Carvalho
        de Assis.
      - apps/graphics/ft80x:  Add the FTDU FT80x GUI support library.
        Consists of some display list helpers, audio helpers, touch helpers,
        RAM access, register access etc.

    * System Utilities (apps/system)

      - apps/system/nxplayer:  Add support for HTTP streaming in nxplayer.
        From Masayuki Ishikawa.
      - apps/system/setlogmask:  Adds 'setlogmask' application that allows
        you to set the syslog priority via a simple command.  From Anthony
        Merlino.
      - apps/system/usbmsc: Added Kconfig options to configure write
        protection for each LUN.  From Fabio D'Urso.
      - system/stackmonitor:  Re-design the stack monitor so that it does not
        make forbidden calls directly into the OS, breaking the portable POSIX
        OS interface.  It now properly uses the PROCFS file system to glean
        information about stack usage.

Bugfixes.  Only the most critical bugfixes are listed here (see the
ChangeLog for the complete list of bugfixes and for additional, more
detailed bugfix information):

    * Core OS:

      - System Timer:  Change the way that the 64-bit time is sampled.
        Previously, we disabled interrupts before sampling the 64-bit
        timer since the uint64_t access is not atomic on most CPUs.  However,
        disabling (local) interrupts does not work in the SMP case.  In that
        case, the timer interrupt may be running on only one of the CPUs;
        disabling interrupts on a different CPU will provide no protection
        from timer rollover.  To work around this, logic was added that
        samples 64-bit timer is sampled twice and if 32-bit rollover was
        detected between samples, then loops until there is no rollover.
      - POSIX Timers:  In SMP mode, running TCB is not always at the head of
        the g_readytorun list.  This change removes DEBUGASSERT() to avoid
        this condition.  From Masayuki Ishikawa.
      - Spinlocks:  Add memory barrier operations in spin_unlock().  In ARM
        document regarding memory barriers, SP_DMB() must be issued before
        changing a spinlock state to SP_UNLOCKED.  However, we found that
        SP_DSB() is also needed to ensure that spin_unlock() works
        correctly for network streaming aging test.  From Masayuki Ishikawa.
      - Sporadic Scheduler:  Fix compiler error in Sporadic Scheduler when
        priority inheritance is enabled.  Noted by eunb.song@samsung.com
      - Priority Inheritance:  Fix some priority inheritance related issues
        noted during review of logic.  Also add some REVISIT comments for some issues noted in the design.
      - boardctl:  Remove the BOARDIOC_TSCTEST_TEARDOWN and
        BOARDIOC_TSCTEST_SETUP boardctl() commands.  Remove all
        implementations of board_tsc_teardown().  Each board now initializes
        the touchscreen controller as a normal part of its board  bring-up.
        board_tsc_setup() is gone; the touchscreen controller is now treated
        like any other on-board device.
      - configs:  CONFIG_MAX_TASKS must be a power of 2.
      - SMP: Introduce a new global IRQ clearing logic and tasklist
        protection.  The previous implementation of clearing global IRQ in
        sched_addreadytorun() and sched_removereadytorun() was done too
        early. As a result, nxsem_post() would have a chance to enter the
        critical section even nxsem_wait() is still not in blocked state.
        This patch moves clearing global IRQ controls from
        sched_addreadytorun() and sched_removereadytorun() to
        sched_resumescheduler() to ensure that nxsem_post() can enter the
        critical section correctly.  For this change,
        sched_resumescheduler.c is always necessary for SMP configuration.
        In addition, by this change, task_exit() had to be modified so that
        it calls sched_resumescheduler() because it calls
        sched_removescheduler() inside the function, otherwise it will cause
        a deadlock. However, I encountered another DEBUGASSERT() in
        sched_cpu_select() during HTTP streaming aging test on LC823450-XGEVK.
        Actually sched_cpu_select() accesses the g_assignedtasks which might
        be changed by another CPU. Similarly, other tasklists might be
        modified simultaneously if both CPUs are executing scheduling logic.
        To avoid this, I introduced tasklist protection APIs. With these
        changes, SMP kernel stability has been much improved.  From Masayuki
        Ishikawa.
      - SMP:  Fix this_task() to be an atomic operation.  In the previous
        implementation, this_task() was defined in sched.h by using just a
        macro current_task(this_cpu()).  However, I found that this is not
        atomic and actually sometimes switching CPU happened in executing
        the macro when we tested audio steaming plus executing commands via
        Telnet.  This change resolves this issue by implementing atomic
        this_task()in sched_thistask.c which is newly introduced.  From
        Masayuki Ishikawa.
      - SMP:  Implements a global scheduler lock capability as part of SMP
        support.  This allows the scheduler to be locked with no knowledge
        or access to the TCB of the currently running task.  This is
        necessary because accessing the TCB of the currently running task
        is, itself, a non-atomic operation.  This global scheduler lock
        capability was add just to support that atomic access to the TCB.
      - SMP:  Extend the last global lock change to work with the
        LC823450-XGEVK which does not support the atomic fetch add but
        does support disabling interprocessor interrupts.  Disabling
        interprocessor interrupts will also guarantee that the TCB address
        calculation is atomic.
      - SMP:  Fix a infinite recursion problems that a recent changes
        introduced into the i.MX6 SMP implementation.  This is not seen
        with the LC823450 because you can disable inter-processor interrupts
        in that architecture; but you cannot in the ARMv7-A/GIC architecture.
      - SMP:  Remove SMP related logic in sig_dispatch.c.   This change
        prevents from a deadlock in up_schedulesigaction.c where inter-CPU
        signal handling is actually implemented.  arch/arm/src/armv7-m: Fix
        signal handling for SMP. In previous implementation, signal handling
        for SMP was incorrect.  Thus, for example, if an inter-CPU signal
        happened an incorrect tcb was signaled and caused ASSERT().  This
        change fixes the issues and works for both inter-CPU signal handling
        and signal handling on the same CPU.  From Masayuki Ishikawa.
      - Tasking:  Add nxtask_create().  Kthread_create() and nxtask_create()
        are internal OS functions and should not modify the errno variable.
        Convert legitimate uses of task_create() to nxtask_create().
        Review handling of returned values from all uses of kthread_create()
        (as well as nxtask_create()).
      - Tasking:  Threads started by board bring-up logic should be kernel
        threads, not user tasks.
      - Tasking:  Threads started by drivers should be kernel threads, not
        user tasks.
      - Semaphore Usage:  Added ECANCELED condition to DEBUGASSERT's
        checking sem_wait result  From Dmitriy Linikov.

      - errno:  Add new internal OS function nxsched_setaffinity() that is
        identical to sched_isetaffinity() except that it does not modify the
        errno value.  All usage of sched_setaffinity() within the OS is
        replaced with nxsched_setaffinity().
      - errno:  Internal functions sched_reprioritize() and
        sched_setpriority() no longer modify the errno value.  Also renamed
        to nxsched_reprioritize() and sched_setpriority().
      - errno:  Add new internal OS function nxsched_getscheduler() that is
        identical to sched_getscheduler() except that it does not modify the
        errno value.  All usage of sched_getscheduler() within the OS is
        replaced with nxsched_getscheduler().
      - errno:  Add new internal OS function nxsched_setparam() that is
        identical to sched_setparam() except that it does not modify the
        errno value.  All usage of sched_setparam() within the OS is
        replaced with nxsched_setparam().
      - errno:  Add new internal OS function nxsched_getparam() that is
        identical to sched_getparam() except that it does not modify the
        errno value (actually, the previous value erroneously neglected to
        set the errno value to begin with, but this fixes both issues).  All
        usage of sched_getparam() within the OS is replaced with
        nxsched_getparam().
      - errno:  wd_start() is an internal OS function and should not set the
        errno value.  Reviewed and updated every call to wd_start() to
        verify if return value is used and if so if the errno value is
        accessed.
      - errno:  Fix several inappropriate accesses to get_errno() that were
        missed in previous changes (some going back to nuttx-7.23).  Add new
        nxsched_setscheduler() and nxsched_getaffinity() which are
        equivalent to their counterparts without the nx on front.  These
        versions do not modify the errno value.  Changed all calls within
        the OS to use these newer versions of the functions.
      - errno:  binfmt/, configs/, graphics/, libc/, mm/, net/, sched/:  OS
        references to the errno variable should always use the set_errno(),
        get_errno() macros.
      - drivers/, fs/ and libc/:  OS references to the errno variable should
        always use the set_errno(), get_errno() macros.

    * File System/Block and MTD Drivers:

      - FAT:  CONFIG_FAT_MAXFNAME may not exceed NAME_MAX (CONFIG_NAME_MAX)
      - NFS:  Correctly infer file type.  The file type is in struct
        nfs_statinfo_s's ns_type field, not in the ns_mode field.  From
        Michael Jung.
      - NFS: Fix buffer corruption.  In case multiple read requests to the
        NFS server are required to fill up the user provided buffer,
        nfs_read() might write behind the end of said buffer.  This is fixed
        with this change.  From Michael Jung.
      - VFS:  reopen() should return NULL when oflags is less than 0, not
        equal to 0. Because negative value is returned on failure of
        lib_mode2offlags() which converts the mode string into file open
        mode flag.
      - ProcFS:  Fix an error in a common function that manages read data.
      - drivers/mmcsd:  Respect SDIO_CAPS_DMABEFOREWRITE on CMD25.  From
        Evgeniy Bobkov.
      - AT24xx:   Correct page size for AT24C02 part.  From Alexander
        Oryshchenko.
      - mtd_config.c:  Add still more error handling (to detect bad
        underlying flash implementations).  Remove MTD_ERASE that was
        erasing data block instead of erase block.  This is a partial
        revert of 4f18b4. Reported-by: Pascal Speck <iktek01@yahoo.com>

    * Graphics/Display Drivers:

      - drivers/lcd:  Fix the default I2C address of SSD1306 OLED display
        (7- vs 8-bit addressing)  From Alan Carvalho de Assis.
      - drivers/lcd:  lcd_framebuffer.c does not need to include board-
        specific board.h.
      - include/lcd:  Eliminate a warning from an SSD1306 header file by
        adding a forward reference to struct i2c_master_s.  From Sebastien
        Lorquet.

    * Networking/Network Drivers:

      - ARP:  Fix an error introduced when ICMP and ICMP6 socket support was
        added in NuttX-7.3.  A gratuitous ARP (or solicitation) was being
        sent after receive of the ECHO replay (advertisement).
      - ARP:  Fix IGMP multicast address computation on NuttX network stack.
        This change fixes the IGMP address computation to allow multicast
        UDP messages. The destination address was created with the incorrect
        bytes of the given IPv4 address.  From Louis Mayencourt.
      - ioctl:  The existence of the network driver ioctl() method should
        depend on CONFIG_NETDEV_IOCTL rather than CONFIG_NETDEV_PHY_IOCTL.
        The former enables the method, the later enables a subset of
        possible driver IOCTLs.
      - TCP:  Write buffering logic should not wait for a free buffer if
        the socket was opened non-blocking.
      - TCP:  Fixed bad return value handling in psock_tcp_send().  send()
        expects psock_tcp_send() to return a negated errno value, not -1
        with the errno set (GN: I added same change for tcp_send_buffered.c
        which has the same issue as tcp_send_unbuffered.c)  From Pelle
        Windestam.
      - TCP:  Fixes hardfault when network goes done and network monitoring
        is in place.  From Gianpaolo Ferroni Ariani.
      - TCP: tcp_send_[un]buffered.c:  Check routing table in
        psock_send_addrchck().  Previously only ARP table was considered
        when determining if the data will actually be sent.  From Juho
        Grundstrom.
      - TCP:  Generalize Juho Grundstrom's IPv4 change for IPv6 as well.
      - UDP:  Remove some conditional logic that was true if there is only a
        single network device, but not true in the multi-device context.
      - UDP:  In sendto(), return EHOSTUNREACH if the network is down.

    * Common Drivers:

      - drivers/pipes:  In poll logic, fix off-by-one error in calculation
        of bytes in the buffer.  Buffer calculation in pipe poll setup is
        off-by-one when read index is larger than write index. This causes
        poll() not getting POLLIN when buffer has one byte as calculation
        gives zero bytes in buffer.  From Jussi Kivilinna.
      - drivers/audio:  Improve stability of the WM8776 driver in SMP mode.
        Apply irq_spin APIs to improve performance.  Repeat to process a
        message to avoid deadlock.  From Masayuki Ishikawa.
      - drivers/ioexpander:  Fixed build of PCF8574 driver when its
        interrupts aren't enabled by config.  From Dmitriy Linikov.
      - drivers/syslog:  Fixes LOG_UPTO macro to include specified log level.
        From Anthony Merlino.
      - drivers/sensors:  Fix HTS221 sensor reset with BOOT bit  From Jussi
        Kivilinna.
      - drivers/loop:  If we want to open read-only in losetup.c, flags
        should be O_RDONLY not O_RDWR.  From Fabio D'Urso.
      - drivers/timers/ds3231.c:  Correct some debug statements.  From
        Alexander Oryshchenko.
      - drivers/sensors/lis2dh:  Use realtime clock if monotonic is not
        available  From Juha Niskanen.
      - drivers/i2c and drivers/spi:  Fix compile error if
        CONFIG_DISABLE_PSEUDOFS_OPERATIONS, fix bad NULL checks  From Juha
        Niskanen.

    * ARMv7-A:

      - Data Cache:  Fix cp15_invalidate_dcache.  In cases where more than
        one dcache line was to be invalidated, a missing branch label
        would result in a false branch target into cp15_flush_idcache.  Also
        the .size macro was fixed for both cp15_invalidate_dcache.  From
        Michael Jung.
      - SMP:  Port the signal-related SMP change by Masayuki Ishikawa to the
        ARMv7-A family.

    * Extensa:

      - SMP:  Port the signal-related SMP change by Masayuki Ishikawa to the
        Xtensa family.

    * Infineon XMC4xxx Drivers:

      - XMC4xxx:   Only setup USB clock when USB PLL is enabled  From Alan
        Carvalho de Assis.
      - XMC4xxx: Fix USIC_BRG_SCLKCFG definition  From Alan Carvalho
        de Assis.

    * Microchip PIC32MZ

      - MIPS32:  In up_idle, the kludge that was conditionally enabled if
        the work queue was enable appears to be needed even when he work
        queue is not enabled on the PIC32MZ.
      - PIC32MZ:  Fix some typos in debug instrumentation in pic32mz-gpio.c;
        fix some typos related to UART5 configuration in pic32mz-serial.c.

    * Microchip/Atmel SAMD/L:

      - SPI:  In sam_spibus_initialize(), the pinmux configuration was
        smashing the previous CTRLA register configuration. There are
        also some typos in samd_spi.h  From Matt Thompson.
      - SPI:  Fixes g_spi2ops and g_spi2dev using incorrect values  From Matt
        Thompson.
      - SPI:  SPI must be disabled before changing the mode bits in CTRLA
        register  From Matt Thompson.
      - DMA:  Fix DMA controller support.  From Matt Thompson.

    * NXP/Freescale LPC17xx Drivers:

      - LPC17xx:  Disable LPC17 FDR when not used.  If a boot loader set the
        fractional divider (FDR) the baud rate in nuttx will be wrong
        (multiplied by this fraction).  So if it is not used, it should be
        disabled. From Harald Gutsche.

    * NXP/Freescale Kinetis Drivers:

      - Kinetis:  Correct some Ethernet PHY register bit tests for the
        KSZ8081 PHY.  From Stewart.

    * On Semiconductor LC823450

      - arch/arm/src/LC823450: Add SP_DMB() into lc823450_testset.c.
        In LC823450, ldrex and strex are not supported. So we implemented
        up_testset() with H/W Mutex. However, there was a bug in memory
        access order. This change ensures correct memory access order in
        up_testset() for LC823450. From Masatoshi Tateishi.

    * STMicro STM32 Drivers:

      - STM32 F3 RCC:  A flash wait state configuration.  Flash latency must
        be fixed according to sysclk frequency.  If this operation is not
        done or done after PLL configuration, the STM32 fail to continue
        boot operation if the frequency if greater than 24MHz according to
        the board variable STM32_SYSCLK_FREQUENCY.  Tested on stm32f334-disco
        board.  From Gwenhael Goavec-Merou.
      - STM32 RTC:  Make STM32 usable with an external RTC.
      - STM32 SPI:  Removed unnecessary (and incorrect) speed limitation.
        From Alexander Oryshchenko.
      - STM32 SPI:  I have a SPI bus with both Mode 0 and Mode 3 devices
        on it.  After performing SPI I/O to a Mode 0 device, switching to a
        Mode 3 device locked up the SPI interface.  Only zeroes would be
        read.  I traced the reason for the lock-up to arm/arm/src/stm32f7/stm32_spi.c function spi_setmode().  Changing
        the mode causes a spurious SPI clock transmission that confuses the
        stm32f7 SPI input hardware.  This problem is solved by (1) changing
        the SPI mode with SPI (and perhaps DMA) disabled, and (2) flushing
        the receive FIFO if the mode change results in garbage in the FIFO.
        From Bob Feretich.
      - STM32 and STM32 F7:  Remove confusing, redundant, and misleading
        definitions of STM32_BKP_BASE from the F2, F3, and F4 memory
        maps.  Unlike the F1, these parts do not have a separate BKP address
        region.  The BKP registers are with the RTCC address regions.
        stm32_bkp.h should only be used for STM32 F1. stm32_rtcc.h should be
        used to access BKP registers on F2, F3, and F4.
      - STM32 and STM32 F7:  Architecture-specific code is not permitted to
        modify the errno variable.
      - STM32 F4 I2C:  Correct some recent changes to STM32F4 I2C that broke
        poll mode of operation.  From Alexander Oryshchenko.
      - STM32 F4 I2C:  Corrections to STM32 F4 I2C to restore functionality.
        From Alexander Oryshchenko.
      - STM32 F4 I2C:  Corrections to STM32 F4 I2C to fix the NORESTART
        flag.  From Alexander Oryshchenko.
      - STM32 F7:  Fixes a bug in multi-block SD-card operations on the
        STM32F7 platform.  DBLOCKSIZE must be the size of SD-card block, not
        the total amount of transferred bytes.  From Evgeniy Bobkov.
      - STM32 F7:  Fix undefined variable when using USART1 for other
        purposes than UART (e.g. SPI).  From Frank Benkert.
      - STM32 F7:  Backport RTC alarm setting changes from STM32L4.  Most
        notably this fixes RTC getting stuck issue when both alarms were
        used.  Root cause was writing RTC ISR register contents to RTC CR
        register.  From Juha Niskanen.
      - STM32 L4 Flash:  Change flash programming to use page buffer for
        unaligned writes.  From Juha Niskanen.

    * STMicro STM32 Boards:

      - Nucleo-L432KC:  Fix some bogus logic noted by Fanda.
      - configs/nucleo-* and configs/stm32l476vg-disco:  Fix more
        stm32_userleds.c bogus logic  From Juha Niskanen.
      - Nucleo-L432KC:  Fixed nucleo-l432kc broken build when
        CONFIG_USERLED_LOWER defined  From Fanda.
      - Nucleo-L432KC:  Issue #85: /dev/userleds is not working for
        Nucleo-L432KC fixed  From Fanda Vacek.
      - STM32F429I-Disco:  Separate SPI4 from MTD init.  I was trying to
        attach a non-MTD peripheral to an STM32F429I Discovery Board's SPI4
        port and was hitting compilation problems, since CONFIG_MTD and
        thus 'struct mtd_geometry_s' was not defined.  This patch separates
        SPI4 initialization logic from MTD initialization logic.  From
        Michael Jung.
      - STM32F103-Minimum:  Remove CONFIG_NX_LCDDRIVER dependence from
        stm32_ssd1306.c  From Alan Carvalho de Assis.

    * C Library/Header Files:

      - libc/stdio:  In dtoa(), up_interrupt_context() is used in a debug
        assertion.  up_interrupt_context() is not available in the user-mode
        phase of the PROTECTED or KERNEL build configurations.  In those
        configurations, enabling libc floating point support and debug
        assertions will result in an undefined reference to
        up_interrupt_context().
      - libc/netdb:  Fixed parsing of DNS response packets having compressed
        names ending with pointer.  There were troubles parsing response
        packets which have compression of QNAME/NAME field when only
        trailing part of the name (not the whole name) is replaced with
        pointer to another part of the packet.  This commit fixes parsing of
        such packets.  Also I added checks to keep parsing only in bounds of
        the read part of DNS response packet.  From Dmitriy Linikov.

    * Tools

      - tools/*.c:  Add #define _GNU_SOURCE to all C files that call
        asprintf() to eliminate a warning.
      - tools/cvsparser.c:  Add a check to avoid access past the end
        of a fixed size array

    * NSH: apps/nshlib:

      - apps/nshlib:  Fix compile error when CONFIG_NSH_DISABLESCRIPT is not
        defined.  The field np_flags does not exist if scripting is disabled.

    * Examples/Tests: apps/examples:

      - apps/examples/touchscreen:  Eliminate BOARDIOC_TSCTEST_SETUP.

    * Network Utilities: apps/netutils:

      - apps/netutils/ftpc:  Fix some corner-cases that could cause FTP to
        access past the end of valid data.

    * Wireless Utilities: apps/wireless:

      - apps/wireless/ieee802154/i8shark: Fixes special XBee compensation
        by purposely chopping off the FCS.  From Anthony Merlino.

NuttX-7.25 Release Notes
------------------------

The 125th release of NuttX, Version 7.25, was made on June 3, 2018,
and is available for download from the Bitbucket.org website.  Note
that release consists of two tarballs:  nuttx-7.25.tar.gz and
apps-7.25.tar.gz.  These are available from:

    https://bitbucket.org/nuttx/nuttx/downloads
    https://bitbucket.org/nuttx/apps/downloads

Both may be needed (see the top-level nuttx/README.txt file for build
information).

Additional new features and extended functionality:

    * File Systems/Block and MTD Drivers

      - fs/cromfs:  Added CROMFS file system.  CROMFS is a compressed, in-
        memory, read-only file system based on LZF.
      - fs/vfs:  Added support for checking if a descriptor is a socket in
        fstat().  From Pelle Windestam.

    * Graphics/Display Drivers:

      - drivers/lcd:  Remove support for the Nokia6100 LCD.  That LCD uses a
        9-bit SPI interface (the 9th bit being the command/data bit that is
        normally a discrete).  That communication was never successfully
        integrated.  I now believe that it would would require some special
        support from the low-level, MCU SPI driver to manage that 9th bit.
        The deleted code is still available in the Obsoleted repository.

    * Networking/Network Drivers:

      - net/tcp:  Added support for TCP Keepalive, add SO_KEEPALIVE socket
        option.  Added socket options needed to manage TCP-keepalive and TCP
        state machine logic to detect if that the remote peer is alive.
      - net/tcp:  In tcp_input(), add the logic to detect, decode, and
        respond to TCP Keep-Alive packets.
      - net/tcp:  Extended support for sending to non-blocking tcp sockets.
        From Pelle Windestam.
      - net/bluetooth:  Added support for AF_BLUETOOTH sockets.
      - drivers/net:  Added TAP (network bridge) mode to tun.c.  In the
        previous implementation, TAP mode did not handle a packet correctly.
        Also, the driver did not set the link layer type and could not
        assign the interface name. This change fixes such issues and supports
        TAP mode correctly.  From Masayuki Ishikawa.

    * Wireless/Wireless Drivers:

      - wireless/ieee802154:  Added basic MAC support for RX-ENABLE.request
        primitive  From Anthony Merlino.
      - wireless/ieee802154:  Added MAC ackreq flag to TX descriptor for use by
        radio driver.  The radio layer is responsible for a full "transaction".
        Because of differences in radio capabilities, the radio must be
        responsible for the handling of acks and retransmissions. This commit
        simply passes the ackreq meta-data flag along to the radio.  Also
        Fixes bug where primitive was freed when it shouldn't have been,
        causing double free call.  From Anthony Merlino.
      - wireless/bluetooth:  Bring in the Bluetooth stack from the Intel/
        Zephyr arduino101_firmware_source-v1.tar package.
      - drivers/bluetooth:  Added re-architected version of the Bluetooth
        UART driver from the Intel/Zephyr arduino101_firmware_source-v1.tar
        package.
      - include/nuttx/wireless:  Added a setbaud() method to the HCI UART
        lower half interface that can be used to change the default BAUD
        selection.
      - wireless/bluetooth and include/nutt/net:  Added support for Bluetooth
        IOCTL commands.
      - drivers/wireless/bluetooth:  Added a NULL device to support some very
        low level testing on the Simulator.
      - drivers/wireless/cc3000:  Eliminate support for the CC3000 wireless
        part because it doesn't use the USRSOCKET.  From Alan Carvalho de
        Assis.
      - drivers/wireless/ieee80211:  Added BCM43428 support.  From hhuysqt.

    * Other Common Device Drivers:

      - drivers/1wire:  Added 1-wire subsystem and ds28e17 driver  From Juha
        Niskanen.
      - drivers/1wire:  Added PM hooks and unlink support to sht21 sensor
        (allowing hot-swappable I2C bus from 1-wire converter).  Unlike most
        other unlink implementations in NuttX drivers, this one does not
        allow any I2C operations after unlink, making it possible to
        deallocate the I2C bus.  From Juha Niskanen.
      - drivers/i2c:  Added support for the pca9540bdp i2cmultiplexer.  From
        Giorgio Groß.
      - drivers/power:  Added pm_unregister  From Juha Niskanen.
      - drivers/power:  Added generic upper-half motor driver  From Mateusz
        Szafoni.
      - drivers/rgbled:  Added support for multichannel PWM (multiple PWM
        channels on a single timer)  From Anthony Merlino.
      - drivers/sensors:  Added support for Sensirion SHT2x humidity sensor.
        From Juha Niskanen.
      - drivers/sensors:  Added LSM330 SPI and ADXL372 drivers along with the
      - drivers/sensors:  Added support for INA3221 power sensor. This has a
        3 channel bus/shunt voltage pairs.  From Anthony Merlino.
        cluster driver infrastructure.  From Bob Feratich.
      - drivers/sensors:  Added multiple MAX31855 sensors feature support.
        From Tiago Almeida.
      - drivers/wireless/cc1101.c:  Driver improvements from from lihaichen.
      - progmem interface:  Discern r/w and erase page sizes.  Introduce new
        up_progmem_erasesize architecture API to be able to communicate the
        read/write page size independently from erase page size.  Implement
        up_progmem_erasesize for all architectures that already support
        progmem, assuming that for those architectures the sizes of both
        read/write and erase pages are identical.  From Michael Jung.

    * Simulation

      - configs/sim:  Added a configuration that will support some limited
        testing of the Bluetooth stack.

    * ARM:

      - ARM:  All ARM architectures now support CONFIG_ARCH_IDLE_CUSTOM.

    * MIPS:

      - MIPS:  All MIPS architectures now support CONFIG_ARCH_IDLE_CUSTOM.

    * Infineon XMC4xxx Drivers:

      - XMC4:  Added SPI support for Infineon XMC45xx microcontroller. From
        Alan Carvalho de Assis.

    * Infineon XMC4xxx Boards:

      - XMC4500-Relax: Added board support for SPI.  From Alan Carvalho de
        Assis.

    * Nordic NRF52:

      - NRF52:  Initial support for the NRF52 including UART, Timer, and
        GPIO support.  From Janne Rosberg.

    * Nordic NRF52 Drivers:

      - NRF52:  Added watchdog timer drivers.  Includes significant
        updates from Levin Li.
      - NRF52:  Added nRF52 Flash PROGMEM support  From Alan Carvalho de
        Assis.

    * Nordic NRF52 Boards:

      - configs/nrf52-pca10040:  Added support for the NRF52-PCA10040 board
        including LEDs and buttons  From Janne Rosberg.
      - configs/nrf52-pca10040:  Added support for starting the watchdog
        timer on the nRF52.  From Alan Carvalho de Assis.
      - configs/nrf52-pca10040:  Added a configuration for testing the
        watchdog timer.  From Alan Carvalho de Assis.

    * NXP Freescale i.MX RT:

      - i.MX RT:  Brings in basic support for the i.MX RT 1050 'crossover'
        SoC.   Includes timer and UART support.  This port was the joint
        effort of Janne Rosberg, Ivan Ucherdzhiev, and myself.  I give
        credit to Ivan for the kill because he is the one to held on to
        the end.  From Ivan Ucherdzhiev.

    * NXP Freescale i.MX RT Drivers:

      - i.MX RT:  Added power management hooks.
      - i.MX RT:  Added eDMA support (unverified).
      - i.MX RT:  Added Ethernet driver.  From Jake Choy.
      - i.MX RT:  Added cache operations to permit the Ethernet driver to
        work with the D-Cache enabled, at least in write-through mode.
        Added support for PHY interrupts and PHY IOCTLs.

    * NX FreescaleP i.MX RT Boards:

      - IMXRT1050-EVK:  Added support for booting from the on board HYPER
        Flash.  From Ivan Ucherdzhiev.
      - IMXRT1050-EVK:  Added logic to support the board's user LED.  From
        Jake Choy.
      - IMXRT1050-EVK:  Added procfs auto-mount support in imxrt_bringup.c.
        From Ivan Ucherdzhiev.
      - IMXRT1050-EVK:  Added LIBCXX test configuration.
      - IMXRT1050-EVK:  Added support for the imxrt1050-evk button.  From
        Jake Choy.
      - MXRT1050-EVK:  Added support for on-board NOR FLASH boot.  From
        Ivan Ucherdzhiev.
      - IMXRT1050-EVK:  Disable LED support because pins conflict with PHY.
        Enable device statistics.  Enable NSH ifup and ifdown commands.
        Added an NSH configuration for testing Ethernet.

    * NXP Freescale Kinetis:

      - K28F:  Added architecture support for the Kinetis K28F.

    * NXP Freescale Kinetis Drivers:

      - SDHC:  Make Kinetis SDHC pullups work the same as the STM32 SDIO
        pullups.

    * NXP Freescale Kinetis Boards:

      - Freedom-K28F.  Added support for the Kinetis Freedom-K28F board.

    * NXP LPC17xx:

      - LPC17xx:  Added support for ARMv7-M run time stack checking on NXP
        LPC17xx MCUs based on CONFIG_ARMV7M_STACKCHECK. Basically copied
        from STM32.  From Michael Jung.

    * NXP LPC17xx Drivers:

      - LPC17xx:  Added a configurable option to allow using a part of
        LPC17xx's internal flash memory as a Memory Technology Device via
        NuttX' mtd_progmem infrastructure. Tested with LPC1769.  From
        Michael Jung.

    * NXP LPC17xx Boards:

      - Olimex-LPC1766STK:  Remove support for the Nokia6100 LCD.  That
        LCD uses a 9-bit SPI interface (the 9th bit being the command/data
        bit that is normally a discrete).  That communication was never
        successfully integrated.

    * NXP LPC43xx Boards:

      - configs/bambino-200e:  Added support for multiple MAX31855 sensors
        to the bambino-200e.  From Tiago Almeida.

    * OpenRISC

      - arch/or1k/src.  Added basic architectural support for the OpenRISK
        mor1kx architecture.  The initial commit was verified on a Qemu
        simulation but is otherwise untested.  From Matt Thompson.

    * OpenRISC Board

      - configs/or1k.  OpenRISK mor1kx Qemu simulation.  From Matt Thompson.

    * STMicro STM32:

      - STM32:  Added support for the STM32F401xB and STM32F401xC families.

    * STMicro STM32 Drivers:

      - STM32 HRTIM:  Added HRTIM software capture trigger, added software
        reset trigger, added outputs polarization configuration  From
        raiden00pl.
      - STM32 ADC:  Added ADC injected channels configuration.  From Mateusz
        Szafoni.
      - STM32 HCIUART:  Added a Bluetooth HCI UART lower half driver for the
        STM32.
      - STM32 HCIUART:  Implement the setbaud() method for the STM32 HCI
        UART interface.
      - STM32 SDIO:  Added support for SDIO card to SDIO driver.  From
        hhuysqt.
      - STM32 SDIO:  Added internal pull-up option for SDIO pins.  From Alan
        Carvalho de Assis.
      - STM32 F2/F4 ADC:  Added Vbat measurement to ADC driver for
        STM32F20xx and STM32F4xxx.  As with the MCU temperature and VREFINT
        measurement, this change requires user to enable the corresponding
        channel first.  For Vbat channel the ioctl cmd is
        IO_ENABLE_DISABLE_VBAT_CH, and its arg should be a pointer to bool
        which must be true to enable and false to disable the Vbat channel.
        Moreover, since Vbat input contains a built-in voltage divider, it
        is highly suggested to disable Vbat input channel after measurement
        is done in order to prevent battery drain through the divider.  From
        Dmitriy Linikov.
      - STM32, STM32L4 1WIRE:  Added one bit read and write to 1-wire
        interface.  This is needed for devices that require single bit
        timeslot generation and for 1-Wire search algorithm triplets.  From
        Juha  Niskanen.
      - STM32 F3 SPI:  Enable DMA for SPI on stm32f30xxx MCUs.  From Michal
        Lyszczek.
      - STM32 L4 1WIRE:  Ported 1wire driver from STM32.  From Juha
        Niskanen.
      - STM32 L4 I2C/SPI/1WIRE:  Added PM hooks to I2C, SPI and 1-wire  From
        Juha Niskanen.
      - STM32 F7 RTC:  Added CONFIG_RTC_PERIODIC support.  Also makes the RTC
        lowerhalf more like in STM32L4.  From Juha Niskanen.
      - STM32 F7 ADC/I2C/SPI:  Added PM hooks to ADC, I2C and SPI.  From
        Juha Niskanen.

    * STMicro STM32 Boards:

      - Indium-F7:  Removed support for the Indium-F7 board.  This was done
        for two reasons:  (1) The board support was just clone of the
        Nucleo-144 board support with naming changes.  There has been no
        support and no further development for the board support.  (2) There
        does not seem to be any available Indium-F7 board available to the
        public anywhere on the Internet.  There is not even a reference to
        the board on the rafresearch.com web stie.
      - Nucleo-L452RE:  Added buttons example  From Juha Niskanen.
      - Nucleo-L476RG:  Added support to Nokia LCD PCD8544 on nucleo-l476rg.
        From Alan Carvalho de Assis.
      - Nucleo-L476RG:  Added nxdemo configuration to nucleo-l476rg using
        PCD8544.  From Alan Carvalho de Assis.
      - Olimex-STM32-P407:  Added a zmodem test configuration.
      - Olimex-STM32-P407:  Added the module configuration.
      - Photon:  Added RGB led support  From Anthony Merlino.
      - STM32F103-Minimum:  Added support for DFU bootloader  From Simon
        Piriou.
      - Spark:  Removes Spark board configuration.  Still available in the
        Obsoleted repository.  If there is no CC3000 support, then there is
        no purpose in supporting the Spark either.
      - STM32F334-Disco:  Added buck/boost converter example configuration.
        From Mateusz Szafoni.
      - STM32F4 Discovery:  Added support for multiple MAX31855 sensors to the
        STM32F4 Discovery  From Tiago Almeida.
      - STM32F4 Discovery:  Added support in bring-up logic to initialize the
        HCI UART and register the HCI UART network device.
      - STM32F4 Discovery:  Added MAX7219 support to STM32F4Discovery board.
        From Alan Carvalho de Assis.
      - STM32F4 Discovery:  Added board configuration for CS43L22 audio
        example.  From Alan Carvalho de Assis.
      - STM32F4 Discovery:  Added a module configuration for testing the
        kernel module example with the STM32F4Discovery board.  From Alan
        Carvalho de Assis.
      - STM32F429I-DISCO:  Added a LittlevGL configuration for stm32f429i-
        disco.  From seyyah.
      - STM32F746G-DISCO.  Added clang support to stm32f746g-disco board.
        From Goran Mekic.
      - STM32L1 Discovery:  Added support for the STM32L152RCT6 version of
        the board.

    * TI TMS570:

      - TMS570:  Added support for the TMS570LS3137ZWT.  From Ivan Ucherdzhiev.

    * TI TMS570 Boards:

      - configs/tms570ls31x-usb-kit:  Added support for the TI Hercules
        TMS570LS31x USB Kit  From Ivan Ucherdzhiev.

    * TI Tiva:

      - CC3200: Remove all support for the CC3200.  This was a port that was
        started but never completed.  What good is partial CC3200 support
        with no wireless support?.

    * TI Tiva Drivers:

      - EEPROM:  Implements an EEPROM driver in compliance with MTD driver
        as provided by NUTTX for TM4C1294.  The EEPROM driver currently
        supports only two functionalities - read bytes(multiple of 4) and
        write bytes (multiple of 4).  From Shirshak Sengupta.
      - FLASH:  Implemented Flash CONFIG_MTD_BYTE_WRITE for TM4c1294.
        Implemented the tiva_write function which will write an arbitrary
        number of bytes to flash (in multiple of 4).  From Shirshak Sengupta.
      - Serial:  Added TERMIOS IOCTL support to the Tiva serial driver.
        From Dmitry Sharihin.

    * TI Tiva Boards:

      - CC3200-Launchpad:  Remove all support for the CC3200-Launchpad.
        This was a port that was started but never completed.  What good is
        partial CC3200-Launchpad board support with no wireless support?.

    * Libraries/Header Files:

      - libs/:  Moved all of the libraries under a common directory called
        libs/ (libc, libnx, and libxx).  This almost certainly break libcxx
        for now.
      - libs/libc/time:  Added an implementation of clock().
      - libs/libc/lzf:  Added a modified version of Marc Alexander Lehmann's
        LIBLZF3.6 library  From Boris Astardzhiev.
      - libs/libc/unistd:  Initial, minimal implementation of sysconf().
        Only sufficient to support the functionality of less standard
        getdtabilesize().  From Michael Jung.
      - libs/libdsp:  Added DSP support library.  From Mateusz Szafoni.
      - include/sys:  Added resource.h.
      - include/nuttx/video:  Add overlay support to framebuffer interface
        definition. From Marco Krahl.

    * Tools:

      - tools/gencromfs.c:  Added tools/gencromfs.c, a tool that can be used
        to generate CROMFS file system images.
      - tools/mkromfsimg.sh:  Include an option in mkromfsimg.sh to ignore
        FAT/RAMDISK. This permits you to build tiny systems with ROMFS but
        with the rather large FAT FS support.  From Alan Carvalho de Assis.
      - tools/nxstyle.c:  Added check for blank lines before and after single
        line comments.  From Bob Feretich.
      - tools/sethost.sh:  Added support for macOS.
      - tools/uncrustify.cfg:  An initial cut at an uncrustify C formatting
        script from Gregory Nutt. Updated, corrected, and verified.  From
        Bob Feretich.

    * Build System:

      - Makefile:  Added support for nconfig frontend for 'make nconfig'.
        From Michal Lyszczek.
      - configs/:  Added definition of strip to many Make.defs files.
      - staging/:  Remove fixed lib/ subdirectory and its content.  Replace
        with new directory called staging/ that is created dynamically when
        building and removed when 'make clean' is done.  This both improves
        the naming and eliminates a garbage directory from the repository.
      - tools/:  Move all build-related files (except the top-level Makefile)
        into the tools/ sub-directory.  This really cleans up the top-level
        directory.

    * NSH: apps/nshlib:

      - apps/nshlib:  Added the mkfatfs -r option which can be used to
        specify the number of entries in the FAT12/FAT16 root directory.
        From Boris Astardzhiev.

    * Examples/Tests: apps/examples:

      - apps/examples/adxl372_test and lxm330spi_test:  Added ADXL372 and
        LSM330 tests.  From Bob Feretich.
      - apps/examples/cc3000:  Removed the CC3000 example.  From Alan
        Carvalho de Assis.
      - apps/examples/cromfs:  Added an example of how to build a CROMFS
        file system image.
      - apps/examples/elf:  Extend the ELF program module demo so that you
        can use compressed ELF programs with CROMFS.
      - apps/examples/elf:  Use strip command to make ELF binaries MUCH
        smaller. Added an option to strip debug symbols even if the debug
        symbols are enabled in the base code.
      - apps/examples/max31855: Added an example to read multiple max31855
        sensors.  From Tiago Almeida.
      - apps/examples/netloop:  Update network loopback example so that it
        can be used to test TCP KeepAlive.
      - apps/examples/nxdemo:  Added nxdemo application  From Alan Carvalho
        de Assis.
      - apps/examples/powerled:  Added arch initialization.
      - apps/examples/uavcan:  Removed because apps/canutils/libuavcan is no
        longer available.

    * System Utilities: apps/system

      - apps/system/lzf:  Added the test case from Marc Alexander Lehmann's
        LIBLZF3.6 librrary  From Boris Astardzhiev.
      - apps/system/embedlog:  Support for embedlog data loggin package from
        https://embedlog.kurwinet.pl/  From Michal Lyszczek.
      - apps/system/zmodem:  Added an option to enable hardware flow control
        via termios.  Allow stack size and priority to be configured.
      - apps/system/zmodem:  Call tcflush() before closing the serial port.
        This is necessary because that close operation may hang if hardware
        flow control is enabled.  Consider this scenario:  After the host
        sz runs on the host, it exits and leaves CTS high.  The target rz
        completes, and tries to close the serial port.  But if there is
        buffered Tx data, then the close will hang when it tries to drain
        the buffered Tx data since there is no where it can go.  tcflush()
        discards the buffered data and permits the close to continue.
        There is additional logic in nuttx/drivers/serial needed to work
        with this.

    * CAN Utilities:  apps/canutils:

      - apps/canutils/libuavcan.  Removed! libuavcan has not built for a
        year or so.  The basic problem is that as NuttX advances, the old
        frozen version of libuavcan has become absolute because it violates
        the portable POSIX OS interface.  No one is maintaining the port so
        there is no alternative but to remove it.

    * Network Utilities: apps/netutils:

      - apps/netutils/tftpc:  Modified the TFTP client functions to use a
        data read/write callback instead of a file.  This allows TFTP to
        write to arbitrary destination (in my case, a MTD device - for
        firmware update).  Two new functions are introduced for this, named
        tftpget_cb and tftpput_cb. They are just made of most of the
        existing code.  The previously existing tftpget/tftpput functions
        are now wrappers on the new ones, with callbacks that read/write
        from files, so my modifications are backwards compatible with
        existing applications, eg the associated nsh commands don't need to
        be changed.  From Sebastien Lorquet.

    * Wireless Utilities: apps/wireless:

      - apps/wireless/bluetooth/btsak:  Added a Bluetooth debug tool.

Bugfixes.  Only the most critical bugfixes are listed here (see the
ChangeLog for the complete list of bugfixes and for additional, more
detailed bugfix information):

    * Core OS:

      - sched/sched: Fix a deadlock in SMP mode.  Two months ago, I
        introduced sched_tasklist_lock() and sched_tasklist_unlock() to
        protect tasklists in SMP mode.  This change works well for HTTP
        audio streaming aging test with lc823450-xgevk.  However, I found a
        deadlock in the scheduler when I tried similar aging tests with DVFS
        autonomous mode where CPU clock speed changed based on cpu load. In
        this case, call sequences were as follows.  To avoid this deadlock,
        I added sched_tasklist_unlock() when calling up_cpu_pause() and
        sched_addreadytorun(). Also, added sched_tasklist_lock() after the
        call.  Also added critical sections to lib_filesem.c, mm_sem.c, and
        net_lock.c for SMP for SMP.  From Masayuki Ishikawa.
      - sched/sched:  Change ordering of round-robin time slice check
        (sched_process_scheduler()) and processing of wdog timers
        (wd_timer()).  wd_timer()'s callback function can change current
        running task and, hence, must be done after the time slice check.
        The time slice check will decrement the currently running task's
        time slice allotment.  If such a context switch occurs, then the
        newly started task will lost one could of that allotment before it
        even has a chance to run.  From EunBong Song.

    * File System/Block and MTD Drivers:

      - fs/fat: In fs_stat(), when stat'ing the root directory, avoid
        calculating the address of the root directory entry.  The
        calculation is bogus (but not harmful) because the root directory
        does not have a directory entry.  Noted by Boris Astardzhiev.
      - fs/fat:  Avoid calculating the bogus directory entry address for
        the FAT root directory (since it has no directory entry).  This
        change should have no effect, other than making the logic clearer.
        From Boris Astardzhiev.
      - fs/mount:  Fix wrong size reported by df -h.  Reason is that size
        in bytes is calculated always on uint32_t types and cards bigger
        than 4GB will overflow uint32_t type. Solution is to use uint64_t
        where possible.  From Michal Lyszczek.
      - fs/smartfs:  Fix a hardfault in SmartFS.  Problem occurred when
        opening a file with O_CREAT (only) when the file arelready exists
        but has a size of zero.  From Michal Lyszczek.
      - fs/vfs:  Fix negative errno set in fs_open.c  From Michal Lyszczek.
      - drivers/mtd:  Fixed a W25 driver w25_cacheflush sector bug.  From
        lihaichen.
      - drivers/mtd:  mtdconfig_register() returned OK instead of -ENOMEM on
        failed allocation.  From Michal Lyszczek.

    * Graphics/Display Drivers:

      - drivers/lcd/ft80x:  ACTIVE host command appears to be formatted
        differently than other host commands; Fix ROM CHIPID.  Appears to
        be big-ending, BCD.  Fix some compile issues when debug features
        are enabled.
      - drivers/lcd/ft80x:  Fix a typo that caused the driver to fail to
        recognize the ft801 chip version. From Gregory Nutt.
      - Review all board implementations of board_lcd_initialize().  The
        NuttX convention is that all internal functions that return errors
        as an 'int' must return a negated errno value on failure and a non-
        negative value on success.  Most were right but eight of them had
        cloned logic that returns 1 on success and zero on failure. both
        of which are interpreted as success by the caller since they are
        non-negative.

    * Networking/Network Drivers:

      - net/tcp:  Fixed problem with send() return value when using
        nonblocking I/O over buffered tcp socket  From Dmitriy Linikov.
      - net/sixlowpan:  Fix a nasty, byte-ordering/endian-ness problem.
        The root cause has been found and corrected.  And a half dozen
        or so bandaid fixes were reverted.
      - net/sixlowpan:  Preserve big-endian (network order) when
        uncompressing address.  From Anthony Merlino.
      - net/sixlowpan: TCP send should have PSH and ACK flags set when
        sending.  This matches the standard network (Ethernet) TCP send
        logic.  From Anthony Merlino.
      - net/udp:  Fix several issues using connected UDP sockets:  sendto()
        should not accept an address.  Normally send() should be used with
        connect UDP sockets instead.  recvfrom() is no longer necessary.
        recvfrom() and poll() should not reset to accept any addresses but
        should, instead, only accept inputs and events from the connected
        remote peer.  On of these issues was noted by ???
        <liguiding@pinecone.net>.  Changes were made as summarized here:
        http://www.masterraghu.com/subjects/np/introduction/unix_network_programming_v1.3/ch08lev1sec11.html
        From Gregory Nutt.
      - net/udp: Resolve race condition in connection-less UDP sockets with
        read-ahead buffering.  In connection-mode UDP sockets, a remote
        address is retained in the UDP connection structure.  This
        determines both there send() will send the packets and which packets
        recv() will be accepted.  This same mechanism is used for
        connection-less UDP sendto:  A temporary remote address is written
        into the connection structure to support the sendto() operation.
        That address persists until the next recvfrom() when it is reset to
        accept any address.  When UDP read-ahead buffering is enabled,
        however, that means that the old, invalid remote address can be left
        in the connection structure for some time.  This can cause read-
        ahead buffer to fail, dropping UDP packets.  Shortening the time
        between when he remote address is reset (i.e., immediately after the
        sendto() completes) is not a solution, that does not eliminate the
        race condition; in only makes it smaller.  With this change, a flag
        was added to the connection structure to indicate if the UDP socket
        is in connection mode or if it is connection-less.  This change
        effects only UDP receive operations:  The remote address in the UDP
        connection is always ignored if the UDP socket is not in connection-
        mode.  No for connection-mode sockets, that remote address behaves as
        before.  But for connection-less sockets, it is only used by sendto().

    * Wireless/Wireless Drivers:

      - drivers/wiresless/ieee80211:  Correct some initialization problems
        with BCM43362 chip.  From hhuysqt.
      - drivers/ieee802154/xbee:  Added a timeout to send logic to handle
        case where XBee module fails to respond to a Transmit request with
        a Transmit Status  From Anthony Merlino.

    * Common Drivers:

      - Per OpenGroup.org, syslog -- and, hence, nonstandard vsyslog, and
        debug wrappers -- does not return a value.  Rename _vsyslog to
        nx_vsyslog.  Use internal nx_vsyslog in the few cases where a
        return value is required.
      - drivers/leds:  Fixes RGB LED issues caused by uninitialized memory
        with CONFIG_RGBLED_MULTICHAN.  The uninitialized pwm_info_s struct
        caused a rogue channel to be started causing errors in the pwm
        driver  From Anthony Merlino.
      - drivers/sensors/lis2dh:  Clear INT1 at SNIOC_WRITE_INT1THRESHOLD
        ioctl.  From Jussi Kivilinna.
      - drivers/sensors/sht21:  Changed I2C_TRANSFER return value so that
        it return on zero on success, not the count of bytes transferred.
        From Juha Niskanen.
      - drivers/serial:  Per Matias Edlund:  I recently used the tcflush
        function and found that it failed with ENOTTY. The reason is that
        the TCFLSH case in the function uart_ioctl in the file
        drivers/serial/serial.c does not update the ret value."  On
        success, the TCFLSH IOCTL logic needs to explicitly set the return
        value (ret) to zero.
      - drivers/serial:  Added a timeout to uart_tcdrain().  Even if
        tcflush() is used to discard buffered data, the close() can still
        hang if (a) hardware flow control is enabled, (b) CTS == 1, and
        (c) there is data stuck in the hardware Tx FIFO.  tcflush() does
        not currently clear the MCU serial drivers' hardware Tx FIFOs.
        This is a workaround for that.
      - drivers/sensors:  Fix APDS9960 work queue BUG found by Kyle Lei.
        From Alan Carvalho de Assis.

    * Simulator:

      - arch/sim:  Various fixes necessary to build the simulator under
        MSYS2.

    * ARMv7-R:

      - ARMv7-R:  Corrected several ARMv7-R issues.  From Ivan Ucherdzhiev.

    * Infineon XMC4xxx Boards:

      - XMC4500-Relax:  Call xmc4_spidev_initialize() in xmc4_boot.c.  From
        Alan Carvalho de Assis.

    * NXP/Freescale LPC17xx Drivers:

      - LPC17xx USB: Fix USB device endpoint allocation bookkeeping.  From
        Michael Jung.
      - LPC17xx USB:  Freeing endpoints should be set the same allocations
        as when endpoint was allocated.
      - LPC17xx USB:  Fix loss of RX initiatives.  USB bulk endpoints are
        double buffered on LPC17xx MCUs.  This means that up to two packets
        might be received on an OUT endpoint that can not be handled
        immediately if the receive request queue is empty.  Thus,
        rxpending must be a counter not a boolean flag.  From Michael Jung.

    * NXP/Freescale Kinetis Drivers:

      - Kinetis USG:  USB device fixes:  Use correct CONFIG OTG control,
        Fix interrupt storm when cable is disconnected.  The DM, DP state
        were incorrect because the pulldowns were not enabled.  Also the
        pending asynchronous resume interrupt needed to be re-armed after
        the suspend is in effect. This is now done in the isr.  From David
        Sidrane.
      - Kinetis Serial:  In kinetis_lowputc.c, fix esBRFA calculation
        effecting baudrate.  Previous BRFA was not cleared and or-ed into
        new BRFA, hence, buadrate was wrong.  Where Baud Rate Fractional
        Divisor (BRFD) UART baud rate = clock / (16 * (SBR + BRFD)).  From
        David Sidrane.
      - Kinetis Serial:  In kinetis_lowputc.c, fixed parity settings.
        Kinetis UART must be placed in 9 bit mode (M=1) with when 8 bit data
        with parity is required. If left in 8 bit mode (M=0) with parity
        then D7 of the TX/RX register becomes parity bit.  Hence what is
        called 9-bit or 8-bit Mode Select is a misnomer.  8 bit mode when
        parity is enabled is really 7 bit with parity.  From David Sidrane.

    * NXP/Freescale Kinetis Boards:

      - configs/teensy-3.x:  Remove CONFIG_USBDEV_DUALSPEED from the usbnsh
        configuration.  Hardware supports only FS.

    * NXP i.MX6 Drivers:

      - i.MX6:  Bring in a few i.MX6 fixes that were committed to similar
        files for the i.MX RT.

    * STMicro STM32:

      - STM32 F3:  Problem: stm32f30xx hangs waiting for LSE to initialize.
        Reason for hang is that operation of setting LSE_ON does not take
        effect because there is no clock on PWR peripheral.  This is
        initialized later in the code  From Michal Lyszczek.

    * STMicro STM32 Drivers:

      - STM32 and STM32 L4 1WIRE:  In 1wire driver, do not write useless
        WRITEBIT zero return value to const buffer  From Juha Niskanen.
      - STM32 HRTIM:  Fixed capture_get function,.  From raiden00pl.
      - STM32 F3 ADC:  Fixed bug in RCC reset logic that resets ADC1
        configuration when both ADC1 and ADC2 are in use  From Mateusz
        Szafoni.
      - STM32 Ethernet:  In case of PHY failure, usually because of the
        lack of 25/50 MHz REFCLK input, the Ethernet block would lock up
        in a while loop waiting for readiness, which will never happened.
        This prevented the board from starting at all in the case of a PHY
        failure.  This commit adds a retry loop to avoid bricking the board
        if the Ethernet block is unable to start.  From Sebastien Lorquet.
      - STM32 F7 SDMMC:  Added support for the second SDMMC device.  The
        second SDMMC device was already supported but the clock was never
        enabled.  This fixes that.  From William Douglas.
      - STM32 Serial:  Fix UART glitch when lowputc is enabled.  From
        Simon Piriou.
      - STM32 USB:  Skip recipient check for descriptor related
        requests  From Simon Piriou.

    * TI Tiva Drivers:

      - Tiva ADC: Fix compilation errors on Tiva ADC code when ADC is
        enable.  From Vinicius Maciel.
      - Tiva Serial:  Allow building of Tiva platform with no serial
        console.  From Dmitry Sharihin.

    * C Library/Header Files:

      - lib/libc/netdb:  Fixed boundary conditions in dns_recv_response().
        Fixed typos in include/nuttx/net/dns.h.  From Masayuki Ishikawa.
      - libs/libc/modlib:  Fixed backward test for an error in
        modlib_verify.c.

    * Build System:

      - Makefiles:  Eliminate the spurious errors reported by 'make
        savedefconfig'.
      - Makefile(s):  There is a sort command in the 'make savedefconfig'
        file.  I found that sort behaves differently on different platforms
        based on the environment variable LC_ALL.  Now, Makefile.unix will
        force LC_ALL=C just for the sort command so that we can all generate
        equivalent defconfig files.
      - Makefile(s):  The clean_context target needs to invoke a
        corresponding clean_context target in the apps/Makefile in order to
        remove linkages.  From Gregory Nutt.
      - LibTargets.mk, tools/Config.mk:  Drop executable bit on installed
        libraries. The rules to install libraries under lib/ were modified
        to use mode 0644 instead of the default 0755.  From Andrey Zabolotnyi.

    * Examples/Tests: apps/examples:

      - apps/examples/ft80x:  Fix some size calculations.  Added option to
        disable primitive tests. just too boring to have to watch over and
        over again. Fix a typo in backlight fade logic; Fix error in
        formatted display light debug dump output.
      - apps/examples/ft80x:  Text is handled by the coprocessor and, hence,
        must use RAM_CMD, not RAM_DL.
      - apps/examples/ft80x:  Fix some errors in co-processor demos.  Correct
        an error in the spinner demo.
      - apps/examples/nsh and posix_spawn:  Must not call exec_setsymtab()
        directly.  That is a non-POSIX internal OS interface.
      - apps/examples/ostest:  Do not call AIO test without
        CONFIG_EXAMPLES_OSTEST_AIO  From Juha Niskanen.
      - apps/examples/smps:  Fix typos in Kconfig.  All power, voltage,
        current values were strings with no default.  I assume they should
        be 'int' with what default?.
      - apps/examples/smps:  Fixes in some printf and in Kconfig  From
        Mateusz Szafoni.
      - apps/system/zmodem:  Fix Makefile.host.  It was broken when zmodem.h
        was moved to apps/include/system.  Fix an incompatibility with the way
        that CRCs are calculated.

    * System Utilities: apps/system:

      - apps/system:  Applications should use the standard clock() interface,
        not the internal NuttX clock_systimer() interface.
      - apps/system/stackmonitor:  Fix comparison between pointer and zero
        character constant.  From Juha Niskanen.

    * Network Utilities: apps/netutils:

      - apps/netutils/netlib:  Various fixes needed to get a clean netlib
        build with Bluetooth only.

    * Wireless Utilities: apps/wireless:

      - apps/wireless:  Applications should use the standard clock()
        interface, not the internal NuttX clock_systimer() interface.

NuttX-7.26 Release Notes
------------------------

The 126th release of NuttX, Version 7.26, was made on September 8, 2018,
and is available for download from the Bitbucket.org website.  Note
that release consists of two tarballs:  nuttx-7.26.tar.gz and
apps-7.26.tar.gz.  These are available from:

    https://bitbucket.org/nuttx/nuttx/downloads
    https://bitbucket.org/nuttx/apps/downloads

Both may be needed (see the top-level nuttx/README.txt file for build
information).

Additional new features and extended functionality:

    * Core OS:

      - General: Eliminate use of the non-standard type systime_t and
        replace it the equivalent, standard type clock_t  From Gregory Nutt.
      - General:  Replace non critical PANIC with DEBUGPANIC to save the
        code space From Xiang Xiao.
      - General: Replace all ASSERT with DEBUGASSERT to save the code
        space  From Xiang Xiao.
      - Initialization:  Add option to mount block device for
        INIT_FILEPATH case.  From anchao.
      - clock():  clock_systimer() is no longer a system interface.  It has
        been replaced with the equivalent, standard interface clock().
        Moved the implementation of clock() from the C library into the OS
        core.  This is necessary because it calls the (now) internal OS
        function clock_systimer().  clock() is now accessed only via a
        system call in certain configurations.  From Gregory Nutt.
      - clock Utilities:  Move clock_timespec_[add|subtract] to
        include/nuttx/clock.h  From Xiang Xiao.
      - Binary Loader:  Add binfmt_initialize().  All binary formats are
        now registered centrally vs. in board-specific logic.  This
        simplifies the usage of the binfmt subsystem.  From Xiang Xiao.
      - Binary Loader:  Reference default symtab name to binfmt  From anchao.
      - mm:  Add mm_heapmember function and reimplement kmm_heapmember base
        on mm_heapmember since this function is very useful if multiple
        heaps exist.  From Xiang Xiao.
      - mm:  Add {kumm/kmm}_calloc API.  Add calloc API for manage user
        memory and kernel memory in Flat Build/Kernel Build without kernel
        heap.  From zhuyanlin.
      - pthreads:  Add support static pthread stack.  Add standard
        pthread_attr_setstack() and pthread_attr_getstack().  In all cases
        where the stack is released, add check to see which allocator must
        be used to free the stack:  The user or the kernel allocator.  From
        xuanlin.
      - Semaphores:  Apply the semaphore wait function
        nxsem_wait_uninterruptible().  This function is a wrapped version
        of nxsem_wait() that is uninterruptible and convenient for use.
        From liuhaiyang.
      - Signals:  Add default signal action to SIGKILL.  From ligd.
      - Signals:  Update the signal default action logic to support
        sigaction().  signaction() must be able to handle and input action
        of SIG_DFL to setup the default signal action; it mast also return
        SIG_DFL it is replacing the default action.  From Gregory Nutt.
      - Signals: Default Signal Actions.  Change some types to
        superficially simplify.  Add configuration options to enabled
        default signal behaviors on a per-signal basis.  I don't think
        users are prepared for SIGALRM to terminate the task (which is the
        correct default behavior if you don't change it).  Extend the
        implementation of default signals so that it is totally table
        driven and extensible by simply mondifying the content of const
        tables.  From Gregory Nutt.
      - Signals:  Add support for SIGINT in addition to SIGKILL.
      - Signals:  Add logic and an interface to determine if a signal can
        be caught or ignored.  sigaction now correctly returns EINVAL on
        any attempt to catch or ignore such signals (only SIGKILL for now
        and only if CONFIG_SIG_DEFAULT=y).  From Gregory Nutt.
      - Signals:  Add support for default signal actions for SIGSTOP,
        SIGSTP, and SIGCONT.  Add procfs support to show stopped tasks.
        From Gregory Nutt.
      - Signals:  Add nxsig_action() to solve a chicken and egg problem:
        We needed to use sigaction to set default actions, but sigaction()
        would refuse to set actions if the default actions could not be
        caught or ignored.  From Gregory Nutt.
      - Signals:  Add configuration option to selectively enabled/disable
        default signal actions for SIGSTOP/SIGSTP/SIGCONT and SIGKILL/SIGINT.
      - Signals:  If a task/thread was already blocked when
        SIGSTOP/SIGSTP was received, it will restart in the running state.
        It will appear that to the task/thread that the blocked condition
        was interrupt by a signal and returns the EINTR error.  From
        Gregory Nutt.
      - Signals:  Update signal default STOP action.  If waitpid was
        called with the WUNTRACED then wake up waitpid().  From Gregory
        Nutt.
      - IRQs:  Monitor the IRQ execution time.  This is very useful for
        measuring the interrupt latency.  From Xiang Xiao.
      - IRQ Dispatch:  Add support interrupt chains in NuttX.  IRQ chain is
        very useful in these cases:  (1) Multiple hardware connect to the
        same request line(e.g. PCI), (2) Need multiple driver to support
        one hardware block (like Linux MFD)  From zhuguangqing.
      - Work Queue:  Modify high priority work queue to support multiple
        threads.   From ligd.
      - System Calls:  Add support for getpeername() and get_sockname()
        system calls.  From Gregory Nutt.
      - System Calls:  svcall/sycall logic needs to get the ucontext
        argument from R4 instead of stack since all syscall parameters pass
        from registers in syscall.h  From Xiang Xiao.
      - CPU Load Measurement:  Support the CPU load measurement using
        timer_lowerhalf_s interface  From Xiang Xiao.
      - Assertions: Change CONFIG_BOARD_RESET_ON_CRASH to
        CONFIG_BOARD_RESET_ON_ASSERT, arch/: Implement call to
        board_reset() if in all implementations of up_assert() when
        CONFIG_BOARD_RESET_ON_ASSERT=y.  From Xiang Xiao.
      - boardctl():  Add support for board_app_finalinitialize() From ligd.
      - Architecture Interface:  Add prototype for an architecture-specific
        up_trigger_irq function.  From dongjianli.
      - Architecture Interface:  Add the garbage collection hook so each
        architecture can do custom memory cleanup if necessary.  From Xiang
        Xiao.
      - Architecture Interface:  Add architecture-specific prototypes for
        conversions between physical and virtual address.  From ligd.

    * File Systems/Block and MTD Drivers

      - ProcFS:  Add support for a procfs entry that will permit examining
        the environment of any task.  From Gregory Nutt.
      - ProcFS:  Add support for proc/self/, a convenient way for getting
        information about the currently running task.  From Gregory Nutt.
      - HostFS:  Add support for open() append mode  From anchao.
      - HostFS:  Add ftruncate support.  From Xiang Xiao.
      - HostFS:  Remove ARCH_SIM dependence since other architectures
        (e.g., arm semihosting) could support hostfs too  From Xiang Xiao.
      - HostFS:  Support remote directory names without a trailing '/'
        From ligd.
      - HostFS:  Add re-try when hostfs mount() fails  From ligd.
      - NFS:  Update NFS client mount to VER3  From zhangyuan7.
      - Partitions:  Add PTABLE parser fs/partion:  Add a partition parser
        framework fs/driver/fs_blockpartition.c:  Add
        register_blockpartition for block partition  From Xiang Xiao.
      - MTD:  Add gd25 driver  From wangyanjiong.
      - MTD:  In MTD partitions, copy the partition name to internal
        buffer so that the caller can free the name argument  From Xiang
        Xiao.
      - MTD:  Support initialization of an FTL block device with a custom
        name  From Xiang Xiao.
      - MTD:  FTL:  Reduce size of stack buffer from 64 to a maximum size
        as determined from NAME_MAX.  From Gregory Nutt.
      - VFS poll():  Send poll() notification when the Tx buffer is flushed
        From ligd.
      - VFS fstat():  Add file_fstat() function for internal OS use. From
        ligd.
      - VFS fcntl():  Add file_fcntl, psock_fcntl, and psock_dupsd for use
        within the kernel.  From Xiang Xiao.
      - VFS dup2():  Addpsock_dupsd for use within the kernel.  From Xiang
        Xiao.
      - VFS poll():  Add poll use in kernel space.  From dongjianli.
      - VFS select():  Make select be more consistent with Linux man page:
        'The timeout ... Some code calls select() with all three sets
        empty, nfds zero, and a non-NULL timeout as a fairly portable way
        to sleep with subsecond precision.'  From anchao.

    * Networking/Network Drivers:

      - Sockets:  Add getpeername() support  From ligd.
      - sockopt():  Move psock check from [get|set]sockopt to
        psock_[get|set]sockopt From Xiang Xiao.
      - getsockname():  Add psock_getsockname function  From Xiang Xiao.
      - Netlink Sockets:  This brings in a fragmentary, experimental
        implementation of NETLINK sockets.  There is not too much to that
        socket support on this initial commit, just the netlink socket
        framework.  However, I decided to bring it into master because
        there is a enough that I would not want to lose what is in place.
        And since it is dependent on CONFIG_EXPERIMENTAL, its presence on
        master should be innocuous.  From Gregory Nutt.
      - Interface Indexes:  Add driver interface index support.  Add
        implementation of if_nametoindex() and if indextoname().  Raw
        AF_PACKET sockets now depend on CONFIG_NETDEV_IFINDEX.  Add syscall
        support for if_nametoindex() and if_indextoname(). Includes an
        algorithm to prevent an interface index from being reused until all
        network interfaces have by assigned once.  The prevents removable
        devices from being removed, unregistered and re-installed,
        re-registered and keeping the same interface index.  From Gregory
        Nutt.
      - Driver Interface:  Add devif_loopback() to check the loopback
        case where a packet is being sent to itself.  Modify the net driver
        to call this function in this case.  This function will simply
        re-inject the packet back into the network and the network driver
        will not put anything on the wire.  From Xiang Xiao.
      - Network Devices:  Remove all references to CONFIG_NET_USER_DEVFMT.
        That feature is now unconditionally enabled.  This was done because
        (1) the feature does not require very much additional memory, and
        (2) it causes confusion in the configuration due to the additional
        complexity.  Any network drivers that fail to zero the device
        structure interface name field (d_ifname) because calling
        netdev_register() will, however, get a nasty surprise.  From
        Gregory Nutt.
      - Network Devices:  Add support for Microchip LAN91C111 driver  From
        Xiang Xiao.
      - Network Devices:  netdev_findby_ipv[4|6]addr return
        netdev_default() as last resort but don't return loopback device
        if another network device is in the UP state.  From Xiang Xiao.
      - Network Device IOCTLs:  Add si_ioctl callback and net_ioctl_arglen
        so usrsock could forward the ioctl to the remote end/  From
        dongjianli.
      - IPv6:  Rename g_ipv6_allzeroaddress with the more meaning
        g_ipv6_unspecaddr since the all-zero address is the IPv6
        unspecified address (sometime IN6_ADDR_ANY).  Replace more inline
        tests for IPv6 multicast with common net_is_addr_mcast() macro.
        From Gregory Nutt.
      - ARP:  arp_find() now checks if the target IP belongs to one of the
        local network devices.  From Xiang Xiao.
      - ARP:  Make the function arp_find() thread-safe.  It now returns a
        copy of the MAC address from the ARP table entry, rather than a
        potentially unstable reference to the ARP table entry.  From
        Gregory Nutt.
      - TCP:  Re-work of TCP receive window size algorithm.  The new logic
        is based only on the ability to buffer TCP read-ahead data. From
        Gregory Nutt.
      - UDP:  Add support for the UDP_BINDTODEVICE protocol socket option
        From Sebastien Lorquet.
      - Slip:  Uncomment the prompt of NET_SLIP_PKTSIZE in Kconfig file.
        From Xiang  Xiao.
      - USRSOCK:  Combine some the duplicated logic.  From Xiang Xiao.
      - USRSOCK:  Optimize option dependence  From Xiang Xiao.
      - USRSOCK:  Add the listen/accept/getpeername/ioctl support  From
        dongjianli.

    * Other Common Device Drivers:

      - Analog DAC:  Add driver for digital to analog converter DAC7571.
        Nucleo-L422KC:  Add support for a connect DAC7571 converter. From
        Daniel Pereira Carvalho.
      - Audio Interface:  Change member samp of apb to pointer so driver
        can customize sample buffer allocation  From ZhongAn.
      - Audio Interface:  Add ioctl cmd 'AUDIOIOC_SETBUFFERINFO' so user
        space could config the buffer  From ZhongAn.
      - Audio Interface:  Add hardware format support  From anchao.
      - I2S Interface:  Add i2s_rxchannels and i2s_txchannels methods to
        the I2S lower half interface.  From ZhongAn.
      - Audio:  Move the I2S character driver to a dedicated folder. From
        Xiang Xiao.
      - Audio:   Add audio_i2s device driver.  From ZhongAn.
      - Audio:  Add the composite audio driver  From Xiang Xiao.
      - Crypto:  Move dev_urandom.c into new crypto folder.  From Xiang
        Xiao.
      - GPIO driver:  Add gpio_pin_unregister function to GPIO driver
        driver/ioexpander:  Add pinset struct to GPIO driver for interrupt
        pins larger than 64.  Initialize pintype/inttype when registering
        ioexpander device.  Add SETPINTYPE ioctl command to the GPIO
        driver. From zhuyanlin.
      - I2C Interface:  Add a definition to distinguish a new START of
        messages from a repeated start.  No lower-half I2C drivers actually
        implement this new flag bit, however. In I2C write/read logic use
        new repeated START definition where appropriate.  Rename
        I2C_M_NORESTART to I2C_M_NOSTART since it may be used in other
        contexts than a repeated start.  Add comments to clarify setup for
        repeated start.  From Gregory Nutt.
      - I2C:  Add the standard speed macros.  From dongjiuzhu.
      - Leds:  Add support to MAX7219 to control 7-segment displays.  From
        Alan Carvalho de Assis.
      - Power: PM: Add pm_stay and pm_relax function so special apps(e.g.
        mediaplayer) could disable suspend during playback much like linux
        kernel counterpart  From Xiang Xiao.
      - Power:  PM: Add pm_querystate function  From zhuguangqing.
      - Power: PM: Don't update the power state in work thread: (1)
        Simplify the code logic and remove the work queue dependence, (2)
        Power calculation is too simple to delay into the work queue From
        Xiang Xiao.
      - Power: PM: Decrease the power state in the reverse order.  Since
        the child driver need power off before parent driver.  From
        zhuguangqing.
      - Power: PM:  Make power manager service available as soon as
        possible:  (1) Initialize g_pmglobals at the definition, (2) skip
        hold the lock if OS isn't ready  From Xiang Xiao.
      - Power: PM:  Add PM_RESTORE to notify driver that device exit WFI
        so the driver could restore state.  For example, WDT may stop
        counting before enter low power state and restore the counting
        again in PM_RESTORE notification  From zhuguangqing.
      - Power: PM:  Add timer to decrease PM level automatically.  From
        ligd.
      - PTYs:  Add support so that a PTY can poll for both IN/OUT event
        simultaneously.  From ligd.
      - PWM:  Move pwm.c into pwm folder  From Xiang Xiao.
      - RTC Interface:  Extend struct rtc_time by adding.  From Xiang
        Xiao. tm_nsec if RTC supports hiresolution time.  From Xiang Xiao.
      - Sensors:  Add support for Telair T6713 carbon dioxide sensor.  From
        Juha Niskanen.
      - Sensors:  Add support for LSM303AGR and LSM6DSL sensors  From
        DisruptiveNL.
      - Sensors:  Add driver for DHTxx sensor.  From Ouss4.
      - syslog:  Enable a partial, crippled version of syslog_flush();
        Call syslog_flush() from assertion handling logic of all
        architectures.  From Gregory Nutt.
      - syslog:  Channel configuration.  Decouple SYSLOG_SERIAL_CONSOLE and
        ARCH_LOWPUTC.  Since some hardware can output log to the special
        debug channel not serial. From anchao.
      - syslog: Support pre-pending a prefix string to log output if
        enabled.  This very useful to identify which CPU send out the log
        in AMP SoC. From anchao.
      - Serial:  Add Ctrl-C/Ctrl-X support.  From ligd.
      - Serial: Support UART direct write for non console device  From
        xuanlin.
      - Serial:  It is no longer necessary to restrict Ctrl-C handling to
        the FLAT build sched/signal:  Add a new configuration option to
        select signal default actions, separate handling of signal default
        actions from both task startup logic and from the serial TTY
        Ctrl-C logic.  Add a signal set in the group structure to keep
        track of what signals have been set to the default action.  In
        dispatching signals in PROTECTED or KERNEL mode, use this signal
        set to determine if the default signal handler is attached and
        dispatch the signal in kernel mode for the default actions.  From
        Gregory Nutt.
      - Serial:  Integrate new Ctrl-C logic with the ISIG flag in the
        termios c_lflag. From Gregory Nutt.
      - Serial:  Use SIGINT instead of SIGKILL when control-C is pressed.
        From Gregory Nutt.
      - Serial:  Add support for Ctrl-Z.  This works just like the
        recently added Ctrl-C support except that SIGSTP is sent when the
        Ctrl-Z characters is encountered vs. SIGINT.  From Gregory Nutt.
      - 16550 UART:  Add a configuration, analogous to the STM32
        configuration option, to suppress the NuttX standard re-ordering
        for /dev/ttySN for special case of the 16550 UART.
      - 16550 UART:  Add CONFIG_SERIAL_UART_ARCH_MMIO option so the a
        memory mapped device doesn't need to provide uart_getreg() and
        uart_putreg() implementations.
      - 16550 UART: Add stub implementations of DMA-related methods in the
        16550 UART v-table.  From ligd.
      - 16550 UART:  Add serial termios handling  From anchao.
      - 16550 UART:  Support 16550 auto hardware flow control
        drivers/serial/uart_16550.c:  Add configuration option
        CONFIG_16550_SUPRESS_INITIAL_CONFIG.  This is identical to the
        standard configuration in arch/Kconfig
        CONFIG_SUPPRESS_UART_CONFIG, but with scope of only the 16550
        driver.  From Xiang Xiao.
      - syslog: Make timestamp output same as linux kernel.  It's very
        useful if NuttX syslog retarget to Linux syslog. From Xiang Xiao.
      - Timers:  Add maxtimeout method to the struct timer_ops_s interface
        From Xiang Xiao.
      - Timers:  Add a new method to the struct oneshot_operations_s
        interface to get the current time from a oneshot timer driver (if
        it is available from the lower half)  From Xiang Xiao.
      - Timers:  Implement timer arch API on top of timer driver.  From
        Xiang Xiao.
      - Timers:  Implement alarm arch API on top of oneshot driver
        interface.  From Xiang Xiao.
      - Timers:  Implement RTC arch API on top of RTC driver interface.
        From Xiang Xiao.
      - CDC/ECM:  Adds USB device support for CDC/ECM  From Michael Jung.
      - USB Host:  Add support for the Maxim M3421E USB host driver.  Not
        yet fully tested.  From Gregory Nutt.

    * General Architecture-Specific:

      - All architectures:  Make sure the up_irq_enable() is available on
        all architectures.  From Gregory Nutt.

    * Simulation

      - Simulator Configurations:  Add dsptest configuration.  From Mateusz
        Szafoni.
      - Simulator:  In network driver (1) Remove up_comparemac() check for
        matching MAC address. Let's trust that the tap device just return
        the packet which belong to us like other real network device
        hardware. (2) Add network device statistics support.  From Xiang Xiao.

    * ARM:

      - ARM (all):  Add CONFIG_DEBUG_MEMFAULT to Kconfig.  From Masayuki
        Ishikawa.
      - ARM:  (1) Add semihost support for syslog, (2) Add semihost support
        for HostFS  From Gregory Nutt.

    * ARMv6-M:

      - ARMv6-M: Introduce CONFIG_DEBUG_HARDFAULT_INFO to up_hardfault.c
        From Masayuki Ishikawa.

    * ARMv7-M:

      - ARMv7-M:  Removes support for the dedicated vector handling from the
        many older architectures. Only common vectors are now supported.
        From Gregory Nutt.
      - ARMv7-M: Introduce CONFIG_DEBUG_HARDFAULT_INFO to up_hardfault.c
        From Masayuki Ishikawa.
      - ARMv7-M:  Implement SYSTICK timer driver  From Xiang Xiao.
      - Simulator:  Add loadable demo for arch sim.  From anchao.
      - ARMv7-M:  Add logic to trigger ARMv7-M interrupts and exceptions.
        From Gregory Nutt (from sample logic by Xiang Xiao).
      - ARMv7-M:  Add NVIC definitions needed by up_trigger_irq().  From
        Gregory Nutt.

    * ARMv7-R:

      - ARMv7-R:  Add general interrupt controller.  This is based on
        ARMv7-A gic controller code.  From EunBong Song.
      - ARMv7-R:  Add invalidate dcache in arm_head.S.  From EunBong Song.

    * Infineon XMC4xxx Drivers:

      - XMC4 GPIO:  Add a specific bit encoding to GPIO driver for
        opendrain GPIO pin.  From Alan Carvalho de Assis.

    * Infineon XMC4xxx Boards:

      - XMC4500-Relax:  Add support to MAX6675 on XMC4500-Relax board.
        From Alan Carvalho de Assis.

    * Microchip PIC32MX Boards;

      - PIC32MX:  Update some PIC32MX configurations so that either the
        MPLAB or Penguino toolchains may be used.  From Gregory Nutt.

    * Microchip/Atmel SAMD2x/L2x:

      - SAMD2x/L2x:  Rename all usage of samdl/SAMDL to samd2l2/SAMD2L2 to
        make room in the name space for samd5e5/SAMD5E5  From Gregory Nutt.

    * Microchip/Atmel SAMD5x/E5x:

      - SAMD5x/E5:  Add a port to the SAMD5x/E5x MCU family.  From Gregory
        Nutt.

    * Microchip/Atmel SAMD5x/E5x Drivers:

      - SAMD5x/E5x SPI/I2C:  Bring in untested SPI and I2C drivers from
        SAMD2L2.  From Gregory Nutt.
      - SAMD5x/E5x DMA:  Leverage the SAMD2L2 DMA controller.  From Gregory
        Nutt.
      - SAMD5x/E5x USB:  Bring the SAMDL2 USB driver into the SAMD5E5
        port.  From Gregory Nutt.

    * Microchip/Atmel SAMD5x/E5x Boards:

      - Metro M4:  Add support for the Adafruit Metro M4 board.  From
        Gregory Nutt.
      - Metro M4:  Add an option to build the Metro M4 image to run out of
        SRAM.  This ought to be a safer and quicker way to do the initial
        bring-up (having bricked the first Metro M4 due to a bad FLASH
        image).  From Gregory Nutt.
      - Metro M4:  Add a configuration option to use OSCULP32K instead of
        XOSC32K.  From Gregory Nutt.
      - Metro M4:  After some final fixes related to the SERCOM console,
        the basic NSH configuration appears fully functional.  From
        Gregory Nutt.
      - Metro M4:  Verify the CMCC and enable it by default in the NSH
        configuration.  From Gregory Nutt.

    * Microchip/Atmel SAMv7 Drivers:

      - SAMv7 CAN:  Add ability for CAN BUS_OFF autorecovery according
        ISO11898-1:2015.  With this change we added an ioctl for triggering
        the autorecovery sequence for BUS_OFF to the CAN-driver and the
        SAMV7 low-level driver.  According the datasheet: If the device
        goes Bus_Off, it will set MCAN_CCCR.INIT of its own accord,
        stopping all bus activities. Once MCAN_CCCR.INIT has been cleared
        by the processor (application), the device will then wait for 129
        occurrences of Bus Idle (129 * 11 consecutive recessive bits)
        before resuming normal operation. At the end of the Bus_Off
        recovery sequence, the Error Management Counters will be reset.
        During the waiting time after the resetting of MCAN_CCCR.INIT, each
        time a sequence of 11 recessive bits has been monitored, a Bit0
        Error code is written to MCAN_PSR.LEC, enabling the processor to
        readily check up whether the CAN bus is stuck at dominant or
        continuously disturbed and to monitor the Bus_Off recovery
        sequence. MCAN_ECR.REC is used to count these sequences.  From
        Frank Benkert.

    * NXP Freescale i.MX RT Drivers:

      - i.MXRT RTC:  Add support for the i.MXRT RTC.  This is code complete
        (with limited features and options) but untested. The HPRTC is
        functional.  However, if the LPSRTC is enabled, then there is a
        hang during LPSRTC initialization.  It appears that there is some
        problem in providing clocking and initializing the LPSRTC domain.
        From Gregory Nutt.
      - i.MXRT SNVS:  Add trivial SNVS from Rev 1. of the Reference Manual.
        From Gregory Nutt.
      - i.MXRT LSPI:  IMXRT1050 LPSPI register and bit definitions added.
        From Ivan Ucherdzhiev.
      - i.MXRT Serial: IMXRT1050 LPUART TERMIOS support added.  From Ivan
        Ucherdzhiev.

    * NXP Freescale i.MX RT Boards:

      - IMXRT1050-EVK:  Add knsh configuration. PROTECTED mode NSH build.
        From Gregory Nutt.

    * NXP Freescale Kinetis:

      - Kinetis: Add DMA support.  From David Sidrane.

    * NXP Freescale Kinetis Drivers:

      - Kinetis:  Use circular DMA as an option to augment the RX FIFOs in
        the Serial driver.  From David Sidrane.

    * NXP LPC54xx:

      - LPC54xx:  The LPC54608 can only run at a maximum frequency of
        180Mhz.  This configuration requires uses the clk_in, external
        crystal clock, to drive the PLL.  When that input was selected, the
        board bootup failed waiting for the PLL to lock.  After referring
        the driver from NXP, we should turn on power sources for the ext
        clock if system pll input select clk_in.  NOTE that the LPC54628
        did not require this step... perhaps because the system oscillator
        power was already enabled.  From kxjiang.
      - LC823450:  Add support for mpu and userspace LC823450-XGEVK: Add
        kostest PROTECTED build LC823450-XGEVK: Add knsh PROTECTED build
        From Masayuki Ishikawa.

    * NXP LPC54xx Boards:

      - Lpcxpresso-LPC54628:  Update lvgl board config to use the new
        version  From Alan Carvalho de Assis.

    * On Semi LPC23450 Drivers:

      - LC823450 Bluetooth:  Add lc823450 Bluetooth support.  From Masayuki
        Ishikawa.
      - LC823450 I2S:  Add tx start threshold to lc823450_i2s.c In
        addition, lc823450_i2s_send() now accepts byte-aligned stream.
        From Masayuki Ishikawa.
      - LC823450 SPI:  Add SPI flash driver for lc823450.  NOTE: Only bus
        accelerator mode is supported.  From Masayuki Ishikawa.
      - LC823450:  Change C-Buffer under-level control.  The under-level
        setting was changed from 1KB to 55KB.  In previous implementation,
        the setting can be changed by the tx threshold but it is fixed at
        startup. Also, check write size and adjust alignment if needed.
        From Masayuki Ishikawa.

    * On Semi LPC23450 Boards:

      - LC823450-XGEVK:  Add loopback test for digital MIC on lc823450 via
        i2schar driver.  From Masayuki Ishikawa.
      - LC823450-XGEVK:  Add lc832450 elf test.  From Masayuki Ishikawa.
      - LC823450-XGEVK:  Add posix_spawn configuration  From Masayuki
        Ishikawa.

    * STMicro STM32:

      - STM32 L4:  Add initial support to STM32L4+ chips  From Juha Niskanen.
      - STM32 H7:  A partial port to the STMicro STM32H7 by Simon Laube was
        brought in from the PX4 repositories.  Numerous changes were
        make(by Mateusz Szafone).  The basic STM32 H7 NSH configuration is
        now functional, thanks to Mateusz Szafoni.

    * STMicro STM32 Drivers:

      - STM32 F0, F1-F4, F7, L4, H7:  Added Single Wire Kconfig variable.
        From David Sidrane.
      - STM32 DAC:  Set OUTEN bit for DAC1CH2 and DAC2CH1 power/motor.
        Direction parameter is now int8 + add overload fault.  From Mateusz
        Szafoni.
      - STM32 F1-F4 ADC:  Allow multiple channels without DMA on
        STM32L15XX.  From Juha Niskanen.
      - STM32 F1:  Add FLASH register definitions for F1 parts that have
        dual banked FLASH.  From Dmitriy Linikov.
      - STM32 F2:  Added progmem interface support for STM32 F2 From
        Dmitriy Linikov.
      - STM32 F4:  Ports STM32 LTDC and STM32 DMA2D to use the
        framebuffer interface  From Marco Krahl.
      - STM32 F7:  This change ports Marco Krahl's STM32F4 framebuffer
        overlays for the LTDC and DMA2D into the STM32F7.  That driver was
        same as the STM32 F4 driver.  From Gregory Nutt.
      - STM32 F7:  Port input capture from stm32.  From Juha Niskanen.
      - STM32 F7 FLASH:  Ported the STM32 F2/F4 driver to the STM32 F7
        platform.  From Evgeniy Bobkov.
      - STM32 F7 SDMMC:  Add SDIO card support to SDMMC driver.  From
        Ramtin Amin.
      - STM32 F7 Serial:  Previous logic would invalidate the data cache as
        each byte was read from the DMA buffer.  This change adds logic to
        invalidate the data cache less frequently by monitoring the state
        of the Rx DMA buffer cache coherency and invalidating only regions
        as necessary.  From Evgeniy Bobkov.
      - STM32 F7:  Add up_stackcheck.c  From Daniel Agar.
      - STM32 F7:  Port the low-level PM functions to STM32 F7. From Juha
        Niskanen.
      - STM32 L4:  STM32L4 has fetchadd and testset  From Juha Niskanen.
      - STM32 L4: Added custom pin mapping for STM32L4X2XX processors.
        From Daniel P. Carvalho.
      - STM32 L4 FLASH:  stm32l4xrxx: allow board to override flash wait
        states  From Juha Niskanen.
      - STM32 L4:  Some updates to analog peripherals ADC, COMP and DFSDM
        for STM32L4XR  From Juha Niskanen.
      - STM32 L4:  Add getstatus and getperiod() method to the timer
        driver (includes coding standard changes made prior to commit)
        From Goden Freemans.
      - STM32 H7:  Remove old references to RXDMA.  Add configuration
      - STM32 H7:  Remove old references to RXDMA.  Add configuration
        option to select the Rx FIFO threshold level.  From Gregory Nutt.

    * STMicro STM32 Boards:

      - STM32F103 Minimum:  Add blackpill LED support  From Russ Webber.
      - Viewtool-STM32F107:  Add a TCP performance test using
        apps/examples/tcpblaster.  From Gregory Nutt.
      - Viewtool-STM32F107:  Add support for the MAX3421E to the
        Viewtool-STM32F107 board support  From Gregory Nutt.
      - STM32F334-DISCO:  Use a PID controller from libdsp in the BuckBoost
        driver. From Mateusz Szafoni.
      - STM32F4-Discovery:  Remove STM32F4BB dependence from RNDIS; add
        RAMDISK support.  From Alan Carvalho de Assis.
      - STM32F4-Discovery  Add board support for MAX7219 as numeric display
        controller.  From Alan Carvalho de Assis.
      - Olimex-STM32-P407:  Add kernel ELF (kelf) configuration. From
        Gregory Nutt.
      - Olimex-STM32-P407:  Add a kmodule configuration that can be used
        for testing installation of kernel modules in the protected build.
        From Gregory Nutt.
      - Olimex-STM32-P407:  Add logic to support initialization of the
        kernel module symbol table installed in the pass1/ directory during
        the application phase of the build.  The kmodule configuration
        appears to be fully functional.  From Gregory Nutt.
      - Olimex-STM32-P407:  Add board support for the DHTxx sensor.  From
        Ouss4.
      - STM32F476G-DISCO:  Add support for STM32F746G-disco board LCD.
        From Marcin Wyrwas.
      - STM32F476G-DISCO:  Add a configuration to build working nxdemo
        application  From Fanda.
      - STM32F476G-DISCO:  Add support for STM32F746G-disco board SDRAM
        Changed fb config to use SDRAM.  From Marcin Wyrwas.
      - STM32F476G-DISCO:  Add touchscreen support and a LittlevGL demo for
        STM32F746G-DISCO  From Marcin Wyrwas.
      - Nucleo-L476RG:  Add support for an external SPI-driven SD card on
        the Nucleo-L476RG.  From Gregory Nutt.
      - Nucleo-L476RG:  Add support for LSM303AGR and LSM6DSL sensors  From
        DisruptiveNL.
      - Nucleo-H743ZI:  Use Nucleo Virtual console as default console in
        the NSH configuration  From Mateusz Szafoni.
      - STM32L4R9-DISCO:  Add stm32l4r9ai-disco support.  From Juha Niskanen.
      - B-L475E-IOT01A:  Add timer driver support.  From Goden Freemans.

    * Libraries/Header Files:

      - libc endian:  Add support for endian.h. From Gregory Nutt.
      - libc net:   Add inet_aton()  From Juha Niskanen.
      - libc netdb:  Add getaddrinfo() and friends.  From Juha Niskanen.
      - libc termios:  Add lib_cfmakeraw.c  From Masayuki Ishikawa.
      - libc stdlib:  Add implementation of random() and srandom().  From
        Gregory Nutt.
      - libc unistd:  Add a crippled version of daemon().  From Gregory Nutt.
      - libdsp:  All floats with f-sufix libdsp: (1) add precision option
        for library, (2) add debug option for library and assertions in
        functions, (3) add current samples correction for SVM3, (4) add
        some motor control specific functions, (5) add basic speed
        observer, (6) fix phase shift in SMO observe, (7) add more logic to
        FOC.  From Mateusz Szafoni.
      - include/nuttx/compiler.h, include/poll.h:  Add logic to determine
        if the compiler supports anonymous structures and unions.  From
        Gregory Nutt.
      - include/nuttx/mutex.h:  Add inline wrapper functions to more
        clearly support semaphores when used as mutexs.  From QianWenfa.
      - include/nuttx/nuttx.h:  Added nuttx.h header file which is
        analogous to the linux.h header file.  Currently, it contains on
        the definition of the container_of() macro.  From zhuyanlin.
      - include/queue.h:  Add dq_tail marco  From zhuguangqing.
      - include/stdio.h:  Add prototypes for popen() and pclose().  Actual
        implementation is in apps/system/popen()  From Gregory Nutt.
      - include/sys/param.h:  Add a dummy sys/param.h header file.  This is
        not a standard file but is used by other systems and having the
        dummy file may minimize some porting efforts.  From Gregory Nutt.

    * Tools:

      - nuttx/tools/kconfig2html.c:  Due to new usage, tool needs to be
        able to handle configuration files with names other than Kconfig.
        From Gregory Nutt.
      - nuttx/tools/kconfig2html.c:  Update tool to handle tristate types.
        From Gregory Nutt.
      - nuttx/tools/Config.mk:  Add function CATFILE definition.  Currently
        only used in apps/builtin/Makefile.  From Gregory Nutt.
      - nuttx/tools/Config.mk:  Add the recursive wildcard function,
        RWILDCARD, to Config.mk.  From Gregory Nutt.
      - nuttx/tools/testbuild.sh:  Add an option to specify the location of
        nuttx directory.  From Gregory Nutt.
      - nuttx/tools/refresh.sh:  Add a --prompt option that will let you
        use --silent but will prompt before overwriting the original
        defconfig. From Gregory Nutt.
      - nuttx/tools/link.sh.  Update link.sh per suggestions by Mark so
        that it can be used with MSYS vs copydir.sh.  From Gregory Nutt.
      - nuttx/tools/mkexport.sh:  Save the System.map file and User.map
        file (if it exists) in the export package so that it can be used to
        extract addresses.  From Gregory Nutt.
      - nuttx/tools/mkexport.sh:  Save the name of the STRIP tool too.  From
        Gregory Nutt.
      - nuttx/tools/nxstyle.c:  Add capability to detect multiple blank
        lines. Single spacing required by the coding standard.  Also coding
        standard fixes to server .c files for problems found during testing
        nxstyle.  From Gregory Nutt.
      - apps/tools:  Add +x to mksymtab.sh.  From Masayuki Ishikawa.
      - apps/tools/define.sh and define.bat:  Move a copy of define.bat
        and sh from nuttx/tools to apps/tools so that they will be
        available for the import build.  From Gregory Nutt.

    * Build System:

      - Apps/ Build System.  The apps/ build system has undergone a major
        renovation to better support building applications as ELF modules.
        Module selections have changed from 'bool' to 'tristate' types.
        This means that building an ELF now is as simple setting the value
        to 'm'.  This effort required many changes, too many to summarize
        here.  The solution was contributed by Masayuki Ishikawa, Anchao
        An, and Xiang Xiao (and myself to a lesser extent).
      - NuttX/ Build System:  This change extends support for the two-pass
        build.  Its primary purpose is to incorporate source logic
        generated by applications into the kernel phase of the build.
        In the two pass build, the application logic is built during the
        first phase, pass 1.  In that phase, the application may generate
        and install source files in the pass1/directory.  The operating
        system is built during phase 2 of the build.  At that time, those
        source files in the pass1/ directory will be built and incorporated
        into the kernel address space.
        The primary purpose of the pass1/ directory is to such
        application-generated kernel symbol tables.  For an example of the
        use of this feature, look at
        apps/examples/module/drivers/Makefile.  Kernel symbol tables are
        needed to support kernel modules.  Of course, addition
        board-specific logic in, say, configs/<board>/src would have to be
        included to make use of the application-installed symbol tables.
        From Gregory Nutt.
      - Remove CONFIG_ARCH_CALIBRATION.  It is awkward to use and no longer
        necessary now that we have apps/examples/calib_udelay.  From
        Gregory Nutt.
      - Build System:  With recent changes to apps/ all configurations that
        build applications as modules must now also select
        CONFIG_APPS_LOADABLE.  From anchao.
      - Build System:  Add dynamic application loadable support.  From
        anchao.
      - Build System:  Add configuration CONFIG_ARCH_GNU_NO_WEAKFUNCTIONS
        to suppress use of weak functions.  Some gnu derived toolchains do
        not support weak symbols.  From Xiang Xiao.
      - Kconfig:  Move 'option modules' from NSH_FILE_APPS to
        BUILD_LOADABLE From anchao.
      - apps/ Build System:  Introduce a build system for loadable apps
        for nsh.  Add 'option modules' to NSH_FILE_APPS so that a user can
        change an application configuration to tristate (y/n/m)
      - apps/import:  Add Makefile.symtab which can be used to compile the
        dynamically created symbol table C file.  Also adds
        tools/mksymtab.sh.  From Gregory Nutt.

    * NSH: apps/nshlib:

      - apps/nshlib:  Add parsing support for back-slash quoted
        characters. Currently only implemented properly if
        CONFIG_NSH_ARGCAT is also selected.  This commit is in response to
        Bitbucket Issue 11 opened by Maciej Wójcik  From Gregory Nutt.
      - apps/nshlib:  Add inverted logic support in the form of 'if !
        <cmd>'  From  Beat Küng.
      - apps/nshlib:  Expand reboot and poweroff commands to include a
        second, optional mode argument  From ligd.
      - apps/nshlib:  Add a force flag (-f) to mksmartfs command.  SmartFS
        will be formatted only if (1) the FLASH does not already hold a
        SmartFS, or (2) the force flag is set.  From Xiang Xiao.
      - apps/nshlib: NSH prompt string is now configurable. nsh> is
        still the default.  From Xiang Xiao.
      - apps/nshlib:  Add control-C support for terminating built-in and
        exec'ed file tasks.  From ligd.
      - apps/nshlib: Call BOARDIOC_FINALINIT after start-up script (or
        immediately after BOARIOC_INIT is there is no start-up script).
        From ligd.
      - apps/nshlib:  When using waitpid() to wait for a built-in
        application or a file application to exit.  Add the WUNTRACED
        options to so the the waitpid() call will also be awakened if the
        waited-for task is stopped as well.  From Gregory Nutt.

    * NSH Builtins: apps/builtin:

      - apps/builtin/Makefile.  This commit changes apps/builtin to search
        the registry recursively. By supporting directories, external
        projects can install the hooks into the registry and easily clean
        them up and reinstall if something needs to be updated.  Based on
        an idea from Anthony Merlino.  From Gregory Nutt.

    * Examples/Tests: apps/examples:

      - apps/examples/calib_udelay:  Add tool for calibrating
        CONFIG_BOARD_LOOPSPERMSEC  From Juha Niskanen.
      - apps/examples/dhtxx: Example for the DHTxx sensor.  From Ouss4.
      - apps/examples/dsptest:  Add unit test for NuttX DSP library  From
        Mateusz Szafoni.
      - apps/examples/elf:  CROMFS and ROMFS configuration currently only
        usable in FLAT build.  Add configuration to use ELF objects on
        external media like SD card or USB drive instead.  From Gregory
        Nutt.
      - apps/examples/elf:  If the test ELF files are on media in
        removable media such as SD or USB FLASH, the wait until the media
        has been installed and initialized before starting the test.  From
        Gregory Nutt.
      - apps/examples/fb:  Adds example to test framebuffer overlay  From
        Marco Krahl.
      - apps/examples/gps:  Add GPS example using MINMEA lib  From Alan
        Carvalho de Assis.
      - apps/examples/i2sloop:  Add i2sloop application.  This application
        can be used to test I2S loopback like: ' nsh> i2sloop &'. From
        Masayuki Ishikawa.
      - apps/examples/lvgldemo:  Update LVGL to version 5.1.1  From Alan
        Carvalho de Assis.
      - apps/examples/module:  Add support for CROMFS and for stripping
        symbols from ELF module binaries.  From Gregory Nutt.
      - apps/examples/module:  Add support for automounting removable media.
        This involves a wait for the block driver to become available
        before performing the mount.  From Gregory Nutt.
      - apps/examples/module:  When built in the PROTECTED or KERNEL
        modes, the symbol table is not built by the application.  That is
        because the build will fail since the kernel module depends on
        internal OS symbols thar are not available to the application
        build.  With this change the examples does not attempt to build
        the kernel symbol table in these modes.  Instead it just copies
        the kernel module symbol table into the nuttx/pass1 directory
        where it can be build directly into the OS during pass2 of the
        build.  From Gregory Nutt.
      - apps/examples/ostest:  Add a small test for SIGSTOP, SIGCONT, and
        SIGKILL actions.  From Gregory Nutt.
      - apps/examples/popen:  Add a test of popen/pclose.  From Gregory
        Nutt.
      - apps/examples/powerled:  Add arch initialization. From Mateusz
        Szafoni.
      - apps/examples/tcpblaster:  Add TCP performance measurement test.
        From Gregory Nutt.

    * System Utilities: apps/system

      - apps/system/cle:  Usage improvements including command line
        history (taken from readline) and support for addition control
        characters. From mst.
      - apps/system/i2c:  Adapt to rename I2C_M_RESTART->i2C_M_START.
        I2C_M_NOSTOP should be in flags of first message in every
        write-read and write-write message sequence.  From Gregory Nutt.
      - apps/system/i2c: Allow registers besides 0x00 in the dev command.
        From Jakob Haufe.
      - apps/system/nsh:  Add logic to automatically register an
        application symbol table as part of NSH initialization.  From
        Masayuki Ishikawa.
      - apps/system/nsh:  The symbol table name and size variable names
        can now be configured.  From Gregory Nutt.
      - apps/system/nsh:  Move apps/examples/nsh to apps/system/nsh.  It
        has become so entrenched that it is hardly an example these days.
        May as well formalized it as a system task.  From Gregory Nutt.
      - apps/system/nxplayer:  Refactor nxplayer.c.  Apply
        netlib_parsehttpurl() and
        remove unnecessary usleep().  From Masayuki Ishikawa.
      - apps/system/nxplayer:  Release buffer before session and release
        semaphore in nxplayer_setvolume system/nxplayer/nxplayer.c:
        Remove & for apb->samp reference. It is already a pointer.  From Xiang Xiao.
      - system/nxplayer/nxplayer.c:  Add playraw command  From ZhongAn.
      - apps/system/nxrecorder:  Add nxrecorder application  From ZhongAn.
      - apps/system/popen:  Add an implementation of the standard popen()
        and pclose() OS interfaces.  These are implemented as applications
        vs. part of the OS because they depend on NSH.  Untested on
        initial commit.  From Gregory Nutt.
      - apps/system/system and popen:  Adapt so that these can be used in
        the KERNEL build mode.  In this case, simply replace task_spawn()
        with posix_spawn().  This depends on the existence of some
        environment where /bin/sh exists and can be used to execute one
        NSH command.  For the case of system(), this change was more
        complete because it previously used task_create().  Now it uses
        either task_spawn() or posix_spawn(), depending upon the
        configuration.  From Gregory Nutt.
      - apps/system/taskset:  Add taskset command for SMP systems.  This
        command can be used to retrieve or set a process's CPU affinity.
        For example,

        nsh> taskset -p 4
        pid 4's current affinity mask: 2

        nsh> taskset -p 3 4
        pid 4's current affinity mask: 3

        nsh> taskset -p 1 busyloop &

        From Masayuki Ishikawa.
      - apps/system/zmodem:  Support -p <path> for rz to change the folder
        for the received file.  Switch debug output from printf to
        syslog.  Send the next packet for ZME_ACK in ZMS_SENDING to avoid
        rz on the host side stuck make send work reliable even without
        hardware flow control.  From Xiang Xiao.

    * Network Utilities: apps/netutils:

      - apps/netutils/dhcpc:  Activates BINDTODEVICE if available.  From
        Sebastien Lorquet.

    * Wireless Utilities: apps/wireless:

      - apps/wireless/i8sak:  i8sak daemon now gets shutdown if not in use.
        Previously, once the i8sak daemon was started, by running any
        command, it would stay running. This means that if you want to use
        i8sak to setup your network, but then want exclusive access to the
        char device, or network device, you have to manually shutdown the
        i8sak daemon.  Now the daemon stays active as long as required to
        finish any commands, or stays open if a new command keeps it on,
        but when all work is finished, it shuts down.  From Anthony Merlino.

    * Filesystem Utilities: apps/fsutils:

      - mkfatfs:  Clean up some name BS_ and MBR_ refer to the same record
        and should use the same naming (MBR_).  From Gregory Nutt.
      - mkfatfs:  Add definitions for the FAT boot record (FBR).  From
        Gregory Nutt.
      - mksmartfs:  Add a check to see if the SmartFS is already
        formatted.  From Xiang Xiao.

    * Graphic Utilities:  apps/graphics:

      - graphics/littlevg/:  Update LVGL to version 5.1.1  From Alan
        Carvalho de Assis.

    * Test Utilities:  apps/testing:

    - testing/unity:  Add Unity - unit testing library from
        ThrowTheSwitch.org. From Mateusz Szafoni.

Bugfixes.  Only the most critical bugfixes are listed here (see the
ChangeLog for the complete list of bugfixes and for additional, more
detailed bugfix information):

    * Core OS:

      - Signals:  Signal handlers maybe run with interrupts enabled or
        disabled, depending on how the task the received the signal was
        blocked. (i.e.: If sem_wait() is called, then we disable
        interrupts, then block the currently running task).  This could be
        dangerous, because user code would be running with interrupts
        disabled.
        This change forces interrupts to be enabled in up_sigdeliver()
        before executing the signal handler calling up_irq_enable()
        explicitly.  This is safe because, when we return to normal
        execution, interrupts will be restored to their previous state when
        the signal handler returns.  From Gregory Nutt (Based on a
        recommendation by Mark Shulte).
      - Signals:  Lock the scheduler while while killing the children so
        that we do not lose priority and let the task group continue to
        run in an indeterminate state.  From Gregory Nutt.
      - Groups:  Fix a deadlock when loading an ELF  From Masayuki Ishikawa.
      - Groups:  In some circumstances, group_killchildren() could have
        called pthread_cancel() to kill a task.  Also, the behavior would
        not be as expected if a pthread had cancellation disabled.  From Gregory Nutt.
      - Posix Message Queues: mq_notify() fix - only part of struct copied
        to internal structure.  As source address the address of the struct
        member sigev_value was used, and it is not located the start of the
        struct. This leads to invalid data being copied to internal
        structure.  Both source and destination should be of type struct
        sigevent* .  From Simon Liedl.
      - vfork():  vfork operation needs to allocate and copy the task
        argument too.  Also correction of the address correction cannot
        depend on the stack pointer since it is not available in all
        architectures.  Rather calculate the offset from the stack
        allocation pointer  From Xiang Xiao.
      - IRQ Dispatch:  Ensure vector never points to NULL since interrupt
        may happen before irq_initialize()  From Xiang Xiao.
      - Work Queue:  workqueues don't need set global data to zero since
        .bss is cleared automatically.  Removing this unnecessary
        initialization also avoids the loss the work items queued before
        initialization.  From ligd.
      - Work Queue:  Remove work queue polling delay to simplify the code
        logic and save the power.  From xuanlin.
      - syslog: Fix syslog crash on 64bit simulation. From anchao.
      - Pipes: Write to a pipe when there are no readers from the pipe
        should return -EPIPE.  From ligd.
      - System Calls:  Fix 6th parameter type of posix_spawnp in
        syscall.csv From Masayuki Ishikawa.
      - System Calls:  Remove unused SYS_nnetsocket from syscall.h.  Because
        SYS_nnetsocket is not implemented so far, it should be removed so
        that SYS_prctl can work correctly.  From Masayuki Ishikawa.
      - Binary Loader:  Refactor binfmt_exec.c.   This change also fixes an
        argv issue for CONFIG_SCHED_ONEXIT=n or CONFIG_SCHED_HAVE_PARENT=n
        From Masayuki Ishikawa.
      - Binary Loader:  Re-architect the way that loadable ELF or NXFLAT
        modules are unloaded.  Memory resources must be recovered when the
        task loaded into memory exits.  The original implementation used
        the death-of-child SIGCHLD signal to perform the unload.  There are
        several problems with this:  It is overly complex, it requires that
        the parent task stay resident while the loaded task runs, and it
        has fatal logic flaws in the protected and kernel model builds
        because the user signal handler attempts to run in the kernel
        address space. This corrects the issue using a mindlessly simply
        BINFMT callback when the task exits.  From Gregory Nutt.
      - ELF Binary Loader:  Set priority level to default if parent has no
        priority.  From anchao.

    * File System/Block and MTD Drivers:

      - Auto-mounter:  Ignore return values from work_cancel(). From
        Gregory Nutt.
      - SmartFS:  Fixed filesystem corruption when writing to small file
        after open(... O_APPEND).  From Dmitriy Linikov.
      - SmartFS stat():  A previous change added support for checking if a
        descriptor is a socket in fstat().' but it changed sys/stat.h in
        way that breaks smartfs file-type stat flags. CROMFS is similarly
        broken, as tools/gencromfs.c was not updated to match the
        sys/stat.h changes.  This commit fixes both issues.  It probably is
        not a good idea to use NuttX sys/stat.h bit-field values directly
        in stored structure of filesystem.  From Jussi Kivilinna.
      - HostFS:  Update duplicated definitions in HOSTFS that must match
        NuttX values.  From ligd.
      - HostFS: Ensure f_type is equal to HOSTFS_MAGIC.  From Xiang Xiao.
      - ROMFS:  Make romfs_devread32 more portable  From anchao.
      - TmpFS:  Correct logic in tmpfs_ioctl() that extracts the priv state
        structure from the file system structures.  It was not getting the
        right value and causing mmap() to fail.  Noted by Jesse. From
        Gregory Nutt.
      - ProcFS network statistics:  Was not handling the output correct for
        the case of an IEEE 802.11 device.  From Gregory Nutt.
      - ProcFS IRQs:  Fix occasional computation error when fracpart >=
        1000  From Xiang Xiao.

    * Networking/Network Drivers:

      - TAP/TUN: Fixed custom tun devname formatting.  From Dmitriy Linikov.
      - Network Drivers:  This change attempts remove some long standard
        confusion in naming and some actual problems that result from the
        naming confusion.  The basic problem is the standard MTU does not
        include the size of the Ethernet header.  For clarity, I changed
        the naming of most things called MTU to PKTSIZE.  For example,
        CONFIG_NET_ETH_MTU is now CONFIG_NET_ETH_PKTSIZE.  This makes the
        user interface a little hostile.  People think of an MTU of 1500
        bytes, but the corresponding packet is really 1514 bytes (including
        the 14 byte Ethernet header).  A more friendly solution would
        configure the MTU (as before), but then derive the packet buffer
        size by adding the MAC header length.  Instead, we define the
        packet buffer size then derive the MTU.
        The MTU is not common currency in networking.  On the wire, the
        only real issue is the MSS which is derived from MTU by subtracting
        the IP header and TCP header sizes (for the case of TCP).  Now it
        is derived for the PKTSIZE by subtracting the IP header, the TCP
        header, and the MAC header sizes.  So we should be all good and
        without the recurring 14 byte error in MTU's and MSS's.  From
        Gregory Nutt.
      - netdev:  Fix.. Too many calls to net_unlock()  From Gregory Nutt.
      - IPv6:  There are many different checks for IPv6 multicast
        addresses. Most of the checks are different.  RFC 3513 clearly
        specifies how to detect an IPv6 multicast address:  they should
        begin with 0xffxx.  I did not change some of the checks in
        ipv6_input.c, however.  In that file, the comments indicate that
        the code should only pick of certain multicast address that begin
        with 0xff02.  From Gregory Nutt.
      - ARP:  Fix some backward logic in an if condition.  From Gregory
        Nutt.
      - TCP Re-assembly:  Rename CONFIG_TCP_REASSEMBLY to
        CONFIG_IPv4_REASSEMBLY.  Add some fixes to get a clean compile with
        CONFIG_IPv4_REASSEMBLY enabled.  There are several problems with
        the current implementation:  It is untested (and depends on
        CONFIG_EXPERMIMENTAL).  It uses some Ethernet specific definitions
        (and depends on CONFIG_NET_ETHERNET).  There is only a single
        reassembly buffer.  The last two issues prevent use of this feature
        in any context where IPv4 packets may be reassembled for multiple
        network devices concurrently).  From Gregory Nutt.
      - TCP:  Set the default TCP MSS to the value required by RFC 879 and
        never change it under any circumstance unless the remote host
        requests a larger MSS via an option the TCP header.  From Gregory
        Nutt.
      - TCP:  Fix a deadlock condition that can occur when (1) all network
        logic runs on a single work queue, (1) TCP write buffering is
        enabled, and (2) we run out of IOBs.  In this case, the TCP write
        buffering logic was blocking on iob_alloc() with the network
        locked.  Since the network was locked, the device driver polls that
        would provide take the write buffer data and release the IOBs could
        not execute.  This fixes the problem by unlocking the network lock
        while waiting for the IOBs.  From Gregory Nutt.
      - TCP: Remove g_netstats.tcp.syndrop++ from tcp_data_event()  From
        Masayuki Ishikawa.
      - TCP Monitor:  Fix net unlock issue when tcp close.  This bug could
        leave the net locked.  From zhangyuan7.
      - UDP:  When sending a broadcast (or multicast) packet do not attempt
        to look up the device by the destination IP address.  Rather, use
        the locally bound address for these cases to select the correct
        network device.  From Gregory Nutt.
      - UDP:  Restore some legacy behavior that was lost with the
        implementation of CONFIG_NET_UDP_BINDTODEVICE:  If no device has a
        local address when the broadcast packet is sent and the UDP socket
        is not bound to a device, there select some arbitrary device.  This
        is certainly lunacy in the case where there are multiple network
        devices registered because the wrong device will probably be
        returned.  It works find, however, for the legacy case where only a
        single network device is registered.  From Gregory Nutt.
      - UDP:  Fix for network byte-order issue when checking if an address
        is a multicast address.  From Jake Choy.
      - USRSOCK:  Correct of semaphore usage issues.  From Gregory Nutt.
      - USRSOCK:  Fix re-definitions of struct iovec.  From ligd.
      - ICMP/ICMPv6 Connection:  Change the type of id in
        icmpv[6]_findconn to uint16_t  From Xiang Xiao.
      - ICMP/ICMPv6:  Fix failure to poll ICMP socket issue.  From
        dongjianli.

    * Wireless/Wireless Drivers:

      - XBee:  Fixes issue with timeouts.  Timeouts were in ticks but
        should have been in ms.  This caused false triggers of timeout
        causing redundant packets, etc.  From Anthony Merlino.
      - BCM43xx:  Add missing logic to the BCM43xx IEEE 802.11 driver to
        poll for more Tx data after the last transfer completes.  From
        Gregory Nutt.
      - BCM43xx:  Bring in some fixes from the 'Haywire' branch.  From
        Ramtin Amin.

    * Common Drivers:

      - Audio:  Fix compile error in i2schar.c (CONFIG_DEBUG_ASSERTIONS=y)
        From Masayuki Ishikawa.
      - Audio I2S:  Fix bad NULL pointer check  From Juha Niskanen.
      - Input:  Fixed FT5x06 driver to correctly close (previously it
        unregistered interrupt handler during close).  From Marcin Wyrwas.
      - MMC/SD:  Fix an error that was causing SDIO multiple block
        transfers from achieving full performance.  From Bob Feretich.
      - Sensors:  Increases SPI frequency in MAX6675 from 400Khz to 4MHz.
        From Alan Carvalho de Assis.
      - Sensors:  Remove comment references to touchscreens from ADXL345
        driver. From Russ Webber.
      - Serial: Don't overwrite nwritten unconditionally on UART write
        failure.  From Xiang Xiao.
      - Serial DMA:  Move head/tail pointer reset to uart_recvchars_dma
        since dma may be still transferring in the background.  From Xiang
        Xiao.
      - Serial DMA:  In DMA mode, the use of uart_disablexinit() is
        insufficient to protect a critical section.
        enter/leave_critical_section() must be used in those cases if
        CONFIG_SERIAL_DMA=y  From Xiang Xiao.
      - Serial DMA: Fix typo error in uart_recvchars_dma() From Xiang Xiao.
      - 16550 UART: u16550_txempty() should check UART_LSR_TEMT to avoid
        some data left in the transmit FIFO  From Xiang Xiao.

    * ARMv7-A:

      - ARMv7-A (and i.MX6):  Add support for per-CPU IRQ and FIQ interrupt
        stacks (bugfix).  Add support so that up_assert will print the
        correct interrupt stack on an assertion (FIQ stack is still not
        printed).  From Gregory Nutt.

    * ARMv7-R:

      - ARMv7-R:  Fix some wrong configuration of program status
        register.  PSR_E_BIT bit should be set for big endian system.
        PSR_A_BIT bis is set automatically as arm cortex-r4 reference
        manual 3.7.4. So we don't need to set this bit.  From EunBong Song.
      - ARMv7-R: Fix some wrong MPU register definition. Change
        MPU_RBAR_ADDR_MASK and MPU_RACR_TEX_SHIFT mask as arm cortex-r4
        reference manual.  Region Base Address Register 0-4 bits are
        reserved.  MPU Region Access control register type 3-5 bits.  From
        EunBong Song.

    * ARMv7-M:

      - ARMv7-M, Cortex F7:  Add a configuration to enable workaround for
        r0p1 Errata 837070: Increasing priority using write to BASEPRI does
        not take effect immediately.  This update is required to be
        serialized to the instruction stream meaning that after this update
        completes, it takes effect immediately and no exceptions of lower
        priority than the new boosted priority can preempt execution.
        Because of this erratum, the priority boosting does not take place
        immediately, allowing the instruction after the MSR to be
        interrupted by an exception of lower priority than the new boosted
        priority. This effect is only limited to the next instruction.
        Subsequent instructions are guaranteed to see the new boosted
        priority. This was raised in Bitbucket issue 113 from Vadzim
        Dambrouski.  From Gregory Nutt.
      - ARMv7-M:  MPU: mpu_log2regionceil needs take into account the
        offset too  From Xiang Xiao.
      - ARMv7-M MPU:  The prototype of mpu_log2regionfloor() changed; an
        additional parameter was added.  However, none of the calls to
        mpu_log2regionfloor() were updated to pass the new, additional
        parameter.  From Gregory Nutt.

    * Infineon XMC4xxx Drivers:

      - XMC4 SPI:  XMC4 SPI was working only for the first transfer  From
        Alan Carvalho de Assis.

    * Microchip/Atmel SAMv7 Drivers:

      - SAMv7 MCAN: Correct an error in the BUS_OFF reporting.  In case of
        BUS_OFF the old implementation was leading to a package storm.  Now
        it reports the error condition BUS_OFF only once.  From Frank
        Benkert.

    * NXP/Freescale LPC43xx Drivers:

      - LPC43xx CAN:  Fix lpc43 CAN configuration.  Configuration settings
        were used and documented in README.txt files, but never in any
        Kconfig file.  From Gregory Nutt.
      - LPC43xx:  Make WWDT usable again.  LPC43xx WWDT driver was not
        updated when irq_dispatch grew an argument parameter.  Also fixes
        two typos and a naming inconsistency (WWDT vs. WWDG).  From Jakob
        Haufe.

    * NXP/Freescale Kinetis Drivers:

      - kinetis:  USB0 fix interrupt storm on error.  The ERROR bit of
        USBx_ISTAT needed to be cleared once an error occurs.  From David
        Sidrane.
      - Kinetis:  SDHC fix SDIO driver so that DMA works. There were 2
        problems. The first was that the interrupt did test DINT and raise
        a completion events. But since DINT is just an indication of DMA
        completion, TC is a valid way to determine that the transfer is
        complete.  The second problem is that Software Reset For DAT Line
        SDHC_SYSCTL[RSTD] clears the bits 24-0 in SDHC_PROTO this looses
        the wide bus setting DTW  From David Sidrane.
      - Kinetis:  (1) PIT add Lifetime and Chaining, (2) flexcan fix
        duplicate line and ordering, (3) kinetis_lowput.c LPUART data
        format with parity fix.  The 9-bit data mode is typically used with
        parity to allow eight bits of data plus the parity, (4) lowputc
        LPUART_BAUD_INIT has to be defined.  Build fails with test case
        enable LPUART0 and make UART1 console.  If HAVE_LPUART_DEVICE is
        defined then LPUART_BAUD_INIT has to be defined even if the LPUART
        is not the console  From David Sidrane.
      - Kinetis:  I2C ensure timeout on bus error.  The code had a dead
        wait on I2C_S_BUSY. Noise on the bus would cause the driver to
        hang.  Add timeout on invalid states of I2C_S_BUSY to allow the
        upper layers do deal with restart or abort.  From David Sidrane.

    * NXP i.MXRT Drivers:

      - i.MXRT Ethernet:  I finally got the Ethernet CRC32 to work properly
        after the FAE pointed me in the right direction:  (1) Added CRC32
        functions for multicast address filtering, (2) Do not reset PHY
        settings when doing an ifup, (2) Use chip's unique id as the device
        MAC, and (4) Enable discard enet frames with errors at PHY layer.
        From Jake Choy.

    * On Semi LC823450 Boards:

      - LC823450-XGEVK:  Fix parallel build on lc823450-xgevk.  This change
        fixes an archive file (*.a) corruption by locking $(TOPDIR).
        Please note that locking the current directory is insufficient
        because some archive files such as libapps.a are specified with
        absolute path.  From Masayuki Ishikawa.
      - LC823450-XGEVK: Change IOB related params for rndis.  Since TCP
        flow control scheme was changed, HTTP audio streaming has not been
        working. These IOB params are not optimized but HTTP audio
        streaming now works.  From Masayuki Ishikawa.

    * STMicro STM32:

      - STM32 F7:  Fix compile error caused by intentional use of fall
        through From Daniel Agar.

    * STMicro STM32 Drivers:

      - STM32 F1-F4:  Port Bob Feritich's change to STM32 F2 and F4 which
        appear to have identical SD support and I/O compensation
        requirements.
      - STM32 F1-F4, STM32 F7, and STM32 L4:  The STM32 RTC driver was
        being selected by the global CONFIG_RTC option.  That is in
        correct.  For example, if you want to disabled the STM32 RTC and
        use an external RTC you cannot because the external RTC also
        depends on the global CONFIG_RTC.  The solution is to add a new
        CONFIG_STM32xx_RTC configuration option the permits to you select
        or deselect the STM32 RTC but still be able to select the external
        RTC.  From Gregory Nutt.
      - STM32 F3 I2C:  Fix compile error with I2C reset.  From Juha
        Niskanen.
      - STM32 F7 Serial:  Fix ioctl TIOCSSINGLEWIRE The TRM notes that UE
        must be disabled in order to write HDSEL in USART_CR3. This was not
        being done, so calls to TIOCSSINGLEWIRE were silently failing.
        This change checks the state of UE in USART_CR1, clears the UE bit
        before writing HDSEL, then re-enables it if necessary.  From Kurt
        Kiefer.
      - STM32 F7 DMA:  DMA macros did not account for the increase from 8
        to 16 DMA channels.  From Gregory Nutt.
      - STM32 F7 I2C:  I2C reset Configure I2C pins as GPIO output.  Pins
        were reset to inputs in the deinit(). This resets them to outputs.
        From David Sidrane.
      - STM32 F7:  All of the SDMMC pins were set to 50 MHz, but not the
        clock. This sets the clock to 50 MHz also.  This combined with
        turning on I/O compensation makes intermittent failures go away.
        From Bob Feritich.
      - STM32 F7:  Port Bob Feritich's change to SDMMC2 and to all other
        STM32 F7 architectures.  Also add a configuration option to
        automatically enable I/O compensation.  From Gregory Nutt.
      - STM32 F7 SDMMC:  Fix data timeout errors with multi-block
        transfers.  From Bob Feretich.
      - STM32 L4:  Corrects some mistakes in pin definitions for the
        STM32 L4 family.  According to datasheet of STM32L496xx, STM32L475xx
        and STM32L443XX the AF2 of PE14 is  TIM1_BKIN2 not TIM2_BKIN.  From
        Daniel Pereira Carvalho.
      - STM32 L4:  Avoid using redundant CONFIG_STM32L4_STM32L4X2.  This is
        almost always same as CONFIG_STM32L4_STM32L4X3. Avoid duplication
        to reduce macro clutter.  This patch limits
        CONFIG_STM32L4_STM32L4X2 usage to dependency tracking and pinmap.
        Also enable ADC for CONFIG_STM32L4_STM32L4X5 (untested, but same
        RM).  From Juha Niskanen.
      - STM32 H7 Serial: don't include stm32_dma.h  From raiden00pl.

    * STMicro STM32 Boards:

      - STM32F4-Discovery:  Fix pca9635pw LED driver compilation on
        STM32F4-Discovery.  From Alan Carvalho de Assis.
      - STM32F4-Discovery:  Krassimir Cheshmedzhiev claims that sys/types.h
        needs to be included in the RGB LED file to avoid undeclared 'OK'
        From Gregory Nutt.
      - STM32F4-Discovery:  Missing EXTERN(_vectors) in linker script.
        From Gregory Nutt.
      - Nucleo-L422KC:  Fix RAM size; STM31L4x2xx has only 64Kb of RAM.
        Remove references to I2C and SDIO:  There is no I2C2 or SDIO on the
        STM32F4x2xx.  From Daniel P. Carvalho.
      - Nucleo-L422KC:  Fix stm32_userleds.  After change LD2 to LD3 in
        board.h stm32_userleds.c was broken.  From Daniel P. Carvalho.
      - Nucleo-L422KC:  Fix TIMx clock configuration.  Also removes
        definitions related to timers not available in the STM32L432KC.
        From Daniel Pereira Carvalho.
      - Nucleo-L452RE:  Fix TIMx clock configuration.  This is cloned from
        similar change to the Nucleo-L422KC.  Also fixes DAC build
        failure.  From Juha Niskanen.
      - B-L475E-IOT01A:  Fix copy paste errors in names:
        stm32_bringup->stm32l4_bringup.  Noted by Freemans Goden.  From
        Gregory Nutt.
      - STM32VL-Discovery:  Changed the status LED to be the green one as
        mentioned in the README file. Removed the global array for buttons
        and replace it with the only button. Improve defconfig for the nsh
        configuration.  From Ouss4.

    * C Library/Header Files:

      - libc audio:  Call nxsem_destroy in apb_free.  From Xiang Xiao.
      - libc netdb:  The 'port' argument to the static alloc_ai() function
        is always in network byte order.  However, that static function was
        still calling HTONS() on the port, incorrectly converting it back
        to host byte order.  From Gregory Nutt.
      - libc netdb: Fix a link error in lib_gethostbynamer.c with protected
        build.  NOTE: g_lo_ipv4addr also exists in
        net/loopback/lo_globals.c which can be linked with kernel build
        only. From Masayuki Ishikawa.
      - libc unistd :  Fix backward conditional logic in Kconfig.  From
        Gregory Nutt.
      - include/nuttx/compiler.h:  Fix warning: __cplusplus is not defined.
        Some gcc derived compiler do not define __cplusplus  From Xiang
        Xiao.
      - include/nuttx/fs/binfs.h:  Fix warning:  Type defaults to 'int' in
        declaration of 'mountpt_operations'  From Xiang Xiao.
      - include/nuttx/net/ethernet.h:  Remove CONFIG_NET_ETHERNET guard
        From Xiang Xiao.
      - include/nuttx/semaphore.h: don't include nuttx/fs/fs.h.  (1) Avoid
        nested loops if CONFIG_SIG_EVTHREAD enabled, (2) semaphore.h
        doesn't depends on fs.h.  From Gregory Nutt.
      - include/crc64.h:  Fix warning: integer constant is too large for
        its type  From Xiang Xiao.
      - include/limits.h and include/sys/types.h:  Fix warning about
        'SIZE_MAX' redefined.  include/nuttx/usb/audio.h: Fix warnings due
        to '-' used whete '_' intended.  From Xiang Xiao.
      - include/spawn.h:  Fix posix_spawnattr_destroy warning:  'the
        address of attr will always evaluate as true'  From Xiang Xiao.
      - include/sys/types:  Move wint_t and wctype_t from wchar.h to
        types.h.  This change is compatible as before since wchar.h
        include types.h indirectly.  This fixes a compilation error with
        newlib's math.h:  'unknown type name wint_t'  From Xiang Xiao.
      - apps/include/netutils/netlib.h:  Eliminate a warning about
        AF_UNSPEC and AF_INET not defined.  From Gregory Nutt.

    * Build System:

      - Build System:  Fix parallel build in making context.  This change
        avoids running $(MKSYSCALL) and .context in parallel and ensures
        that tools/mksyscall is built before it is actually used.  From
        Masayuki Ishikawa.
      - Kconfig files:  Fix several errors noted by Alex Denisov in
        Bitbucket issue 115.  From Gregory Nutt.
      - apps Build System:  Fix an error when building apps/ without
        nuttx/, using only the NuttX export package and assuming that the
        nuttx/ directory in not even present.  In this case, the problem
        fixed where the apps/Make.defs file was selecting tools from the
        /tools directory which does not exist because TOPDIR=apps/import.
        Instead, for this build case, I have not thought of any option but
        to duplicate scripts as necessary in the apps/tools directory.
        Also added a top-level target to compile the symbol table.  Misc
        fixes: quoting in scripts, some errors in script syntax.  From
        Gregory Nutt.
      - apps/Application.mk:  If a loadable module is generated the we
        need to add logic to remove the loadable module in the 'make
        clean' logic.  From Gregory Nutt.

    * Tools:

      - nuttx/tools/Makefile.unix:  Was not cleaning up export directory
        if it was left from a failed export.  From Gregory Nutt.
      - apps/tools: Fix an error in mksymtab.sh  From Masayuki Ishikawa.

    * NSH Library: apps/nshlib:

      - apps/nshlib:  Fix 'while' and 'until' loop condition The loop
        condition logic was inverted:  'while true; do echo "test"; done'
        would exit immediately, while using 'until' would stay in the
        loop.  This is the opposite of how it is supposed to work.  The
        reason is that 'state' was set wrong because 'whilematch' is a
        bool.  From Beat Küng.
      - apps/nshlib:  I was able to cause an assertion with some typos in
        testing the 'fi' command.  Not an important thing, but this will
        protect against the assertion.  From Gregory Nutt.
      - apps/nshlib:  Increase the default configuration for the maximum
        number of command line arguments to 7 (CONFIG_NSH_MAXARGUMENTS).
        This is needed for 'mount' with the -o option.  From Xiang Xiao.
      - apps/nshlib:  Do not dereference NULL 'pstate' in nsh_console.c.
        From Juha Niskanen.

    * Examples/Tests: apps/examples:

      - apps/examples:  Remove illegal calls into OS to initialize BINFMT
        support.  This must be moved to the board initialization logic
        within the OS. From anchao.
      - apps/examples/nettest:  Fix typo: NET_LOOPBACK ->
        CONFIG_NET_LOOPBACK nettest: Fix compilation error. Should enable
        NET_SETSOCKOPT for preventing compilation error.  From EunBong Song.
      - apps/examples/ostest:  Signal handling tests should use the same
        configurable stack size as used in other tests, not
        PTHREAD_STACK_DEFAULT.  From Gregory Nutt.
      - apps/examples/ostest:  Attempt to make the nested signal test
        compatible with the suspend/resume test.  Some signals cannot be
        caught when the suspend/resume configuration is in place.  From
        Gregory Nutt.
      - apps/examples/smps:  Fixes in some printf and in Kconfig. From
        Mateusz Szafoni.

    * System Utilities: apps/system:

      - apps/system/cu: (1) Protect from possible re-definition of signal
        values, (2) Fix CU ctrl-C hand when remote core hang.  From ligd.
      - apps/system/i2c:  Fix a backward comparison in i2c_main.c.  Noted
        by Jakob Haufe.  From Gregory Nutt.
      - apps/system/nsh: Fix compile errors with
        CONFIG_EXAMPLES_NSH_SYMTAB=y.  From Masayuki Ishikawa.
      - apps/system/ping and ping6:  Send ID and seqno in network byte
        order.  From Xiang Xiao.
      - apps/system/ping and ping6:  Change dependency in ping and ping6
        Kconfig.  These may be implemented in users sockets and, hence,
        may need to be available even if ICMP and ICMPv6 sockets are not
        support.  From Xiang Xiao.
      - apps/system/system:  Add 'const' to make function prototype
        compatible with OpenGroup.org requirement  From Xiang Xiao.
      - apps/system/zmodem:  Fix error "sz_main.o: No such file or
        directory"  From Xiang Xiao.

    * Network Utilities: apps/netutils:

      - apps/netutils/ftpc:  Fix handling of url-encoded strings  From
        Dmitriy Linikov.
      - apps/netutils/ping:  Remove unsupported ping.  netutils/ping is not
        supported anymore.  It's better to remove this folder for
        preventing confusing.  ping is supported by system/ping.  From
        EunBong Song.

    * Wireless Utilities: apps/wireless:

      - apps/wireless/wapi:  Remove dependency on CONFIG_EXPERIMENTAL from
        Kconfig  From Gregory Nutt.

    * GPS Utilities: apps/gpsutils:

      - apps/gpsutils/minmea:  Include wchar.h in minmea.c file to fix
        wint_t error  From Alan Carvalho de Assis.

    * Interpreters:  apps/interpreters:

      - Remove apps/interpreters/micropthon.  There are several reasons
        for this.  (1) the current version 1.3.8 is very old and no one is
        supporting it.  (2) the port only includes the core micropython
        logic and none of the Python libraries.  As such it is useless in
        any real application.  (3) There have recently been compile
        failures reported.  It looks like this is due to changes in newlib
        based toolchains that now bring in incompatible newlib header
        files.  See issue 104 at
        https://bitbucket.org/nuttx/nuttx/issues/104/build-micropython-138-error.
        With no one dedicated to the support of micropython, it can no
        longer be carried in the NuttX apps/ repository.  From Gregory Nutt.

NuttX-7.27 Release Notes
------------------------

The 127th release of NuttX, Version 7.27, was made on November 14, 2018,
and is available for download from the Bitbucket.org website.  Note
that release consists of two tarballs:  nuttx-7.27.tar.gz and
apps-7.27.tar.gz.  These are available from:

    https://bitbucket.org/nuttx/nuttx/downloads
    https://bitbucket.org/nuttx/apps/downloads

Both may be needed (see the top-level nuttx/README.txt file for build
information).

Additional new features and extended functionality:

    * Core OS:

      - Assertions:  Add 'BOARD_ASSERT_RESET_VALUE' in config/Kconfig and
        replace reboot status '0' to 'CONFIG_BOARD_ASSERT_RESET_VALUE'.  From
        Gregory Nutt.
      - Assertions:  up_registerdump capture the general register if not yet
        saved and up_saveusercontext is implemented, the register dump is very
        useful to find the cause of failure.  From Xiang Xiao.
      - Assertions:  up_stackdump() dump the full stack if stack overflow the
        stack info is very useful to find the backtrace  From Xiang Xiao.
      - binfmt/ and libs/libc:  Make exepath_*() more common:  Move
        exepath_*() related code to libc/misc, rename exepath_ to envpath_,
        and rename BINFMT_EXEPATH to LIB_ENVPATH.  From nchao.
      - CLOCK:  Support CLOCK_MONOTONIC in clock_getres.c.  From Xiang Xiao.
      - Clock Timekeeping:  Use clock_basetime() to initialize
        g_clock_wall_time to get the best initial RTC value and initialize
        g_clock_last_counter too since the hardware may not start counting
        from zero.  From Xiang Xiao.
      - exit():  Add SCHED_EXIT_KILL_CHILDREN option to kill all child threads
        when the main thread of a task exits.  From nchao.
      - IOBs:  Add an IOB notifier that will notify any registered threads
        that want to known when an IOB has been freed.  This is basically just
        a wrapper around the generic notifier.  Includes a divider that can be
        used to reduce the rate of IOB notifications.  From Gregory Nutt.
      - Memory Manager:  In mm_free(), add DEBUGASSERT()'s to catch memory
        corruption early.  From Petteri Aimonen.
      - Memory Manager:  Add debug option CONFG_MM_FILL_ALLOCATIONS to fill
        all mallocs() with recognizable value.  From Petteri Aimonen.
      - sched/signal and syscall/:  Add support for pselect() and ppoll()
        functions  From dongjianli.
      - Task Groups:  group_foreachchild() now iterates in reverse order since
        the callback (e.g. group_killchildren) may remove the tcb from list.
        From zhangyuan7.
      - WDOG Timer:  Improve accuracy of wd_gettime() in tickless mode  From
        ligd.
      - Work Queues:  Add a generic notification facility that runs on a work
        queue.  The notification facility can notify a group of subscribers to
        an event via callbacks.  This API is for use within the OS only.  From
        Gregory Nutt.

    * File Systems/Block and MTD Drivers

      - FAT:  Add CONFIG_FAT_LFN_ALIAS_HASH to speed up creating long
        filenames.  Long filenames on FAT file systems have associated 8.3
        character alias short filenames. The traditional form of these is
        FILENA~1.EXT with a running count of the number of similar names.
        However creating this unique count can take several seconds if there
        are many similarly named files in the directory. Enabling
        FAT_LFN_ALIAS_HASH uses an alternative format of FI0123~1.TXT where
        the four digits are a hash of the original filename. This method is
        similar to what is used by Windows 2000 and later.  From Petteri
        Aimonen.
      - FAT: Add CONFIG_FAT_LFN_ALIAS_TRAILCHARS alternative format for 8.3
        filenames.  Traditional format for long filename 8.3 aliases takes
        first 6  characters of long filename. If this option is set to N > 0,
        NuttX will instead take first 6-N and last N characters to form  the
        short name. This is useful for filenames like "datafile12.txt"  where
        the first characters would always remain the same.  From Petteri
        Aimonen.
      - FAT: if block driver wait seems to be a long one, give time for other
        threads to run.  From Petteri Aimonen.
      - file_open():  Add file_open() implementation with some fully-function,
        interim, placeholder logic.  Change occurrences of open() followed by
        file_detach() in the OS to file_open().  From Gregory Nutt.
      - MX25LF25635F:  Add support to Macronix MX25LF25635F serial NOR flash
        From David Sidrane.
      - nx_open():  Add nx_open() which is the same as open() except that it
        does not create a cancellation point nor does it modify the errno
        variable.  Change most other, non-controversial calls to open() to
        nx_open().  From Gregory Nutt.
      - file_ioctl():  Replace calls to ioctl() in the OS to file_ioctl().
        From Gregory Nutt.
      - mount:  Add mount() support for file systems that require  MTD drivers
        (vs. block drivers).  From Gregory Nutt.
      - mount:  Add support for mounting a file system with either a block or
        an MTD driver.  From Xiang Xiao.
      - MTD FTL:  Support BIOC_FLUSH ioctl  From Xiang Xiao.
      - MTD FTL:  Make READAHEAD and WRITEBUFFER work independently of each
        other.  There have cases we use writebuffer but not readbuffer, so the
        write buffer must be flushed before read.  Let rwb driver do it.  From
        zhuyanlin.
      - MTD FTL:  Allocate eblock only when it's really needed  From Xiang Xiao.
      - MTD FTL:  Add support support unlink operation to avoid the memory
        leak.  From Xiang Xiao.
      - MTD Partition: Add register_mtdpartition() for MTD partition  From
        Xiang Xiao.
      - MTD Partition:  Remove the hard code partition name length From Xiang
        Xiao.
      - MTD Proxy:  Make MTD device accessible via a character driver proxy
        like block devices  From Xiang Xiao.
      - ProcFS:  Change output of the ProcFS 'env' file so that it looks more
        like output from the 'env' command.  From Gregory Nutt.
      - ProcFS:  Add support to provide MLD statistics at /proc/net/mld.  From
        Gregory Nutt.
      - ProcFS:  Remove MTD ProcFS and mtd_procfsoperations() since we can now
        get the same information from inode  From Xiang Xiao.
      - ProcFS:  Add /proc/version support to get version info  From iuhaitao.
      - ProcFS:  Add support for named MTD drivers in the pseudo file system.
        This will, eventually, allow us to mount file systems that need MTD
        drivers without having to fake an intervening block driver.
      - R/W Buffer:  Don't queue work to flush write buffer if
        CONFIG_DRVR_WRDELAY == 0  From Xiang Xiao.
      - R/W Buffer: Improve the rwb_read/write overlap performance  From
        zhuyanlin.
      - SIM HOSTFS:  Support S_IFSOCK, DT_LNK, O_DIRECT and O_SYNC From Xiang
        Xiao.
      - SPIFFS:  Brings in a NuttX port of version 0.3.7 of Peter Anderson's
        SPIFFS flash file system into NuttX.  From Gregory Nutt.

    * Networking/Network Drivers:

      - Network Configuration  Add new configuration CONFIG_NET_MCASTGROUP.
        This option is selected automatically if either CONFIG_NET_IGMP or
        CONFIG_NET_MLD are selected.  Most conditional logic based on
        CONFIG_NET_IGMP replaced with conditioning on CONFIG_NET_MCASTGROUP.
        From Gregory Nutt.
      - Network Device:  Add notification logic for the case where the network
        goes down.  From Gregory Nutt.
      - Network Device:  Rename netdev_dev_lladdrsize() to netdev_lladdrsize()
        and move the prototype to include/nuttx/nex/netdev.h, giving is global
        scope within the OS.  From Xiang Xiao.
      - ARP:  Redesign ARP table aging to simplify the net initialization
        From Xiang Xiao.
      - ARP:  Check ifname match before sending packet.  From Xiang Xiao.
      - ARP and ICMPv6:  Double the delay time on each iteration for ARP/ICMP
        to fight work jitter better.  From Xiang Xiao.
      - ICMP/ICMPv6:  Add NET_ICMP[v6]_NO_STACK for usrsock case  From Xiang
        Xiao.
      - ICMPv6:  Encapsulate the link scope address generation into
        icmpv6_linkipaddr()  From Xiang Xiao.
      - ICMPv6:  Remove the coupling between ICMPv6 and Ethernet by moving all
        Ethernet stuff to neighbor_ethernet_out.c and make the mac address as
        first field.  From Xiang Xiao.
      - ICMPv6 MLD:  Implement Multicast Listener Discovery (MLD) protocol based
        on RFC 2710 and RFC 3810.  From Gregory Nutt.
      - ICMPv6 MLD:  Implement MLDv1 compatibility mode.  From Gregory Nutt.
      - ICMPv6 MLD:  Implement 'Other Querier Present Timer'.  This timer is
        used to revert to Querier mode if there is no other querier on the
        network.  From Gregory Nutt.
      - IGMP:  Backport some MLD design improvements/fixes.  From Gregory Nutt.
      - IPv4 setsockopt(): Add implementation for all IPv4 socket options that
        have implemented IOCTL command counterparts.  From Gregory Nutt.
      - IPv4/6 Socket Options:  Add framework to support IPv4 and IPv6
        protocol socket options (i.e., SOL_IP and SOL_IP6).  Handling of these
        socket options was a necessary step on the way to ICMPv6 MLD support.
        From Gregory Nutt.
      - ICMPv6 Autoconfiguration:  Don't take the network device down when
        reconfiguring only the IP address from within ICMPv6 logic.
        Recommended by Xiang Xiao in order to avoid the long delays of
        bringing some networks back up.   Normally it is required that the
        network be in the "down" state when re-configuring the network
        interface.  This is thought not to be a necessary here because:  (1)
        The ICMPv6 logic here runs with the network locked so there can be no
        outgoing packets with bad source IP addresses from any asynchronous
        network activity using the device being reconfigured. And (2) incoming
        packets depend only upon the MAC filtering.  Network drivers do not
        use the IP address; they filter incoming packets using only the MAC
        address which is not being changed here.  From Gregory Nutt.
      - IPv6 Input:  Add logic to skip over the variable number of IPv6
        extension headers that may be present between the IPv6 header and the
        transport layer header.  The extension headers are simply ignored.
        This is necessary because with MLD, certain incoming messages may
        have, at a minimum, a Router Alert Hop-by-hop extension header.
        Additional changes to ICMPv6, TCP, and UDP input to handle the offset
        protocol headers.  From Gregory Nutt.
      - IPv6 Neighbor: Simplify the neighbor table aging process  From Xiang
        Xiao.
      - IPv6 Neighbor:  Simplify neighbor_dumpentry() implementation  From
        Xiang Xiao.
      - IPv6 Neighbor:  neighbor_lookup() checks if the target IP belongs to
        one of the local network devices.  From Xiang Xiao.
      - IPv6 Neighbor: Support neighbor_out() for multiple link layer at the
        same time  From Xiang Xiao.
      - IPv6 setsockopt():  Implement the IPV6_JOIN_GROUP and IPV6_LEAVE_GROUP
        socket options. From Gregory Nutt.
      - TCP:  Extend the TCP notification logic logic so that it will report
        loss of connection events.  From Gregory Nutt.
      - SLIP:  Add IPv6 support and fix minor issue  From Xiang Xiao.
      - TCP:  Add TCP poll() logic to receive notifications when IOBs are
        freed.  From Gregory Nutt.
      - TCP:  In TCP backlog, add SOMAXCONN definition and implementation per
        OpenGroup.org.  From zhangyuan7.
      - TCP/UDP:  Extend send()/sendto() logic it also requires that at least
        one IOB is also available to be able to send.  From Gregory Nutt.
      - TCP/UDP:  Add notification logic when TCP or UDP read-ahead data is
        buffered.  From Gregory Nutt.
      - TUN:  Call ipv[4|6]_input dynamically by checking packet header and
        remove the code duplication  From Xiang Xiao.

    * Wireless/Wireless Drivers:

      - Broadcom IEEE 802.11:  Add capability for Broadcom chips to get
        firmware and CLM data from a mounted file system vs. in-memory data
        structures.  From Ramtin Amin.
      - XBee IEEE 802.15.4: Add support for setting/getting tx power.  From
        Anthony Merlino.

    * Other Common Device Drivers:

      - GPIO:  Support multiple registrations of GPIO signal events.  From
        Xiang Xiao.
      - INA226:  Add INA226 device driver.  From Daniel P. Carvalho.
      - MAX7219:  Support all digits presented in the MAX7219 datasheet.  From
        Alan Carvalho de Assis.
      - MLX90614:  Add support for the Infrared Thermometer MLX90614  From
        Alan Carvalho de Assis.
      - RTC Driver:  up_rtc_set_lowerhalf call clock_synchronize() for
        external RTC.  From Xiang Xiao.
      - SYSLOG:  Uncomment the g_syslog_channel->sc_flush call in
        syslog_flush().  From Xiang Xiao.
      - SYSLOG:  syslog_initialize initialize dev/syslog too and call syslog
        to add the prefix and timestamp.  From Xiang Xiao.
      - USB Composite and DFU drivers: Add support for Microsoft OS
        descriptors.  These Microsoft-only descriptors help in loading the
        correct driver on Windows.  They are especially helpful to give libusb
        access to a custom device without having to manually configure/install
        WinUSB driver. With this change DFU interface works automatically on
        Windows 10 with dfu-util 0.9 and libusb 1.0.22. On Windows 7 it still
        appears to need driver installation.  From Petteri Aimonen.
      - USB DFU Device: Add DFU Runtime driver for activating boot-loader
        through USB command.  From Petteri Aimonen.
      - USB RNDIS Device:  Account for CONFIG_NET_GUARDSIZE in allocation of
        packet buffer allocation:  Make USB device parameters configurable.
        From Sakari Kapanen.
      - USB RNDIS Composite Device:  Fix strid comparison. Add support for
        composite configuration.  From Petteri Aimonen.

    * Microchip PIC32MX Boards;

    - PCBLOGIC-PIC32MX:  Remove support for the PCB Logic PIC32MX board.  I do
      not find any references to PCB Logic on the web and I do not believe
      that this breakout board is available any longer.  From Gregory Nutt.

    * NXP Freescale i.MX RT:

      - i.MXRT:  Added support for the i.MXRT 106x family.  From David Sidrane.

    * NXP Freescale i.MX RT Drivers:

      - i.MXRT:  Add LPI2C driver.  From Ivan Ucherdzhiev.
      - i.MXRT LPSPI:  Add full support for the LPSPI in poll mode; includes a
        minor fix for LPI2C.
      - i.MXRT USDHC:  Initial commit of the i.MXRT SDHC driver working in PIO
        mode.  From Dave Marples.
      - i.MXRT USDHC:  Complete the interrupt driven USDHC1 functionality for
        the IMXRT EVKB.  Improve SD card handling in the DMA case.  From Dave
        Marples.

    * NXP Freescale i.MX RT Boards:

      - IMXRT1060-EVK:  Add support for the IMXRT1060-EVK.  From David Sidrane.

    * NXP LPC17xx Boards:

      - Olimex-LPC1766STK:  Add support to initialize a USB HID keyboard.  Add
        a configuration for testing the HID keyboard.  From Gregory Nutt.

    * On Semi LPC23450 Drivers:

      - LC823450: MPU support for FLAT build  From Masayuki Ishikawa.

    * STMicro STM32:

      - STM32:  Add support for STM32F303xD/E.  From Mateusz Szafoni.
      - STM32 L4:  Add initial support for STM32L412 and STM32L422 chips  From
        Juha Niskanen.

    * STMicro STM32 Drivers:

      - STM32 ADC: Major refactor:  Use STM32 ADC IP core version and ADC
        available functions instead of chip family names in conditional
        compilation.  Replace family specific ADC headers with STM32 ADC IP
        core version headers.  Configurable sample time supported for all
        chips, not just L1.  Enable/disable interrupts supported for all
        chips, not just L1.  Add ADC resolution configuration.  From Mateusz
        Szafoni.
      - STM32 PWM: Improvements in STM32 PWM low level driver:  Support
        complementary outputs, dead-time configuration, output polarity and
        IDLE state configuration.  From Mateusz Szafoni.
      - STM32 PWM:  Break and lock configuration and some cosmetics  From
        Mateusz Szafoni.
      - STM32 SPI.  Enable separate DMA per SPI configuration  From Daniel Agar.
      - STM32 F7 FLASH:  Allow programming OTP blocks through progmem
        interface  From Jussi Kivilinna.
      - STM32 H7 I2C:  Add I2C support for STM32H7.  From raiden00pl.
      - STM32 H7 RCC:  Update RCC definitions, add SPI clock configuration and
        some fixes in RCC.  From raiden00pl.
      - STM32 H7 SPI:  Add basic SPI support for H7.  Enable SYSCFG clock in
        RCC.  From Mateusz Szafoni.

    * STMicro STM32 Boards:

      - Nucleo-F302R8:  Add support for Nucleo-F302R8 board  From raiden00pl.
      - Nucleo-F302R8:  Add PWM support.  From Mateusz Szafoni.
      - Nucleo-F303ZE:  Add basic support for nucleo-f303ze.  From Mateusz
        Szafoni.
      - Nucleo-F303ZE:  Support for ADC and ADC example.  From Mateusz Szafoni.
      - Nucleo-L432KC:  Added support for AT45DB Serial Flash  From Daniel P.
        Carvalho.
      - Nucleo-L432KC:  Add support for the INA226.  From Daniel P. Carvalho.
      - Nucleo-H743ZI:  Add NRF24L01 support.  From Mateusz Szafoni.
      - Olimex-STM32-P407:  Add a HID keyboard configuration.  From Gregory
        Nutt.
      - STM32F4-Discovery:  Add MLX90614 support for the STM32F4-Discovery
        board  From Alan Carvalho de Assis.
      - STM32F429I-DISCO:  Add PWM support.  From Mateusz Szafoni.
      - STM32F429I-DISCO:  Support for ADC and ADC example.  From Mateusz
        Szafoni.

    * MIPS32:

    - MIPS32 Toolchain.defs:  Add toolchain flags for the pinguino toolchain
      under Linux.  From Ouss4.

    * RISC-V:

      - RISC-V GAP:  This commit brings in support for the GAP8 architecture.
        The GAP8 is a 1+8-core DSP-like RISC-V MCU.  Also included is support
        for the Gapuino GAP8 evaluation board.  From hhuysqt.

    * Other Tools:

      - tools/tesbuild.sh:  No longer installs and builds the NxWidgets
        libraries.  They are now a port of apps/.  From Gregory Nutt.

    * Libraries/Header Files:

      - include/net and include/sys:  Align the constant values with values in
        the Linux kernel which makes targeting the usrsock server to Linux
        kernel easier.  From Xiang Xiao.
      - include/netdb.h  Add NO_ADDRESS definition  From zhangyuan7.
      - include/netinet/in.h:  Adds definitions for IPPROTO_IPV6 socket
        options to netinet/in.h.  Adds missing fields to sockaddr_in6.  Adds
        struct ipv6-mreq.  These changes all follow the opengroup standard for
        netinet/in.h  From Anthony Merlino.
      - include/netinet/in.h:  Add IPv4 SOL_IP socket options for symmetry
        with IPv6 definitions added in a previous commit.  Remove some
        duplicate types from sys/sockio.h.  From Gregory Nutt.
      - include/netinet/in.h:  Add other definitions required by
        OpenGroup.org.  From Gregory Nutt.
      - include/netinet/in.h:  Add Linux IP_PKTINFO and IPV6_PKTINFO
        definitions.
      - include/nuttx/net/ipv6ext.h:  Create header file with all of the
        definitions of IPv6 extension headers that I could find.  From Gregory
        Nutt.
      - include/nuttx/net/mld.h:  Add MLD header file based on RFC2710 and
        RFC3810.  From Gregory Nutt.
      - include/sys/socket.h:  With increased size of struct sockaddr_in6, the
        size of struct sockaddr_storage in include/sys/socket.h must also be
        increase so that it can contain the new, larger sockaddr_in6.  From
        Gregory Nutt.

      - libs/libc/misc:  Add implementation of CRC8-CCITT.  From Alan Carvalho
        de Assis.
      - libs/libc/modlib:  Add per-module library symbol table support.  From
        nchao.
      - libs/libc/net:  Add basic implementation for recvmsg() and sendmsg()
        per OpenGroup.org specification.  From ligd.
      - libs/libc/netdb:  A few improvements to getaddrinfo:  (1)  Use the
        protocol and socktype hints in returned address, (2) Ignore AI_PASSIVE
        argument if hostname is not NULL  From Anthony Merlino.
      - libs/libc/netdb:  Make DNS receive timeout configurable.  From ligd.
      - libs/libc/stdio:  Eliminate recursive in conversion functions of
        lib_vsprintf().  From Xiang Xiao.
      - libs/libc/string:  Add some new functions defined in POSIX.1-2017:
        stpncpy(), strsignal(), psignal(), psiginfo().  From Gregory Nutt.
      - libs/libc/string:  Add memrchr() function  From Xiang Xiao.
      - libs/libc/string:  Make strerror() return the string "Success" for
        error = 0.  From Petteri Aimonen.

    * Build System:

      - Makefile.unix/win:  Remove deletion of Eclipse project files from make
        distclean target.  From Gregory Nutt.
      - apps/Application.mk:  Fix some build issues.  (1) Unable to found
        target 'context' when CONFIG_NSH_BUILTIN_APPS disabled. (2) Unable to
        generate multiple programs.  From Chao An.
      - apps/Directory.mk:  Fix distclean targets.  Makefiles were not
        removing generated Kconfig files.  There was then no way to remove
        this Kconfig files without manually deleting them one at a time.  From
        Gregory Nutt.

    * NSH: apps/nshlib:

      - apps/nshlib/, apps/examples/:  Update to show newer file system
        object types returned by stat().  From Gregory Nutt.
      - apps/nshlib:  Add support for the 'env' command.  From Gregory
        Nutt.
      - apps/nshlib:  Add support for NSH local variables if
        CONFIG_NSH_VARS are set.  These are like environment variables but
        are local to NSH.  The importance of this is that these variables
        are *not* inherited when NSH creates a new task.  The new command
        'export' was added.  In this case, the NSH variable will be promoted
        to an environment variable and will then be inherited by any tasks
        executed by NSH.  From Gregory Nutt.
      - apps/nshlib:  If CONFIG_NSH_VARS=y, the NSH 'set' command with no
        argument will list all of the local NSH variables.  From Gregory
        Nutt.

    * Examples/Tests: apps/examples:

      - apps/examples/gpio:  Align with GPIO driver update  From wangyanjiong.
      - apps/examples/ina226:  Added INA226 example  From Daniel P. Carvalho.
      - apps/examples/mld:  Add a test of MLD.  Provides a mechanism for some
        low-level bring-up of MLD.  From Gregory Nutt.
      - apps/examples/mlx90614:  Add mlx90614 test example  From Alan Carvalho
        de Assis.
      - apps/examples/mlx90614/:  Include support to change device address on
        mlx90614  From Alan Carvalho de Assis.
      - apps/examples/fstest: Adapt the existing fstest example for SPIFFS:
        For SPIFFS, add garbage collection and file system integrity IOCTL
        calls. Call statfs() and show state of file system on each loop.  Add
        logic to dump logic content of SPIFFS.  Ignore EINTR errors while
        reading or writing.  Add configuration option to customize stack
        size.  Detect when the media is full and stop writing files.  Report
        total file size.  From Gregory Nutt.
      - apps/examples/tcpblaster:  Add an option to use poll() to pace input
        or output.  From Gregory Nutt.
      - apps/examples/tcpblaster:  Select CONFIG_LIBC_FLOATINGPOINT
        automatically.  Units in output are wrong:  Not Kbps bus Kb/Sec.  From
        Gregory Nutt.
      - apps/examples/udpblaster:  Add option to use poll() on output (only).
        From Gregory Nutt.

    * System Utilities: apps/system

      - apps/system/ping and apps/system/ping6:  Set optind to zero in the
        error case/.  Move all ping preparation work into icmp_ping.  Support
        -W <timeout> and -s <size> option.  Decouple the output from ping
        logic.  From Xiang Xiao.
      - apps/system/ping and pings and apps/netutils/ping:  Extract icmp ping
        and icmpv6 ping6 logic from system/ to C-callable library in
        netutils/.  From ligd.
      - apps/system/progmem:  Remove this utility.  It makes illegal direct
        calls into the OS.  From Gregory Nutt.

    * Network Utilities: apps/netutils:

      - apps/netutils/netlib and apps/examples/igmp:  Adapt to use the
        corrected, semi-standard version of struct ip_msfilter.  From Gregory
        Nutt.
      - apps/netutils/chat and apps/examples/chat:  'constify' chat variables
        and parameters  From Xiang Xiao.

    * Wireless Utilities: apps/wireless:

      - apps/wireless/ieee802154/i8sak: Properly shuts down event thread.
        From Anthony Merlino.
      - apps/wireless/ieee802154/i8sak:  Fixes i8sak name. Accidentally renamed
        to i8ask in recent changes  From Anthony Merlino.
      - apps/wireless/ieee802154/i8sak:  Adds support for getting/setting
        transmit power.  From Anthony Merlino.

    * Graphic Utilities:  apps/graphics:

      - apps/graphics/NxWidgets:  Move the NxWidgets repository into the apps/
        repository.  Remove old apps/NxWidgets directory.  Move NxWidgets
        files into apps/graphics/NxWidgets. Integrate configuration/build
        system.  Fix file paths in file headers.  Remove some duplicate
        tools.  Add new NxWidgets Unit Test configuration and build logic.
        From Gregory Nutt.
      - apps/graphics/NxWidgets:  Add CNxString string + operator and
        ::format() function.  Add CNumericEdit option to include unit name
        after the value.  Make CNxWidget useWidgetStyle() public.  From
        Petteri Aimonen.
      - apps/graphics/NxWidgets:  Add CLabelGrid control for displaying text
        in grid format.  From Petteri Aimonen.

Bugfixes.  Only the most critical bugfixes are listed here (see the
ChangeLog for the complete list of bugfixes and for additional, more
detailed bugfix information):

    * Core OS:

      - Clock:  Remove g_monotonic_basetime and g_clock_monotonic_time since
        we don't need ensure monotonic time start from zero as state here:
        http://pubs.opengroup.org/onlinepubs/009696899/functions/clock_getres.html
        From Xiang Xiao.
      - Clock:  Don't call up_timer_gettime in clock_gettime() and
        clock_systimer() to ensure the return value from them consistent with
        clock_systimespec  From Xiang Xiao.
      - Clock Initialization:  clock_inittime() needs to be done with
        CONFIG_SCHED_TICKLESS and clock_initialize should skip
        clock_inittime() for external RTC case since the RTC isn't ready yet.
        From Xiang Xiao.
      - IOBs:  Work around some issues with the IOB throttle semaphore.  It
        has some odd behaviors that can cause assertions in sem_post().  Also,
        it seems to get outside of its range occasionally.  Need to REVISIT
        this.  From Gregory Nutt.
      - IOBs:  iob_navail() was returning the number of free IOB chain queue
        entries, not the number of free IOBs.  Completely misnamed.  From
        Gregory Nutt.
      - PM:  Use the start time of state btime to calculate thrcnt; remove the
        loop whose count may be very big after the long idle  From ligd.
      - PM Uninitialization:  Fix pm_domain_s.stime un-initialize caused time
        error.  From ligd.
      - sched_kfree() and sched_ufree():  This patch prevent heap corruption
        in a corner case where memory is freed while switching contexts.  This
        change forces all de-allocations via sched_kfree() and sched_ufree()
        to be delayed.  Eliminating the immediate de-allocation prevents the
        problem with the the re-entrant semaphore because the deallocation
        always occurs on the worker thread, never on the suspended task.  From
        EunBong Song.
      - sigsuspend():  sigsuspend() shouldn't eat the pending signal but
        dispatch all instead  From Xiang Xiao.
      - task_restart():  Was restarting tasks with all signals set in the
        sigprocmask set.  Should have restarted with the sigprocmask cleared.
        Noted by Jeongchan Kim  From Gregory Nutt.
      - unsetenv():  Fix and error in unsetenv() when un-setting the last of
        the environment variables.  From Gregory Nutt.
      - waitpid():  Remove a bad error check.  From Gregory Nutt.

    * File System/Block and MTD Drivers:

      - FAT: Fix file data corruption in fat_truncate().  From Petteri Aimonen.
      - Partitions:  Try MTDIOC_GEOMETRY IOCTL before bops's geometry.
        From Xiang Xiao.
      - MTD Progmem:  Change up_progmem_npages() to up_progmem_neraseblocks().
        page is a unit for read/write operation.  eraseblock is a unit for
        erase operation.  up_progmem_npages() is a little bit confusing
        because it returns number of erase blocks in flash memory.  This patch
        changes up_progmem_npages to up_progmem_neraseblocks.
        up_progmem_eraseblock erase a block. so it's better to return the
        erase block size than page size.  From EunBong Song.
      - R/W Buffer:  Fix a lock issue  From Xiang Xiao.
      - SmartFS:  Current sector should have a space for next entry size.  If
        not, we should move to next sector.  From EunBong Song.

    * Networking/Network Drivers:

      - 6LoWPAN: Fixes bug in uncompress_addr handling of odd postfix.  This
        affected multicast compress/uncompress since it's the only logic that
        used an odd postfix. The odd byte needs to be handled first, not
        last.  From Anthony Merlino.
      - ARP and ICMPv6:  Don't call d_txavail directly since it may point to
        NULL  From Xiang Xiao.
      - ICMPv6:  icmpv6_neighbor() shouldn't use the out of scope
        variable(dripaddr)  From Xiang Xiao.
      - IPv6 input:  Fixes logic in ipv6_input to handle more than ff02::/16
        multicast addresses. Don't forward mcast packets if scope is not
        appropriate  From Anthony Merlino.
      - IPv6 Input:  Fix a logic error when the received IPv6 srcaddr is a
        multicast address.  Exiting logic only supported UDP multicast.  But
        MLD and certain other ICMPv6 packets also require acceptance of
        multicast packets.  From Gregory Nutt.
      - TCP:  In TCP recv window calculations, in order to receive data we
        must not only have IOBs available, but we must also have at least one
        IOB chain qentry available.  Otherwise, we will advertise that we an
        buffer a lot of data when, in fact, we cannot.  This is an
        experimental fix to a performance problem noted by Masayuki Ishikawa.
        From Gregory Nutt.
      - TCP:  Fix compiler error and warning when CONFIG_NET_SENDFILE=y  From
        Xiang Xiao.
      - TCP Input:  Fix recovery when ackseq > unackseq.  The comment near
        this line says "reset the number of outstanding, unacknowledged
        bytes".  However, the code actually resets the whole TCP connection.
        It was changed to the current form in commit f034d84ea1f with no
        explanation of the intent. Recover the line to what it was before that
        commit.  From Sakari Kapanen.
      - TCP Write Buffering:  Fix buffer release handling on failed buffer
        allocation.  Attempt to release write buffer on failed TCP write I/O
        buffer alloc and tryalloc failed to wrb->wb_iob assertion.  From Harri
        Luhtala
      - TCP/UDP:  In the POLLOUT poll logic, request an immediate Tx poll from
        the network device bound to the socket.  From Gregory Nutt.
      - UDP:  On a failure to find the destination device, fallback to
        netdev_default device if the device is not found, rather than
        arbitrary using the device at the head of the list of devices.  From
        Xiang Xiao.
      - USRSOCK:  Revert previous commit to re-allow combination of usrsock
        and NuttX TCP/IP stack.  For example, in case device has Ethernet and
        mobile connectivity and NuttX TCP/IP stack is used when configured to
        use Ethernet connection and usrsock when configured to use modem
        (modem TCP/IP stack through usrsock).  From Jussi Kivilinna.
      - USRSOCK accept():  Mark newconn ready before issue accept request to
        avoid the case that the request is discarded due to the socket being
        in the invalid state  From Xiang Xiao.

    * Wireless/Wireless Drivers:

      - Broadcom 802.11 Driver:  There were two functions that have a address
        issue.  In bcmf_read_sbreg() and bcmf_write_sbreg():
        SBSDIO_SB_OFT_ADDR_MASK should be used before map address space.
        Noted by Shao Li in Bitbucket issue #126.  From Gregory Nutt.
      - Broadcom 802.11 Driver:  Remove incorrect OR condition.  Always true.
        Noted by Shao Li in Issue 127.  From Gregory Nutt.
      - NRF24L01:  Fix compilation errors.  From Mateusz Szafoni.

    * Other Common Drivers:

      - ALARM Upper Half: Fix alarm ISR error when no CONFIG_SCHED_TICKLESS
        drivers/timers/arch_alarm.c: Use uint64_t to avoid alarm 32-bit
        overflow.  From ligd.
      - MAX11802: Fix compilation errors and allow setting PULL and SAMPLE
        registers.  From Petteri Aimonen.
      - S25FL1:  During a MTDIOC_GEOMETRY ioctl call, the driver was
        incorrectly reporting the blocksize to be the same as the erasesize.
        The blocksize should be 256 (the page size).  This patch fixes that,
        and now the SmartFS configuration is working.  From Ken Pettit.
      - SYSLOG:  nx_syslog's return value should include the timestamp length
        From Xiang Xiao.
      - SYSLOG:  syslog_putc() calls sc_force in idle task even if interrupt
        buffer enabled.  The following cases may hang randomly in the bring up
        phase: (1) boot up process and (2) suspend/resume process.  Either
        case runs in the idle task context, so it's difficult to debug the
        hang issue if these output go through the interrupt buffer.  From
        Xiang Xiao.
      - SYSLOG:  Ensure interrupt log doesn't interlace in normal log.  Don't
        call syslog_putc in syslog_default_write because syslog_putc will try
        to empty the interrupt buffer every time.  From Xiang Xiao.
      - UART 16550:  Fix UART flow control issue.  UART_MCR_RTS need be high
        even UART_MCR_AFCE is enabled  From zhangyuan7.
      - USB RNDIS Device:  Fix buffer overrun check in rndis.c.  The rndis
        driver has been working since 13 Nov 2017.  However, I finally found
        that it depends on network and buffer configurations.  If a receiving
        TCP packet is divided into smaller ones based on USB max packet size,
        this condition check works correctly.  From Masayuki Ishikawa.

    * ARMv7-A:

      - ARMv7-A:  Replicate the same fix was previously committed for the
        ARMv7-R.  From Gregory Nutt.

    * ARMv7-R:

      - ARMv7-R:  Fix error in cp15_flash_dcache.  Change mcrne to mcr for
        unconditional dcache.  From EunBong Song.

    * ARMv7-M:

      - ARMv7-M Interrupts:  Correct all ARMv7-M architectures.  Interrupts
        were not be disabled correctly on power up.  Writing zero to the NVIC
        SET-ENABLE registers has no effect.  In order to disable interrupts,
        it is necessary to write all ones to the NVIC CLEAR-ENABLE register.
        Noted by David Sidrane.  From Gregory Nutt.

    * Broadcom BCM2708 Drivers:

      - BCM2708 Serial:  Juha Niskanen's fix related to STM32
        CONFIG_SERIAL_OFLOWCONTROL also applies to cloned logic in BCM2708.
        From Gregory Nutt.

    * Intel x86:

      - Qemu i486:  Correct .bss, IDLE stack, heap organization.  From Gregory
        Nutt.

    * NXP/Freescale LPC43xx Drivers:

      - LPC43 Ethernet:  Fix Ethernet TX_EN pin definitions.  TX_EN on LPC43xx
        can be routed via P0.1 and PC.4 in both MII and RMII mode.  Before,
        P0.1 was hard-coded for MII and PC.4 was hard-coded for RMII.  Also,
        the definitions used inconsistent naming (TXEN vs. TX_EN).  From Jakob
        Haufe.
      - LPC43 Serial:  Fix copy-paste error: g_usart1port->g_uart1port.  From
        Dave Marples.
      - LPC43 SDMMC:  Fix the LPC43 family SDMMC card access: Clocks were
        wrongly configured, way too fast because there is no primary divider
        on LPC4330, the LPC43_SDMMC_DELAY register was not being set, the
        LPC43_SDMMC_BLKSIZ and LPC43_SDMMC_BYTECNT registers had the wrong
        values.  From Dave Marples.
      - LPC43 SDMMC:  Corrected a problem in lpc43_dmasendsetup().  There was
        no linked DMA descriptor code on the send side.  The end result was
        stalls while sending multiple sectors.  This commit adds that in and
        the send code is working much better.  From Dave Marples.
      - LPC43 SDMMC:   With these changes the SDMMC card for LPC43 is now
        working properly:  Timing was dependent on CPU speed rather than
        absolute time, end of transfer handling was a bit mixed up.  It is
        possible for data to still be in the FIFO (i.e. not have reached the
        card) when a next write is requested, so we need to wait for that to
        complete.  Interrupt Status could be carried over from one transfer
        episode to the next, corrupting progress.  Multi-descriptor DMA
        writing simply wasn't implemented.  From Dave Marples.

    * NXP/Freescale LPC43xx Boards:

      - Bambino-200E:  Correct calculation of SDMMC clock configuration.  The
        LPC43 has no SDMMC source clock divider.  Error noted by Dave
        Marples.  From Gregory Nutt.

    * NXP/Freescale Kinetis:

      - Kinetis:  Remove all attempts to reprioritize interrupts. From Gregory
        Nutt.

    * NXP/Freescale Kinetis Drivers:

      - Kinetis I2C:  I2C On failed reset re-initialization I2C and clocking.
        If a reset fails, we still must reinitializes the I2C block so that
        subsequent transfers will not cause a hard-fault due to the clock
        being off.  If that transfer fails it can try to reset again.  From
        David Sidrane.
      - Kinetis Serial:  Juha Niskanen's fix related to STM32
        CONFIG_SERIAL_OFLOWCONTROL also applies to cloned logic in Kinetis.
        From Gregory Nutt.

    * NXP i.MXRT Drivers:

      - i.MXRT Ethernet: The board would not come up if I ran NuttX from cold.
        I dumped the PHY registers to see what the differences were and the
        PHY was coming up in NANDTree mode. This is a mode for testing
        connectivity between the PHY and the MAC.  Switching this mode off in
        the PHY registers has fixed the problem.  From Dave Marples.
      - i.MXRT Ethernet:  Fix a race condition in setting up the Ethernet Tx
        transfer.  From Dave Marples.
      - i.MXRT Ethernet:  Corrections for the i.MXRT Ethernet: (1) Now the
        Ethernet is completely re-initialized when an error occurs by means of
        taking the interface down and back up but the PHY is _not_
        renegotiated for that case because that is very time consuming and an
        error in the Ethernet is no reflection on the state of the PHY
        anyway.  (2) Explicitly sets the expected PHY address to zero (this
        could be moved into the config rather than searching for it which
        takes ages, and it's zero anyway for this board (that's the broadcast
        address, and anything that cannot respond on that has multiple PHYs,
        so that would be a new board).  (3) Allows for the renegotiation of
        the PHY to be optional when a reset is needed. If a non-renegotiated
        reset doesn't result in good comms to the PHY then it'll automatically
        be escalated to a renegotiated one.  (4) Only performs a reset for
        errors that need it (the CRITICAL_ERROR define).  The list of errors
        that need reset are somewhat arbitrarily chosen based on my prejudices
        and might need to be revisited, but certainly the jabber errors don't
        need reset, the partial packet is thrown away by the layer above
        anyway.  (5) Re-loads the multicast table on reset.  (6) Adds a bit
        more logging into the imxrt Ethernet module.  From Dave Marples.
      - i.MXRT LPI2C:  Fixes 2 bugs in the for IMXRT1050: (1) I2C time out and
        did not send STOP condition when sending single byte, (2) I2C could
        not receive bytes after repeated start.  From Ivan Ucherdzhiev.
      - i.MXRT LPSRTC:  SVNC LPCR register bits 0 & 1 are NOT reserved and
        are, in fact, needed to enabled the SRTC.  Now the SRTC is working.
        From Ivan Ucherdzhiev.
      - LPC54 SDMMC:  Add support for and SDMMC errata.  It appears that now I
        can read the SD card successfully, but I get CRC errors when writing
        to the card.  From Gregory Nutt.
      - LPC54 SDMMC:  Ported Dave Marples fixes LPC43 SDMMC to the LPC54.
        From Gregory Nutt.
      - i.MXRT WDOG:  Typos in bit definitions, wdog registers are 16 bits,
        wdog update has to be within 255 clocks of unlock, define board
        clocking based on divisor and muxes.  From David Sidrane.

    * NXP i.MXRT:

      - i.MXRT:  clockconfig bug fix:  Fixed logic that was not clearing bits
        as ~ was  missing in &= mask operations.  Use values from the board.h
        file so set the Mux that selects the clock sources.   Use board
        defined PODF values to select clock.  Only configure USDHC2 clocks
        when board defines clocks.  From David Sidrane.

    * NXP i.MXRT Boards:

      - IMXRT1050-EVK:  Previous committed implemented SPI-based MMC/SD card
        support conditioned on CONFIG_MMCSD.  This interferes with the
        implementation of MMC/SD card support using the SDIO-based
        peripheral.  This commit renames that atypical support to *mmcsd_spi*
        and conditions using the SPI-based support on CONFIG_MMCSD_SPI which
        will then not interfere with the MMC/SD support that can be
        conditioned on CONFIG_MMCSD_SDIO.  From Gregory Nutt.

    * On Semi LC823450 Boards:

      - LC823450:  Fix up_allocate_heap() in lc823450_allocateheap2.c.  For
        lc823450, heap area in flat build mode must start just after
        _eronly.  Because bss/data area is allocated in lower address than
        text area in SRAM. See ld.scripts for details. Also, this change
        removes unused up_allocateheap.c  From Masayuki Ishikawa.

    * Silicon Labs EFM32 Drivers:

      - EFM32 Serial:  Juha Niskanen's fix related to STM32
        CONFIG_SERIAL_OFLOWCONTROL also applies to cloned logic in EFM32.
        From Gregory Nutt.
      - EFM32 USB Device:  The epin_configure() function used the same eptype
        as the TxFIFO number for all endpoints.  This should probably be the
        physical EP number, not the EP type.  Suggested by Key Two.  From
        Gregory Nutt.

    * STMicro STM32 Drivers:

      - STM32* SPI:  Don't rely on SPI_CR1_SPE to determine if peripheral has
        been initialized.  This change is needed specifically for the case
        where a boot loader sets the SPE bit before starting NuttX.  In that
        case, the test in the SPI driver is wrong.  This change fixes that by
        assuring that NuttX has booted and initialized at least once (whether
        or not SPE is set) before the driver starts refusing to initialize.
        From Anthony Merlino.
      - STM32 F0, F7, H7, L4 Serial:  Fix use of CONFIG_SERIAL_IFLOWCONTROL
        where CONFIG_SERIAL_OFLOWCONTROL was intended.  From Juha Niskanen.
      - STM32 TIM:  Don't use hard-coded UIF interrupt in some functions.
        From raiden00pl.
      - STM32 (FS/HS), STM32F7, and STM32L4 OTGFS/HS Device:  The
        epin_configure() function used the same eptype as the TxFIFO number
        for all endpoints.  This should probably be the physical EP number,
        not the EP type.  Suggested by Key Two.  From Gregory Nutt.
      - STM32 F2:  Fixes Kconfig options to include all STM32F20XX processors,
        not just STM32F207.  Also removes redundant STM32_STM32F429 depends
        from Kconfig. STM32F4XXX already does this.  From Anthony Merlino.
      - STM32 F4 DAC:  STM32F407VG has only one DAC.  NDAC=2 causes
        compilation error when trying to use e.g. STM32_DAC1_CR macro.  From
        Petteri Aimonen.
      - STM32 F7 Serial:  Force invalidation of data cache after DMA re-enable
        when returning from low-power mode  From Juha Niskanen.

    * STMicro STM32 Boards:

      - B-L475E-IOT01A:  Correct timer source clock frequencies.  From Freemans
        Goden.
      - Nucleo-L432KC:  Fix SPI pin definitions in board.h.  From Daniel P.
        Carvalho.

    * MIPS32:

      - CP0 Definitions:  Fix some copy-paste errors that cause malformed
        comments and syntax errors when certain CP0 CONFIG1 bits are
        referenced.  Note in Issue 123 by Anonymous.  From Gregory Nutt.
      - microMIPS:  Reported by Anonymous in Bitbucket Issue #129:   When MIPS
        port is built for microMIPS and then loaded as an application, the
        __start entry point is entered in microMIPS mode, but the CPU core
        initialization code there misses to set the config3ISAOnExc bit to 1.
        Subsequently, exceptions are entered in MIPS32 mode, but the code base
        was built for microMIPS.

     * Microchip PIC32MZ:

      - PIC32MZ Startup:  In pic32mz-head.S, initialize the global pointer in
        all shadow sets.  From Ouss4.

     * Microchip PIC32MZ Drivers:

      - PIC32MZ Serial:  Fix a typo in assignment of TTYS0 to UART6  From Ouss4.

    * Simulation:

     - SIM Network Driver:  Fix error 'invalid operands to binary &' From
       Xiang Xiao.

    * C Library/Header Files:

      - Fix typographical error in endian.h and resource.h  From anchao.
      - include/net/if.h:  Adds extern "C" guard in include/net/if.h  From
        Anthony Merlino.
      - include/netinet/in.h:  Per OpenGroup.org, type of sin_port in struct
        sockaddr_in must be in_port_t vs uint16_t.  NOTE: in_port_t is
        typdef'ed as uint16_t anyway.  From Gregory Nutt.
      - include/nuttx:  Fix definitions used to access OS functions within the
        libraries.  In the FLAT build, we must always set the errno and/or
        create cancellation points because the same library functions are used
        within the OS as are used by applications.  This could cause issues
        for the OS but corrects some problems at the user interface.  Noted by
        Federico Braghiroli in Bitbucket issue 121.  From Gregory Nutt.
      - include/nuttx/clock.h:  Fix uptime wrong if DEBUG_FEATURES and
        SCHED_TICKLESS enabled.  From Xiang Xiao.
      - include/nuttx/fs/fs.h:  Fix some backward parameters in a new macro
        definition.  From Gregory Nutt.
      - include/nuttx/fs/fs.h:  Register_mtddriver should depend on CONFIG_MTD
        not CONFIG_MTD_PARTITION  From Xiang Xiao.
      - include/sys/socket.h:  Renumber the socket types.  They must begin at
        1, not zero. Socket type zero has a special meaning for some
        interfaces.  For example, getaddrinfo() uses a socket type of zero to
        many any type of socket.  The is no standard name for the
        any-type-socket, but macOS uses SOCK_UNSPEC.  NuttX will do the same.
        Issue noted by Anthony Merlino. From Gregory Nutt.

      - libs/libc:  Correct some errors in psignal() and stpncpy().  From
        Lokesh B V.
      - libs/libc/math:  Add variable convergence in log() and logf() to avoid
        hangs caused by failure to converge for very specific input values.
        Also includes a small change to log() and logf() that improves
        accuracy and convergence time.  From Rajan Gill.
      - libs/libc/stdio: Fix conversion for format specifiers in sscanf() that
        appear right after a floating point format specifier.   When
        performing a floating point conversion the parsing code could consume
        more than required characters from the input buffer. This made
        impossible to convert input of form "1.1K" using format "%f%c".  Fix
        the issue by advancing the input buffer with the actual characters
        converted as a float point number.  From Mihai Serban.
      - libs/libc/stdio:  Remove CONFIG_NOPRINTF_FIELDWIDTH.  That option
        does, indeed, make the printf family of functions much smaller.  But
        it also adds a lot of complexity and makes the functions
        non-standard.  Removing this might break some of the tinier platforms
        but it is the best thing to do for long term maintenance for for
        OpenGroup.org compliance.
      - libs/libc/stdio:  Update to vsprintf().  This resolves the integer
        field width problem if Issue 35 for the cases of integer, long and
        long long integer types.  The output now matches the output form
        glibc.  From Gregory Nutt.
      - libs/libc/string:  Correct the return pointer value from stpncpy() for
        the case where the NUL terminator is transferred.  From Gregory Nutt.
      - libs/libc/string:  Fix strrchr() so that it considers null terminator
        as part of string.  From Petteri Aimonen.
      - libs/libc/wqueue:  Eliminate a race condition noted by Xiang Xiao.
        Use sigprocmask() so that we do not lose a signal.  From Gregory Nutt.
      - libs/libnx/nxfonts: Fix kerning of 'I' in Sans17x22 font.  From
        Petteri Aimonen.
      - libs/libnx/nxfonts:  In nxfonts_getfont(), avoid unnecessary warnings
        for other whitespace chars also.  From Petteri Aimonen.
      - libs/libnx/mxmu:  NXMU now re-validates window pointer for mouse
        events.  NXMU caches the previous window pointer so that further mouse
        events can be sent to the same window. However, if the window is
        destroyed while mouse button is held down, the pointer may become
        invalid and cause a crash. This patch revalidates the pointer before
        using it.  From Petteri Aimonen.
      - libs/libnx/nxtk: nxtk_bitmapwindow: Fix warning message when bitmap is
        fully off-screen.  From Petteri Aimonen.

    * Build System:

      - Fix issue with libcxx build.  This was changed multiple times, but
        should be fixed now.  From Anthony Merlino.
      - configs/Makefile and tools/Config.mk:  Move single file copy to the
        new function COPYFILE.  This fixes the Windows native build case when
        there is no cp or cp does not recognize Windows paths.  From Anatol
        Ivanov.
      - tools/Config.mk and tools/Makefile.win:  Force use 'cmd' for shell
        with windows native build  From Anatol Ivanov.
      - tools/Directories.mk:  Correct the path to the installed libcxx
        directory.  From Gregory Nutt.
      - tools/Makefile.win/unix:  Staging directory (and its libraries) should
        be removed on 'make clean' (issue noted by Dave Marples).  From
        Gregory Nutt.

      - apps/Directory.mk:  If the current directory contains a Kconfig file
        and MENUDESC is not defined, then Directory.mk must not trash the
        Kconfig in the current directory.  From Gregory Nutt.
      - apps/Makefile:  Fix Windows native build patch extension.  From Anatol
        Ivanov.

    * Other Tools:

      - tools/Config.mk:  Fix an error in RWILDCARD implementation  From
        Anthony Merlino.
      - tools/configure.c: Add missing '\n' in printf statement
      - tools/configure.c:   Add missed -g option to getopt() string.  From
        Anatol Ivanov.
      - tools/configure.c and tools/configure.sh:  Fix Windows native
        pre-build kconfig-conf incompatibility.  From Anatol Ivanov.
      - tools/csvparser.h:  Extend MAX_PARMSIZE to 256.  Fixes this issue:
        70: Parameter too long: ...  From Xiang Xiao.
      - tools/link.bat: Fix .fakelink creation.  From Anatol Ivanov.
      - tools/mkdeps.c:  Fix '\0' missing with MinGW.  From Anatol Ivanov.

    * NSH Library: apps/nshlib:

      - apps/nshlib:  Correct maximum number of arguments that can be provided
        to the mksmartfs command.  From Eunbong Song.
      - apps/nshlib:  Add fflush to nsh_consolewrite().  This resolves this
        problem:  'cat /dev/ttyCP &' followed by 'echo ls >/dev/ttyCP'.  In
        that case we can't get the 'ls' result immediately, because 'cat' cmd
        uses nsh_consolewrite() and that uses fwrite with no fflush. We can
        get the 'ls' result after type '\n', because nsh will fflush output
        when get '\n'.  From ligd.
      - apps/nshlib:  nsh_catfile() should not append '\n' if the last char in
        file is already '\n'  From Xiang Xiao.
      - apps/nshlib:  Fix warning g_oldpwd defined but not used
      [-Wunused-const-variable] in nsh_envcmds.c.  From Xiang Xiao.

    * Examples/Tests: apps/examples:

      - apps/examples/adc/Kconfig:  CONFIG_BOARDCTL_ADCTEST does not exist
        anymore and should removed as a dependency.  From Eunbong Song.
      - apps/examples/webserver/Kconfig:  The webserver "app" allows for DHCP
        client to be enabled. However, the Kconfig infrastructure does not
        contain EXAMPLES_WEBSERVER_DHCPC config.  Based on patch from
        "Anonymous" attached to Bitbucket Issue #130.  From Gregory Nutt.

    * System Utilities: apps/system:

      - apps/system/hexed:  Fix memory leak  From zhuyanlin.
      - apps/system/i2c:  Fix i2c_msg freq initialization problem.  Typo
        prevented I2C frequency initialization in a struct i2c_msg.  From
        dongjiuzhu.
      - apps/system/system:  Fix warning when passing argument 6 of
        'task_spawn' from incompatible pointer type
        [-Wincompatible-pointer-types]  From Xiang Xiao.

    * Network Utilities: apps/netutils:

      - Correct some network-related configuration variable names.  All *_MTU
        defines were changes to *_PKTSIZE gut that was not reflected in
        apps/  From Gregory Nutt.
      - apps/netutils/netlib/netlib_parsehttpurl.c:  Correct handling of long
        URLs as noted in Bitbucket issue #119 (in the nuttx/ repository, not
        the apps/ repository).  From Gregory Nutt.
      - apps/netutils/codecs:  "dst" overflow protection when base64 string
        ends with "="  From Aleksandr Vyhovanec.
      - apps/include/netutils/ipmsfilter.h:  Eliminate error generated by bad
        pre-processor logic.  From Gregory Nutt.

    * GPS Utilities: apps/graphics:

      - apps/graphics/NxWidgets:  Fix garbage returned when
        CCycleButton::getValue() is called after removeAllOptions().
        CScrollingPanel should not draw outside the widget area.  From
        Petteri Aimonen.

NuttX-7.28 Release Notes
------------------------

The 128th release of NuttX, Version 7.28, was made on January 19, 2019,
and is available for download from the Bitbucket.org website.  Note
that release consists of two tarballs:  nuttx-7.28.tar.gz and
apps-7.28.tar.gz.  These are available from:

    https://bitbucket.org/nuttx/nuttx/downloads
    https://bitbucket.org/nuttx/apps/downloads

Both may be needed (see the top-level nuttx/README.txt file for build
information).

Additional new features and extended functionality:

    * Core OS:

      - Critical Section Monitor:  Adds data collection logic in support of
        pre-task monitoring critical sections and pre-emption state.  From Gregory
        Nutt
      - Critical Section Monitor:  Add support for global pre-emption and
        global critical sections to monitor as suggested by Xiang Xaio.  From
        Gregory Nutt
      - Interrupt Time:   Measurement of interrupt handler duration used to
        be available only in Tickless mode since it used the high resolution
        Tickless timer to measure interrupt time.  This change adds
        CONFIG_SCHED_IRQMONITOR_GETTIME which, if enabled, will force the
        interrupt duration calculation to use the same high-resolution,
        platform-specific timer as is used with the Critical Section Monitor.
        This leads to two improvements:  (1) You can now measure interrupt
        duration in non-Tickless mode, and (2) in either mode, the interrupt
        duration and the critical section measures will use the same
        high-resolution timer and should, therefore, never be any discrepancy
        due to different clock sources.  From Gregory Nutt
      - Context Switching Protection:  Add debug assertions before each call
        to up_block_task() to assure that there is no attempt to block an
        IDLE task.  From Dave Marples
      - init Task:  Allow the init task priority to be configurable.  From
        David Sidrane
      - pthreads:  Implement pthread_key_delete().  This involves some minor
        changes to the group data structure.  From Gregory Nutt

    * File Systems/Block and MTD Drivers

      - ProcFS:  Extended the process ID ProcFS output to show per-thread
        maximum time for pre-emption disabled and maximum time within a
        critical section.  From Gregory Nutt
      - NXFFS:  Pass unrecognized IOCTL commands to the contained MTD
        driver.  From Daniel P. Carvalho
      - LittleFS:  Adds an initial port the ARM mbed littlefs to NuttX.  This does
        not include FLASH formatting utilities.  Depends on CONFIG_MTD_BYTE_WRITE.
        From lihaichen
      - AT25 MTD Driver:  Added support for AT25DF081A serial flash chip.
        From Marc Rosen
      - MTD Configdata Device:  Extends the MTD configdata device with the
        following features / additions:
          1. Configurable option to use named config items instead of enumerated
             ID/Instance numbers.
          2. Ability to iterate through the existing configdata items in the
             /dev/config device.
          3. Ability to "unset" a configdata item.
          4. Ability to perform "flash_eraseall" on the /dev/config device.
        From Ken Pettit

    * Networking/Network Drivers:

      - Telnet Driver:  Add NAWS and poll interface to telnet for screen size
        negotiation used with termcurses.  From Ken Pettit

    * Wireless/Wireless Drivers:

      - BLE HIC Core:  Add second RX work function  From Lwazi Dube
      - BLE IOCTL Commands:  Add SIOCBTCONNECT and SIOCBTDISCONNECT ioctl
        commands  From Lwazi Dube
      - CC2564:  Add cc2564 HCI UART driver.  From Lwazi Dube

    * Graphics/Display Drivers:

      - Sitronix ST7032i:  Add support to Alphanumeric Sitronix ST7032i
        display  From Alan Carvalho de Assis
      - NXP TDA19988:  This commit brings in a complete, but untested,
        implementation of a driver for the TI TDA19988 HDMI Encoder.  This encoder
        is used on the Beaglebone Black board.  Since this driver is untested, it
        requires CONFIG_EXPERIMENTAL in the configuration.  From Gregory Nutt

    * Crypto:

      - crypto/aes.c:  This change provides an improved AES cipher API in
        addition to the existing routines.  The reasons for this new API are:
        1) better performance, giving the possibility to avoid re-setting-up
        the key for each AES block when the same key is used multiple times.
        This is important for the current single user of AES, which is
        related to storage and FTL.  And 2) suitable for simultaneous use of
        multiple AES keys, which will be required by the upcoming crypto
        framework.  It retains compatibility with the previous API, so there
        is no need to change anything else right now.  From Sebastien Lorquet

    * Other Common Device Drivers:

      - MMCSD SDIO:  The mmcsd_sdio driver makes calls for dcache
        invalidation through the chip specific architecture function
        SDIO_DMARECVSETUP(). I changed the arch/arm/stm32f7 chips to use
        arch_invalidate_dcache_by_addr() instead of arch_invalidate_dcache().

        This commit includes additional changes to mmcsd_sdio.c.  I
        created SDIO_DMADELYDINVLDT() (DMA delayed invalidate) to
        invalidate store-into mode dcaches after the DMA transfer.  I
        have been using SDIO_DMADELYDINVLDT() for several weeks now and
        it has fixed the problems that I previously reported regarding
        non-cache aligned buffer invalidation errors (for my store-through
        dcache). However, it does not permit use of unaligned DMA buffers
        for store-into mode dcaches.

        SDIO_DMADELYDINVLDT() is a NoOp unless the chip specific Kconfig
        file selects CONFIG_ARCH_HAVE_SDIO_DELAYED_INVLDT. I have modified
        all the stm32f7 chips to select it.  From Bob Feretich
      - SPI Lower Half Interface:  Extend the HW features supported by SPI.
        It now supports a deferred DMA trigger hardware configuration.  From
        Dave Marples
      - DS28E17 1-Wire Driver:  Optimize I2C write followed by read to same
        address.  From Juha Niskanen
      - LMP92001:  Add support for the TI LMP92001 Multi-channle DAC/ADC
        device.  From Abdelatif Guettouche.
      - EEPROM Character Driver:  Add support to Microchip AT24CM02  From
        Alan Carvalho de Assis
      - Microchip MCP73871:  Add support to Microchip MPC73871 Battery Charger.
        From Alan Carvalho de Assis
      - MCP7941x:  Add support for the Microchip MCP741x external RTC.  From Ouss4
      - Sensirion SCD30:  Driver for Sensirion SCD30 CO2 sensor.  From Jussi
        Kivilinna
      - Sensirion SGP30:  Driver for Sensirion SCD30 gas sensor.  From Jussi
        Kivilinna
      - Sensirion SPS30:  Driver for Sensirion SCD30 particulate matter sensor.
        From Jussi Kivilinna
      - USB CDC/ACM Device:  When implemented usb cdc on nrf52840, I found
        some issues with  cdc driver:
          1. Lost data when receiving buffer is full;
          2. Low-water mask implement issue;
          3. Re-flush cdc buffer when enabling
          4. Serial dma is conflict with cdc , modify the serial.h
        From Levin Li

    * MIPS32:

      - Configuration System:  Allow Penguino for windows for the Windows
        Ubuntu platform as well.

    * Maxim Integrated MAX326xx

      - MAX32660:  Support for the MAX32660 was added (along with partial
        support for other members of the MAX326xx family).  The initial port
        includes  Clock configuration, timer, GPIO pin configuration, ICC,
        and UART.  Additional untested drivers are complete and ready for
        testing:  DMA, GPIO interrupts, SPI0 Master, TC, WDT.  The following
        drivers are not yet implemented: I2C and I2S.

    * Maxim Integrated MAX326xx boards

      - MAX32550-EVSYS:  Basic support for the Maxim Integrated MAC3X660
        EVSYS is included.  A basic NSH configuration is available and is
        fully functional.  Includes unverified support for an SPI0-based
        SD card.

    * Microchip/Atmel SAMD21/L21 Drivers:

      - SAMD21/L21:  Adds a complete ADC header file for SAMD21 and a partially
        complete ADC header file for the SAML21.  From Alexander Vasiliev
      - SAMD21/L21:  Export sam_i2c_master_initialize(int bus) to be used by
        board config.  From Alan Carvalho de Assis

    * Microchip PIC32MZ Drivers:

      - PIC32MZ I2C:  Add support for the I2C bus.  From Ouss4

    * ARMv7-A

      - ARMv7-A MMU:  Use TLBIMVA vs TLBIMVAAIS to invalidate the Cortex-A8
        cache.  From Petro Karashchenko

    * ARMv7-M

      - Cortex-M7 Cache:  This commit adds a new function
        arch_invalidate_dcache_by_addr(). It takes the same parameters as
        arch_invalidate_dcache(), but performs invalidation of only the lines
        in cache that need to be invalidated.  This new function could be
        used as a a direct replacement for arch_invalidate_dcache().  From
        Bob Feretich
      - ARMv7-M:  In the current implementation we only use very high
        priority interrupts (levels 0, 0x10 and 0x20 in CORTEX-M speak) but
        that means there are loads of lower priority ones that are
        effectively unused. I have *not* changed the semantics of these
        levels but have 'shifted' them to be based around the midpoint of the
        available interrupts (0x80) rather than at the top end....that allows
        for interrupts to be defined above (or, indeed, below) them as needed
        by the application.  This should have no functional effect on
        existing code but adds in a clean capability to define higher
        priority interrupts.  From Dave Marples

    * Broadcom BCM2708:

      - BCM2708:  Remove all support for the BCM2708/2835.  This was added
        only for support of the RaspberryPi Zero board which was previously
        removed.  The support was minimal and unverified.  The removed files
        can still be found in the Obsoleted directory.  From Gregory Nutt

    * Broadcom BCM2708 Boards:

      - Raspberry Pi Zero:  Remove the partial support for the Raspberry Pi
        Zero.  This port was started with the best of intentions but was
        never  completed.  The board support can still be found in the
        Obsoleted repository.  From Gregory Nutt

    * Nordic NRF52 Boards:

      - Improve LED handling #if~#endif in nrf52_autoleds.c and
        nrf52_userleds.c
          Add Adafruit Feather nRF52 board LED support
          Add Adafruit Feather nRF52 board
          Add nrf52-generic
          Replace 'pca10040' with 'generic'
          Copy from nrf52-pca10040 to nrf52-generic
        From Zou Hanya

    * NXP i.MX RT Drivers:

      - i.MXRT:  Add PIT, GPT, and QIMER(TMR) header files  From David Sidrane
      - i.MXRT:  Add FLEXPWM.  From David Sidrane
      - i.MXRT:  Add ADC chip header  From David Sidrane
      - i.MXRT Build:  Include up_systemreset and up_stackcheck.c  From David Sidrane
      - i.MXRT GPIO:  Add GPIO Support Input daisy selection.  From David Sidrane
      - i.MXRT Serial:  Support independent input and output flow control.  From
        David Sidrane
      - i.MXRT USB:  Use single define for USB pin definitions.  From David Sidrane
      - IMXRT106X:  Add FLEXCAN3 to pinmux header file. From David Sidrane

    * NXP Freescale i.MX RT Boards:

      - IMXRT1050-EVK:  GPIO device driver support added and tested by
        Pavlina Koleva and Ivan Ucherdzhiev.  From Pavlina Koleva

    * On Semi LPC23450:

      - LPC23450:  Add support for SPI flash boot.  Also, remove unnecessary
        code for the SPI flash boot.  From Masayuki Ishikawa

    * On Semi LPC23450 Boards:

      - LC823450-XGEVK:  Add linker script for SPI flash boot.  From
        Masayuki Ishikawa
      - LC823450-XGEVK:  Enable NFS client for RNDIS configuration.  Also, some
        stack size were adjusted to work with NFS  From Masayuki Ishikawa

    * Simulation

      - Critical Section Monitor:  Add low level timer support for simulation. From
        Gregory Nutt

    * STMicro STM32:

      - Configuration:  Simplify ARM core selection logic  From Mateusz Szafoni
      - Configuration:  USB Host is an option.  From David Sidrane
      - STM32 L0:  Brings in initial support for the STM23 L0.  From Mateusz
        Szafoni

    * STMicro STM32 Drivers:

      - STM32 ADC:  Configurable ADC DMA mode (one shot mode, circular
        mode).  From Mateusz Szafoni
      - STM32 ADC:  Start conversion on startup is now possible if TIM
        triggering selected.  This can be useful to start ADC TIM conversion
        for ADC IPv2 when opening ADC device.
      - STM32 DAC:  Unified naming for DAC interfaces  From Mateusz Szafoni
      - STM32 DMA:  Add interfaces to interact with high priority DMA
        interrupts. From Mateusz Szafoni
      - STM32 DMA:  Use STM32 DMA IP core version instead of chip family
        names.  From Mateusz Szafoni
      - STM32 DMA:  Add support for DMA v1 CSELR support.  From Mateusz Szafoni
      - STM32 HRTIM:  Do not enable timers on startup if option from Kconfig
        selected and add interface to enable/disable timers.  From Mateusz
        Szafoni
      - STM32 PWM:  Add timer enable/disable and frequency update to
        low-level ops.  From Mateusz Szafoni
      - STM32 SPI:  Implements the new deferred DMA trigger feature.  From
        Dave Marples
      - STM32 F0 Build:  Rename the stm32f0 directory to stm32f0l0 to make a
        space for STM32 L0.  Rename files, functions and defines, removing
        the f0_ from the names in order to make them MCU agnostic.  From
        Gregory Nutt
      - STM32 F0 GPIO:  Add support for GPIO EXTI.  From Mateusz Sfafoni
      - STM32 F2 FLASH:  stm32_flash_writeprotect() supported the same for
        STM32F20XX as STM32F4XXX  From Anthony Merlino
      - STM34 F7 DMA:  stm32f7 enable separate DMA per SPI configuration
        From Daniel Agar
      - STM32 F7 QEncoder:  Ported the QEncoder from F4 to F7.  From Eduard
        Niesner
      - STM32 F7 SPI:  Port Dave Marples STM32 deferred trigger enhancement
        to the STM32 F7 SPI drivers.  From Gregory Nutt
      - STM32 H7 SPI:  Port Dave Marples STM32 deferred trigger enhancement
        to the STM32 H7 SPI drivers.  From Gregory Nutt
      - STM32 L4 SPI:  Port Dave Marples STM32 deferred trigger enhancement
        to the STM32 L4 SPI drivers.  From Gregory Nutt

      * STMicro STM32 Boards:

      - B-L072Z-LRWAN1:  Add basic support for b-l072z-lrwan1.  Nucleo boards
        use as default ST LINK MCO as clock input from MCU and for this
        HSEBYP must be enabled.  From Mateusz Szafoni
      - Nucleo-F103RB:  Add board support. From Mateusz Szafoni
      - Nucleo-F103RB:  Add ADC and PWM examples.  From Mateusz Szafoni
      - Nucleo-F207ZG:  Add board support. From Mateusz Szafoni
      - Nucleo-F207ZG:  Add ADC and PWM examples.  From Mateusz Szafoni
      - Nucleo-F302R8:  Add high priority ADC interrupts example to the
        'highpri' configuration.  From Mateusz Szafoni
      - Nucleo-F334R8:  Add support for ADC injected sequence to the 'highpri'
        configuration, add triggering from TIM1.  From Mateusz Szafoni
      - Nucleo-F334R8:  Add example for the SPWM generation (custom STM32 PWM
        usage).  From Mateusz Szafoni
      - Nucleo-F767ZI:  Use on board USB UART as default console.  Board is powered
        by USB which can be used as UART link for upload and console.  Previously
        it was set to use Arduino shield which developer may not have.  From Phil
        Coval
      - Nucleo-F767ZI:   Add ethernet config based on nsh configuration plus
        stm32f769i-disco/nsh-ethernet.  From Phil Coval
      - Nucleo-L073RZ:  Add basic support for nucleo-l073rz.  Nucleo boards
        use as default ST LINK MCO as clock input from MCU and for this
        HSEBYP must be enabled.  From Mateusz Szafoni
      - Nucleo-L152RE:  Add board support. From Mateusz Szafoni
      - STM32F4 Discovery:  Add timing support for the critical section
        monitor using the DWT CYCNT register.  From Gregory Nutt
      - STM32F4 Discovery:  If the Critical Section Monitor, modify the
        ITM_LAR register to assure that the DWT cycle counter is enabled.
        Suggested by Dave Marples.  From Gregory Nutt
      - STM32F4 Discovery:  Add board support to display ST7032i  From Alan
        Carvalho de Assis
      - STM32F4 Discovery:  Add loadable application build support in
        Make.defs  From Masayuki Ishikawa
      - STM32F4 Discovery:  Update RNDIS configuration: (1) Add NFS and adjusted
        stack size for usermain and telnetd client.  (2) Add support for loadable
        application and ping. From Masayuki Ishikawa
      - STM32F4 Discovery:  Update nsh configuration: (1) Add
        CONFIG_BOARD_INITIALIZE=y, (2) Add CONFIG_EXAMPLES_HELLO=y.  From Masayuki
        Ishikawa
      - STM32F429I-DISCO:  Add high priority ADC interrupts example to the
        'highpri' configuration.  From Mateusz Szafoni
      - configs/nucleo-l073rz:  Support for nrf24l01.  From Mateusz Sfafoni

    * TI CCxx:

      - CC13x0 family and  CC13x2/CC26x2:  Basic, minimal support was added
        for these two chip families.  This is a Work-In-Progress:  There is
        just enough logic in place to support a simple NSH configuration.
        However, the port is still missing certain, necessary hooks into the
        TI ROM-based 'DriverLib'.  As a result, the support is not fully code
        complete and is totally untested.   Support for the CC26x2, which is
        nearly identical to the CC13x2 is fragmentary.  Stay tuned.
        Hopefully full support will be available in NuttX 7.29.

    * TI CCxx Boards:

      - LAUNCHL-CC1312R1:  Board support is available for the TI
        LAUNCHL-CC1312R1.  That board support consists only of an unverified
        NSH configuration.  The primary purpose of this port for the time
        being is simply support the core architecture bring-up.

    * TI AM335x:

      - AM335x:  Adds initial support for the TI AM355x family.
      - AM335x:  Add minimal wdog logic needed to disable the watchdog timer.
        Otherwise, the board is rebooted after certain time expires while NuttX is
        running.  From Petro Karashchenko
      - AM335x:  Switch to DMTimer2 for system tick generation. U-Boot does not
        enable DMTimer1ms clocks hence it is not possible to use it until
        implementation in am335x_clockconfig.c is ready.  From Petro Karashchenko

    * TI AM335x Boards:

      - Beaglebone Black:  Initial port for BeagleBone Black board support
        (TI AM335x family based on Cortex-A8).  Includes a basic functional NSH
        configuration .  From Petro Karashchenko

    * TI Tiva:

      - LM3S9B92:  Add support for LM3S9B92.  From Lwazi Dube

    * TI Tiva Drivers:

      - Tiva HCI UART:  Port bluetooth HCI uart interface from stm32 to tiva
        From Lwazi Dube

    * TI Tiva Boards:

      - TM4C1294-Launchpad:  Add IRQBUTTONS support to tm4c1294 launchpad.
        From Lwazi Dube

    * Tools:

      - tools/convert-comments.c:  Add a tool to convert C++-style comments
        to C89 C-style comments.  From Gregory Nutt
      - tools/detab.c:  Add detab.c which will convert all tabs in a file to
        spaces.  From Gregory Nutt
      - tools/lowhex.c:  Add lowhex.c that will convert hexadecimal constants
        in a file to use lower case representation.  From Gregory Nutt
      - tools/mkconfig.c:  Add definitions to distinguish between tristate
        'y' and 'm' options.  From Gregory Nutt
      - tools/nxstyle.c:  Add logic to detect long lines.  From Gregory Nutt
      - tools/nxstyle.c:  Add -h for help.  From Gregory Nutt

    * Libraries/Header Files:

      - include/nuttx/lcd/edid.h:  Add EDID definitions  From Gregory Nutt
      - libs/libc/netdb:  Make DNS retries configurable  From Juha Niskanen
      - libs/libc/netdb:  Harden query logic against DNS spoofing.  This
        commit implements most of the RFC 5452 guidelines for making DNS more
        resilient. We now verify response matches against what was queried
        and use unpredictable query IDs. It is also checked that response
        come from correct DNS server.  Also fixes a buffer overflow when
        querying hostnames longer than CONFIG_NETDB_DNSCLIENT_NAMESIZE.  From
        Juha Niskanen
      - libs/libc/netdb:  Support multiple IP addresses per hostname  From
        Juha Niskanen

    * NSH: apps/nshlib:

      - apps/nshlib:  Add support to use SLCD as NSH Console  From Alan Carvalho de
        Assis
      - apps/nshlib:  Add support for CROMFS start-up script. From David Sidrane
      - apps/nshlib:  Add var expansion in NSH parse.  From Daniel Agar
      - apps/nshlib:  Display built-in apps using multi-column mode like the NSH
        commands.  From Ken Pettit
      - apps/nshlib:  In all multi-column help output, calculate an optimal column
        width rather than using a hard-coded width that may or may not be
        appropriate.  Also make the number of rows presented dependent upon the
        maximum width of the widest column.  From Gregory Nutt
      - apps/nshlib:  Adds addroute command options for setting default gateway.
        Like 'addroute default <ipaddr> <interface>'.  From Anthony Merlino

    * Examples/Tests: apps/examples:

      - apps/examples/battery:  Add Battery Charger Monitor Example  From Alan
        Carvalho de Assis

    * System Utilities: apps/system

      - apps/system/configdata:  Adds an "cfgdata" command which allows
        manipulation of the /dev/config items via the command line.  One such use
        for this utility would be to set a "macaddr" configdata item, etc.  The
        utility is sort-of like a u-boot env variable edit function:

        For instance, to set a "macaddr" when the new CONFIG_MTD_CONFIG_NAMED
        option is selected, you would do:

          nsh> cfgdata set macaddr [0xfc 0x01 0x0b 0x45 0xa1 0x12]
          (The brackets denotes an array of bytes)
          nsh> cfgdata set hostname myboard

        or using the old ID,INSTANCE numeric method:

          nsh> cfgdata set 0,0 [0xfc 0x01 0x0b 0x45 0xa1 0x12]
          (The brackets denotes an array of bytes)
          nsh> cfgdata set 1,0 myboard

        You can also display all config items:

          nsh> cfgdata print all
          Name                    Len   Data
          macaddr                 6     0xFC 0x01 0x0B 0x45 0xA1 0x12
          hostname                8     myboard

        From Ken Pettit
      - apps/system/critmon:  Add a daemon to monitor critical section usage. From
        Gregory Nutt
      - apps/system/nsh:  Set NSH priority if the NSH task was scheduled at a
        different priority than the configured priority.  From Gregory Nutt
      - apps/system/nxplayer:  Introduce CONFIG_NXPLAYER_MAINTHREAD_STACKSIZE. From
        Masayuki Ishikawa
      - apps/system/termcurses:  Addition of termcurses libraries in
        apps/system/termcurses  From Ken Pettit
      - apps/system/vi:  New feature additions
          1.  Vi startup feature to prepend the current working directory to the
              supplied filename if it does not start with '/' absolute path
              specifier.  This allows editing files in the current directory
              without needing to fully qualify the filename.
          2.  Standard '~' empty screen line characters for proper identification
              of empty '\n' only lines at the end of the file.
          3.  Moving into insert or append mode now prints '--INSERT--' in the
              status line and clears it upon exit.
          4.  Integration with termcurses to detect special keystrokes and to
              handle terminal type differences.  Haven't yet converted all vt100
              print codes to termcurses equivalents.
          5.  Support for up, down, left, right arrows, page-up, page-down keys in
              command mode.
          6.  Added 'b' command to move cursor 'b'ack to previous word.  Honors the
              command repeat value for multiple word moves.
          7.  Added 'w' command to move cursor to next 'w'ord.  Honors the command
              repeat value for multiple word moves.
          8.  Added 'f' and 't' commands to find characters on the current line.
              Honors the command repeat value.
          9.  Added the find 'n'ext command to repeat the previous find operation.
          10. Added the 'H', 'M', and 'L' commands to move the cursor to top,
              middle and bottom of the display.
          11. Extended yank/paste to manage a paste buffer with character mode in
              addition to line mode.  Character mode allows cut / paste of
              individual characters or groups of characters vs. full lines.
          12. Added support in the 'd'elete and 'y'ank commands for character mode
              deletions such as 'dw', 'dfa', '2yw', etc.
          13. Added support in paste routine for multiple paste using command value
              argument.
          14. Added support for the 'D' and 'C' delete and change to end of line
              commands.
          15. Added support for 's'ubstitute key ('x' followed by insert mode).
          16. Modified yank / paste allocation scheme to avoid repeated alloc and
              free of paste buffer.  Uses a minimum allocation size scheme and only
              does free / realloc when paste does not fit.  If the paste is smaller
              than the current allocation and the current allocation is larger than
              the threshold, then the buffer is freed and a smaller buffer
              allocated.  Otherwise the existing buffer is used.
          17. Support for 'P'aste before current cursor position.
          18. Support for '?' reverse search mode.
          19. Support for 'J'oin next line with current line command.
          20. Printing of current row,col in status line of display.
          21. Command repeat '.' support for commands that modify text.
          22. Support in replace  / insert mode for arrow keys, PGUP / PGDN, HOME,
              and END.  Using these will cause the command repeat buffer to reset
              such that only the last text addition after a cursor movement is saved.
          23. Added 'X' delete previous command.
          24. Added "gg" go to top of document command sequence.
          25. Added "ZZ" save and quit command (equivalent to :wq).
          26. Implemented '^' goto first non-whitespace on current line, along with
             '+' and '-' goto first non-whitespace on next / previous line.
          27. Added CR / LF goto first non-whitespace on next line in command
              mode.  From Ken Pettit ?

    * Network Utilities: apps/netutils:

      - apps/netutils/webserver:  The webserver/httpd app is was broken when script
        support was enabled (CONFIG_NETUTILS_HTTPD_SCRIPT_DISABLE). The root cause
        has been tracked down to the "Content-length" not being available ahead of
        time in this case (length of -1 passed to send_headers() ).  On the other
        hand, the server closing the socket does not result in FIN being sent to
        the browser either (FIN not supported by NuttX yet).

        Simple solution: Add support for HTTP Chunked Encoding to webserver/httpd.
        The change is simple. It adds a configuration option to enable chunked
        encoding. When enabled, the implementation will auto-detect the cases where
        content length is not available ahead of time, and will automatically
        engage chunked encoding transfers.

        Without this patch, the browser/client hangs forever, as it is expecting
        more data. With this patch, the browser displays the content.  From Vlado
        Vidovic

    * Wireless Utilities: apps/wireless:

      - apps/wireless/bluetooth/btsak: Add connect and disconnect commands to
        btsak.  From Lwazi Dube

    * Graphic Utilities:  apps/graphics:

      - apps/graphics/pdcurs34:  Integration of termcurses into pdcurses, plus
        pdcurses updates for multi-thread support  From Ken Pettit
      - apps/graphics/pdcurs34:  Adds a configuration option to pdcurses to enable
        line-drawing character (ALTCHARSET) when using the short 16-bit chtype.
        This is done by limiting the characters to 7-bit ASCII values and using the
        8-th bit as the A_ALTCHARSET bit.  This allows a significant RAM savings 4K
        - 20K depending on terminal size) while still allowing the nicer
        line-graphic characters for border drawing.  From Ken Pettit

    * Testing:  apps/testing:

      - apps/testing/ostest:  Add test for pthread-specific data.  From Gregory
        Nutt

Bugfixes.  Only the most critical bugfixes are listed here (see the
ChangeLog for the complete list of bugfixes and for additional, more
detailed bugfix information):

    * Core OS:

      - Assertions:  Identify the running task correctly when dumping task
        state information.  It takes time to switch to the target task after
        g_readytorun has been modified.  If panic/assert happen during this
        period, the dump will contain the incorrect and confusing information
        due to the difference between the real running task and the return
        value of this_task(). This change resolve this problem by adding
        g_running_task to track the real running task through the context
        switch.  From Xiang Xiao
      - Assertions:  Correct duplicated logic from commit
        dbf01d12b7321d1b48b68d3b69842a853b049376.  Checking for PID == zero
        is not a valid way to test for the IDLE task in all configurations!
        This is only true in the single CPU configuration.  In multiple CPU
        configurations, there will be a separate IDLE task for each CPU with
        a different PID and an alternative check must be used.  NOTE:  The
        logic fixed in some places still lacks sufficient intelligence in SMP
        mode to find the right stack for the CPU IDLE thread and could still
        show the wrong stack.  From Gregory Nutt
      - Interrupt Prioritization:  Remove all driver-specific logic that may
        set the interrupt priority to anything but the default.  There is no
        good reason to change the interrupt priority unless you just want to
        debug a difficult problem.  OR if you want to use high priority
        interrupts.  In that case the specific interrupt priorities will need
        to be set by board-specific logic.  From Gregory Nutt
      - Memory Management:  Revert "This patch prevent heap corruption as in
        below case."  This solution to the problem noted by EunBong Song
        results in major memory fragmentation and out-of-memory
        conditions on the PX4 platform.  On that platform the lower priority
        work queue is very low priority and essentially never runs when the
        system is busy.  As a result, the systems gets slowly starved of
        memory until failures and bad behaviors begin to occur.  From Gregory Nutt
      - Memory Management:  This is a replacement for EunBong Song's reverted
        change.  This change adds (1) logic in getpid() to return an error instead
        of the PID if the (apparent) currently executing task is not marked as
        RUNNING.   Then (2) mm_trysemaphore() (the root implementation of both
        kmm_trysemaphore() and umm_trysemaphore()) will know that the (apparent)
        running task cannot be the holder of the semaphore.  How could the
        non-running task be trying to get the MM semaphore?  I think only in the
        exact scenario that Eunbong Song has described.  So this new solution
        should provide the same protection as the original change but without the
        bad  consequences to memory usage.  From Gregory Nutt (with corrections
        from David Sidrane)
      - Memory Management:  In implementation of calloc(), verify that the number of
        elements times the size of an element will not overflow type size_t.  This
        is required by the SEI CERT C coding style and resolves anonymous Bitbucket
        Issue #139  From Gregory Nutt
      - sigtimedwait():  Remove unnecessary disable of pre-emption.  From
        Gregory Nutt
      - _exit():  Update all architecture-specific _exit() implementations
        so that they correctly call the scheduler instrumentation layer for
        the new task that runs when the old one exits.  This missing
        instrumentation was confusing the Critical Section Monitor logic with
        uses this instrumentation to track the state of critical sections.
        From Gregory Nutt
      - sched_foreach():  sched_foreach() should not have to hold the
        critical section over the entire traversal.  It should be acceptable
        to simply only the critical section while one entry is being
        processed (the caller can always call sched_foreach within a critical
        section is greater stability is needed).  From Gregory Nutt
      - task_spawn():  Correct description of input parameters to
        task_spawn_exec().  Noted by: JeongchanKim  From Gregory Nutt

    * Crypto:

      - crtypo/:  This change:

          Avoids the use of up_aesinitialize() entirely, which resolves
          dependency problems, because this function does not make sure that
          an actual hardware aes implementation was made available: each SoC
          is now responsible to ensure the AES hardware is initialized before
          first use.  This applies to lpc43xx, stm32 and sam34.

          Remove definitions of the NEVER used aes_init and aes_update
          operations.  The new AES API will be more suitable.

        From Sebastien Lorquet

    * File System/Block and MTD Drivers:

      - opendir():  Corrects a problem with opendir() noted by Petteri
        Aimonen in Bitbucket Issue 132: "opendir() fails for FAT filesystem
        with trailing slash in path".  I see the following behaviour on NuttX
        7.26, where I have SD card mounted on /flash and a directory called
        "frm" on it:

          opendir("/flash")  returns  (DIR *) 0x1000c580
          opendir("/flash/") returns (DIR *) 0x1000c5d0
          opendir("/flash/frm")  returns (DIR *) 0x1000c620
          opendir("/flash/frm/")  returns (DIR *) 0x0

        From POSIX specs for opendir(): "A pathname ... that ends with one or
        more trailing slashes shall be resolved as if a single dot character
        ( '.' ) were appended to the pathname."  So for mount points,
        opendir() works correctly, but for FAT32 filesystem it fails to open
        directory if the path has a trailing slash...

        NOTE: You would not see this problem if you call opendir() indirectly
        in NSH (like 'ls -R /') because NSH contains logic to remove trailing
        '/' characters from paths.  From Gregory Nutt
      - dup()/dup2():  dup() and dup2() were broken some time back.
        fs_dupfd() was return returning OK on success, not the file
        descriptor of the duplicated fd.  From David Sidrane
      - ProcFS:  Remove the unnecessary critical section  From Xiang Xiao
      - CROMFS:  Fix hardfault.  From David Sidrane
      - SmartFS MTD Driver:  Fix smart_write_alloc_sector sector size mapping.
        Was not correctly calculating the encoded sector size for small (256)
        byte or large (>= 4096 byte) sectors.  Noted by Daniel P. Carvalho.
        Fix from Ken Pettit
      - AT25 MTD Driver:  Fixed missing opening parenthesis.  From Marc Rosen
      - MTD Configdata MTD Driver:  Check return value mtdconfig_readbytes().
        From Jussi Kivilinna
      - S25FL1 MTD Driver:  Minor change for the s25fl1 QSPI FLASH driver which
        fixes additional sectorshift vs. pageshift confusion.  From Ken Pettit

    * Networking/Network Drivers:

      - All network drivers!  Change pre-processor logic that selects the
        high priority work queue or gives preferential treatment to the high
        priority work.  All network logic must run on the low priority work
        queue!  Or suffer the consequences.  From Gregory Nutt
      - Socket Clone/Dup:  On a failure to start the TCP monitor, the cloned
        socket is closed but is not properly freed, leaving it attached to a
        TCP connection structure with the wrong reference count.  From
        Gregory Nutt
      - ARP:  Fix whitespace after ARPHRD_IEEE80211 in ARP header file.  From
        Daniel Agar
      - 6LoWPAN:  Fixes decompression of ipaddr from MAC address.  The logic
        used to populate the IP from the radio address should match
        sixlowpan_ipfromsaddr/sixlowpan_ipfromeaddr  From Anthony Merlino
      - 6LoWPAN: Fixes logic surrounding the Universal/Local bit.  This bit
        represents whether the IID is locally/globally administered. The U/L
        bit is bit 1 of the MSB of the EUI-64. It should only be inverted in
        cases where there is a full EUI-64. In cases where the IID is derived
        from say, a short address, this bit should be forced to 0, indicating
        that it is locally administered.   See:
          https://tools.ietf.org/html/rfc4291#section-2.5.1
          https://tools.ietf.org/html/rfc4944#section-6
          https://tools.ietf.org/html/rfc2464#section-4
        From Anthony Merlino
      - 6LoWPAN: IEEE802.15.4 stores and uses addresses in little endian
        order.  From Anthony Merlino
      - 6LoWPAN:  Address comment regarding avoiding double lookup of address
        context.  From Anthony Merlino
      - 6LoWPAN:  Record and restore d_buf on entry/exit of sixlowpan_input.
        This avoids an issue where d_buf gets set to NULL by 6LoWPAN, and
        then is used by forwarding logic from another network interface
        before getting set back to the drivers internal buffer.  From Anthony
        Merlino
      - 6LoWPAN:  sixlowpan_input should always return 0 if the incoming frame was
        consumed.  From Anthony Merlino
      - TUN Driver:  Fixes a problem reported by Masayuki Ishikwawa:  Recently I
        noticed that ARP response packet is corrupted when I tried to run
        bluekitchen with the latest tun.c in TAP mode.  If I revert commit
        8193c28e9126c9cb89042e80d6ebab7485a831e4, then it works again.  From Xiang
        Xiao
      - Telnet Driver:  Add missing logic to set read event flags in poll()
        method.  From Ken Pettit

    * Wireless/Wireless Drivers:

      - BLE:  Fix uninitialized variables.  From Lwazi Dube
      - BLE GATT header file:  Fix struct name.  From Lwazi Dube
      - BLE GATT:  Remove unnecessary GATT ioctls  From Lwazi Dube

    * Graphics/Display Drivers:

      - ST7032:  Fix seek method.  Was not taking into account the offset for the
        SEEK_END case.  Did not account for negative offsets.  On errors, it was
        clobbering the filep->f_pos setting.  From Gregory Nutt
      - PCF8574 Backpack:  Fix seek method.  Had the same problems as noted for
        ST7032 driver.  From Gregory Nutt

    * Common Drivers:

      - Button Upper Half:  Fix two bad NULL checks  From Juha Niskanen
      - PWM Interface:  Remove dependency on CONFIG_PWM for the upper-half
        PWM header.  This allows compilation for the lower-level PWM drivers
        even if the upper-half PWM logic is not used.  From Mateusz Szafoni
      - Various I2C Drivers:  In most I2C drivers, correct upper index value
        in I2C trace dump. Eliminates the extra NONE event from the trace
        dump output. From Ouss4
      - Battery Gauge:  Add missing initialization of semaphore.  From Alan
        Carvalho de Assis
      - Batter Charger:  Add missing initialization of semaphore.  From Alan
        Carvalho de Assis
      - MCP73871:  Fix Microchip MCP73871 Battery Charger driver to register
        correctly as a battery charger.  The first element of a 'struct
        battery_charger_dev_s' should be a pointer to operations structure. From
        Alan Carvalho de Assis
      - MCP794xx:  Fix MCP794xx driver to wait for OSCRUN and fix tm_year.  From
        Abdelatif Guettouche
      - Numerous files:  Fixes usage of CONFIG_BIG_ENDIAN; should be
        CONFIG_ENDIAN_BIG  From Anthony Merlino

    * ARMv7-A:

      - ARMv7-A MMU:  Fix end address calculation for mmu_invalidate_region() API
        From Petro Karashchenko

    * ARMv7-M:

      - ITM:  Fix missing space causing macro issues  From Alan Carvalho de
        Assis
      - Common Exception Handlers:  This commit changes the lazy and non-lazy
        exception handler to remove a couple of cpsid instructions from them
        on ARMv7-m.  If my understanding is correct then these interrupt
        manipulations aren't doing anything anyway because prioritization
        stops secondary interrupts arriving and, even if they did work, they
        would have introduced race conditions for the period of time between
        the interrupt arriving and further interrupts being disabled.  From
        Dave Marples
      - MPU/Protected Mode Build:  Revert "arch/arm/armv7-m:  MPU:
        mpu_log2regionceil needs take into account the offset too".  Masayuki
        Ishikawa reports that this commit breaks ALL PROTECTED mode builds.  It
        violates the basic requirements of the use of the MPU in protected mode.
        Those basic requirements are:
          1. The MPU region must be aligned to the base address of the memory
             region being mapped (it may NEVER extend before the memory region).
             That is, the following MUST always be zero: (base & ((1 << l2size) - 1))
          2. The MPU region must never extend beyond the end of the memory region.
             That is, the following must be true:  size >= (1 << l2size)
        From Gregory Nutt

    * Microchip PIC32MX Drivers:

      - PIC32MX Ethernet:  Fix a comparison in a debug assertion.  Should be
        <= vs <.  Noted by Anonymous in Bitbucket Issue 134.  From Gregory Nutt

    * Microchip PIC32MZ:

      - PIC32MZ chip.h Header:  Add a missing " in an error message. From Ouss4

    * Microchip PIC32MZ Drivers:

      - PIC32MZ Ethernet:  Fix a comparison in a debug assertion.  Should be
        <= vs <.  Noted by Anonymous in Bitbucket Issue 134.  From Gregory Nutt

    * Microchip/Atmel SAMD21/L21

      - SAMD21/L21:  Corrects behavior of the I2C_M_NOSTART flag.  Also adds
        a release a bus on RXNACK and corrects typo priv->flags to msg->flags
        as priv->flags is never set.  From Alexander Vasiliev
      - SAMD21/L21:  Fix SAMD2L2 arch to use calibrated oscillator value.  Now
        SAMD20 and SAMD21 should work fine without external crystal.  Note that
        SAML21 Xplained board has an external crystal and doesn't need this change,
        unless you don't want to use the crystal.  From Alexander Vasiliev
      - SAMD21/L21 I2C Master:  Adds calculation of a timeout and disables
        interrupts in case of error.  From Alexander Vasiliev

    * Microchip/Atmel SAMD21/L21 Boards

      - SAML21-Xplained:  Fix removed MAXCOARSESTEP from saml21-xplained board.
        From Alan Carvalho de Assis

    * Microchip/Atmel SAMD51/Ex

      - SAMD51/Ex:  Alexander Vasiliev's fix to the SAMD21 I2C Master (commit
        b1110ba91c549572e94c24ebed202643233deee3) should probably also be
        applied to the SAMD51 I2C Master which is identical.  From Gregory Nutt

    * Microchip/Atmel SAMV7

      - SAMV7 Serial:  Fix case where TTYS0 is not defined.  From Ken Pettit

    * Maxim Integrated MAX326xx

      - MAX326xx:  WFI instruction in IDLE loop seems to interfere with
        stability.  Commented out for now.  Needs to be investigated further.
        From Gregory Nutt

    * NXP i.MXRT Drivers:

      - i.MXRT FLEXPWM:  Correct duplicated definitions  From David Sidrane
      - i.MXRT SERIAL:  Fix TTYS0 defined definitions of higher numbered ports
        From David Sidrane
      - i.MXRT LPSPI:  Removed unused clock, that borked the build.  From David
        Sidrane
      - i.MXRT LPI2C:  I2C Reset rework  From David Sidrane

    * On Semi LC823450:

      - LC823450:  Fix up_allocate_heap() in lc823450_allocateheap2.c.  This
        change fixes heap size and also implements up_addregion().  From
        Masayuki Ishikawa
      - LC823450:  Fix go_os_start() in lc823450_start.c. I found a bug in
        go_os_start() that it returns immediately because it does not compare
        r1 to zero. This commit fixes this bug. Also, this commit fixes its
        description.  From Masayuki Ishikawa
      - Other Architectures:  Masayuki Ishikawa's change to go_os_start() was
        also to all MCU-specific start-up functions that support
        go_os_start(). From Gregory Nutt

    * On Semi LC823450 Boards:

      - LC823450-XEVK:  Fix IOB params in rndis/defconfig.  These parameters
        work for HTTP audio streaming. From Masayuki Ishikawa
      - LC823450-XGEVK:  Change RNDIS MAC address assignment in rndis
        configuration.  In previous implementation, mac[0] was assigned to
        0xaa for RNDIS host to avoid MAC address conflicts with RNDIS
        device..  However, I noticed that this assignment causes a random MAC
        address generation on ubuntu16.04 or later which is inconvenient to
        set up network interface.  This new assignment scheme fixes this
        issue.  From Masayuki Ishikawa
      - LC823450-XGEVK:  Fix overlapped memory settings in memory.ld.  From
        Masayuki Ishikawa

    * STMicro STM32 Drivers:

      - STM32:  Remove redundant STM32 family definitions from chip.h header
        file. It is already done in arch/arm/src/stm32/Kconfig  From Mateusz
        Szafoni
      - STM32 ADC:  There is no DMA CFG bit for the basic IPv1 ADC.  From
        Mateusz Szafoni
      - STM32 ADC:  Refactor adc_reset. It should be easier to maintain this
        code if it's divided into smaller functions  From Mateusz Szafoni
      - STM32 F0 Clocking:  Fixes the problem in GPIO port clocks. Only port
        A clock was enabled although the comment states otherwise.  From Juha
        Paalijärvi
      - STM32 F7 I2C:  I2C out of bounds access on priv->msgv.  Error in if
        statement. It was checking for msgc > 0.  If message count is 1, only
        index 0 is valid on priv->msgv.  Therefore random values in memory
        were used to set next_norestart.  From David Sidrane
      - STM32 H7 I2C:  Applied David Sidrane's I2C fix to the identical logic
        for STM32 H7. From Gregory Nutt
      - STM32 L4 I2C:  Applied David Sidrane's I2C fix to the identical logic
        for STM32 L4. From Gregory Nutt

    * STMicro STM32 Drivers:

      - STM32 ADC:  Fix RCC reset logic.  From Mateusz Szafoni
      - STM32 ADC:  Fix compilation errors for chips with one ADV TIM.  From
        Mateusz Szafoni
      - STM32 DMA:  Add missing DMA channel configuration.
      - STM32 PWM:  STM32 MOE is not being appropriately handled for PWM for
        advanced timers.  It is only ever reset and so no PWM train is
        generated.  This change addresses this.  Noted by Dave Marples. From
        Mateusz Szafoni
      - STM32 PWM:  Fix compilation errors if the upper-half PWM logic is not
        enabled. From Mateusz Szafoni
      - STM32 SPI:  STM32F446 & STM32F469 correct PC1 SPI assignments From
        David Sidrane
      - STM32 TIM:  Fix compilation error if there is no TIM8.  From Mateusz
        Szafoni
      - STM32 F0:  Fix GPIO EXTI lines assignment for STM32 M0.  From Mateuz Szafoni
      - STM32 F3 I2C:  Remove the extra NONE event from the trace dump
        output.  From Ouss4
      - STM32 F4 I2C:  Remove the extra NONE event from the trace dump
        output.  From Ouss4
      - STM32 F7 I2C:  Use clock_t for ticks instead of uint32_t to hold system
        time.  From Jussi Kivilinna
      - STM32 L4 I2C:  Use clock_t for ticks instead of uint32_t to hold system
        time.  From Jussi Kivilinna

    * STMicro STM32 Boards:

      - STM32F429I-DISCO:  Fix lvgl demo removing STM32_FB_CMAP.  From Alan
        Carvalho de Assis
      - STM32VL Discovery:  Fix SRAM and FLASH size in the linker script.
        There is STM32F100RB with 8KB RAM and 128KB FLASH on the STM32VL
        Discovery kit. Invalid memory size could cause a hard fault.  From
        Matous Pokorny
      - STM32VL Discovery:  Fix memory size configuration and documentation.
        There is STM32F100RB instead of STM32F100RC on the STM32 VL Discovery
        kit.  From Matous Pokorny
      - Viewtool-STM32F107:  Change RNDIS MAC address assignment in rndis
        configuration. In previous implementation, mac[0] was assigned to
        0xaa for RNDIS host to avoid MAC address conflicts with RNDIS
        device..  However, I noticed that this assignment causes a random MAC
        address generation on ubuntu16.04 or later which is inconvenient to
        set up network interface.  This new assignment scheme fixes this
        issue.  From Masayuki Ishikawa

    * TI Tiva:

      - Tiva LM/TM4C Start-Up:  Remove option CONFIG_TIVA_BOARD_CLOCKCONFIG.  It is
        not used and unnecessary.  Fix some naming.  up_clockconfig() is
        inappropriate.  Change tiva_clockconfig() to tiva_clock_reconfigure()
        then we can change up_clockconfig() to tive_clock_configure().  From
        Gregory Nutt
      - Tiva LM/TM4C GPIO Interrupts:  Fix tiva gpio interrupts  From Lwazi Dube
      - Tiva LM/TM4C:  Improve GPIO interrupt support by removing unnecessary,
        hard-coded per-MCU defines and using the existing Kconfig configuration
        options instead.  From Lwazi Dube

    * TI Tiva Drivers:

      - Tiva TM4C Serial:  After commit
        51b78034ac8d1fdf598107bf4093f0beccd5b80b, my tiva console does not
        work - enter key produces garbage characters.  This commit fixes the
        problem for me.  From Lwazi Dube

    * C Library/Header Files:

      - include/dsp.h:  Fix missing semicolon error in dsp.h  From MYAPICI
      - include/nuttx/compiler.h:  Correct support of C-version-specific features.
        Cannot depend on GCC version because -std=c89 may be used on comomand
        line.  Need instead to use __STDC_VERSION__ to determine if a feature is
        supported.  Also add conditional support inline, depending on C99.  From
        Gregory Nutt
      - libs/libc/stdio:  fread() should always set EOF if fewer than the
        requested number of bytes was not read.  Per Anthony Merlino. From
        Gregory Nutt

    * Build System:

      - sched/irq/Make.defs:  Fix warning about irq_csection.o appearing
        multiple times in the same rule.  From Gregory Nutt

    * Tools:

      - tools/gencromfs.c:  "gencromfs.c:1171:3: warning: ignoring return
        value of 'asprintf'", declared with attribute warn_unused_result
        [-Wunused-result].  From David Sidrane
      - tools/gencromfs.c:  Fix build on macOS.  From David Sidrane

    * NSH Library: apps/nshlib:

      - apps/nshlib:  Fixes an error in the NSH parser.  There was a bug when
        executing an nsh shell script which contains a redirection. When the
        command in the script is executed, it sets the vtbl->np.np_redirect flag
        (as it should), but then doesn't restore it, leaving it set at the end of
        the script execution.  Then the vtbl->np.np_redirect flag is set when the
        'sh' command completes, causing a restore from un-initialized variables,
        thus leading to a crash.  See the code snippet below for an example test
        case.

        Test case:

          NuttShell (NSH)
          nsh> mkrd -s 1024 40
          nsh> mkfatfs /dev/ram0
          nsh> mount -t vfat /dev/ram0 /tmp
          nsh> echo "echo 1 > /dev/null" > /tmp/test.sh
          nsh> cat /tmp/test.sh
          echo 1 > /dev/null
          nsh> sh /tmp/test.sh
          ...

        The nsh prompt doesn't get printed.  You can type a couple of commands,
        but then the system will crash because of bad pointers.  From Ken Pettit
      - apps/nshlib:  Fix buffer overrun when redirected to a file.  SAVE_SIZE
        must be the same as sizeof(struct serialsave_s).  From Masayuki Ishikawa

    * System Utilities: apps/system:

      - system/system.c:  Fixes build error; There is no result variable, use
        errcode instead.  From Anthony Merlino
      - apps/system/vi:  Bug fixes:
          1.  Deletion of last line in file using 'dd' caused infinite loop
              searching for 'nextline'.  Fixed.
          2.  Insertion of line above 1st line using 'O' caused line to be
              inserted on 2nd line.  Fixed.
          3.  Paste buffer from 'dd' was being free'd after the 'p'aste operation,
              preventing multiple paste opportunity.  Fixed.
          4.  The cursor was not being bound to the line end and was allowed to
              'hover' over the '\n' EOL character.  This caused weird (relative to
              standard vi) insertion locations and cursor movement with 'a'ppend
              and 'i'nsert.  Fixed.
          5.  The 'vi_shrinkpos' position didn't take the end of file pointer into
              account when calculating 'curpos', 'prevpos' variables causing
              weirdness when deleting things near the end of the file.  Fixed.
          6.  The 'yy'ank command was improperly deleting the text from the
             document instead of simply yanking to the paste buffer.  Fixed.
          7.  The 'dd'elete line function was not copying the deleted line to the
              paste buffer as part of the delete operation.  Fixed.
          8.  The bottom line of the screen was sometimes being used for document
              text and other times for command / find entry.  Fixed by reserving
              the bottom the bottom line for status / command only.
          9.  When scrolling up / down through a file, the cursor position was not
              preserved and moved further and further to the left column based on
              the line lengths of the lines visited.  Fixed.
          10. The display was being COMPLETELY redrawn with each keystroke,
              causing the responsiveness to be unbearable.  Fixed.  Added logic to
              dynamicall indicated which portions of the screen need to be updated
              (full display, current line to end of screen, current line only,
              none).
          11. The individual display line updates were being performed a character
              at a time by calling the vi_putch() function, causing slow
              performance, especially in telnet or USBCDC sessions where there is
              a lot of overhead per packet.  Fixed by calling vi_write() instead
              with a block of characters with breaks as needed for TAB exansion.
          12. The forward delete 'x' operation allowed deletion through '\n'
              characters causing lines to be joined.  This is different from
              standard vi where 'x' at the end of a line performs a delete
              backward operation.  Fixed.
          13. When in 'ex' or find sub-modes (':' or '/' bottom line modes),
              hitting backspace with empty text did not return the operation to
              command mode like it does in standard vi.  Fixed.
          14. Performing a 'find' opertation would only search from the current
              cursor position to the end of the file and did not wrap like in
              standard vi.  Fixed.
          15. Loading a file that was larger than the initial text allocation
              would force a call to 'vi_extendtext', marking the file as modified
              when in fact it hadn't even been loaded yet.  Fixed.
          16. Combined vi_insert_mode and vi_replace_mode into a single function
              to save code space since they are nearly identical routines.
          17. In command mode, backspace was deleting characters which is
              different from standard vi.  Backspace in command mode normally
              simply moves the cursor left / to the previous line.  Fixed.
          18. Added code to handle boundary conditions when the file is new and
              commands are applied to an empty file.
          19. Fixed vi_shrinktext so it doesn't allocate a zero-length buffer when
              the last character in the file is deleted.
          20. The 'x' command was not copying to the paste buffer.  Fixed.
          21. Fixed parsecolon routine to properly deal with ":wq" command sequence.
        From Ken Pettit

    * Wireless Utilities: apps/wireless:

      - apps/wireless/bluetooth/btsak:  'bt bnep0 info' outputs a reversed addr. It
        should print BDAddr: aa:bb:cc:dd:ee:ff instead of BDAddr:
        ff:ee:dd:cc:bb:aa.  From Lwazi
      - apps/wireless/bluetooth/btsak:  Fix some errors in btsak.  From Lwazi Dube
      - apps/wireless/bluetooth/btsak/btsak_main.c: Fix address parsing.  From
        Lwazi Dube
      - apps/wireless/bluetooth/btsak:  Remove unnecessary gatt get commands. From
        Lwazi Dube
      - apps/wireless/bluetooth/btsak/btsak_scan.c:  Fix reversed address.  From
        Lwazi Dube
      - apps/wireless/ieee802154/i8sak:  Fixes issues related to re-running
        daemon. Releases lock when releasing daemon. Re-sets daemon_shutdown so
        that a subsequent daemon launch does not immediately return.  From Anthony
        Merlino

NuttX-7.29 Release Notes
------------------------

The 129th release of NuttX, Version 7.29, was made on March 25, 2019,
and is available for download from the Bitbucket.org website.  Note
that release consists of two tarballs:  nuttx-7.29.tar.gz and
apps-7.29.tar.gz.  These are available from:

    https://bitbucket.org/nuttx/nuttx/downloads
    https://bitbucket.org/nuttx/apps/downloads

Both may be needed (see the top-level nuttx/README.txt file for build
information).

Additional new features and extended functionality:

    * Core OS:

      - Configuration:  CONFIG_NFILE_DESCRIPTORS=0 can no longer be used to
        disable the file system.  NuttX with no file system does not make
        sense and is no longer supported.  From Gregory Nutt.
      - Rename most internal OS functions from sched_* to nxsched_* to
        indicate that they are NuttX internal functions (some renaming is
        still needed).  From Gregory Nutt.
      - Rename all internal OS functions from task_* to nxtask_* to indicate
        that they are NuttX internal functions.  From Gregory Nutt.
      - Rename sched_process_timer to nxsched_process_timer.  Rename
        sched_timer_expiration to nxsched_timer_expiration.  Rename
        sched_alarm_expiration to nxsched_alarm_expiration.  Those are the
        appropriate names for an internal sched/ function (still many named
        incorrectly).  From Gregory Nutt.
      - Standardize naming:  Rename os_start() to nx_start(), rename os_smp*
        to nx_smp*, rename os_bringup to nx_bringup, rename all internal
        static functions to begin with nx_ vs os_.  From Gregory Nutt.
      - Initialization:  Remove the option CONFIG_BOARD_INITTHREAD.  Now, if
        CONFIG_BOARD_INITIALIZE is selected, then the board_initialize()
        logic will ALWAYS run on an internal kernel thread.  This will
        prevent the problems people have had doing inappropriate
        board_initialization on the IDLE thread.  From Gregory Nutt.
      - Initialization:  Add support for CONFIG_BOARD_EARLY_INITIALIZE.  If
        this option is selected then nx_start() will call a board-provided
        function board_early_initialize() immediately after calling
        up_initialize().  Rename board_initialize() to
        board_late_initialize().  From Gregory Nutt.
      - Signal Delivery:  Add a flag to the TCB to indicate that we are in a
        signal handler.  Use this flag to assure that a there is never
        attempts to nest signal handling operations on a thread.  This was
        guaranteed before but when locking of pre-emption during signal
        delivering was eliminated in a previous commit, there was a remote
        possibility of an attempt to do nested signal handling.  This flag
        assures that there is only one signal handled at a time.  From
        Gregory Nutt.
      - Signal Handler Security:  The architecture-specific signal handler
        return register state is saved and available on the user stack.
        This commit reorders some logic so that certain, critical registers
        are preserved in the TCB.  This eliminates most malicious exploits
        which more the return address, for example, but does not make the
        logic 100% secure.  From Gregory Nutt.
      - Timer Interrupt Procssing:  Add a configurable call out to a
        user-provided function, 'timer hook', on each timer interrupt.  From
        Gregory Nutt.
      - PM Activity:   Add pm_staycount() API for get stay numbers.  This
        function is currently not used and a waste of FLASH space.  From ligd.
      - Pthreads:  Add support for pthread_mutex_timedlock  From Leif Jakob.
      - Pthread Spinlocks:  Add a very preliminary implementation of the new
        POSIX pthread_spinlock_* interfaces.  From Gregory Nutt.
      - Critical Section Monitor:  Remove SCHED_IRQMONITOR_GETTIME to
        simplify the clock source selection:  (1) Use up_critmon_gettime if
        SCHED_IRQMONITOR, (2) Call clock_systimespec if SCHED_TICKLESS, (3)
        Don't collect timing info for all other cases.  From Xiang Xiao.
      - Work Queue Notification:  Notifier can now work with either lpwork
        or hpwork. From Xiang Xiao.
      - Protected Build:  Add add a new field (us_heapend) to struct
        userspace_s that labels the end of the heap.  From Xiang Xiao.

    * Binary Loader/Kernel Modules/Shared Libraries

      - Shared Libraries:  Implement dlerror() using strerror().  From Xiang
        Xiao.
      - Shared Libraries:  Add LD_LIBRARY_PATH environment variable
        support.  From anchao.
      - ELF Loaders:  Optimize elf load speed:  (1) Don't zero out memory,
        (2) Reduce the initial buffer size to 32 bytes.  From Xiang Xiao.
      - ARM ELF Relocation:  Add support for the R_ARM_THM_JUMP11 relocation
        type.  This relocation type may be generated when LTO optimization
        is enabled.  From anchao.
      - ELF Modules:  Add relocation buffer table to reduce filesystem
        access.  From anchao.
      - ELF Modules:  Add symbol buffer table to reduce filesystem access.
        From anchao.

    * File Systems/Block and MTD Drivers

      - Filesystem Mount:  Move the union inode_ops_u i_mtd field into the
        mount section of inode_ops_u and remove the guard to simplify fs
        which support both block and mtd.  From Xiang Xiao.
      - ROMFS:  Add support to mount a ROMFS volume using an MTD driver
        interface using the standard mount() operation.  From Xiang Xiao.
      - LittleFS:  VFS wrapper improvement:  (1) Support block device
        interface, (2) support ioctl, stat and sync file operation, (3)
        support forceformat and autoformat option, (4) update file->f_pos
        and dir->fd_position, (5) remove the internal struct from dir, and
        (6) remove mtd byte read/write requirement.  From Xiang Xiao.
      - UnionFS:  Support mount of UnionFS from the NSH command line.  From
        Xiang Xiao.

    * Networking/Network Drivers:

      - UsrSock:  Add mutual exclusion so that only user can perform a
        socket request  From zhangyuan7.
      - UDP:  Initialize callback address structure to avoid random values
        in padding.  From anchao.

    * Wireless/Wireless Drivers:

      - SX127x:  Initial support for SX127x LoRA radio  From Mateusz Szafoni.

    * Graphics/Display Drivers:

      - Graphics:  Fix a naming collision:  Ye olde nx_start that started
        the NX graphics is now nxmu_start().  nxmu_start() is now
        prototyped in nxmu.h (instead of nx.h).  From Gregory Nutt.
      - NX Server Startup:  Extend nxmu_start() so that receives a display
        number as an argument.  This makes it possible to have multiple
        instances of the NX server running on boards that support multiple
        displays.  Also includes updates to boardctl() to accept display
        number parameters.  From Gregory Nutt.
      - Graphics:  nx_openwindow() and nxtk_openwindow() now accept an
        additional 'flag' parameter.  This argument is current used only to
        select a RAM backed, per-window framebuffer.  From Gregory Nutt.
      - Per-Window Framebuffers:  Windows may now be optionally created
        with a RAM framebuffer backing up the window content.  Rending into
        the window will result in rending into the backup framebuffer, then
        updating the physical display from the framebuffer.  The advantage
        of this option is that the application that manages window will no
        longer receive redraw() callbacks.  Those calls normally occur when
        a window "above" moves exposing a portion of the window below.  If
        this option is selected, then the system will redraw the exposed
        portion of the window from the backup framebuffer without
        intervention of the window applications.  This greatly reduces the
        complexity of the application and performance of the window at the
        expense of increased memory usage.  Redraw requests in other cases
        are also suppressed:  Changes to window position, size, etc.  As a
        consequence, some manual updates will be required when certain
        events occur (like removing a toolbar from a window).  NOTE:  A
        significant amount of RAM, usually external SDRAM, may be required
        to use per-window framebuffers.

    * Other Common Device Drivers:

      - Driver Notifications:  Support signal notification through
        SIGEV_THREAD in all drivers that provide signal notifications:
        RTC, Joysticsks, buttons, Zero-Crossing, wireless, FT80x, Timer,
        PHY. From Xiang Xiao.
      - Watchdog Driver:  Support auto-monitor service  From Gregory Nutt.
      - Timer and Alarm Drivers:  Implement up_critmon_gettime and
        up_critmon_convert and remove the critical section from
        current_usec to infinite recursion.  From Xiang Xiao.
      - RTC Driver:  Protect the RTC state with a semaphore.  From Xiang
        Xiao.
      - Serial Upper Half:  Call pm_activity() when characters are received
        on a console device.  From Gregory Nutt.
      - MPU60x0:  Initial support for TDK InvenSense MPU6000 and MPU6050
        6-axis gyroscope and accelerometers.  This commit supports SPI
        media only.  From Bill Gatliff.
      - EEPROM Driver:  Add configurable SPI eeprom frequency.  From
        Valmantas Paliksa.
      - GPIO Driver:  Support reading and writing gpio pins using cat and
        echo.  From Valmantas Paliksa.
      - MCP2515:  Add MCP2515 clock input config to KConfig.  From
        Valmantas Paliksa.
      - MAX7456:  Support for the Maxim MAX7456 on-screen-display chip.
        From Bill Gatliff.

    * Common Board Logic:

      - boardctl():  up_testset() can now be accessed by applications via
        the boardctl() interface rather than attempting to call it
        directly.  pthread Spinlocks are not available unless the
        architecture supports the   up_testset() operation.  From Gregory
        Nutt.
      - boardctl():  Add support for BOARDIOC_NXTERM which can be used to
        create an NxTerm terminal.  From Gregory Nutt.
      - boardctl():  Add boardctl() commands to replace direct calls to
        nxterm_redraw() and nxterm_kbdin().  From Gregory Nutt.

    * Microchip PIC32MZ Drivers:

      - PIC32MZ Timers:  Add support for the PIC32MZ timers (driver,
        lowerhalf, freerun and oneshot)  From Abdelatif Guettouche.

    * Common ARM Options:

      - arch/arm:  Move FPU options to a common place and unify the usage
        by removing ARCH_CORTEXRxF.  From Xiang Xiao.
      - arch/:  Unify the cache interface for all architectures that
        support a data cache.  From Xiang Xiao.
      - ARMv7-M/A/R:  Add a architecture-specific new barriers.h header
        file that provides the memory barrier definitions that were
        previously in the (now unified) cache.h header files.  From Gregory
        Nutt.

    * ARMv7-A

      - ARMv7-A:  Support thumb mode and fix interworking issue. From
        zhangyuan7.
      - ARMv7-A:  Add weak attribute to arm_data_initialize so platform
        could provide the new implementation as needed.  From zhangyuan7.
      - ARMv7-A:  Add SCR bit definitions.  From Xiang Xiao.
      - ARMv7-A:  Add mmu_l1_map_regions() to remove the code duplication.
        From Xiang Xiao.
      - ARMv7-A:  Add the initial cortex-a7 architecture support  From
        zhangyuan7.

    * ARMv7-M

     - ARMv7-M:  stackcheck allow faulting stack calculation to make it to
       the up_assert reg dump  From David Sidrane.

    * Microchip/Atmel SAMD21/L21 Drivers:

      - SAMD2/L2:  Add RS485 support to SAMD2L2 serial.  From Alan Carvalho
        de Assis.

    * Misoc:

      - Minerva:  Add support for the Minerva architecture.  From Ramtin
        Amin.

    * Misoc Boards:

      - misoc:  Add support for an NSH configuration using the Verilator
        board.  From Ramtin Amin.

    * Nordic NRF52:

      - NRF52:  1. Added 52840 family support 2. Use common IRQ and memory
        layout header file for 52832 & 52840.  From Levin Li.

    * Nordic NRF52 Drivers:

      - NRF52 RNG:   1. added RNG device driver 2. added errdata to correct
        temp which will be used by RNG module 3. use general task_trigger /
        event_clear inline api for all driver.  From Levin Li.

    * NXP i.MX RT Drivers:

      - i.MXRT XBAR:  Add XBAR Support.  From David Sidrane.
      - i.MXRT USB:  Add USB analog header file.  From David Sidrane.
      - i.MXRT OCOTP:  Added OCOTP Support.  From David Sidrane.
      - i.MXRT LCD:  Adds framebuffer support for the i.MXRT 1050.
        Includes DCD initialization for SDRAM to provide space for the
        framebuffer. External code I used/ported is from NXP and is BSD
        3-clause license.  From Johannes.

    * NXP i.MX RT Boards:

      - IMXRT1050-EVK:  Adds framebuffer support for the i.MXRT 1050.
        From Johannes.

    * NXP LPC17xx

      - LPC17xx:  Add a configuration option to skip over the framebuffer
        when adding DRAM to the heap.  From Gregory Nutt.

    * NXP LPC17xx Boards

      - Open1788:  Add a configuration to test NxTerms in the PROTECTED
        mode.  From Gregory Nutt.
      - Open1788:  Re-arrange PROTECTED mode link map to make more space
        for large kernels with debug enabled.  From Gregory Nutt.
      - Open1788:  Add a configuration for testing per-window frame buffers
        using apps/examples/pwfb.  From Gregory Nutt.

    * NXP LPC54xx Boards

      - LPCXpresso-LPC54628/pwfb:  Add per-window framebuffer configuration
        using apps/examples/pwfb.  From Gregory Nutt.
      - LPCXpresso-LPC54628:  Add a configuration for addition per-window
        framebuffer using apps/examples/pwlines.  From Gregory Nutt.

    * STMicro STM32 Drivers:

      - STM32F0/L0 SPI:  Add SPI support for F0.   From Mateusz Szafoni.
      - STM32 ADC, PWM and TIM:  (1) configure injected channels external
        trigger when ADC enabled, (2) update injected conversion queue of
        context after configuration, (3) support for offset configuration,
        and (6) support for advanced timers channel 5 and 6.  From Mateusz
        Szafoni.
      - STM32 DFU Mode:  Add logic to reboot the STM32 in DFU mode.
        Current implementation only works for STM32F2 and F4.  From Bill
        Gatliff.
      - STM32F7 LSE:  Add configuration of LSE oscillator drive capability
        From Jussi Kivilinna.
      - STM32F7 I2C:  Fix another memory access issue on a bus error.  From
        David Sidrane.
      - STM32F7 TIM:  Add OUTTOGGLE mode for STM32f7 timer  From Valmantas
        Paliksa.
      - STM32F7 Timer Lower Half:  Add timer lowerhalf driver for stm32f7.
        From Valmantas Paliksa.
      - STM32F7 ITM:  Add ITM syslog support.  From Valmantas Paliksa.
      - STM32F7 CAN:  Add CAN driver with support for three bxCAN
        interfaces.  From Valmantas Paliksa.
      - STM32F7 QSPI:  Add stm32f7 Quad SPI support.  From Valmantas Paliksa.
      - STM32L4 LSE:  Ports Jussi Kivilinna's recent STM32F7 LSE change to
        STM32L4.  From Juha Niskanen (Haltian).
      - STM32H7 I2C:  Apply David Sidrane's fix for the STM32F7 to the
        STM32H7.  From Gregory Nutt.
      - STM32H7 DMA:  Rename  DMA1/2 IRQ names to match those from other
        STM32.  Add auxiliary definitions.  Add DMAMAP definitions for
        MDMA, DMA1, DMA2 and BDMA.  Add some address blocks.  Change RCC
        definitions to match other STM32 ports.  Enable clock for MDMA and
        BDMA.  Rename DMA channel definitions.  Separated files for MDMA,
        DMA, BDMA and DMAMUX.  Add missing definitions for MDMA, BDMA and
        DMAMUX.  SPI DMA mode.  Add base addresses for D1, D2 and D3
        domain; use 2 bytes to specify memory region.  Add D1 domain core
        prescaler configuration.  From Mateusz Szafoni.
      - STM32H7 OTG:  Initial OTG support for STM32H7 and some minor
        improvements.  Add support for HSI48 clock.  From Mateusz Szafoni.
      - STM32H7 Build:  Initial support for protected build mode. From
        Mateusz Szafoni.
      - STM32L4 I2C:  Apply David Sidrane's fix for the STM32F7 to the
        STM32L4.  From Gregory Nutt.

    * STMicro STM32 Boards:

      - B-L072Z-LRWAN1:  Add SX127x configuration.  From Mateusz Szafoni.
      - Nucleo-F091RC:  Add support for SX127x radio.  From Mateusz Szafoni.
      - Nucleo-F091RC:  Add SX127x configuration.  From Mateusz Szafoni.
      - Nucleo-F207ZG:  Add support for USB and initialize CDCACM if
        configured.  From Mateusz Szafoni.
      - STM32F429I-DISCO:  Add an apps/examples/examples/nxhello
        configuration.  From Gregory Nutt.
      - Nucleo-F446RE:  Add support for the Nucleo F446RE.  From Sebastien
        Lorquet.
      - B-L072Z-LRWAN1:  Use HSI as default clock source.  From Mateusz
        Szafoni.
      - Nucleo-L073RZ:  Add SX127x configuration.  From Mateusz Szafoni.
      - Nucleo-L073RZ:  Port button logic from nucleo-f072 which appears to
        be the same.  From Gregory Nutt.
      - Nucleo-L432KC:  Add support for I2C driver initialization.  From
        Nikolay Semenov.
      - Nucleo-H743ZI:  Add support for USB and initialize CDCACM if
        configured.  From Mateusz Szafoni.
      - OmnibusF4: Initial support for the OmnibusF4 family of flight
        management units.  "OmnibusF4" is not a product name per se, but
        rather a design spec that many product vendors adhere to. The spec
        defines the major components, and how those components are wired
        into the microcontroller. Airbot is one such vendor, and they
        publish a schematic here:  http://bit.ly/obf4pro.   Other software
        that supports the OmnibusF4 family include Betaflight, iNAV, and
        many others. PX4 recently added support as well, using their own,
        non-upstreamed, bespoke port of NuttX. No code from those resources
        is included in this port.  From Bill Gatliff.
      - OmnibusF4:  Add MAX7546 support.  From Bill Gatliff.

    * TI CCxx:

      - CC1312R1:  Code complete and builds successfully.  Stalled on
        further radio development.  I planned to integrate the IEEE 802.15.4
        radio interface, but the Cortex-M0 interface is not available with
        an open license.

    * TI CCxx Boards:

      - LaunchXL-CC1312R1:  Add support for on-board LEDs and buttons.  The
        LauchXL-CC1312R1 NSH Configuration is now fully functional. From
        Gregory Nutt.
      - LaunchXL-CC1310:  Clone LED and button support from the
        LaunchXL-CC1312R1.  The number of LEDs and buttons as well as DIO
        usage is identical (Still not functional).  From Gregory Nutt.

    * Tools:

      - tools/rmcr.c:  Add a tool to remove carriage returns and dangline
        whitespace at the end of lines.  From Gregory Nutt.
      - tools/nxstyle.c:  Can now detect if the C comment closing is not on
        a separate line.  From Gregory Nutt.
      - tools/nxstyle.c:  Make sure that all files begin with a comment on
        line 1 (which should be the file header).  From Gregory Nutt.
      - tools/nxstyle.c:  Add check for multiple definitions of local
        variables on a line.  From Gregory Nutt.
      - tools/nxstyle.c:  Beef up logic that detects multiple variable
        definitions per line.  From Gregory Nutt.
      - tools/nxstyle.c:  Add capability to detect CamelCase identifiers.
        From Gregory Nutt.
      - tools/nxstyle.c:  Add logic to detect a blank line following a left
        brace or a blank line preceding a right brace.  From Gregory Nutt.
      - tools/nxstyle.c:  Don't complain about certain lowercase characters
        in otherwise uppercase pre-processor identifiers:  IPv6, IPv4,
        ICMPv6, IGMPv2, p as a decimal point, d signifying a divisor.  It
        was a bad idea to let the door open a crack for there.  While they
        improve readability, the inconsistently also causes other
        problems.  From Gregory Nutt.

    * Build System:

      - Makefiles:  Modify tools/Makefiles to add a "Do not Edit" warning
        on defconfig files  From Alan Carvalho de Assis.

    * Libraries/Header Files:

      - lib_vsprintf() (Nano):  Add newlib-nano lib_vsfprintf has been
        added and is now the default support for the printf family.  This
        fprintf code was originally adapted from AVR libc and provides
        improved floating point output support, including 'g' mode and
        making 'f' mode include digits past the decimal by default.  The
        newlib version can be found here:
        https://salsa.debian.org/electronics-team/toolchains/newlib-nano.
        That project is GPL overall, but the newlib-nano printf portions
        are BSD licensed as described in the COPYING.NEWLIB file.  From
        Keith Packard.
      - lib_vsprintf() (Nano):  Added support for long lont types.  From
        Johannes.
      - lib_vsprintf() (Nano):  Added hh type modifier (without extending
        the flag variable).  From Johannes.
      - lib_vsprintf() (Nano): Adds configurable support for numbered
        arguments.  From Johannes.
      - lib_vsprintf() (Nano): Cleaned naming and allow for leading zeros
        in argument number (which doesn't make sense but should be).  From Johannes.
      - lib_vsprintf() (Legacy):  Add support for %g format which, for
        these purpose, is equivalent to %f except that trailing zeroes are
        suppressed.  From Gregory Nutt.
      - vscanf():  Moved vscanf logic to lib_sscanf.c  Switched to stream
        interface (tricky, because the old implementation used massive read
        ahead, which isn't suitable for streams, chars already read are
        gone).  Added hh, h, and ll modifiers.  From Johannes.
      - scanf() and fscanf():  Added scanf and fscanf based on enhanced
        vscanf().  From Johannes.
      - uname():  Add build date and time to uname output (like Linux).
        From Gregory Nutt.
      - strsep():  Add strsep BSD/Linux function.  From Xiang Xiao.
      - netdb:  Hostname support no longer depends on CONFIG_NET since the
        host name is also useful in the non-network environment.
        CONFIG_NET_HOSTNAME changed to CONFIG_LIB_HOSTNAME.  From Xiang Xiao.
      - netdb:  Support the nameserver change notification then we can pass
        DNS info from server to client in usrsock case.  From Xiang Xiao.
      - include/fixedmath.h:  Add macros for conversion between types
        b16_t and type double  From Gregory Nutt.
      - include/limits.h:  Define NL_ARGMAX (as well as some of the other
        'invariant values' per
        http://pubs.opengroup.org/onlinepubs/7908799/xsh/limits.h.html).
        From Johannes.
      - linclude/limits.h:  Add 'range 9 999999' to CONFIG_LIBC_NL_ARGMAX
        to Kconfig.  Per OpenGroup.org, the minimum value for NL_ARGMAX is
        9.  From Gregory Nutt.
      - include/nuttx/lcd/edid.h:  Add extended EDID block IDs  From
        Gregory Nutt.

    * apps/ General:

      - apps/:  Follow up the kernel signal-related change in various files
        under examples/ and graphics/.  From Xiang Xiao.
      - apps/:  Update for corrected name of standard header file.  Should
        be dlfcn.h, not dllfcn.h.  From Gregory Nutt.
      - apps/:  The file system can no longer be disabled.  Remove all
        conditional logic based on CONFIG_NFILE_DESCRIPTORS==0  From
        Gregory Nutt.
      - apps/:  Remove/replace all conditional logic based on
        CONFIG_NSOCKET_DESCRIPTORS == 0.  That value is always greater than
        zero now.  In places just replace with #ifdef CONFIG_NET.  From
        Gregory Nutt.
      - apps/:  Some updates due to NuttX renaming:
        CONFIG_BOARD_INITIALIZE is now CONFIG_BOARD_LATE_INITIALIZE;
        board_initialize() is now board_late_initialize().  From Gregory
        Nutt.
      - apps/: Graphics interfaces nx_openwindow() and nxtk_openwindow()
        now accept an additional 'flag' parameter.  From Gregory Nutt.

    * NSH: apps/nshlib:

      - apps/nshlib/nsh_netinit.c:  Update for changes to signal
        notification structures.  From Gregory Nutt.

    * Examples/Tests: apps/examples:

      - apps/examples/ini_dumper:  New example program.  ini_dumper is
        example program that dumps content of ini file in pretty ascii table.
        It is using inih ini library in fsutils/inih.  From Michal Lyszczek.
      - apps/examples/modbusmaster:  Add Simple Modbus master example.
        This example only supports Read/Write HoldingRegisters, but it is
        easy to extend it to support Read/Write Input/Coils/etc.
        Originally creatd by Vytautas in 2016 and updated with minor fixes
        for this commit.  From Alan Carvalho de Assis.
      - apps/examples/pwfb:  Added a test/example at apps/examples/pwfb
        that was used for initial testing of the per-window framebuffer
        feature.  From Gregory Nutt.
      - apps/examples/pwlines:  Added another a test/example at
        apps/examples/pwlines that was used for further testing of the
        per-window framebuffer feature.  From Gregory Nutt.
      - apps/examples/sx127x:  Add sx127x demo  From Mateusz Szafoni.

    * File System Utilities: apps/system

      - apps/fsutils/inih:  New package.  inih (INI Not Invented Here) is a
        simple .INI file parser written in C.
        https://github.com/benhoyt/inih.  From Michal Lyszczek.

    * Network Utilities: apps/netutils:

      - apps/netutils/codecs/:  Remove the big Base64 stack array.  From
        Xiang Xiao.
      - apps/netutils/codecs/:  Add base64_[de|en]code_length() API  From
        ligd.

    * System Utilities: apps/system

      - apps/system/cfgdata:  Make builtin task stack size and priority
        configurable.  Set default to 2048 (from 1024) per recommendation
        of Ken Pettit.  From Gregory Nutt.
      - apps/system/embedlog:  Update to version 0.4.0. From Michal Lyszczek.
      - apps/system/nxplayer and nxrecorder:  Change 'int prio' to
        'unsigned int prio'.  Required by changes to MQ function
        prototypes. From Michal Lyszczek.
      - apps/system/psmq: New package.  psmq is publish subscribe message
        queue. It's a set of programs and libraries to implement
        publish/subscribe way of inter-process communication on top of
        POSIX message queue.  From Michal Lyszczek.
      - apps/system/zmodem:  Switch to the raw mode before transfer and
        restore to the original setting after finishing the transfer.  From
        Xiang Xiao.

    * Testing:  apps/testing:

      - apps/testing/:  Move all file system tests from examples/ to
        testing/ (cxxtest, fstest, nxffs, smart, smart_test, smp).  From
        Gregory Nutt.
      - apps/testing/cxxtest:  Add a README file.  From Gregory Nutt.
      - apps/testing/ostest:  Add test of pthread_mutex_timedlock()  From
        Gregory Nutt.
      - apps/testing/ostest:  Fix several errors in the setvbuf() test.
        From Gregory Nutt.
      - apps/testing/scanftest:  Port of Greg King's scanf test
        (https://github.com/cc65).  From Johannes.

    * Tools: apps/tools:

      - apps/tools/check-hash.sh:  Add a tool check hash on downloaded
        packages.  From Michal Lyszczek.

Bugfixes.  Only the most critical bugfixes are listed here (see the
ChangeLog for the complete list of bugfixes and for additional, more
detailed bugfix information):

    * Core OS:

      - Signals:  Restructure nxsig_deliver() so that the signal handler is
        not called with the pre-emption disabled (or, at least no with
        pre-emption disabled by nxsig_deliver() itself).  From Gregory Nutt.
      - Critical Section Monitor:  Move up_critmon_* to arch.h avoid the
        duplicated declaration.  From Xiang Xiao.
      - Assertions:  Architecture-specific assertion logic should dump CPU0
        IDLE stack only when PID equals 0.  IDLE threads of other CPUs do
        not need this special check.  From Xiang Xiao.
      - Message Queues:  Change 'int prio' to 'unsigned int prio'.
        According to open group specification, priority field in mq_*
        functions should have unsigned type:
        http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/mqueue.h.html.
        From Michal Lyszczek.
      - Timer Expiration:  Fix macro SEC2TICK() 32-bits overflow by using
        uint64_t in calculation.  From ligd.
      - Kernel Memory Manager:  In mm/kmm_heap/kmm_kernel.c, remove unused,
        duplicated kmm_heapmember(). From Xiang Xiao.
      - User Memory Manager:  Ensure all user allocation try sbrk before
        fail  From Xiang Xiao.
      - waitid():  Could exit without leaving critical section on some
        error conditions.  From Gregory Nutt.
      - IOBs:  iob_allocwait() should decrease semcount manually. From
        Xiang Xiao.
      - IOBs:  iob_copyin() should wait for each buffer and adjust the
        return value of iob_copyin_internal return to simplify the code
        From Xiang Xiao.
      - IOB Notifier:  Don't check iob_navail in iob_notifier_setup to
        avoid a potential race condition.  From Xiang Xiao.
      - IOB Debug Dump:  Format the whole line before log to avoid the
        multiple timestamp prefix in each line.  From Xiang Xiao.
      - SHM:  Convert bytes to pages by MM_NPAGES instead of MM_PGALIGNUP
        From Xiang Xiao.
      - SHM:  shmget() should hould call shm_extend() to allocate the
        physical memory.  From Xiang Xiao.
      - Page Allocator:   mm/pgalloc: shouldn't just allocate one page
        always.  From Xiang Xiao.
      - Granule Allocator:  Fix the wrong data in g_1bit_info and make the
        internal function static.  From Xiang Xiao.
      - srbk():  Fix a backward conditional test.  Should call
        mm_initialize() when brkaddr equal zero  From Xiang Xiao.
      - sbrk():  Pass ARCH_HEAP_VEND as maxbreak argument  From Xiang Xiao.
      - ELF Headers:  Move elf related arch function to include/nuttx/elf.h
        because the implementation is located in libs/libc/machine and in
        order to avoid the conflict with the 3rd party libraries and clean
        up the file inclusion:  (1) Remove redundant elf32.h, (2) Remove
        nuttx/binfmt/elf.h in libs/libc/machine, (2) Remove
        nuttx/binfmt/elf.h in modlib, and (4) Remove nuttx/module.h in
        modlib. From Xiang Xiao.
      - ELF Executables:  If there is an address environment
        (CONFIG_ARCH_ADDRENV), binfmt/elf doesn't need to free ctor/dtor
        alloc since freeing the address environment releases the heap
        automatically.  From Xiang Xiao.
      - ELF Configuration:  Correct libcxx exception handling by
        introducing the generic config(CXX_EXCEPTION and CXX_LIBSUPCXX)
        From Xiang Xiao.
      - ELF Loaders:  Call umm_initialize as soon as possible  otherwise
        elf_loadctors/elf_loaddtors may fail to allocate memory.  From
        Xiang Xiao.

    * Crypto:

      - Crypto AES:  After NuttX 7.28 crypto/aes.c would no longer
        compile.  From Gregory Nutt.

    * File System/Block and MTD Drivers:

      - open():  Fix not returning failure for block_proxy() call. From
        David Sidrane.
      - AIO: aio_cancel() needs to signal caller after success.  Also fix
        minor issue in the error handler.  From Xiang Xiao.
      - HostFS:  Remove the unnecessary use of host_stat() in
        hostfs_bind()  From ligd.
      - LittleFS:  Fix a minor issue found in code review:  (1) Replace
        printf to finfo/fwarn/ferr, (2) Replace malloc/free to
        kmm_malloc/kmm_free, (3) define LFS_NAME_MAX to NAME_MAX, (4) Check
        the big endian using CONFIG_ENDIAN_BIG.  From Xiang Xiao.
      - LittleFS:  VFS Lookahead should use bit unit not byte unit. From
        Xiang Xiao.
      - NxFLAT:  Correct a double free debug assertion.  This occurs when
        groups are enabled:  (1) once via binfmt_exit and unload_module,
        and (2) once via sched_releasetcb().  this was corrected by adding
        logic to free/unload the memory once and nullify the pointer so
        that cannot be freed a second time.  This commit resolves Bitbucket
        issue #145.  From Valmantas Palikša.
      - NxFLAT:  File descriptor leaks when nxflat loading fails.  From
        Valmantas Palikša.
      - ProcFS:  Fix typo in procfs uptime logic.  From Sebastien Lorquet.

    * Networking/Network Drivers:

      - Network Configuration:  The setup seems to support a network
        without sockets (CONFIG_NSOCKET_DESCRIPTORS == 0).  That is not the
        case; if the network is enabled, sockets must be provided.  From
        Gregory Nutt.
      - Networking:  The value ERROR should never be returned from internal
        OS functions.  That is reserved for returning values to appliations
        with the errno value set.  Within the OS, errors are returned with
        a negated errno value ALWAYS.  From Gregory Nutt.
      - Networking:  The struct in_addr doesn't have the member sin_addr.
        The function lib_lo_ipv6match() is for IPv6.  Correct the function
        it calls from lib_lo_ipv4matchto() to lib_lo_ipv6match().  Also add
        CONFIG_NET_IPv6 for configuration.  From Kejun ZHOU.
      - TCP (buffered) send:  Fix assertion crash when window size is
        zero.  From Gregory Nutt.
      - ICMP/ICMPv6:  Bind icmp callback from device to connection.
        Resolves the issue that bind() could not be called before send()
        From anchao.
      - TUN/TAP Driver:  Re-order all TUN/TAP driver state data.  Not only
        was was with wasting memory due to alignment requirements, it was
        also causing network packet buffers to be improperly aligned
        causing problems because the network requires 16-bit packet buffer
        alignment for uint16_t accesses.  This alignment problem was
        discovered by Alan Carvalho de Assis.  From Gregory Nutt.
      - TUN/TAP Driver:  Packet buffer size should include the configured
        GUARD_SIZE.  And, given how the buffers are allocated, the
        allocation size must be an even number of 16-bit values to preserve
        alignment.  From Gregory Nutt.
      - Local Sockets:  In local_connect(), initialize lc_result before
        giving lc_waitsem  From zhangyuan7.
      - Local Sockets:  Fixed deadlock issue by replacing nxsem_wait() with
        net_lockedwait() so that we do not wait with the network locked.
        From zhangyuan7.

    * Graphics/Display Drivers:

      - NX Graphics:  Remove naming associated with the now non-existent
        NXFE graphics layer: Rename nxfe_reportposition to
        nxmu_reportposition.  Rename nxfe_redrawreq to nxmu_redrawreq.
        Rename nxfe.h to nxmu.h.  Rename nxfe_state_s to nxmu_state_s.
        Rename nxfe_conn_s to nxmu_conn_s.  From Gregory Nutt.
      - NxTERM:  Remove the nxterm_unregister interface.  The correct way
      to unregister a device is to unlink it.  From Gregory Nutt.
      - NxTerm:  Needs to clear display initially.  Otherwise, garbage from
        previous display may still be present from preceding NxWM window.
        From Gregory Nutt.
      - Font Cache:  Fix a memory leak in the font cache.  With a busy
        NxTerm display, this could drain off all the memory pretty quickly!
        From Gregory Nutt.
      - Graphics:  Nothing under graphics/ should set the errno.  From
        Gregory Nutt.
      - Graphics:  Fix a coordinate system error in nx_filltrapezoid().
        When no clipping rectangle is falls, it falls back to use the
        entire window as for the clip.  However, that window must then then
        be in window relative coordinates, not in absolute device
        coordinates.  From Gregory Nutt.

    * Common Board Logic:

      - boardctl(): Fix compiling error when set
        CONFIG_BOARDCTL_IOCTL/CONFIG_BOARDCTL_UNIQUEID.  From Kevin Liu.

    * Common Drivers:

      - INA3221:  Fix errors in INA3221 register field addresses and
        bitfield values.  Signed value was losing its signed-ness due to
        use of unsigned type for register.  From Ken Pettit.
      - Serial Upper Half:  Initialize OPOST and ONLCR in uart_register.
        From Xiang Xiao.
      - Serial Upper Half:  Don't reset the circular buffer on close since
        DMA may still be transferring data in the background if the user
        closes the handle too quickly and the handle is opened with
        O_NONBLOCK.  From Xiang Xiao.
      - 16550 UART:  Fix error: 'g_uart0port' undeclared.  From Xiang Xiao.
      - 16550 UART:  Fix typo for UART1 flow field initialization  From
        Gregory Nutt.
      - CDC/ACM HCD:  Fixes to the IOCTL method in recovery of UART pointer
        and in names of Termios-related field.  From xhbm.
      - USB Device:  Fix type for USBDEV_TRACE_INITIALIDSET in Kconfig.
        From Mateusz Szafoni.
      - TCA64xx: Fix some errors in the TCA64XX driver.  From Bruno
        Schwander.
      - SYSLOG RAMLog:  Fix error: Conflicting types for 'ramlog_addchar'
        From Xiang Xiao.
      - NRF24L01:  Fix uninitialized irq_work which was causing a
        hard_fault on interrupt handler whenever something was sent from
        nrf24l01_term  From Petri Ahonen.
      - MCP2515:  Use kmm_zalloc to allocate device state structure.  Fix
        some compiler errors. From Valmantas Paliksa.

    * Architecture Common:

      - arch/ Common:  Remove architecture-specific watchdog.h and
        arm-elf.h because they are empty.  The arm-elf header file was
        never used; the empty watchdog.h header file was used in only one
        place.  From Xiang Xiao.
      - arch/ Common:  Move up_pminitialize() after timer_initialize()
        From ligd.
      - arch/ Common:  Align semi-hosting call style with other syscalls in
        architecture-specific syscall.h.  From Xiang Xiao.
      - arch/ Common:  Every file that uses serial IOCTLs (TIOC*) must
        explicitly include nuttx/fs/ioctl.h.  This was included previously
        via sneak path in the now deleted arch/serial.h.  From Gregory Nutt.
      - arch/ Interfaces:  Rename sched_process_cpuload to
        nxsched_process_cpuload.  All internal sched_ functions should be
        prefixed with nx.  From Valmantas Paliksa.

    * ARMv7-A:

      - ARMv7-A MMU:  Updating the cp15_wrttb and cp15_wrdacr functions to
        use inline assembly in the correct way.  The incorrect method was
        generating errors as ARMv7-a expects the MCR/MRC instructions to
        provide registers as an argument(MRC p15, 0, <Rt>, c2, c0, 0) and
        the code was providing a constant value(and hence the build
        error).  From Bilal Wasim.
      - ARMv7-A:  Remove inclusion pg_macros.h for armv7-a since this
        header file does not exist.  From zhangyuan7.
      - ARMv7-A:  Guard some assembly files if configuration not selected.
        From zhangyuan7.
      - ARMv7-A GIC:  Fix assemble error when including gic.h  From Xiang
        Xiao.
      - ARMv7-A GIC:  Don't use GIC_ICDDCR_ENABLEGRP1 for GIC NONSECURE
        since this bit doesn't exist in this mode.  From liuzhuang.

    * ARMv7-R:

      - ARMv7-R Syscall:  In arch/arm/include/syscall.h, add missing
        inclusion of arch/armv7-r/syscall.h for Cortex-R.  From Xiang Xiao.

    * ARMv7-M:

      - ARMv7-M Initialization:  As noted by Roland Takacs in Bitbucket
        issue 141, there is a compilation error for STM32 if CONFIG_NET and
        CONFIG_NETDEV_LATEINIT are selected.  That was due in part to the
        commit which extended up_netinitialize() with a
        !defined(CONFIG_NETDEV_LATEINIT) guard but did not add the guard to
        concrete implementations.  I say "in part" because I don't think
        that the original intent of commit 19e16cb was to enable an
        alternative initialization of MCU internal Ethernet support but
        rather to enable support of external Ethernet devices that may have
        dependencies on, for example, SPI.  However, this is still a proper
        fix to avoid the compilation error that can occur with this
        combination of configuration options.  From Gregory Nutt.
      - ARMv7-M Configuration: ARCH_HIPRI_INTERRUPT shouldn't select
        ARMV7M_USEBASEPRI.  First because that is a violation of the
        layered nature of the Kconfig architecture, but also because then
        Kconfig will generate errors when high priority interrupts are used
        with other architectures.  From Xiang Xiao.
      - ARMv7-M Vector Table:  Make the default NVIC_VECTAB_TBLOFF_MASK
        safer.  The base address of the new vector table must be aligned to
        the size of the vector table extended to the next larger power of
        2.  From Xiang Xiao.
      - ARMv7-M RAM Vectors:  Correct bad NVIC_VECTAB_TBLOFF_MASK
        definitions in previous commit.  Were missing bits in the mask.
        Raised DEBUGASSERT in armv7-m/up_ramvec_initialize.c line: 144.
        From Mateusz Szafoni.

    * Espressif ESP32 Drivers:

      - ESP32 Timer ISR:  Fix backward comparison.  From Gregory Nutt.
      - ESP32 Serial:  Fix some backward arguments.   Correct 2-stop bit
        setting.  From Gregory Nutt.

    * Microchip/Atmel SAMD2x/L2x Drivers:

      - SAMD2/L2 Serial:  SAMD2/L2 serial driver.  It needs
        sam_usart_enable(). to work  From Alan Carvalho de Assis.

    * Microchip/Atmel SAMD3/4 Drivers:

      - SAM3/4 Ethernet:  Port Anthony Merlino's SAMv7 fix to similar
        Ethernet driver for the SAM3/4.  From Gregory Nutt.

    * Microchip/Atmel SAMV7 Drivers:

      - SAMv7 SPI:  Fix DMA Tx/Rx timeout issue.  From Kevin Liu.
      - SAMv7 QSPI:  Compile error when set CONFIG_SAMV7_QSPI_DLYBCT.
        From Kevin Liu.
      - SAMv7 Ethernet:  The logic for determining the number of queues for
        SAMV71 must be extended.  All SAMv7 parts increase the number of
        queues from 3 to 6 at revision B, not just the SAMV71.  From
        Gregory Nutt.
      - SAMv7 Ethernet:  Fixes rxdesc index logic to handle Buffer Not
        Available (BNA) condition.  If a SOF is found, but no EOF, don't
        move past the frame. Instead, keep the index at the SOF buffer
        until the rest of the data is written.  This fixes a receiver
        lockup condition where the peripheral and this driver get out of
        sync with there head pointers. In this case the driver has moved
        past buffers it owns, without clearing ownership,  which results in
        the peripheral and driver in a deadlock with each other.  From
        Anthony Merlino.

    * Microchip/Atmel SAMA5Dx Drivers:

      - SAMA5Dx Ethernet:  Port Anthony Merlino's SAMv7 fix to similar
        Ethernet driver for the SAMA5Dx.  From Gregory Nutt.

    * Microchip/Atmel SAMA5Dx Board:

      - SAMA5D2-XULT:  Move console from FLEXCOM4 to UART1.  FLEXCOM4 does
        not work for the Arduino serial.  UART1 is used with the VCOM
        provided by the EDBG.  From Gregory Nutt.

    * NXP i.MXRT:

      - i.MXRT Clock Configuration:  If SDRAM is activated it was only
        running at 40MHz.  This was because imxrt_clockconfig.c changed the
        SEMC clock divider after the DCD was configured.  This commit
        corrects that.  From Johannes.

    * NXP i.MXRT Drivers:

      - i.MXRT GPT:  Correct register offsets.  From David Sidrane.
      - i.MXRT TMR:  Fix addressing and restructure using common offset.
        From David Sidrane.
      - i.MXRT ADC:  Error in offset.  From David Sidrane.

    * NXP/Freescacle Kinetis Boards:

      - Teensy-3.x:  Fix a mismatch in types in defconfig.  From Gregory
        Nutt.

    * NXP LPC17xx:

      - LPC176x Clock Configuration:  The code preserves undocumented
        reserved bits only if board does not set them to keep previous
        behavior for boards where developers (hopefully) know what values
        should be set into these bits.  From Pavel Pisa.
      - LPC17xx Clock Configuration:  The enable of EMC clocks has to be
        preserved when already enabled by loader.  EMC and related pins
        configuration has to be skipped if the system is run from SDRAM.  A
        region of SDRAM which is used by system must not be used for heap.
        From Pavel Pisa.

    * NXP LPC17xx Drivers:

      - LPC17xx CAN:  The name can_txready clashes with NuttX CAN core
        global function.  LPC178x has only single LPC17_SYSCON_PCLKSEL with
        only single divisor.  From Pavel Pisa.

    * NXP LPC17xx Boards:

      - Open1788:  Add missing MPU configuration option.  From Gregory Nutt.

    * On Semi LC823450 Boards:

      - LC823450-XGEVK:  Remove -nostdinc to avoid build error  From
        Masayuki Ishikawa.

    * STMicro STM32:

      - STM32:  Don't try including stm32_gpio.h from within chip/*.h
        header files.  Not only is bad style for a layered inclusion
        system, but it doesn't always work.  From Gregory Nutt.

    * STMicro STM32 Drivers:

      - STM32 PWM: Fix polarity and IDLE state configuration From Mateusz
        Szafoni.
      - STM32 ADC, PWM and TIM:  (1) missing T1TRGO2 for JEXTSEL, (2) fix
        sample time configuration for channels. The array index for
        channels was missing, (3) fix TRGO/TRGO2 configuration, and (6)
        support for advanced timers channel 5 and 6.  From Mateusz Szafoni.
      - STM32 Heap:  Change 'if CONFIG_STM32_HAVE_CCM' to 'ifdef
        CONFIG_STM32_HAVE_CCM' to avoid a warning when
        CONFIG_STM32_HAVE_CCM is not defined.  From Gregory Nutt.
      - STM32 Oneshot Timer:  Fix an error introduced be a previous timer
        commit.  From Maximilian Kriegleder
      - STM32 Tickless Mode and Free-Running Timer:  Apply Max's
        stm32_oneshot.c fix to the tickless implementation and to the
        freerunning time.  From Mateusz Szafoni.
      - STM32 PWM: Set CCPxP and CCPxNP bits if polarity is negative.
        Missing commas in initializers could break compilation in certain
        configurations.  From Mateusz Szafoni.
      - STM32F7 Interrupts:  Add the missing macro STM32_IRQ_NIRQS used by
        arch/arm/src/stm32f7/stm32_irq.c.  From Kejun ZHOU.
      - STM32H7 DMA:  Fix AHB1 base addresses memory map. From Mateusz
        Szafoni.
      - STM32H7 SysTick:  H7 appears to ignore the SysTick CLKSOURCE bit
        and use the CPU clock in all cases.  From Mateusz Szafoni.

    * STMicro STM32 Boards:

      - B-L072Z-LRWAN1:  Fix typo in SPI1 pin definitions.  From Mateusz
        Szafoni.
      - STM32F429I-DISCO:  Handle multiple calls to the LCD
        up_fbinitialize() function.  From Gregory Nutt.
      - STM32F769I-DISCO:  Florian R. Hölzlwimmer reports that
        stm32_appinitialize.c often has missing OK and NULL definitions.
        This should be fixed by including sys/types.h where they are
        defined.  From GregoryN.
      - STM32F769I-DISCO:  Remove CONFIG_STM32F7_QUADSPI=y from the
        configuration.  This was apparently set before the implementation
        was added.  Now that the implementation was added, the configuration
        will not build because it requires that QSPI GPIO pin definitions
        be provided in the board.h header file.  From Gregory Nutt.

    * TI AM335x Drivers:

      - AM335x Serial:  Eliminate an error 'TIOCSBRK undeclared.  From
        Gregory Nutt.

    * C Library/Header Files:

      - strto*:  In alll strto* function family, did't consume single '-'
        or '+', allow sign in strotul(l)).  From Johannes.
      - getopt():  Add logic to reinitialize the stale context for the
        FLAT/PROTECTED builds.  In these builds getopt() global variables
        may be shared by many tasks.  If any task exits the getopt() loop
        before all command line arguments have been parsed, then getopt()
        global variables will be left in a bad state.  The next time
        getopt() is called, this logic should detect the bad state and
        force the state of getopt() to be re-initialized so that it can be
        reused.  This logic is not full proof (it would fail, for example,
        if you tried to parse the same command line twice) but should catch
        the typical misuse cases.  From Xiang Xiao.
      - sscanf(): Initialized the lastc pointer to avoid the checks for
        NULL.  Removed a bug in the floating point parsing which allowed
        several signs after each other.  From Johannes.
      - lib_vsprintf() (Legacy):  No precision specifier resulted in
        precision 0 but should be precision 6.  From Johannes.
      - lib_vsprintf() (Legacy):  Correct justification for alternate forms
        of %p and %P  From ligd.
      - lib_vsprintf() (Nano):  Add long long support.
        CONFIG_LIBC_LONG_LONG needs at least CONFIG_NANO_PRINTLEVEL 2.
        Code size for compile without CONFIG_LIBC_LONG_LONG shouldn't be
        affected.  From Johannes.
      - lib_vsprintf() (Nano):  Remove CONFIG_LIBC_PRINT_MINIMAL.  The
        output in that configuration is unsatisfactory and inappropriate
        for use with NuttX.  For example, the output from many NSH commands
        become corrupted and useless.  Doesn't belong in this context.
        From Gregory Nutt.
      - libs/libc/symtab:  Remove unused symtab_findorderedbyvalue().  From
        Xiang Xiao.
      - libs/libc/machine/arm:  Fix the minor issue in libc arm machine
        folder; MOVW/MOVT should use zero(not sign) extension.  From Xiang
        Xiao.
      - libs/libc/libc.csv:  Should be locale.h not local.h.  From Joao
        Matos.
      - libs/libc/libc.csv:  Needed logic for correct compilation if not
        using CONFIG_LIBC_WCHAR.  From Joao Matos.
      - libxx:  Always include libxx_cxa_guard.cxx in the build for for
        uclibcxx. From zhangyuan7.

      - include/stdbool.h:  Define bool only when __cplusplus isn't
        defined.  From Xiang Xiao.
      - include/nuttx/list.h:  Added a Linux-compatible list
        implementation.  From zhuyanlin.
      - include/nuttx/irq.h:  Fix enter_critical_section/spin_lock_irqsave
        macro typo error and remove the duplicated inclusion of
        arch/irq.h. From Xiang Xiao.
      - include/dlfcn.h: Correct naming of standard header file.  Should
        be dlfcn.h, not dllfcn.h.  From Gregory Nutt.
      - include/nuttx/nx/nxmu.h:  This header file could be lethal; it
        declared an #error if CONFIG_DISABLE_MQUEUE=y.  From Gregory Nutt.
      - include/nuttx/compiler.h:  Important fix for C++ users.
        compiler.h was using the value of __STDC_VERSION__ to determine if
        inline functions are supported or not.  If not then the keyword
        inline was defined out. Good for C but bad for C++ because C++
        does not define __STDC_VERSION__ at all.  C++ applications may
        draw in compiler.h indirectly via other head files and this can
        result in C++ compiler problems since 'inline' is defined out.
        This fix is to ignore the (undefined) __STDC_VERSION__ if
        __cplusplus is defined.  From Gregory Nutt.
      - include/nuttx/elf.h:  Adds missing extern "C" __cplusplus guard.
        From Anthony Merlino.
      - include/poll.h:  Remove un-named union from 'struct pollfd'.  It
        is not required by OpenGroup.org and violates the NuttX C coding
        standard because it is not C89 compatible.  From Gregory Nutt.
      - libs/libc/Makefile, libs/libnx/Makefile, and mm/Makefile:  Remove
        obj-path MKDEPS option since make dependency target (MT) is not
        supported by some toolchains.  From anchao.
      - include/nuttx/compiler.h:  Assume inline support if
        __STDC_VERSION__ not defined.  From Xiang Xiao.

    * Tools:

      - tools/convert-comments.c:  Fix an error in handling of a blank C++
        comment before a comment block.  From Gregory Nutt.
      - tools/lowhex.c:  Fix an initialization problem that was causing
        some odd behavior at the beginning of lines.  From Gregory Nutt.
      - tools/nxstyle.c:  Fix logic that detects if an operator is
        correctly delimited with spaces.  sched/:  Various changes because
        sched/ C files were used as Guinea Pigs to test nstyle.c.  From
        Gregory Nutt.
      - tools/nxstyle.c:  Was confusing hex constants with strings staring
        with 'x'.  Added logic to complain about hex constants containing
        upper case characters.  From Gregory Nutt.
      - tools/nxstyle.c:  Fix logic error that prevent detecion of '/' and
        '/=' as operators.  net/:  Minor updates resulting from testing
        tools/nxstyle.  From Gregory Nutt.

    * NSH Library: apps/nshlib:

      - NSH Console:  Fix copy paste errors. Some Kconfig configuration
        names needed CONFIG_ prefix.  From David Sidrane.
      - nshlib/nsh_timcmds.c:  Uninitialized struct tm caused 'date -s' to
        fail.  From Valmantas Palikša.

    * Examples: apps/examples:

      - apps/examples/nxterm:  Replace direct calls to nxtk_register()
        with legal, indirect calls via boardctrl(BOARDIOC_NXTERM).
        Replace calls to (deleted) nxterm_unregister().  The correct way
        to delete a driver is by unlink'ing it.  From Gregory Nutt.
      - apps/examples/nxterm:  Most configuration options were not
        available in the Kconfig file.  From Gregory Nutt.
      - apps/examples/nxterm:  Replace illegal direct calls to
        nxterm_redraw() and nxterm_kbdin() with new boardctl() calls.
        From Gregory Nutt.
      - apps/examples/nxterm:  NxWM passed the size of the NxTK sub-window
        but nxterm example passed the size of the complete NxTK window.
        They must be made consistent.  From Gregory Nutt.

    * Graphics Utilities: apps/graphics:

      - apps/graphics/NxWidgets/nxwm:  Correct an error in the type of the
        return value in CCalibration.  From Gregory Nutt.
      - apps/graphics/NxWidgets/nxwm:  Replace direct calls to
        nxtk_register() with legal, indirect calls via
        boardctrl(BOARDIOC_NXTERM).  Replace calls to (deleted)
        nxterm_unregister().  The correct way to delete a driver is by
        unlink'ing it.  From Gregory Nutt.
      - apps/graphics/NxWidgets:  Replace illegal direct calls to
        nxterm_redraw() and nxterm_kbdin() with new boardctl() calls.
        From Gregory Nutt.

    * Modbus: apps/modbus:

      - apps/modbus/Kconfig:  Fix modbus master Kconfig.  Modbus Master
        ASCII compiles correctly.  From Alan Carvalho de Assis.

    * Network Utilities: apps/netutils:

      - apps/netutils/dhcpc/dhcpc.c:  Fix an error for DHCP REQUEST
        receiving a NAK.In DHCP Request operation, no need to update
        ciaddr to the client address and keep it as 0.  From Kevin Liu.

    * System Utilities: apps/system:

      - apps/system/vi/vi.c:  Fix an infinite loop bug that can show up in
        some cases (plus a couple of other items).  From Ken Pettit.
      - apps/system/vi: Condition KEY_CMDMODE_REPEAT with
        CONFIG_SYSTEM_VI_INCLUDE_COMMAND_REPEAT to avoid build error when
        option is not selected.  From Anthony Merlino.
      - apps/system/nxplayer/nxplayer.c:  Fix build error when only enable
        CONFIG_AUDIO_EXCLUDE_VOLUME is enabled.  From ZhongAn.
      - apps/system/system/system.c:  Correct a path name.  From anchao.
      - apps/system/taskset:  Fix command arguments are not passed.  From
        Masayuki Ishikawa.

    * Testing: apps/testing:

      - apps/testing/ostest/timedmutex.c:  pthread_mutex_timedlock()
        returns EDTIMEDOUT on a timedout, not EAGAIN.  From Gregory Nutt.

    * Tools: apps/tools:

      - apps/tools/mksymtab.sh:  'export LC_ALL=C' to get the traditional
        sort order  From anchao.

NuttX-7.30 Release Notes
------------------------

The 130th release of NuttX, Version 7.30, was made on May 19, 2019,
and is available for download from the Bitbucket.org website.  Note
that release consists of two tarballs:  nuttx-7.30.tar.gz and
apps-7.30.tar.gz.  These are available from:

    https://bitbucket.org/nuttx/nuttx/downloads
    https://bitbucket.org/nuttx/apps/downloads

Both may be needed (see the top-level nuttx/README.txt file for build
information).

Additional new features and extended functionality:

    * Core OS:

      - pthreads:  Added non-standard pthread_get_stackaddr_np() and
        pthread_get_stacksize_np().  From Joao Matos.
      - boardctl():  Add a command to start the VNC server.  From Gregory
        Nutt.
      - Signals:  Remove references to CONFIG_DISABLE_SIGNALS in many
        files.  Signals can no longer be disabled.  From Gregory Nutt.

    * Wireless/Wireless Drivers:

      - NRF24L01:  Add support for "multicast" TX mode - no waiting for ACK
        (needs to be enabled with fcntl SETTXPAYLOADNOACK)  From Leif Jakob.

    * Graphics/Display Drivers:

      - NX Graphics:  Add new server->client callback to notify the window
        client of server events. Remove the old 'blocked' callback and just
        make it one case of an 'event' callback.  From Gregory Nutt.
      - NX Graphics:  Implement new interfaces nx_synch() and nxtk_synch().
        This are used to synchronize the NX server with the window client.
        Currently most of the logic is equivalent to nx_block() and
        nxtk_block(), but with slightly different semantics.  They are
        separate now because they are likely to diverge in the future.
        From Gregory Nutt.
      - NX Graphics:  Add support for modal windows.  From Gregory Nutt.
      - NX Graphics:  Implement a software cursor.  The cursor behaves
        like a "sprite", always at the top of the display with a
        transparent background.  Includes new NX interfaces to show/hide
        the cursor, set the cursor image, and to move the cursor position.
        From Gregory Nutt.
      - NX Graphics:  Added support for hiding windows. This features is
        needed by Twm4Nx:  When a window is iconified, the icon should
        appear on the background and the window should disappear (i.e., be
        hidden).  The windows needs to remain healthy and to be updated in
        all ways, but it cannot affect the display content.  Conversely,
        when the icon is clicked, the icon needs to be hidden on the
        background and the window needs to be restored in its current
        state (which may be different than the state of the window at the
        time it was iconified.  From Gregory Nutt.
      - NX Graphics:  Windows can now be created in the hidden state.
        This can be used to clean up initial window presentation which may
        involve several steps.  This makes those steps all invisible until
        nx[tk]_setvisibility() is called to make the windows visible.
        From Gregory Nutt.
      - NX Graphics:  Add new NX interfaces to query if a window is hidden
        or not.  From Gregory Nutt.
      - NxTerm IOCTLs:  Replace specific interfaces between boardctl and
        nxterm with a generalized IOCTL interface.  From Gregory Nutt.
      - NxTerm:  Add a new IOCTL that can be used to inform NxTerm that
        the size of a window has changed.  From Gregory Nutt.

    * Other Common Device Drivers:

      - CAN Upper Half:  Support multiple readers of the same port  From
        Valmantas Paliksa.
      - MAX7456:  Adds a read-only (for now) /dev/osd0/CM interface for
        obtaining the chip's onboard NVM character map data.  Use seek()
        to position the cursor over a desired subset of bytes, or request
        a large read to obtain the entire EEPROM memory contents.  Values
        are returned in binary form. Use hexdump, etc. to format them for
        viewing.  From Bill Gatliff.
      - Serial Upper Half:  The upper half serial driver configuration
        CONFIG_SERIAL_DMA used to enable DMA on both RX and TX streams.
        This was replaced with CONFIG_SERIAL_RXDMA and CONFIG_SERIAKL_TXDMA
        which will permit supporting DMA on only one or both streams.
        From Gregory Nutt.
      - FUSB303:  Add FUSB303 driver  From Juha Niskanen.

    * Microchip PIC32MZ Drivers:

      - PIC32MZ GPIO:  Adds support for edge detect mode.  Slew Rate was
        also added for completeness.  From Abdelatif Guettouche.

    * Microchip/Atmel SAMv7 Boards

      - SAME70-xplained:  Add a configuration for test Twm4Nx using VNC.
        From Gregory Nutt.

    * Microchip LPCxx Drivers:

      - LPC17xx Ethernet:  Added support for KSZ8081RNA PHY to LPC17xx
        Ethernet driver.  From jjlange.
      - LPC17xx Ethernet:  Added support for Ethernet PHY ioctl() on
        LPC17xx.  From jjlange.

    * NXP i.MX RT:

      - .i.MXRT1020:  Gets imx1020 family support started. It is pretty
        similar, but subtly different, to 1050/60 (less PLLs, less GPIO
        banks, differently numbered ports etc. etc.).

        Moved each of the imxrt family-specific files into its own
        subdirectory to tidy things up a bit, and remove the vast majority
        of ifdefs from the mainline code.

        From Dave Marples.

    * NXP LPC54xx Drivers

      - LPC54xx USB FS Host:  Bring in the USB FS OHCI driver from LPC17.
        This is a quick'n'dirty port from LPC17 that I hope finish
        sometime later.  Currently, it is missing hardware clocking setup
        and is not even hooked into the build system yet.  From Gregory
        Nutt.

    * NXP LPC54xx Boards

      - LPCXpresso-LPC54628:  Add a Twm4Nx configuration.  From Gregory Nutt.

    * Sony CXD56xx

      - CXD56xx:  Add initial CXD56xx chip driver sources.  From Nobuto
        Kobayashi.

    * Sony CXD56xx Spresense Board

      - Spresense:  Add Spresense board support.  This is not the full
        Spresense BSP from Sony, only the barebones logic to present an
        NSH console.  From Nobuto Kobayashi.

    * STMicro STM32:

      - STM32F7 Clocking: Add support for using the HSE in bypass mode,
        configured by board.h  From Anthony Merlino.
      - STM32F7 Clocking:  Added support for TICKLESS mode.  From Valmantas
        Paliksa.
      - STM32H7 Backup Domain:  Add backup domain control registers.  From
        Jukka Laitinen.
      - STM32H7 Clocking:  Set the STM32H7 default HSI pre-divider to 4.
        The I2C driver currently assumes HSI clock to be 16MHz.  From Jukka
        Laitinen.
      - STM32H7 Memorymap.:  Add the STM32H7 SYSTEM_UID and DEBUGMCU_BASE
        register definitions.  From Jukka Laitinen.
      - STM32L071x:  Add support for STM32L071x.  From Mateusz Szafoni.

    * STMicro STM32 Drivers:

      - STM32 OTGHS Host:  Allow VBUS monitoring for the OTG_HS host
        driver.  From Jason Harris.
      - STM32F0/L0 ADC:  Initial ADC support for the STM32 M0  From Mateusz
        Szafoni.
      - STM32F0/LO I2C: Port STM32F7 I2C to STM32F0/L0,  From Mateusz Szafoni.
      - STM32F1 FLASH:  As noted by Matias N, the FLASH base address used
        was incorrect.  It was using the address of the FLASH data, not
        the address of the FLASH registers.  From Gregory Nutt.
      - STM32F3 I2C: Port STM32F7 I2C to STM32F3.  From Mateusz Szafoni.
      - STM32F7 Ethernet.c:  Auto-generate Ethernet MAC address from
        device unique ID.  From Valmantas Paliksa.
      - STM32F7 FLASH:  Add flash block mapping support for progmem.  From
        Valmantas Paliksa.
      - STM32F7 FMC:  Updated stm32_fmc.h with more FMC definitions.  From
        Joao Matos.
      - STM32F7 GPIO:  Adds additional pin alternate function for SPI2.
        From Anthony Merlino.
      - STM32F7 PWM:  Ported the PWM from F4 to F7.  From Eduard Niesner.
      - STM32F7 SDMMC: Support bypassing the input clock divider on the
        SDMMC interface. This enables using the full clock speed provided
        to the SDMMC interface with no dividing.  From Anthony Merlino.
      - STM32F7 SPI:  Add SPI DMA threshold configuration.  From Valmantas
        Paliksa.
      - STM32F7 UID:  Add UID access.  From Valmantas Paliksa.
      - STM32F7 USB:  USB High speed for STM32F7 series  From Ramtin Amin.
      - STM32H7 Ethernet:  Add stm32h7 Ethernet driver.  This is the
        initial push for the Ethernet driver.  The driver has been tested
        to be working on a nucleo board.  This is still WIP, it doesn't
        for example do MAC filtering on HW level, but just receives all
        Ethernet packets.  From Jukka Laitinen.
      - STM32H7 GPIO:  Add the GPIO_ETH_RMII_RXD1 pinmap definition for
        STM32H7.  From Jukka Laitinen.
      - STM32H7 SDMMC:  Add STM32H7 SDMMC driver.  It is mostly copied
        from STM32F7, with modified register addresses and bits, and IDMA
        dded.  This is still WIP; it only works with IDMA.  From Jukka
        Laitinen.
      - STM32H7 Timers:  Add timer devices driver for STM32H7.  This i
        mostly a forklift from stm32f7 with some h7 specific
        modifications.  From Jukka Laitinen.
      - STM32L0 AES:  Add support for AES for L0.  From Mateusz Szafoni.
      - STM32L0 RND:  Add support for RND.  From Mateusz Szafoni.
      - STM32L0 HSI48:  Add support for HS148 for L0. Move HSI48 enable
        from stm32_usbdev.c to stm32xx_rcc.c  From Mateusz Szafoni.
      - STM32L4 USB FS Device:  Add USB FS device support.  From Juha
        Niskanen.
      - STM32L4 HSI48:  Port HSI48 from STM32F0/L0  From Juha Niskanen.
      - STM32L4 CRS:  Port CRS from STM32F0/L0  From Juha Niskanen.

    * STMicro STM32 Boards:

      - B-L072Z-LRWAN1:  Add ADC example.  From Mateusz Szafoni.
      - B-L072Z-LRWAN1:  Add nxlines_oled example (ssd1306).  Add support
        for the I2C tool  From Mateusz Szafoni.
      - Nucleo-144:  Added STM32_RCC_DCKCFGR2_DSISRC definition to board.h.
        From Joao Matos.
      - Nucleo-144:  Mount sysfs for ifconfig for f767-netnsh/defconfig.
        Even if ifconfig is working to set IP, it will not work to display
        NICs (without args)  From Phil Coval.
      - Nucleo-144:  Add basic PWM support to nucleo-144 board.  More PWMs
        and multi channels support may be investigated and added later.
        Tested on Nucleo-F767ZI.  From Phil Coval.
      - Nucleo-F303ZE:  Add nxlines_oled example (ssd1306)  From Mateusz
        Szafoni.
      - Nucleo-H743ZI:  Enable the FPU.  From Jason Harris.
      - Nucleo-H743ZI:  Add support for I2C devices: ssd1306, pca9635,
        i2ctools  From Mateusz Szafoni.
      - Nucleo-H743ZI:  Add default clock configuration for SDMMC for
        Nucleo-H743ZI's board.h.  From Jukka Laitinen.
      - Nucleo-H743ZI:  Add the input clock frequency definitions in
        board.h for all the drivers. Assumes internal clock source for
        all the timers.  From Jukka Laitinen.
      - STM32F4 Discovery:  Keep c++ global constructor symbols  From
        Masayuki Ishikawa.
      - Nucleo-L073RZ:  Add MFRC522 support  From Mateusz Szafoni.
      - OmnibusF4:  Add boardctl() reset logic.  From Bill Gatliff.
      - OmnibusF4:  Add board_ioctl() which is needed only if
        CONFIG_BOARDCTL_IOCTL=y is selected;  Update NSH configuration
        to enable board IOCTLs and DFU mode reset.  From Bill Gatliff.
      - STM32L Discovery:  Add support for board_late_initialize(), Move
        common initialization logic out of board_app_initialize() into new
        file stm32_bringup.c  From Gregory Nutt.
      - STM32F103-Minimum:  Add PROCFS automount support  From Alan
        Carvalho de Assis.

    * Libraries/Header Files:

      - include/alloca.h:  Add alloca.h.  Included limited implementation
        of alloc() that is only available for GCC versions 3 and above.
        From Joao Matos.
      - include/cxx/cstdlib:  Add std::random()  From Gregory Nutt.

    * apps/ General:

      - Many locations:  Remove references to CONFIG_DISABLE_SIGNALS.
        Signals can no longer be disabled.  From Gregory Nutt.

    * Examples/Tests: apps/examples:

      - apps/examples/fb:  Add some awareness of overlays to
        apps/examples/fb  From Matthew Koch.
      - apps/examples/lvgldemo.  Update to Littlevgl 5.3.  From Matthew
        Koch.
      - apps/examples/pwfb:  Extend example to verify software cursors.
        From Gregory Nutt.
      - apps/examples/pwfb:  Add options to reduce the number of windows.
        This is helpful during debug to reduce the complexity.  From
        Gregory Nutt.

    * Network Utilities: apps/netutils:

      - apps/netutils/cjson:  Support for the current version of cJSON.
        From Mateusz Szafoni.
      - apps/netutils/libcurl4nx:  This is an initial commit libcurl4nx.
        It is not complete yet, but I still wish to commit the unfinished
        bits to describe the roadmap, and because it is already usable.  It
        will be updated and fixed in the future weeks and months, certainly
        including POST support and later, SSL.  From Sebastien Lorquet.
      - apps/netutils/netinit.  This commit removes the private network
        initialization logic from NSH and puts in a common location at
        apps/netutils/netinit.  Now that netork initialization logic can be
        used by applications that do not include NSH.  From Gregory Nutt.
      - apps/netutils/netlib:  Add a  more flexible version of
        netlib_parsehttpurl().  This one can parse any URL, and is
        extensible so future improvements keep the same API.  From Sebastien
        Lorquet.

    * System Utilities: apps/system

     - apps/system/spi:  I needed a small test tool for spi in the style of
       the I2C tool, but I didn't see one so I've hacked one out of the I2C
       tool source.  From Dave Marples.

    * Graphics:  apps/graphics:

      - apps/graphics/twm4nx.  This release introduces Twm4Nx.  Twm4Nx is a
        "port" of TWM, Tab Window Manager (or Tom's Window Manager) version
        1.0.10 to NuttX NX windows server.  No, a port is not the right
        word.  It is are-design of TWM from the inside out to work with the
        NuttX NX server and NXWidgets.  The name Twm4Nx reflects this
        legacy.  But Twm4Nx is more a homage to TWM than a port of TWM.

        The original TWM was based on X11 which provides a rich set of
        features.  TWM provided titlebars, shaped windows, several forms of
        icon management, user-defined macro functions, click-to-type and
        pointer-driven keyboard focus, graphic contexts, and user-specified
        key and pointer button bindings, etc.

        Twm4Nx, on the other hand is based on the NuttX NX server which
        provides comparatively minimal support.  Additional drawing support
        comes from the NuttX NxWidgets library (which necessitated a
        conversion to C++).

        Twm4Nx is greatly stripped down and targeted on small embedded systems
        with minimal resources.  For example, no assumption is made about the
        availability of a file system; no .twmrc file is used.

        The state of the "port" is available in
        apps/graphics/twm4mx/README.txt.  To summarize:  The port is fully
        functional but probably only at an alpha release level.  The only
        missing critical feature is built-in touchscreen calibration.

      - apps/graphics/littlevgl.  Update to Littlevgl 5.3.  From Matthew
        Koch.
      - apps/graphics/nxglyphs:  Put all NxWidgets and NxWM glyphs into a
        common directory where they can eventually be shared. Decouple
        from nxwidgets and nxwm so that they can be used elsewhere.
        Creates include/graphics/nxglyphs.h  From Gregory Nutt.
      - apps/graphics/nxglyphs:  Add some new cursor bitmap images.  From
        Gregory Nutt.
      - apps/graphics/nxglyphs:  Add mkcursor.c.  Will auto-generate
        cursor image header file from Gimp C output.  From Gregory Nutt.
      - apps/graphics/nxglyphs:  Add 16x16 cursor images.  30x30 are kind
        of large on small displays.  From Gregory Nutt.
      - apps/graphics/nxglyphs:  Add a new resize cursor image. From
        Gregory Nutt.
      - apps/graphics/nxwm:  Separate NxWidgets and NxWM into separate
        directories.  Remove old, common NxWidgets directory.  From
        Gregory Nutt.
      - apps/graphics/nxwm:  Move the NxWM unit test main() to apps/nxwm.
        It is no longer a unit test, but the main startup entry point for
        NxWM.  From Gregory Nutt.
      - apps/graphics/nxwidgets:  Update NX window clients so that they
        use the new 'event' callback (vs. the obsoleted 'blocked' callback).
        From Gregory Nutt.
      - apps/graphics/nxwidgets:  Add a synchronize method to every window.
        This is a wrapper arounc nx[tk]_sync and permits C++ applications
        to synchronize with the NX server.  From Gregory Nutt.
      - apps/graphics/nxwidgets:  Add support for modal windows.  From
        Gregory Nutt.
      - apps/graphics/nxwidgets:  Add cursor control methods to the
        CNxServer class.  From Gregory Nutt.
      - apps/graphics/nxwidgets:  Add a method to CButtonArray that will
        allow us to dynamically resize the array (at the cost of losing all
        button labels).  From Gregory Nutt.
      - apps/graphics/nxwidgets:  Fix a possible deadlock condition when
        waiting for window geometry data that will never come.  Fixed by
        re-requesting geometry data if we don't already have it.  From
        Gregory Nutt.
      - apps/graphics/nxwidgets:  Add handshake to
        CWidgetControl::getWindowHandle() to avoid returning a NULL
        handle.  From Gregory Nutt.
      - apps/graphics/nxwidgets:  CNxTkWindow, CNxWindow, CNxServer:  Add
        support to create RAM backed windows.  From Gregory Nutt.
      - apps/graphics/nxwidgets:  Add methods to all windows to query if a
        window is visible or hidden.  From Gregory Nutt.

Bugfixes.  Only the most critical bugfixes are listed here (see the
ChangeLog for the complete list of bugfixes and for additional, more
detailed bugfix information):

    * Core OS:

      - Clock Initialization:  A recent change broke Tickless mode for all
        architectures.    The original change was intended to handle the
        case where up_timer_gettime may not start from zero case.  The
        side effect is that this changed to order of initialization of
        clocking, breaking Tickless mode::  After this change the tickless
        timer structures are used before they are initialized in
        clock_inittime().  The commit has been reverted.
      - pthread Stack Attribute:  Fixed pthread_attr_get/setstacksize
        param type to size_t.  From Joao Matos.
      - Signals:  The abnormal termination signal handler was just calling
        exit() conditionally when, for example, Ctrl-C is sent to a task.
        The abnormal termination handler must obey the rules of cancellation
        points:  If cancellation is disabled, then the abnormal termination
        logic must wait for cancellation to be re-enabled; If cancellation
        is deferred then the abnormal termination logic may have to wait
        for the victim task to enter or exit a cancellation point.  From
        Gregory Nutt.
      - Syscall: Added support for munmap() syscall.  From Joao Matos.
      - Syscall: Fix a warning due to inconsistencies in return type in
        syscall.csv.  From Gregory Nutt.
      - Syscall:  Correct an error syscall.csv. Error occurred when
        creating the munmap() proxy if CONFIG_FS_RAMMAP is not defined.
        From Gregory Nutt.

    * File System/Block and MTD Drivers:

      - fs/littlefs/lfs.c:  Fix lfs_format bug.  In superblock disk root-
        block assignment, the second must be root[1].  From YanLin Zhu.

    * Networking/Network Drivers:

      - getsockname():  Fix addrlen check in socket debug features.
        Getsockname() checked erroneously a pointer against 0, where the
        intention was to dereference the pointer and to check the length.
        This causes also a compilation failure if the code is compiled
        with CONFIG_DEBUG_FEATURES and with -Werror flag set.  From Jukka
        Laitinen.
      - Network Locking:  net_lock() and net_restorelock() now return a
        value.  That values is the standard zero on success; negated errn
        value on failure.  This return value is only needed for
        -ECANCELED.  That cancellation indication needs to ripple all the
        way back to the highest levels where the cancellation can be acted
        on.  This commit only adds the return value; it does not add
        checking for the return values of net_lock() and net_restorelock()
        at higher levels.  That is required too.  From Gregory Nutt.
      - PHY Notification Driver:  Change sprintf to strncpy in phy_notify.
        On some platforms, the sprintf doesn't accept a const char* as a
        format argument.  From Jukka Laitinen.
      - 6LoWPAN HC06:  Correct an endian-ness problem in HC06 decompression.
        From Ivan Ucherdzhiev.

    * Wireless/Wireless Drivers:

      - NRF24L01:  Don't block in read if file descriptor is O_NONBLOCK.
        From Leif Jakob.

    * Graphics/Display Drivers:

      - NX Graphics:  Fix an error in coordinate system usage.  Expected
        rectangle in device coordinate frame, but was passing the
        rectangle in window-relative coordinate frame.  From Gregory Nutt.
      - NX Graphics:  Fix an oversight in the implementation of per-window
        framebuffers.  It is true that redraw callbacks can be suppressed
        for all cases ... EXCEPT ONE:  When the window is resized to a
        larger size, then the newly exposed territory must be drawn for
        the first time.  From Gregory Nutt.
      - NxTK:  Fix an error in handling mouse events for framed windows.
        When drawing, NX may report mouse positions outside of the Window.
        The is only for NX windows, but the outside-the-side positions were
        being discarded by nxtk_events().  From Gregory Nutt.
      - NxTK:  Refuse to open a toolbar of height zero or less.  From
        Gregory Nutt.
      - Nxglib:  Correct bogus logic in nxgl_interesting().  From Gregory
        Nutt.
      - VNC Server:  Fix an error in color conversion.  From Gregory Nutt.

    * Common Drivers:

      - APDS9960:  Initial state of allocated structure was not being set.
        Noted by Leif Jacob.  From Gregory Nutt.
      - MFRC522:  In mfrc522_read uid.sak must be different from 0x04 not
        as before from 0x00. SAK == 0x00 is a valid PICC type.  Add
        interface to read MIFARE Ultralight data  From Mateusz Szafoni.
      - Power:  Fix build for battery gauge  From Tom Kopriva.
      - Syslog:  In syslog buffered mode, avoid IOB alloc lock-up with
        heavy network activity.  This change alters the buffered syslog
        logic to use 'iob_tryalloc' instead of blocking 'iob_alloc' to
        avoid syslog printing from getting stuck when all IOBs are
        depleted by network activity.  An issue was seen when large
        incoming TCP transfer uses free IOB buffers and processing
        threads try to use syslog which then block at iob_alloc.  From
        Jussi Kivilinna.
      - USB CDC/ACM Device:  This fixes a problem where the host sent a
        "get descriptor" message of type "standard" with a recipient of
        type "interface". Since the composite driver would only pass
        messages to the child interfaces when a message was not
        "standard", this message was not handled. I changed the condition
        so that the composite driver checks not only if this is a
        "standard" message but if it is also directed to the device.
        Otherwise, the handling is delegated to the children of the
        composite device.  From Matias N.
      - USB HID:  The usbhid_descriptor_s struct defined in hid.h included
        some optional fields that should not be hard-defined as part of
        that structure.  An arbitrary number of optional entries could be
        included in the descriptor, but that is not properly represented.
        No code on NuttX currently depends on the structure definition
        with an optional descriptor so it is safe to remove.  From Matias N.
      - USB MSC Device:  Correct typo "const const" to "const".
        arch/arm/src/stm32/stm32_i2s.c:  In debug assertions, it on a
        sample rate of 0, but based on other code comments this value
        implies disabling the i2s master clock.  From Jason Harris.
      - Zerocross Driver:  Fix some errors when debug assertions are
        enabled.  From Matous Pokorny.
      - User Leds:  Fix ledset validity check in ULEDIOC_SETALL ioctl.
        From Jussi Kivilinna.

    * Architecture Common:

      - All board interfaces (those starting with board_) must be defined
        in board-specific logic.  Otherwise, they cannot be customized for
        specialized usage by different boards.  The board_reset()
        interface was defined in architecture-specific logic that only
        called up_systemreset().  That is useless!  This change removes
        the board_reset() implementation from the architecture-specific
        code and re-implements it in the src/ directory of each board that
        has CONFIG_BOARDCTL_RESET enabled.  That is the correct functional
        partitioning.  From Gregory Nutt.
      - Start-up:  Remove dependency on CONFIG_ARCH_FPU for inclusion of
        nvic.h in all other *_start.c files.  From Gregory Nutt.
      - Architecture initialization:  up_initialize() needs to know about
        ramlog_consoleinit()  From Jason Harris.

    * Microchip PIC32MZ Drivers:

      - PIC32MZ GPIO:  Corrects the gpioirq when mismatch mode is
        selected.  From Abdelatif Guettouche.

    * ARMv7-A:

      - ARMv7-A Build:  Fix 'cc1: warning: switch -mcpu=cortex-a7 conflicts
        with -march=armv7-a switch'  From Xiang Xiao.

    * Nordic NRFxx

      - NRF52:  Fix compiler error in nrf52832_errdata.c when following
        C89.  From Erik Englund.

    * STMicro STM32:

      - STM32 Configuration:  It seems one option in the timer configuration
        was lost at some point.  From Matias N.
      - STM32 start-up:  Inclusion of nvic.h should not be conditioned on
        CONFIG_ARCH_FPU.  From Mateusz Szafoni.
      - STM32H7 Clocking:  Fixes for STM32H7 RCC definitions.  From Jukka
        Laitinen.

    * STMicro STM32 Drivers:

      - STM32F0/L USART:  A few fixes for USART.  From Mateusz Szafoni.
      - STM32F1/F30 FLASH:  RCC register access should not be offset by
        FLASH register base.  From Matias N.
      - STM32F7 CAN:  CAN fixes.  From Valmantas Paliksa.
      - STM32F7 I2C:  I2C Interrupt storm fix.  I2C track bad state.  Now
        we track bad state and so the SW reset only when it occurs.  From
        David Sidrane.
      - STM32F7 OTG: Fixes some macros related to OTGFS/OTGHS preventing
        OTGHS from working.  From Anthony Merlino.
      - STM32F7 OTG Device:  Correct hard-coded FIFO size that is wrong
        for OTG FS.  From Ramtin Amin.
      - STM32F7 QSPI:  Fix QuadSPI interrupts.  This commit essentially
        replaces wrongly named configuration variable STM32F7_QSPI_INTERRUPTS
        into CONFIG_STM32F7_QSPI_INTERRUPTS.  Also fixes some getreg/
        putreg where register addresses were used instead of register
        offsets  From Pierre-Olivier Vauboin.
      - STM32H7 I2C: Fix I2C4 compilation for STM32H7.  From Jukka
        Laitinen.
      - STM32H7 UART: Fix compilation for UART7, UART8 and I2C4s.  From
        Jukka Laitinen.
      - STM32L4 USB Device:  Add missing PWR USBV enable, correct two USB
        register bits  From Juha Niskanen.

    * STMicro STM32 Boards:

      - STM32F103-Minimum:  USB reset was not working appropriately since
        the pin connected to D+ was incorrectly defined and the pullup/down
        logic was reversed.  From Matias N.
      - Nucleo-l476RG:  Fix some errors in GPIO logic when debug assertions
        are enabled.  From Matous Pokorny.
      - Nucleo-L476RG:  Add missing files of BMP180 example for Nucleo-L476RG.
        From Fabian Justi.
      - STM32F103-Minimum GPIO:  Fix some errors when debug assertions are
        enabled.  From Matous Pokorny.
      - STM32L4 PWM:  Fix register addr, en_bit and resetbit for pwm timers.
        From Fabian Justi.
      - STM32F746G-DISCO: I2C1 config on stm32f746g-disco. Typo in
        stm32f7/stm32_i2c.c  From Matthew Koch.

    * C Library/Header Files:

      - include/limits.h:  Remove the duplicate TMP_MAX definitions.  The
        standard requires that TMP_MAX defines be in stdio.h.  From
        Xiang Xiao.
      - include/sys/select.h:  Fix compiler error when
        CONFIG_NSOCKET_DESCRIPTORS is undefined.  From Xiang Xiao.
      - include/signal.h:  Add commented out definition of the si_addr
        field.  From Joao Matos.
      - include/unistd.h:  Fixed R_OK/X_OK definitions to match POSIX.
        From Joao Matos.

      - libs/libc/locale: Improved error handling in setlocale().  From Joao
        Matos.
      - libs/libc: Fixed return code in uname().  From Joao Matos.
      - libs/libc/stdio:  Restore support for printing NULL string as
        "(null)".  Legacy printf supported printing "(null)" in place for
        NULL string:  printf("null: %s\n", NULL); => null: (null).  This
        commit restores this functionality for new printf library.  From
        Jussi Kivilinna.

    * Examples: apps/examples:

      - apps/examples/pca9635/pca9635_main.c: fix compilation error. From
        Mateusz Szafoni.

    * Graphics Utilities: apps/graphics:

      - Various graphics apps (and apps/examples):  If CONFIG_VNCSERVER=y,
        don't call vnc_default_fbinitialize() directly.  That is a violation
        of the portable POSIX interface.  Instead, call
        boardctl(BOARDIOC_VNC_START);.  From Gregory Nutt.
      - apps/graphics/nxwidgets:  CWidgetControl::handleLeftClick now
        returns a value to indicate if the click was actually processed or
        not. CWidgetControl::pollMouseEvents:  Correct return value.  From
        Gregory Nutt.
      - apps/graphics/nxwidgets/:  NXWidgets::CNxWidgets:  Fix some issues
        with returned values.  On setting the widget size or position, it was
        returning false if there was no change in size or position.  Many
        places in the code were treating the false return value as an error.
        From Gregory Nutt.

    * System Utilities: apps/system:

      - apps/system/nxplayer:  Fix some logical errors from recent commits.
        They broke the build of the nxplayer as a library vs. a task.

NuttX-7.31 Release Notes
------------------------

The 131st release of NuttX, Version 7.31, was made on July 21, 2019,
and is available for download from the Bitbucket.org website.  Note
that release consists of two tarballs:  nuttx-7.31.tar.gz and
apps-7.31.tar.gz.  These are available from:

    https://bitbucket.org/nuttx/nuttx/downloads
    https://bitbucket.org/nuttx/apps/downloads

Both may be needed (see the top-level nuttx/README.txt file for build
information).

Additional new features and extended functionality:

    * Core OS:

      - poll():  Removed all references to CONFIG_DISABLE_POLL.  The
        standard POSIX poll() can no longer be disabled.  From Gregory Nutt.
      - LWL console:  Add support for OpenOCD 'Lightweight Link' protocol
        between a target and debugger for use when you need a console but
        the target doesn't have a spare serial port or other available
        resource.  From Dave Marples.

    * Network/Network Drivers:

      - Socket Options:  Previous change removed some incorrect SO_LINGER
        socket option functionality.  SO_LINGER was always enabled if
        CONFIG_NET_SOLINGER was selected.  This change implements a proper
        version of SO_LINGER.  It is based on new logic to drain the
        buffered TX data, integrated with network event notification system.
        Supports notification when UDP or TCP write buffer becomes empty.
        From Gregory Nutt.
      - Telnet Driver:  Handle ctrl events (SIGINT, SIGSTP).  From
        Valmantas Paliksa.
      - Telnet Driver:  I/O thread now offloads reading from socket
        from client thread to the I/O thread.  From Valmantas Palikša.

    * Wireless/Wireless Drivers:

      - GS2200M:  Add support for Telit GS2200M Wi-Fi module  From Masayuki
        Ishikawa.
      - GS2200M:  Introduce CONFIG_WL_GS2200M_SPI_FREQUENCY.  Also, changed
        usleep(100) to up_udelay(100) to avoid invalid response.  From
        Masayuki Ishikawa.
      - GS2200M: Add channel parameter for AP mode in gs2200m.c  From
        Masayuki Ishikawa.

    * Graphics/Video/Display Drivers:

      - Video Streaming:  Add basic Video Stream and Capture implementation
        based on the SPresence SDK code release  From Alin Jerpelea.
      - video/:  Create video/ directory to hold non-driver video-related
        logic.  From Gregory Nutt.
      - EDID:  Add some initial EDID logic ported from FreeBSD.  From
        Gregory Nutt.
      - EDID:  Add logic to sort video modes by how close they are to the
        preferred mode.  This is part of the logic to pick the best possible
        video mode.  From Gregory Nutt.
      - EDID/Video Modes:  Separate EDID and from videomode management.
        They really are separate things.  From Gregory Nutt.
      - EDID/Video Modes:  Add debug functions to dump the EDID and
        videomode content.  From Gregory Nutt.
      - VESA GTF:  Bring VESA Generalized Timing Formula (GTF) from FreeBSD.
        From Gregory Nutt.
      - Video Modes:  At some additional lookups from FreeBSD.  Not
        currently used in NuttX so ifdef'ed out for now.  From Gregory Nutt.
      - tda19988:  Now uses the new common videomode structure of
        include/nuttx/video/videomode.h as do other video components.  From
        Gregory Nutt.
      - ILI9340:  Add ILI9340 LCD Single Chip Driver.  Required LCD driver
        settings:  LCD_MAXCONTRAST should be 255, but any value >0 and <=255
        will be accepted.  LCD_MAXPOWER should be 1:  0=off, 1=on.  From
        Alin Jerpelea.
      - LPM013M091A:  Add JDI LPM013M091A LCD Driver.  From Alin Jerpelea.
      - ISX012:  Add support for ISX012 Image sensor.  From Alin Jerpelea.

    * Other Common Device Drivers:

      - SPI Interface:  Added standard definitions for ADC SPI device ID.
        From Daniel P. Carvalho.
      - AK09911/AK09912:  Add Asahi AK09911/AK09912 compass sensor over I2C
        bus From Alin Jerpelea.
      - AS726X:  Add support for AS726X spectral sensor  From Fabian Justi.
      - BMI160:  Add driver support for the Bosch BMI160 Inertial Measurement
        sensor.  This driver can be used with the BMI160 sensor connected
        over SPI or I2C bus.  From Alin Jerpelea.
      - BMP280:  Add Bosch BMP280 Barometic pressure sensor connected over
        I2C bus.  From Alin Jerpelea.
      - INA3221:  Adds INA3221_I2C_ADDRx macro helpers.  From Anthony
        Merlino.
      - VL53L1x:  Added support for VL53L1x TOF sensor.  From Juan Flores.

    * Microchip PIC32MZ Drivers:

      - PIC32MZ DMA: Add DMA support.  From Abdelatif Guettouche.

    * NXP i.MXRT Drivers:

      - i.MXRT EHCI:  Add i.MXRT EHCI driver.  From Dave Marples.
      - i.MXRT USDHC:  Implements SDIO and Multi-card support for i.MXRT.
        From Dave Marples.
      - i.MXRT USDHC:  Implements USDHC1 & 2 selection on the imxrt. If
        only one port is active (either 1 or 2) it will always be numbered
        as 0, if both are active then USDHC1 will be number 0, USDHC2 will
        be 1.  From Dave Marples.
      - i.MXRT Serial:  Add TIOCSINVERT ioctls.  From Beat Küng.
      - i.MXRT Serial:  Implemented RS485 RX/TX switching and RTS/CTS flow
        control for the IMXRT family.  It has been tested on 1020 but I
        don't see any reason for issues on any other family member.  From
        Dave Marples.

    * NXP/Freescale Kinetis Drivers:

      - Kinetis Serial:  Add UART signal inversion support  From Beat Küng.

    * NXP LPC11xx:

      - LPC11xx:  Support for the LPCXpresso-LPC1115 and for the LPC1115
        architecture in general was removed after NuttX-7.30.  The LPC11
        port was never really used (to my knowledge) and was no longer
        supported. A snapshot of the port is still available in the
        Obsoleted repository.  It can be brought back into the main
        repository at any time if anyone is willing to provide support
        for the architecture.  From Gregory Nutt.

    * NXP LPC17xx Boards:

      - PNEV5180B:  Add support for NXP Semiconductors' PN5180 NFC Frontend
        Development Kit.  This board is based on the NXP LPC1769 MCU.  At
        the moment there is just support for a minimal nsh configuration via
        UART0.  From Michael Jung.
      - PNEV5180B:  Add usbnsh configuration.  This is basically the same as
        the 'nsh' defconfig, but uses CDC/ACM as the NuttShell console
        device.  From Michael Jung.
      - PNEV5180B:  Adds NSH configuration with UART0 and eth0 via CDC/ECM
        on USB device.  From Michael Jung.
      - PNEV5180B:  Add new configuration includes a USB Composite Device
        with both CDC/ACM and CDC/ECM.  NuttShell provides a terminal via
        CDC/ACM.  A network interface (eth0) is provided via CDC/ECM.  From
        Michael Jung.
      - PNEV5180B ROMFS: Auto-mount baked-in ROMFS image.  Includes support
        for linking a binary ROMFS image into the nuttx executable and for
        mounting it during board bring-up.  From Michael Jung.
      - PNEV5180B PROTECTED:  Add PROTECTED mode configuration with
        NuttShell.  From Michael Jung.

    * NXP LPC40xx:

      - LPC40xx:  Add support for LPC40xx family chips.  Renamed LPC17XX to
        LPC17XX_40XX in directory, configuration, file names, etc., as
        appropriate.  Corrected a few peripheral definitions and pin
        functions for the LPC17xx family.  Added configuration options, chip
        definitions, and additional pin functions for the LPC40xx family.
        From jjlange.

    * NXP LPC40xx Boards:

      - LPC4088-Devkit:  Added board configuration for Embedded Artists
        LPC4088 Developer's kit.  From jjlange.
      - LPC4088-Quickstart:  Added board configurations for Embedded Artists
        LPC4088 Quickstart board.  From jjlange.

    * NXP LPC54xx Boards

      - LPCXpresso-LPC54628:  Enable DATE command in twm4nx1 and twm4nx2
        configurations.  From Gregory Nutt.

    * Sony CXD56xx

      - CXD56xx:  Adds (1) the HW pin configuration, (2) GPIO support for
        CXD56xx, (3) GPIO interrupts, (4) clock support, (5) PMIC (Power
        management integrated circuit) support (6) add a simple FIFO
        scheduler that minimizes overhead, (6) Inter Core Communication.
        From Alin Jerpelea.
      - CXD56xx:  Add Package Configuration. The CXD56xx can come in FCBGA
        185 pin or WLCSP 100 pin package.  For each package we have to pick
        the right pin setup.  The default configuration is set to FCBGA 185
        pin package  From Alin Jerpelea.
      - CXD56xx:  Add Power Management support  From Alin Jerpelea.
      - CXD56xx: (1) Add syscontrol, (2) Add the function to change the
        clock speed, (3) Add pinctrl and clock ctrl functionality.  From
        Alin Jerpelea.

    * Sony CXD56xx Drivers:

      - CXD56xx USB: Add basic support for USB connectivity.  From Alin
        Jerpelea.
      - CXD56xx SDHC:  Add SDHCI driver for the CXD56xx.  From Alin
        Jerpelea.
      - CXD56xx SPI:  Add SPI support.  From Alin Jerpelea.
      - CXD56xx DMA:  Add DMA support.  From Alin Jerpelea.
      - CXD56xx RTC:  Add RTC support.  From Alin Jerpelea.
      - CXD56xx PWM:  Add support for PWM.  From Alin Jerpelea.
      - CXD56xx Power Management:  Add Power Management PROCFS support. From
        Alin Jerpelea.
      - CXD56xx Timer:  Add Timer driver.  From Alin Jerpelea.
      - CXD56xx Watchdog Timer:  Add watchdog timer support.  From Alin
        Jerpelea.
      - CXD56xx UID:  Add support to be able to read the HW UID.  From Alin
        Jerpelea.
      - CXD56xx I2C:  Add I2C support.  From Alin Jerpelea.
      - CXD56xx I2C:  Add I2C character driver support.  For testing
        purposes, we use the CXD56_I2C_DRIVER to register the /dev/i2c[]
        character devices.  Add battery gauge and battery charger drivers.
        Add SPI-based SP card support.  From Alin Jerpelea.
      - CXD56xx SCU:  Add Sensor Control Unit (SCU); Use DMAC for reading
        sensing data from SCU on CXD56xx chip.  From Alin Jerpelea.
      - CXD56xx ADC:  Add ADC interface support.  From Alin Jerpelea.
      - CXD56xx eMMC:  Add eMMC support for CXD56xx chip  From Alin Jerpelea.
      - CXD56xx Camera:  Add driver for hardware image processor device to
        enable the hardware image processor set CXD56_GE2D=true.  From Alin
        Jerpelea.
      - CXD56xx CISIF:  Add CISIF support to be able to use cameras.  From
        Alin Jerpelea.
      - CXD56xx GNSS:  Add GNSS device, add Geofence Support, add UART0
        interface. UART0 is an interface with hardware flow control in the
        application subsystem.  From Alin Jerpelea.

    * Sony CXD56xx Spresense Board:

      - Default Configurations:  (1) We are using the framework to
        initialize the CPU, (2) Enable PowerManager on SPresence board, (3)
        Initialize the UART interfaces, (4) Enable clock management using
        the CXD56 framework, (5) Use timerisr on the SPresence board, (6)
        Enable USBDEV on Spresense board, (7) Enable SD Card support on
        SPresence board, (8) Enable Mass Storage on Spresense board  From
        Alin Jerpelea.
      - Default Configurations: Add support for RNDIS configuration.  From
        Masayuki Ishikawa.
      - RTC:  Enable RTC functionality on SPresence board  From Alin
        Jerpelea.
      - SPI FLASH:  Enable SPI Flash arch/arm/src/cdx56xx:  (1) Group all
        CXD56xx Options in one menu, (2) Add Storage Options menu and
        Peripheral Support comment, (3) Add SPI Flash support  From Alin
        Jerpelea.
      - Add SPI configuration for SPresence board. Enable PWM support on
        SPresence board;  The powermanager procfs is disabled by default and
        need to be enabled by the CONFIG_CXD56_PM_PROCFS option.  Timers can
        be used on the SPresence board.  Watchdog timer support also added.
        From Alin Jerpelea.
      - Add USERLED for SPresence board.  From Alin Jerpelea.
      - Enable I2CDEV for SPresence board.  Add useful diagnostic LEDs on
        the SPresence board.  From Alin Jerpelea.
      - Add support for Tilt GS2200M Wi-Fi module.  From Masayuki Ishikawa.
      - Remove SPI MMC/SD support and enable ADC support for SPresence
        board.  From Alin Jerpelea.
      - Enable BMI160_I2C sensor over I2C on SPresence board.  From Alin
        Jerpelea.
      - Add I2CTOOL support and extend GPIO for future use. Add delay
        support for CXD56xx chip.  For development is useful to register
        I2C buses when the I2CTOOL is built.  Enable GPIO interface on
        the Spresense board.  From Alin Jerpelea.
      - Add use o the CXD56_I2C_DRIVER to register the /dev/i2c character
        devices.  Enable battery gauge and battery charger support.  From
        Alin Jerpelea.
      - Enable UID functionality.  To enable the UID functionality for
        SPresence board  set BOARDCTL_UNIQUEID in menuconfig.  From Alin
        Jerpelea.
      - Add USBDEV_SETNOTIFYSIG signal ID.  Set signal ID for notify USB
        device connection status and supply current value.  From Alin
        Jerpelea.
      - Register the procfs in the NSH configuration.  This is a
        configuration change in sync with the other ones.  Enable
        READLINE_CMD_HISTORY, enable by default SPI 4 and 5, and enable
        SPI to keep all configurations in sync.  From Alin Jerpelea.
      - Add support for MSC and USB Composite device.  Adds usbmsc
        configuration.  Spresense board does not have buttons and but a
        template for gpio buttons that can be connected on the external
        header From Alin Jerpelea.
      - LCD:  Add support for LPM013M091A LCD, add support for ILI9340
        LCD, add a new configuration to support an LCD.  From Alin
        Jerpelea.
      - WiFi:  Improve performance for webserver:  (1) Enable SPI DMA for
        both TX and RX, (2) Increase SPI clock speed from 4MHz to 10MHz,
        (3) Increase buffer size for sendfile() from 512B to 1KBm abd (4)
        Enable sendfile() for webserver.  From Masayuki Ishikawa.
      - MPY:  Add MPY defconfig.  From Alin Jerpelea.
      - Update defconfigs rndis and wifi:  Enable RTC and webserver with
        directory listing support.  Also, changed start year/month/day for
        NuttX 2019.  From Masayuki Ishikawa.
      - Build nuttx.spk images.  Enable nuttx.spk binary image that can be
        flashed on SPresence board.  From Alin Jerpelea.
      - configs/SPresence:  Add entry point for MPY.  The entry point is
        needed for the downstream projects based on SPresence.  From Alin
        Jerpelea.
      - Enable internal flash storage for SPresence boards. The SmartFS
        flash is mounted under /mnt/spif folder.  From Alin Jerpelea.
      - For compatibility with SDK we need to change the USER_ENTRYPOINT
        in all configurations to spresense_main().  From Alin Jerpelea.

    * STMicro STM32:

      - STM32 Kconfig:  Add MEDIUM_DENSITY selection.  From Dave Marples.
      - STM32 Kconfig:  Add the missing STM32 LCD Clock Source Selections.
        From Alan Carvalho de Assis.
      - STM32G0:  Initial support for STM32G0 family.  From Mateusz Szafoni.
      - STM32F0L0G0:  Renamed directories STM32F0L0 to STM32F0L0G0 since
        they now also supports the STM32G0 thanks to Mateusz Szafoni's
        contribution  From Gregory Nutt.
      - STM32H7x3:  Added ADC pins to pin map.  From David Sidrane.

    * STMicro STM32 Drivers:

      - STM32 PWM:  Add support for all PWM modes.  Add an interface to
        change PWM mode.  Refactor pwm_mode_configure(). STM32_PWM_CHANx
        corresponds to the timer channel and STM32_PWM_OUTx corresponds to
        the timer channel output.  Add CHAN5 and CHAN6 to
        PWM_TIMx_NCHANNELS.  Calculate thePWM_TIMx_NCHANNELS if
        CONFIG_STM32_PWM_MULTICHAN is selected.  From Mateusz Szafoni.
      - STM32 FSM/FSCM:  Split the STM32 FMC/FSMC functionality.  Makes FMC
        it's own thing rather than piggy backing on the FSMC code.  The
        peripherals have a few utility functions and this commits lets you
        have a common architectural functions rather than having duplicate
        functions in each board implementation.  From Jason Harris.
      - STM32F7 DTCM:  Add procfs register  From Daniel Agar.
      - STM32F7 GPIO:  Add GPIO driver.  Code is inspired from STM32F3-
        Discovery and Nucleo-L476RG platforms.  Tested on Nucleo-F767ZI.
        From Phil Coval.
      - STM32F7 Serial:  This adds the ability to invert and swap RX/TX on
        STM32F7 UARTs.  I added the TIOCGINVERT as well to reserve the IOCTL
        number, but did not implement it. This is the same as for
        TIOCGSINGLEWIRE.  From Beat Küng.
      - STM32L4 CRS:  Make STM32L4 CRS synchronization source board
        configurable.  From Juha Niskanen.
      - STM32L4 HSI48:  Enable CRS_CR_CEN with CRS_CR_AUTOTRIMEN.  From
        Jussi Kivilinna.
      - STM32L4 I2C:  Add support for 16 and 120 MHz timings.  Board can use
        HSI16 clock for I2C  From Juha Niskanen.
      - STM32L4 PWR:  Enable PWR peripheral for setting USV.  From Jussi
        Kivilinna.
      - STM32L4 RCC:  Use Range 1 Boost mode if SYSCLK is higher than 80
        MHz.  From Juha Niskanen.
      - STM32L4 Serial:  Add TIOCSINVERT and TIOCSSWAP ioctls.  From Beat
        Küng.
      - STM32H7 ADC:  Added ADC Driver, ADC clocking.  From David Sidrane.
      - STM32H7 Ethernet: Fix typo in define.  From Pierre-Olivier Vauboin.
      - STM32H7 PWM:  Port PWM from STM32  From Mateusz Szafoni.
      - STM32H7 QEncoder:  Ported the QEncoder from F7 to H7.  From Eduard
        Niesner.
      - STM32H7 Serial:  Add TIOCSINVERT and TIOCSSWAP ioctls.  Ensure
        TIOCSSINGLEWIRE is atomic and UE disabled.  From Beat Küng.

    * STMicro STM32 Boards:

      - Olimex-STM32-E407:  Added BMP180 initialization and a configuration
        to test the BMP180.  From Juan Flores.
      - Olimex-STM32-E407:  Add DAC support, add IN219 support, add timer
        driver support.  From Juan Flores.
      - Olimex-STM32-E407:  Add support for MRF24J40 radio.  From Gregory
        Nutt.
      - Axoloti:  Adds initial support for the Axoloti sound/music
        synthesizer board.  Board is based on STM32F427 SoC.  See
        http://www.axoloti.com/.  From Jason Harris.
      - Nucleo-G071RB:  Initial support for nucleo-g071rb.  From Mateusz
        Szafoni.
      - Nucleo-L432KC:  Add new configuration settings for CRS
        synchronization to board.h.  From Juha Niskanen.
      - Nucleo-L432KC:  Add support for testing the ina219 current sensor.
        From Sebastien Lorquet.
      - Nucleo-L452RE: Add new configuration settings for CRS
        synchronization to board.h.  From Juha Niskanen.
      - Nucleo-144: Add ROMFS support.  Image was generated using genromfs
        tool.  Tested on Nucleo-F767ZI.  From Phil Coval.
      - Nucleo-144:  Add reset feature.  Code is derives from STM32F4-
        Discovery.  It can be enabled using CONFIG_BOARDCTL_RESET  From Phil
        Coval.
      - Nucleo-L476RG:  (1) Add I2C tool to board init, (2) Add support for
        AS726X spectral sensor  From Fabian Justi.
      - Nucleo-L496ZG: Add new configuration settings for CRS
        synchronization to board.h.  From Juha Niskanen.
      - STM32L476VG-Disco: Add new configuration settings for CRS
        synchronization to board.h.  From Juha Niskanen.
      - STM32L4R9AI-Disco:  Add ksh config, some updates for I2C, SPI and
        DFSDM support.  From Juha Niskanen.
      - Nucleo-H743ZI: Add ADC support.  From David Sidrane.
      - STM32F769I-Disco PWM:  Enable PWM support for stm32f769i-disco
        board.
      - STM32L-Discovery:  Add button support for stm32Ldiscovery.  Add
        chronometer board config.  From Alan Carvalho de Assis.

    *  TI AM335x:

      - AM335x Clock Module:  Add clock module registers definition.  Switch
        to DMTIMER1 for systick.  From Petro Karashchenko.

    *  TI AM335x Drivers:

      - AM335x CAN, LCD:  Add register description files for DCAN and LCD.
        From Petro Karashchenko.
      - AM355x I2C:  Add register description files for I2C (plus various
        improvements to the WDOG register definitions)  From Petro Karashchenko.
      - AM355x MCSPI:  Add register description files for MCSPI.  From Petro
        Karashchenko.
      - AM355x LCDC:  This change brings in an initial LCD driver into the
        AM335x architecture.  Ported from FreeBSD.  From Gregory Nutt.
      - AM335x Framebuffers:  Add logic to map the framebuffer to a non-cached,
        non-buffered memory region.  From Gregory Nutt.
      - AM335x LCDC:  Add logic to get/set the module reference clock.  From
        Gregory Nutt.

    *  TI AM335x Boards:

      - Beaglebone-Black LCD:  Add a configuration for bringing up the LCDC
        driver.  From Gregory Nutt.
      - Beaglebone-Black LCD:  Framework (only) for TDA19988 and LCD support
        for Beaglebone Black.  Can't use TDA19988 yet because there is no I2C
        driver.  In the mean time, support LCD initialization using a fixed,
        configurable video mode.  From Gregory Nutt.

    * ZiLOG z16f ZNeo:

      - z16f ZNeo:  Add support for the latest 5.2.1 version of the ZDS-II
        toolchain.  From Gregory Nutt.

    * ZiLOG eZ80Acclaim!:

      - Integrate support for the newest eZ80 ZDSII 5.3.0 toolchain.  From
        Gregory Nutt.

    * ZiLOG eZ80Acclaim! Drivers:

      - eZ80 RTC:  Integrate and verify the RTC driver  From Gregory Nutt.
      - eZ80 RTC:  Add an RTC lower half driver.  From Gregory Nutt.

    * ZiLOG eZ80Acclaim! Boards:

      - MakerLisp:  Add initial support for the MakerLisp eZ80 board.  Ref:
        https://makerlisp.com/  From Gregory Nutt.
      - MakerLisp:  Add hooks needed by SPI driver.  Move SPI MMC/SD chip
        selected configuration from ez80_lowinit.c to here as is done in
        other NuttX architectures.  This enables support for multiple
        devices on the SPI bus.  From Gregory Nutt.
      - MakerLisp:  Add Smart Flash Programmer project.  From Gregory Nutt.
      - MakerLisp:  Enable Procfs, RTC, SPI-based SD support, task name, NSH
        data command in NSH configuration..  From Gregory Nutt.
      - MakerLisp:  Use .ztgt files from MakerLisp SDK.  From Gregory Nutt.
      - MakerLisp:  Add a tiny FLASH-resident loader that will load and
        start applications in Intel HEX format from an SD card.  From
        Gregory Nutt.
      - MakerLisp:  Bring in a new configuration to support execution
        entirely out of external SRAM.  From Gregory Nutt.
      - MakerLisp:  Add an sdboot configuration that will load .hex files
        from the SD card.  From Gregory Nutt.
      - MakerLisp:  Add a linker script to support copying the NuttX image
        from FLASH into external SRAM.  From Gregory Nutt.
      - MakerLisp:  The VGA display controller and keyboard controller come
        up by default emulating a terminal with 'newline mode' on.  That is
        newlines expance to carriage-return, newline.  This change turns that
        mode off.  From Gregory Nutt.

    * Libraries/Header Files:

      - include/cxx/cstddef:  Add C11++ std::nullptr_t  From junmin-kim.
      - libc netdb: Implemented the netdb functions getnameinfo(),
        getservbyport(), and getservbyport_r().  From Michael Jung.

    * Documentation

      - Applied a style sheet to static HTML files. Put the TOC of each
        document to the side, where it made sense (in some documents the
        TOC was actually inside a section so it wasn't possible). In some
        cases the TOC is built with a table, in others with a <ul> element,
        so I had to accommodate for this. I also didn't go into collapsing,
        although this could really help for some long TOCs.  From Matias N.
      - Coding Standard:  Add a brief section summarizing the major
        differences between the NuttX C and C++ coding standards.  This is a
        stop-gap measure in lieu of having a real C++ coding standard.  From
        Gregory Nutt.
      - Coding Standard:  Update requirements for indenting C pre-processor
        statements.  From Gregory Nutt.
      - Coding Standard:  Small change discouraging the practice of
        enclosing the value argument of 'return' statements in parentheses.
        From Gregory Nutt.
      - COPYING.  Tools in the tools/ directory are not intended for binary
        redistribution and may not all conform to BSD licensing.  From
        Gregory Nutt.

    * Tools:

      - tools/ocdconsole.py:  OCD TCL interface changed after version 0.10
        of OpenOCD.  This change allows the script to work with both the
        older and newer TCL interface.  From Dave Marples.
      - tools/nxstyle.c:  Tool depends on the file under test containing
        "Private Functions" or "Public Functions" block comments.  Emit an
        error if neither are present in a C source.  From Gregory Nutt.
      - tools/nxstyle.c:  Bandaid-up logic that detects left brackets on the
        same line in global structure/enumeration types and initializers.
        From Gregory Nutt.
      - tools/nxstyle.c:  No warning for declarations that begin in column 1
        within 'extern "C"'.  This is because the 'extern "C"' is conditioned
        on __cplusplus so the declarations are not normally indented.  From
        Gregory Nutt.
      - tools/:  Add spk binary format.  The .spk binary format is used on
        SPresence and other boards based on the CXD56 arch.  To enable this
        binary format set in your config CONFIG_CXD56_BINARY=y.  From Alin
        Jerpelea.
      - tools/:  Add flash_writer for CXD56 boards.  This flash writter is
        using the xmodem for firmware transfer for flashing please use:
        'tools/flash_writer.py -s -c /dev/ttyUSB0 -d -b 115200 -n nuttx.spk'.
        From Alin Jerpelea.

    * apps/ General:

      - Removed all references to CONFIG_DISABLE_POLL.  The standard POSIX
        poll() can no longer be disabled.  From Gregory Nutt.

    * Examples/Tests: apps/examples:

      - apps/examples/abntcodi:  Adds test/demo program for ABNT CODI
        library.  From Alan Carvalho de Assis.
      - apps/examples/webserver:  Update to compile with
        CONFIG_NETUTILS_HTTPD_SENDFILE=y.  Also some configs such as
        CONFIG_NETUTILS_HTTPDFILESTATS can be selected by menuconfig.
        From Masayuki Ishikawa.
      - apps/examples/chrono:  Add chronometer apps example.  From Alan
        Carvalho de Assis.

    * Network Utilities: apps/netutils:

      - apps/netutils/webserver:  Add mp3 mime type to httpd.c.  From
        Masayuki Ishikawa.
      - apps/netutils/webserver:  Add directory listing to httpd.  From
        Masayuki Ishikawa.
      - apps/netutils/webserver:  Add web server info based on uname().
        From Masayuki Ishikawa.

    * Network Utilities: apps/wireless

      - apps/wireless/gs2200m:  Add usrsock daemon for Tilt GS2200M Wi-Fi
        module.  From Masayuki Ishikawa.
      - apps/wireless/gs2200m:  Add channel parameter for AP mode.  From
        Masayuki Ishikawa.

    * Graphics:  apps/graphics:

      - apps/graphics/nxglyphs:  Add more modern looking button images for
        the Twm4Nx CONTEMPORARY theme.  From Gregory Nutt.
      - apps/graphics/slcd:  Adds a CSLcd class that will generate graphic
        simulated segments of an SLCD display.  From Gregory Nutt.
      - apps/graphics/twm4nx:  This change adds a calibration screen to
        Twm4Nx.  In addition to the Calibration screen port from NxWM, this
        required extensions to the event handling logic to support (1)
        receiving raw, uncalibrated touchscreen inputs, (2) shutting down
        of externally controlled windows.  From Gregory Nutt.
      - apps/graphics/twm4nx:  Move application-related files into different
        directories to separate them from the core Twm4Nx files.  From
        Gregory Nutt.
      - apps/graphics/twm4ndx:  Compile out cursor support if we are using a
        mouse.  From Gregory Nutt.
      - apps/graphics/twm4nx:  Add an alternative COMPONTEMPORARY theme.
        Still has some artifacts on the display.  From Gregory Nutt.
      - apps/graphics/twm4nx:  Use custom CWidgetStyle to force Icon
        background to match selected desktop background.  From Gregory Nutt.
      - apps/graphics/twm4nx:  Add some definitions to support Themes.
        Background image is now optional.  From Gregory Nutt.
      - apps/graphics/twm4nx:  Add a configuration option to control the
        number of buttons in one column of the Icon Manager.  The Icon
        anager no longer relies the default window width; now it
        determines a preferred window width based primarily on the font
        size.  From Gregory Nutt.
      - apps/graphics/tmw4nx:  Add a CClock class that implements the
        Twm4Nx digital clock based on the CSLcd simulated SLCD segments.
        From Gregory Nutt.
      - apps/graphics/twm4nx/README.txt:  Add an overview of how to create
        Twm4Nx applications.  From Gregory Nutt.

    * Industry:  apps/industry:

      - apps/industry/abnt_codi:  Adds support for ABNT CODI library.  This
        is an energy meter protocol used in Brazil.  From Alan Carvalho de
        Assis.

Bugfixes.  Only the most critical bugfixes are listed here (see the
ChangeLog for the complete list of bugfixes and for additional, more
detailed bugfix information):

    * Core OS:

      - Semaphores:  Fix a bad assertion in priority inheritance logic.
        The comments state correctly that we cannot make any assumptions
        about the number of holders of the semaphore, yet the code
        asserts if there are any holders.  This makes the code behave
        closer to what the comments say.  From Gregory Nutt.
      - Memory Manager:  Fix error that occurs when CONFIG_CPP_HAVE_VARARGS
        is not defined.  In that case, the arguments to the debug macro will
        all be evaluated even though they are not used any variables that
        are references must at least be defined.  From Gregory Nutt.
      - System Calls:  Adapt the conditional compile logic on when to
        include the vfork() syscall proxy and stub to the logic used for
        vfork() itself.  From Michael Jung.
      - System Calls:  Fixed SYS_mount syscall define when CONFIG_FS_READABLE
        is undefined.  From Joao Matos.
      - waitpid():  In waitpid, remember to grab the exited child ptr.  After
        being unblocked in waitpid, the child pointer might be NULL.  Modify
        to use group_exitchild to get the pointer of recent exited child.
        From Yang ChungFan.

    * File System/Block and MTD Drivers:

      - MMC/SD: Fixes bug where thread gets deadlocked due to recursive call
        and addresses comment regarding events.  When initializing the
        MMCSD, if we are being told there is a card, but we fail to
        initialize it, we should not re-register for an insertion event as
        this will immediately cause us to call in again. Instead, we should
        register for a removal event and wait for the card to be removed and
        re-inserted.  From Anthony Merlino.

    * Networking/Network Drivers:

      - UsrSock:  Fix debug logs and remove DEBUGASSERT from
        usrsockdev_do_request().  In a client mode, socket() will be the
        first request for usrsockdev_do_request().  However, in a server
        mode, the first request to accepted sockets will be recv() or other
        which depend on applications. So I think we should remove thi
        DEBUGASSERT from usrsockdev_do_request().  From Masayuki Ishikawa.
      - ICMPV6 Autoconfig:  Use ntohs() to convert IPv6 address from
        network to host order int network debug output.  From Bernd Walter.
      - TCP Buffering:  Fix TCP buffer send deadlock in iob_copyin() when
        IOB buffers are exhausted and network lock is taken.  From
        Valmantas Paliksa.
      - TCP Close:  Fix TCP active close in inet_close.c.  In previous
        implementation, FIN packet was not sent when a socket is actively
        closed (e.g. telnetd or webserver) without SO_LINGER.  This issue
        happens because the socket closing sequence waits for the
        status.cl_sem only if lingering timeout is set. However, in many
        server use-cases, SO_LINGER is not usually set and even in these
        cases, FIN packet must be sent correctly.  This changes the logic
        in inet_close.c so that it can wait for status.cl_sem regardless
        of SO_LINGER. Instead, if SO_LINGERis set, it waits for the
        semaphore with timeout option.  From Masayuki Ishikawa.
      - UDP:  Fix C89 compatibility problem.  Empty initializers are not
        permitted.  Caused eZ80 build failure.  From Gregory Nutt.
      - Telnet:  Fix a C89 non-compliance that was breaking the eZ80 build.
        From Gregory Nutt.

    * Wireless/Wireless Drivers:

      - NRF24L01: Fix NRF24L01_NCMDS in ioctl.h.  The last one in
        nrf24l01.h is _WLCIOC(NRF24L01_FIRST + 15)  From Masayuki Ishikawa.
      - NRF24L01:  Fix PIPENO/PKTLEN bitmask in RX FIFO header.  In RX FIFO
        header, the first byte should use 5 lsb to store PKTLEN and 3 msb
        to store PIPENO. However, FIFO_PIPENO_SHIFT was set to 4 which
        causes the lsb of pipe number to interfere with the received packet
        size stored in the FIFO.  This fix RX corruption when using pipe
        number > 0.  From Federico Braghiroli.

    * Graphics/Display Drivers:

      - Raising Windows:  Fix a critical list handling bug in the graphics
        system.  When a lower-level window was raised while a model window
        was in place, then list corruption could occur.  From Gregory Nutt.

    * Common Drivers:

      - Serial:  Limit the number of times that the poll semaphore is
        incremented.  From Dave Marples.
      - USB Host:  Remove duplicate const in USB Host files.  From Adam
        Porter.
      - USB Host Composite:  Class-specific descriptors were not available
        if the interface is part of a composite device, since only interface
        and endpoint descriptors are copied by usbhost_copyinterface().
        This change will  copy any class-specific interface descriptors for
        use in downstream class drivers.  The loop was aborting due to
        finding two interface descriptors back-to-back.  From Adam Porter.
      - USB Host Composite:  The cfgdesc pointer was initialized after the
        buffer had been advanced, so it was not pointing where it should.
        The totallen operations at the end of the function ended up
        overwriting memory belonging to the first copied interface
        descriptor.  From Adam Porter.
      - USB MSC:  Fix usbmsc_exportluns declaration.  Fixes the following
        error "...undefined reference to `usbmsc_exportluns'".  From Alin
        Jerpelea.

    * Architecture Common:

      - Rename all arch/<family>/src/<chip>/chip directories to
        arch/<family>/src/<chip>/hardware.  This eliminates a name collision
        that is usually harmless but does cause problems at the time.  The
        problem is because the include path includes '.' and 'chip/.',
        therefore an inclusion like '#include <chip/mcu_header.h' can be
        ambiguous if a file named mcu_header.h exists in both at both
        arch/<family>/src/<chip>/chip and at arch/<family>/src/chip/chip.
        From Gregory Nutt.

    * Board Common:

      - Default Configurations:  Update configurations for changes to
        apps/netutils/netinit configuration.  MAC address configuration
        was represented by type long long.  That is a problem for
        architectures that do not support type long long.  Replaces by
        two long configuration items.  From
        Gregory Nutt.
      - Default Configurations:  Change CONFIG_NSH_MACADDR to
        CONFIG_NETINIT_MACADDR  From Masayuki Ishikawa.
      - Default Configurations:  Fix mac address settings for RNDIS.
        Recently CONFIG_NETINIT_MACADDR_2 and CONFIG_NETINIT_MACADDR_1 were
        newly introduced instead of CONFIG_NETINIT_MACADDR.  This change
        conforms to this change.  From Masayuki Ishikawa.
      - Default Configurations:  Kconfig files should not select
        SCHED_WORKQUEUE since that is really only is only the logical OR if
        SCHED_LPWORK and SCHED_HPWORK.  Selecting it has no effect other
        than to produce an erroneous configuration.  From Gregory Nutt.
      - Linker Scripts:  Make sure sections are aligned to 32-bits in all LD
        linker scripts.  This fixes and issues noted specifically for the
        SAMD21 by Bernd Walter, but should be applicable to all other LD
        scripts as well.
      - Linker Scripts:  Add . = ALIGN(4); before every .data section,
        add . = ALIGN(4); before every ARM.extab section, add . = ALIGN(4);
        before every definition of __exidx_start, add . = ALIGN(4); before
        every .init_section.  Convert TABs to spaces in all ld linker
        scripts.  This just makes things easier to modify with scripts
        because the files are more consistent.  From Gregory Nutt.
      - configs/Board.mk:  Cannot call $(AR) directly.  That works only with
        GCC.  It must, instead use the ARCHIVE command from Config.mk as do
        other Makefiles.  From Gregory Nutt.

    * MIPS32:

      - Fix a copy-paste error.  On vfork, the GP register was being set to
        the new SP value vs. the context GP value.  NOTED in Bitbucket issue
        155.  From Gregory Nutt.
      - An older commit used CP0 register definitions that were not defined
        in the NuttX cp0.h header file.  Probably these were from the
        Microchip hacked up GCC toolchain but are not generally available
        outside that toolchain.  Fix: Add definitions to NuttX cp0.h header
        file.  From Gregory Nutt.

    * Microchip PIC32MZ Drivers:

      - PIC32MZ GPIO: Use LAT instead of PORT when writing.  From Ouss4.

    * Microchip/Atmal SAM3/SAM4 Drivers:

      - SAMD2/L2:  Correct TC register bit field definitions used with
        TC_CTRLBCLR and TC_CTRLSET registers.  From Bernd Walter.

    * NXP LPC17xx Boards:

      - LPC17xx PROTECTED:  On the LPC1769 there are two 16 KiB AHB SRAM
        blocks, which are mapped back to back at physical address 0x2007C000
        and 0x20080000 (i.e. right below and right above a 512 KiB boundary).
        Memory from those two blocks is considered continuous when assigned
        to a heap.  In the protected build mode, when the memory protection
        unit is used, though, it must be split into two MPU regions.  This
        is because MPU regions must be naturally aligned, and the 32KiB
        continuous address space of the two 16KiB AHB SRAM blocks does not
        start at an address divisible by 32KiB.  The only other
        configurations that use protected build mode on lpc17xx are
        currently open1788/knsh and open1788/knxterm.  The LPC1788 has the
        AHB SRAM blocks mapped more sanely (from an MPU region point of
        view), which is probably why no problems emerged here.  Both still
        compile with my change and other than wasting an MPU region (which
        would otherwise remain unused) should work fine.  That said, I
        have no hardware to confirm.  From Michael Jung.

    * NXP LPC54xx Boards:

      - LPCXpresso-LPC54628:  Modify the TWM configurations to properly
        inject keyboard data.  This way, in the case of multiple NxTERMs,
        only the NxTerm at the top of the hierarchy gets the keyboard input.
        Otherwise, it is not possible to use multiple NxTerms with each the
        keyboard input going to a different NxTerm window.  From Gregory
        Nutt.

    * NXP i.MXRT Drivers:

      - i.MXRT Serial:  Fix serial TIOCSINVERT  From David Sidrane.
      - i.MXRT USDHC:  USDHC Stopgap Fix for build breakage  From David
        Sidrane.
      - i.MXRT USDHC:  Fix compiler error for CONFIG_IMXRT_USDHC1 &&
        !CONFIG_IMXRT_USDHC2  From David Sidrane.

    * On Semiconductor LC823450:

      - LC823450-XGEVK:  Remove CPU assignment for LPWORK.  This change will
        reduce audio under-run when running dvfs auto mode.  From Masayuki
        Ishikawa.

    * SiLabs EFM32 Drivers:

      - EFM32 USB Host:  Apply Adam Porter's STM32 fix to EFM32 which has
        the same IP.  From Gregory Nutt.

    * STMicro STM32:

      - STM32F1 Pinmap:  Fix names for complementary PWM outputs  From
        Mateusz Szafoni.
      - STM32L4:  If SRAM3 is used as heap, do not power it off in stop 2
        mode.  From Juha Niskanen.

    * STMicro STM32 Drivers:

      - STM32 ADC:  Fix a compilation error when verbose analog debugging is
        enabled for the STM32 ADC. not all STM32s have an SQR4 register.
        From rajan gill.
      - STM32 PWM:  Fix pulse count for the number of counts greater than 128.
        From Mateusz Szafoni.
      - STM32 USB OTG FS/HS Host:  In stm32_ctrlout() in the HS and FS host
        drivers, the data buffer isn't sent. This patch passes the buffer
        and buflen to the stm32_ctrl_senddata() function.   With this change,
        I am able to send MBIM control messages to my USB modem, and read the
        response.  From Adam Porter.
      - STM32L4 USB:  Fix USB device PMA accesses.  USB PMA accesses are
        done as 16-bit words on STM32L4 instead of 32-bit words on STM32L1.
        From Jussi Kivilinna.
      - STM32L4 OTG FS/HS:  Fix constant using in comparison to determine
        endpoint is interrupt type.  From Adam Porter.
      - STM32F7 OTG FS/HS:  Fix constant using in comparison to determine
        endpoint is interrupt type.  From Adam Porter.
      - STM32H7 PWM:  Fix pulse count for the number of counts greater than 128.
        From Mateusz Szafoni.
      - STM32H7 Serial: Fix error when SINGLEWIRE or
        CONFIG_STM32H7_SERIALBRK_BSDCOMPAT defined.  From David Sidrane.
      - STM32H7 SPI:  Correct a typo in condition compilation.  From
        Jonathan Richner.
      - STM32H7 Timer:  Fixed compile errors with TIM13, TIM14, TIM7.  From
        David Sidrane.
      - STM32H7 USB OTG FS/HS:  Fix constant using in comparison to determine
        endpoint is interrupt type.  From Adam Porter.
      - STM32G0 Serial:  Fix STM32G0 error when SINGLEWIRE or SERIALBRK_BSDCOMPAT
        defined (it reflects previous changes in STM32H7). From Mateusz Szafoni.

    * STMicro STM32 Boards:

      - Nucleo-L432KC:  Shorten some long lines, fix i2c pinout.  From
        Sebastien Lorquet.
      - STM32L476VG-Disco:  Fix an error in defconfig files because a line
        in the rcS file was longer than the configured NSH command line.
        From Juha Niskanen.
      - STM32L4R9AI-Disco:  Fix an error in defconfig files because a line
        in the rcS file was longer than the configured NSH command line.
        From Juha Niskanen.
      - OmnibusF4:  Correct naming of a configuration variable for ROMFS.
        From Phil Coval.
      - Olimex-STM32-E407:  Change initialization to match the way it is
        done with other boards.  From Gregory Nutt.
      - Olimex-STM32-E407 SPI:  Add SPI initialization logic.  From Juan
        Flores.
      - STM32F4-Discovery ROMFS:  Missing colon in declaration of local
        variable.  From Phil Coval.
      - STM32F4-Discovery ROMFS:  Correct naming of a configuration variable
        for ROMFS.  From Phil Coval.
      - STM32F4-Discovery Build:  Fix .ARM.exidx section overlap Source:
        https://stackoverflow.com/questions/30778614/arm-none-eabi-ld-section-arm-exidx-overlaps-section-data.
        From Alan Carvalho de Assis.
      - STM32F4-Discovery PROTECTED:  Fix a problem with undefined symbol
        'abort' from GCC library in PROTECTED build.  Fix by moving libgcc
        into recursive archive group between --start-group and --end-group.
        Other kernel/Makefiles suffer from this same issue  From Gregory
        Nutt.
      - Nucleo-H743ZI SPI:  Correct typos in function naming.  From Jonathan
        Richner.

    * TI AM335x:

      - AM335x SYSCLK:  Add a function to return a frequency of the system
        clock.  From Gregory Nutt.
      - AM355x CM:  Fix a typo in a macro name.  From Gregory Nutt.
      - AM355x LCD:  Fix a few typos.  Add things needed by the LCDC driver.
        From Gregory Nutt.

    * TI Tiva Drivers:

      - Tiva Ethernet: Add a workaround for tiva with qemu.   With qemu,
        tiva_ifup() hangs because Ethernet link status can not be set
        correctly. This change is a workaround to avoid this issue.  From
        Masayuki Ishikawa.

    * TI Tiva Boards:

      - TM4C1294-Launchpad:  Fix syntax error in oocd.sh script.  From
        Nathan Hartman.

    * ZiLOG Common:

      - z80:  up_addregion() must be prototyped in nuttx/mm/mm.h, not
        up_internal.h.  Various name changes to better conform to the coding
        standard, naming conventions, and use by other architectures.  From
        Gregory Nutt.

    * ZiLOG Z80 Boards:

      - z80sim:  Remove unused function up_earlyserialinit() from serial
        driver.  From Gregory Nutt.

    * ZiLOG z16f ZNeo:

      - z16f ZNeo:  Replicate build changes make for eZ80 and z8 for ZNeo.
        From Gregory Nutt.
      - ZNeo compile fixes:  Fix misuse of FAR which makes a difference on
        this platform.  Be consistent in use of WDOG_ID type.  ZDS-II doesn't
        like auto-conversions of struct wdog_s * to WDOG_ID (which is type
        struct wdog_s *).  From Gregory Nutt.

    * ZiLOG eZ80Acclaim!:

      - eZ80:  Fix eZ80 compile problems due to New ZDS-II toolchain and
        ongoing bit rot due to non-C89 code creeping into the core OS.  From
        Gregory Nutt.
      - eZ80:  Fix some backward conditional logic in Make.defs.  From
        Gregory Nutt.
      - eZ80:  Fix a logic error in vector initialization.  From Gregory Nutt.

    * C Library/Header Files:

      - signal.h:  Fix a C89 compliance problem that cause the eZ80 build to
        fail.  Empty structure and unions are not accepted by the compiler.
        From Gregory Nutt.
      - wqueue.h:  Allow definitions even if work queues are not enabled.
        This solves build failures when work queues are not enabled.  From
        Gregory Nutt.
      - fixedmath.h:  Regarding the single precision float to/from fixed
        point conversions in fixedmath.h, I believe the floating point
        literals should be appended with the letter 'f' to avoid (expensive)
        conversions from single to double precision, and thereby also avoid
        (expensive if done in SW) double point arithmetic (which is what is
        happening upon inspection of my disassembly).  From rajan gill.

      - stdio:  Fix long long usage in all of the newer printf-related
        logic:  The selection CONFIG_LIBC_LONG_LONG must be ignored if the
        architecture does not support long long types.  From Gregory Nutt.
      - gm_time_r():  Spurious reorganization of a loop in gm_time_r() to
        work around and ZDD-II internal compiler error.  Might be a little
        bigger now, but is also probably a more structured use of C.  From
        Gregory Nutt.
      - Debug:  For platforms whose CPP tool does not support a variable
        number arguments to pre-processor macros, we may still need to build
        the debug functions even when CONFIG_DEBUG_FEATURES is not selected.
        For example, __alert() may be needed if CONFIG_ARCH_STACKDUMP is
        set.  From Gregory Nutt.

    * Tools:

      - tools/nxstyle.c:  Fix error in conditional logic that was preventing
        detection bad brace alignment.  Add logic to handle alignment of
        braces in data initializers which following slightly different
        indentation rules.  From Gregory Nutt.
      - tools/mkexport.sh:  The mcu sub-directory chip/ was renamed to
        hardware/ in late May of 2019.  The mkexport.sh script that copies
        these files was not updated, however, until now.  Noted by Alin
        Jerpelea.  From Gregory Nutt.

    * NSH Library: apps/nshlib:

      - apps/nshlib:  Fix all places where cle() and readline() are used.
        readline() returns EOF on a failure.  cle() returns a negated errno
        value.  Checking only for EOF causes failures to be missed (and
        infinite loops ensuing).  From Valmantas Paliksa.
      - nshlib/nsh_parse.c:  Fix a warning about an uninitialized variable
        from the ZDS-II compiler.  From Gregory Nutt.
      - apps/nshlib/nsh_ddcmd.c:  Seemingly nonsense change but somehow
        works around a compilation error using the ZDS-II toolchain.  It
        was claiming that vtbl was undefined indd_outfopen().  From Gregory
        Nutt.

    * Network Utilities: apps/netutils:

      - apps/netutils/netinit:  MAC address configuration was represented
        by type long long.  That is a problem for architectures that do not
        support type long long.  Replaces by two long configuration items.
        From Gregory Nutt.
      - apps/netutils/telnetd/telnetd_daemon.c:  Fix a C89 violation that
        caused the eZ80 build to fail.  From Gregory Nutt.
      - apps/netutils/json:  Removed.  Replaced with apps/netutils/cjson.
        From Gregory Nutt.

    * Graphics Utilities: apps/graphics:

      - apps/graphics/twm4nx:  Fix an uninitialized variable that was
        causing toolbar buttons to randomly come up enabled or disabled.
        Remove some unused event definitions.  From Gregory Nutt.
      - apps/graphics/twm4nx:  Fix a calibration screen startup issue.
        Make an initial calibration screen optional.  From Gregory Nutt.
      - apps/graphics/twm4nx:  Revise logic to detect clicks on the
        background image.  The original implementation had some side
        effects.  From Gregory Nutt.
      - apps/graphics/twm4nx:  Remove some remaining stuff from TWM that
        was never used.  Menus need to close after the 'terminal' selection
        is made.  Otherwise, the menu can become buried under a newly open
        menu and not easily recovered.  From Gregory Nutt.
      - apps/graphics/twm4ndx:  Add a 'critical' bit to the eventID.  While
        resizing, all events will be ignore except those marked critical.
        From Gregory Nutt
      - apps/graphics/twm4nx:  CBackground now brings up the main menu if
        the background image is clicked.  This makes the behavior the same
        across all of the background except when an icon is clicked.  From
        Gregory Nutt.
      - apps/graphics/twm4nx:  Fix a bug in placement of icons on the
        desktop. When many windows are displayed, a bug in the looping logic
        could cause an infinite loop.  From Gregory Nutt.
      - apps/graphics/twm4nx:  Fix some errors found when enabling NX
        keyboard support. The most important being that the mouse and
        keyboard drivers need to be opened non-blocking.  From Gregory Nutt.

NuttX-8.1 Release Notes
------------------------

The 132nd release of NuttX, Version 8.1, was made on September 14, 2019,
and is available for download from the Bitbucket.org website.  Note
that release consists of two tarballs:  nuttx-8.1.tar.gz and
apps-8.1.tar.gz.  These are available from:

    https://bitbucket.org/nuttx/nuttx/downloads
    https://bitbucket.org/nuttx/apps/downloads

Both may be needed (see the top-level nuttx/README.txt file for build
information).

The major release version number is only incremented when there is a major
change to the OS that makes it more-or-less incompatible with preceding
versions.  This release bumps the major version number from 7 to 8 due
primarily to a major reorganization in the what was the configs/ directory
in nuttx-7.31.  That directory has been renamed boards/ and now has a
directory structure that mirrors the organization of the arch/ directory
for the most part:

    board/ - Holds all board-related information
    board/<arch> - Holds board-related information for all boards that use
      the same CPU architecture.  For example, all ARM-based boards will be
      found under board/arm
    board/<arch>/<chip> - Holds board-related information for all boards
      that use the same MCU chip family.  For example, all STM32-based
      boards will be found under board/arm/stm32
    board/<arch>/<chip>/<board> - Holds board-related information for a
      specific board.  This is analogous to the configs/<board> directory in
      nuttx-7.31.  So, for example, the STM32F4-Discovery board support that
      was at configs/stm32f4disovery can now be found under
      boards/arm/stm32/stm32f4discovery.
    boards/<arch>/<chip>/<board>/<configs> - All configurations for a
      specific board can now be found together in this configs/
      subdirectory.  So, continuing the example, the STM32F4-Discovery NSH
      configuration can now be found at
      boards/arm/stm32/stm32f4discovery/configs/nsh.

In additional, common MCU logic can be found at board/<arch>/<chip>/common
and MCU common drivers can be found at board/<arch>/<chip>/common.  Related
changes include changes to tools/, comments, and documentation that depend
on the board directory structure.

This re-organization is the work of Alin Jerpelea.  Not only did Alin do
this major directory re-organization, but he ran the code standard
compliance tool and corrected every .c and .h file under boards/ so that
they all correctly follow the NuttX coding style.  These changes were very
extensive and, hence, will not be addressed individually in the ReleaseNotes.

You have to give Alin credit for his effort to take on really big jobs and
stick with it until it is finished.  Kudos!

A more constrained re-organization of the drivers/ directory was also
contributed by Augusto Fraga Giachero.  Augusto reorganized some driver
directories to make better functional associations and also to make space
for a new set of RF-related drivers.

Additional new features and extended functionality:
---------------------------------------------------

    * Core OS:

      - POSIX Message Queues:  Add a test to verify that message queue is
        closed by the same task group that opened it.  If not, then list
        corruption would result.  This test is only performed if
        CONFIG_DEBUG_FEATURES is enabled since it should not normally be an
        issue:  It would be a strange programming practice to open a
        message queue in open task group, then close it in another.  From
        ???.
      - Signal Notifications:  Add configuration option to select either the
        high-priority or low-priority work queue for SIG_EVTHREA
        notifications.  From ligd.
      - System Calls:  In order to support built-in in function in protected
        mode, a task_spawn() system call must be supported.  task_spawn()
        and posix_spawn() are NuttX OS interfaces.  In PROTECTED and KERNEL
        build modes, then can be reached from applications only via a system
        call.  Unfortunately this is overly complex because there is a (soft)
        limit of 6 parameters in a system call; task_spawn has seven
        parameters.  This is a soft limit but still difficult to extend
        because it involves assembly language changes to numerous
        architectures.  Better to get more creative.  Rather than extend the
        maximum number of parameters across all architectures, I opted
        instead to marshal the seven parameters into a structure and pass
        only a single parameter:  A pointer to the structure containing the
        seven marshaled parameters.  From Gregory Nutt.
      - /etc/passwd and /etc/group:  Improve the format of the /etc/passwd
        file as used in the sim:nsh configuration.  It is now a little
        more similar to other systems and includes user and group IDs.  Add
        also an /etc/group file to support future testing.  From Gregory
        Nutt.
      - User/Group IDs:  Implement 'real' setuid, getuid, setgid, and getgid
        interfaces is so configured (otherwise fall back to stubs that
        support only the 'root' user ID and group.  Once set, these IDs will
        be inherited by all child task groups.  From Gregory Nutt.
      - Debug Output:  Add debug macros for contactless.  The various
        contactless device drivers currently define device specific debug
        macros within their local header files.  This patch adds generic
        ctls[info|warn|err] macros for the overall contactless subsystem to
        be used in future drivers.  Ported the existing contactless device
        drivers to use these generic logging macros and fixed some logging
        bugs along the way.  From Michael Jung.
      - IOB instrumentation.  Introduces producer/consumer id to every IOB
        call.  This is so that the calls can be instrumented to monitor the
        IOB resources and to collect usage statistics.  From Anthony
        Merlino.
      - IOB ProcFS:  Adding ProcFS support at /proc/iobinfo to show the data
        collected from the IOB instrumentation.  From Anthony Merlino.
      - Versioning:  Report GIT information via ProcFS.  GIT info reported:
        branch, version, GIT hash, hostname, user, build date.  Integrates
        into existing .version and ProcFS.  From David Alessio.

    * File System/Block and MTD Drivers:

      - BinFS:  The BinFS file system uses the same built-in library and
        built-in arrays as does NSH.  The built-in arrays are simple name-
        value pairs that map built-in function names with the user-space
        entry point.  In the FLAT build, the built-in arrays are available
        everywhere via the backdoor left open by the FLAT address space.
        In the PROTECTED build, however, the kernel must maintain its own
        reference to the user-space built-in array.  This commit adds those
        kernel globals and a new boardctl(BOARDIOC_BUILTINS) that can be
        used by applications to the provide the built-in list reference to
        the kernel.  From Gregory Nutt.
      - MMC/SD:  Added support for MMC (eMMC) bigger than 2 GB (Tested with
        IMXRT1050EVKB and samsung eMMC 16GB).
      - AT24CSxx:  Register a character driver for UUID of AT24CSxx chips.
        Allows the UUID to read as a file or displayed from an nsh prompt with:
        nsh> hexdump /dev/eeprom.uuid  From David Alessio.
      - Macronix FLASH:  Add support for 4-byte addressing on >128Mb
        Macronix flash parts  From jjlange.
      - MX25Rxx:  Add support for 512B sectors.  From Simon Piriou.
      - SST26:  Accept the 16MBit Flash when reading the JEDEC-ID at
        initialization time.  From Ouss4.

    * Network/Network Drivers:

      - IPv4 Options:  Now handles reception of IPv4 packets with larger
        IPv4 headers containing options.  From Gregory Nutt.
      - Sockets:  Re-order the content of all address-family socket
        'connection' structures so that they begin with a common prologue.
        This permits better use of logic for different address family
        types.  From Gregory Nutt.
      - TCP:  Make RTO and WAIT_TIME configurable.  This fix is not really
        correct:  TCP RTO really should be calculated dynamically for each
        TCP connection:  http://sgros.blogspot.com/2012/02/calculating-tcp-rto.html.
        From zhangyuan7.
      - IP Forwarding:  Check if interface is up early on when forwarding to
        avoid extra work.  As noticed in a previous wireless commit, when
        forwarding is enabled and a packet comes in, the packet is attempted
        to be sent on each other netdev without regard for whether it is in
        the UP state.  Of course this is eventually caught, but it can be
        caught earlier to avoid unnecessary work, especially in the 6LoWPAN
        case where a useless packet conversion will occur.  From Anthony
        Merlino.
      - RNDIS:  Expose option to change the number of write requests that
        can be in flight.  From Anthony Merlino.
      - GS2200M:  Add UDP support.  From Masayuki Ishakawa
      - GS2200M:  Implement GS2200M_IOC_IFREQ IOCTL command.  From Masayuki
        Ishikawa.
      - GS2200M:  Enable NuttX's DHCP client instead of GS2200M's DHCP
        client.  From Masayuki Ishikawa.
      - GS2200M:  GS2200M now supports SIOCGIFHWADDR  From Masayuki
        Ishikawa.

    * Wireless/Wireless Drivers:

      - IEEE802.15.4 Network Driver:  Allow 64-bit prefix to be configurable
        when auto-configuring the IPv6 address during bring-up.  Previously,
        only the link-local prefix fe80::/64 was used.  Also, put the
        network in the DOWN state at the end of initialization.  From
        Anthony Merlino.
      - IEEE 802.15.4 MAC:  Adds support for energy detect.  Adds support
        for energy detect by introducing a new radio call/callback, as the
        PHY layer is required to perform the energy detect.  From Anthony
        Merlino.
      - IEEE 802.15.4 MAC:  Adds support for getting/setting
        macMaxFrameRetries via IOCTL.  Add get support for rxonidle
        attribute  From Anthony Merlino.
      - IEEE 802.15.4 MAC:  Move the global iobuffer into the macnet struct
        so that more than one macnet device can exist.  From Anthony
        Merlino.
      - IEEE 802.15.4 MAC:  Defer handling of extracting association
        response to LPWORK queue.  From Anthony Merlino.
      - IEEE 802.15.4 Radios:  Support dynamic FCS length.  Adds
        IEEE802154_ATTR_PHY_FCSLEN.  This change introduces
        IEEE802154_ATTR_PHY_FCSLEN which the radio layer can support to
        set/get the FCS length that's added to the end of the frame.  One
        use case, in promiscuous mode, is to add back in the FCS of the
        received frame by increasing the iob->io_len by the FCS length.
        From Anthony Merlino.
      - Xbee:  Support "WR" AT command for writing parameters to non-
        volatile memory.  From Anthony Merlino.
      - Xbee:  Add configuration option for setting the default prefix
        to use when bringing up the network and setting the IP address.
        From Anthony Merlino.

    * Other Common Device Drivers:

      - RTC:  If the RTC time is successfully set, then update the current
        system time to match.  From ligd.
      - ADT7320:  Add support for the ADT7320 temperature sensor.  From
        Augusto Fraga Giachero.
      - DAC7554:  Add support to the DAC7554 digital-to-analog converter.
        From Augusto Fraga Giachero.
      - DAT-31R5-SP+: Add support to the DAT-31R5-SP+ digital attenuator.
        Creates a the new device driver directory drivers/rf/ to support
        drivers related to RF peripherals.  It also adds support for the
        DAT-31R5-SP+ digital attenuator.  From Augusto Fraga Giachero.
      - ISL29023:  Add basic driver of ISL29023 ambient light sensor.  The
        basic driver can set operational mode, range, and resolution.  It
        can also read lux value in continuous mode. Interrupt and the alarm
        is not implemented.  From Matous Pokorny.
      - SHT3x:  Add Sensirion SHT3x driver.  From Markus Bernet.

    * Simulator:

      - Simulator Build:  Even though the simulation has no "chips", it
        needs to have CONFIG_ARCH_CHIP and chip sub-directories.  Otherwise,
        we would have to treat it as a special case in the build system
        after the changes to the boards/ directory.  From Gregory Nutt.

    * Microchip PIC32MZ:

      - PIC32MZ.  Make the PLL input clock configurable.  From Ouss4.

    * ARMv7-M

      - Add ARMv7-M setjmp/longjump functions.  From David S. Alessio.

    * NXP i.MXRT:

      - i.MXRT Clocking:  Enable TRACE clocks if the divider has been
        defined in the board's board.h file.  From Dave Marples.

    * NXP i.MXRT Drivers:

      - i.MXRT QEncoder:  Adds quadrature encoder driver for IMXRT.  From
        Nicholas Chin.
      - i.MXRT uSDHC:  This change completes SDIO support for IMXRT, and
        also adds support for WiFi using the AP6212A module based on Simon
        Piriou's rather excellent work. The patch should also address
        DavidS's concern about width setting for USDHC1 and 2.  Testing of
        the WiFi is minimal so far but functionality is proven.  I'm
        specifically not happy that the driver doesn't recover elegantly
        from a DMA data checksum failure, but that is an issue that can be
        dealt with in due course ... I'm trying to get the rest of the
        interfaces fleshed out and the hardware proven so it can go for pre-
        production build. I _think_ there's only Bluetooth and USB-device
        left to implement now.  From Dave Marples.
      - i.MXRT uSDHC:  IMXRT uSDHC driver cmd line reset logic modified.
        From Ivan Ucherdzhiev.

    * NXP/Freescale Kinetis Drivers:

      - Kinetis Serial:  Add possibility to specify pull-up instead of
        open drain for serial single-wire mode.  From Beat Küng.

    * NXP LPC17xx/40xx:

      - LPC17xx/40xx Build:  Cortex-M system reset is applicable to
        LPC17xx/40xx too.  From Pavel Pisa.

    * NXP LPC17xx/40xx Drivers:

      - LPC17xx/40xx Ethernet:  Follow the procedure listed in the
        LPC176x/5x User Manual when reading from and writing to the PHY's
        registers (section 10.11.14). I couldn't see any behavioral change
        after this commit, but nonetheless is a good practice to follow the
        manufacturer's recommended procedure.  From Augusto Fraga Giachero.

    * NXP S31K1xx:

      - Added architecture support for the NXP S32K1xx family.  Basic
        support includes the boot up logic, clock configuration, LPUART
        console, Systick timer, GPIO controls, and eDMA (unverified).

    * NXP S31K1xx Drivers:

      - S32K1xx eDMA  Leverage eDMA logic from i.MXRT to S32K1XX.  Appears
        to be the same IP but with fewer channels and features than the
        i.MXRT implementation.  From Gregory Nutt.
      - S32K1xx LPUART:  Bring in the LPUART from i.MXRT.  It is the same
        IP.  From Gregory Nutt.
      - S32K1xx SysTick:  Bring in Cortex-M0+ SysTick and interrupt handling
        from samd2l2; bring in Cortex-M4F Systick and interrupt handling
        from LPC54xx.  From Gregory Nutt.
      - S32K1xx GPIO:  Bring in GPIO logic from Kinetis.  Looks like similar
        IP.  From Gregory Nutt.
      - S32K1xx Ethernet:  Unverified port of the i.MXRT Ethernet driver to
        the S32K1xx.  The i.MXRT uses the same IP.  From Gregory Nutt.
      - S32K1xx LPSPI and LPI2C:  Brings in the LPSPI and LPI2C peripheral
        drivers from the i.MXRT which used the identical IP.  From Gregory
        Nutt.

    * NXP S31K1xx Boards:

      - S32K118EVB.  This commit adds initial board support for the NXP
        S32K118EVB development board.  Currently supports only a minimal
        NSH configuration.  From Gregory Nutt.
      - S32K118EVB:  Implement board support for on-board LEDs and buttons.
        This is taken from the Freedom-K66f with has the same LED and
        button configuration as the S32K116EVB and uses the same GPIO IP.
        LEDs, but not buttons, have have been verified.  From Gregory Nutt.
      - S32K146EVB:  Adds initial board support for the S32K146EVB
        development board.  Currently supports a NSH configuration with a
        richer feature set than the minimal configuration of the S32K118EVB.
        From Gregory Nutt.
      - S32K146EVB:  Add support for execution out of SRAM.  This is helpful
        for bring-up when you want to avoid putting a lethal image in FLASH.
        From Gregory Nutt.
      - S32K148EVB:  Add support for the NXP S32K148EVB development board.
        Very similar to the S32K146EVB but with more on-chip memory and
        hardware features.

    * Sony CXD56xx

      - CXD56xx:  Migrate CXD56xx common code to the common/ directory:
        Boot code, FLASH code, I2C driver, UID.  From Alin Jerpelea.
      - CXD56xx:  Add SPH.  The SPH is used by the ASMP implementation from
        the SDK.  From Alin Jerpelea.

    * Sony CXD56xx Drivers:

      - CXD56xx:  Add sensors connected to the SCU on Spresense board:
        o Avago APDS9930 Proximity and Ambient light Sensor.
        o Rohm BH1721FVC Ambient Light Sensor.
        o Rohm BH1745NUC Color Sensor.
        o Rohm BM1383GLV/BM1383AGLV Pressure Sensor.
        o Rohm BM1422GMV/BM1422AGMV Magnetic Sensor.
        o Bosch BMI160 Sensor support.
        o Bosch BMP280 Barometic Pressure Sensor.
        o Kionix KX022/KX122 Acceleration Sensor.
        o Murata LT1PA01 Proximity and Ambient light Sensor.
        o Rohm RPR0521RS Proximity and Ambient light Sensor.
        o BMI160:  Add optional I2C address.
        From Alin Jerpelea.
      - CXD56xx:  Add the sensor initialization for CXD56xx boards in the
        common board folder:
        o APDS9930: typo fix
        o cxd56_ak09912 initialization.
        o cxd56_bmi160 initialization.
        o cxd56_apds9960 initialization.
        o cxd56_bh1721fvc initialization.
        o cxd56_bh1745nuc initialization.
        o cxd56_bm1383glv initialization.
        o cxd56_bm1422gmv initialization.
        o cxd56_bmi160 initialization.
        o cxd56_bmp280 initialization.
        o cxd56_kx022 initialization.
        o cxd56_lt1pa01 initialization.
        o cxd56_rpr0521rs initialization.
        o cxd56_sensors initialization.
        o Backup Log driver.
        o crashlog driver.
        o Move gs2200m initialization.
        o Move ili9340 initialization.
        o Move lpm013m091a initialization.
        From Alin Jerpelea.

    * Sony CXD56xx Spresense Board:

      - Spresense:  Enable SmartFS and UDP support  From Masayuki Ishikawa.

    * STMicro STM32:

      - STM32F4 PLLI2S:  Add support to enable the I2S Phase Locked Loop on
        STM32F427 and STM32F437 MCUs.  From Michael Jung.

    * STMicro STM32 Drivers:

      - STM32 ADC:  Add ADC calibration procedure for IP_ADC_V1.  Tested on
        STM32F100, and it magically increased result accuracy.  STM32F103
        has the same calibration procedure.  I am not sure about others.
        From Matous Pokorny.
      - STM32 SPI:  TI Synchronous Serial Frame Format.  The SPI macros on
        STM32 MCUs now support the Texas Instruments Synchronous Serial
        Frame Format protocol (TI protocol).  Defined a new SPIDEV_MODETI
        and add support for it in stm32_spi.c.  From Michael Jung.
      - STM32 UART:  Serial add HW HS on UART 4 & 5.  From David Sidrane.
      - STM32 PWM:  Configure multi-channel duty only if channel specified.
        This allows you to update duty cycle for a single channel.   From
        Mateusz Szafoni.
      - STM32F7 Ethernet:  Add a timeout on MAC reset  From David Sidrane.
      - STM32F7 FLASH:  Exposes stm32_flash_xxx functions.  From Anthony
        Merlino.
      - STM32F7 PWM:  Configure multi-channel duty only if channel specified.
        This allows you to update duty cycle for a single channel.   From
        Mateusz Szafoni.
      - STM32F7 UART:  Serial add HW HS on UART 4 & 5.  From David Sidrane.
      - STM32H7 ADC:  Fix internal channel numbers.  From Markus Bernet.
      - STM32H7 BBSRAM:  Add BBSRAM support.  From David Sidrane.
      - STM32H7 DTCM:  Port DTCM from F7  From David Sidrane.
      - STM32H7 I2C:  Select ARCH_HAVE_I2CRESET in configuration.  From
        David Sidrane.
      - STM32H7 PWM:  Configure multi-channel duty only if channel
        specified.  This allows you to update duty cycle for a single
        channel.  From Mateusz Szafoni.
      - STM32H7 RCC:  Fix RCC register definitions and typos for ADC/UART.
        From Markus Bernet.
      - STM32H7 RTC:  Ported over F7 RTC.  From David Sidrane.
      - STM32H7 SPI:  Allow more clock sources.  From David Sidrane.
      - STM32H7 UART:  Serial add HW HS on UART 4 & 5.  From David Sidrane.
      - STM32H7 UART:  Fix typo in UART8 configuration.  From Markus Bernet.
      - STM32H7 UID:  Ported UID from F7  From David Sidrane.
      - STM32L4 PWM:  Configure multi-channel duty only if channel specified.
        This allows you to update duty cycle for a single channel.   From
        Mateusz Szafoni.
      - STM32L4 UART:  Serial add HW HS on UART 4 & 5.  From David Sidrane.

    * STMicro STM32 Boards:

      - B-L475E-IOT01A:  Add mx25rxx memory chip and smartfs support in NSH
        configuration.  From Simon Piriou.
      - LX_CPU:  Add support for the PIKRON LX_CPU board.  From Pavel Pisa.
      - Nucleo-F303RE:  Add basic NSH configuration.  From Mateusz Szafoni.
      - Nucleo-F303RE:  Enable console on UART2 and set entry point to
        nsh_main() in the PWM configuration.  From Mateusz Szafoni.
      - Nucleo-H743ZI:  Add RTC support.  From David Sidrane.
      - Nucleo-L432KC:  Added GPIO drivers for use with /apps/examples/gpio.
        From Daniel P. Carvalho.
      - Nucleo-L432KC:  Added Zero Cross sensor to nucleo-l432kc.  From
        Daniel P. Carvalho.

    * TI Tiva:

      - Tiva:  Add support for Tiva TM4C123AH6PM.  From Nathan Hartman.
      - Tiva Configuration:  Modify preprocessor logic to support
        configurations with no UART.  Now similar to logic for other
        architectures.  From Nathan Hartman.
      - Tiva Interrupts:  Add handling for IRQs 128 through 159.  From Nathan
        Hartman.

    * TI Tiva Drivers:

      - TM4C QEncoder:  Reinstate TM4C qencoder driver and expand its
        ioctls. Add TIVA_HAVE_QEI0, TIVA_HAVE_QEI1 as applicable to each
        ARCH_CHIP_TM4C12*.  Rewrite tiva_qe_setup().  Replace tiva_qe_ppr()
        with tiva_qe_resetatppr().  Add tiva_qe_resetatmaxpos() and
        tiva_qe_resetatindex().  Add missing definitions:
        SIGMODE_QUADRATURE, SIGMODE_CLK_AND_DIR, SWAP_NO_SWAP, SWAP_PHA_PHB.
        Rename TIVA QEI ioctl QEIOC_PPR to QEIOC_RESETATPPR; add TIVA QEI
        ioctl identifiers QEIOC_RESETATMAXPOS, QEIOC_RESETATINDEX.  From
        Nathan Hartman.

    * TI Tiva Boards:

      - TM4C1294-Launchpad:  Enables /dev/userleds in board bring-up for
        tm4c1294-launchpad by calling userled_lower_initialize() in
        tm4c_bringup().  From Nathan Hartman.

    * TI Tiva Drivers:

      - Tiva GPTM timers:  Implement 16-bit PWM mode.  Add
        tiva_pwm16_sel_event() to choose GPTMCTL.TnEVENT value.  Implement
        tiva_pwm_mode16().  This also involved numerous corrections to the
        16-bit timer logic.  Add tiva_timer16pwm_setperiodduty() to set
        initial period, duty cycle, and enable interrupts if requested in
        GPTM peripheral. Interrupts are not enabled in NVIC until
        tiva_timer16_start() is called.  Add tiva_timer16pwm_setduty() to
        update duty cycle at any time.  Add new TIMER_FLAG_* configuration
        flags to enable configuring the 16-bit PWM feature.  Extend type of
        "flags" in tiva_timer32config_s and tiva_timer16config_s from 8- to
        32-bits to allow more flags.  From Nathan Hartman.

    * Build System:

      - Export Build:  Export all variables/files to support architecture
        independent build against NSH.  From Pavel Pisa.
      - Application Export:  This change too build tools allows to export
        built-in applications registry into temporarily created directory
        where export archive content is prepared.  If the Makefile in apps/
        directory does not define export:  target then error is print but
        export continues without interruption. It would be more logical to
        print warning but there is no way instruct apps make to not print
        error.  From Pavel Pisa.
      - boards/Board.mk:  Add support to pass dependency paths.  From
        Gregory Nutt.

    * Libraries/Header Files:

      - libs/libc/libc.csv:  Add some missing C library functions.  From
        Pavel Pisa.
      - libs/libc/libc.csv: Add ioctl() to fs_ioctl() wrapper for varidic
        case.  From Pavel Pisa.
      - libs/libc/builtin/:  Moves shared built-in information out of
        binfmt/libbuiltin and into libs/libc/builtin where it can be shared
        with applications.  This should permit built-in application in the
        PROTECTED build where binfmt/libbuiltin was not available in user
        space.  From Gregory Nutt.
      - libs/libc/dirent/:  Added alphasort() implementation, scandir()
        implementation and DT_* definitions to include/dirent.h.  Apparently
        those definitions are not required by POSIX, but are part of
        4.3BSD and available in glibc as well.  From Michael Jung.
      - libs/libc/grp/:  Added stubbed implementations of getgrgid,
        getgrgid_r, getgrnam, getgrnam_r, and initgroups.  These functions
        are essentially stubs pretending that NuttX supported groups and
        that the only configured group in the system was 'root' with gid 0.
        The intend is not to provide meaningful new features, but to ease
        porting of foreign source code to NuttX.  From Michael Jung.
      - libs/libc/machine/arm/armv7-m/:  Add Cortex M4F machine optimized
        fabsf and sqrtf.  From David S. Alessio.
      - libs/libc/pwd/:  Added stubbed implementations.  Added stubbed
        implementations of getpwuid, getpwuid_r, getpwnam, and getpwnam_r.
        These functions are essentially stubs pretending that NuttX
        supported users and that the only configured user in the system
        was 'root' with uid 0.  The intend is not to provide meaningful
        new features, but to ease porting of foreign source code to NuttX.
        From Michael Jung.
      - libs/libc/pwd and libs/libc/grp/:  Modify to get user/group data
        from /etc/passwd and /etc/group if so configured.  From Gregory
        Nutt.
      - libs/libc/stdio/:  Add support for the size_t integer qualifier 'z'
        to the printf family.  This is kind of tricky due the variety of
        sizeof(size_t) on different platforms.  From David Sidrane.
      - libs/libc/unistd.h:  Added stubbed implementations of setuid() and
        setgid().  These functions are essentially stubs pretending that
        NuttX supported users and groups and that the only configured user
        and group in the system were both 'root' with a uid and a gid of 0,
        respectively.  The intent is not to provide meaningful new features,
        but to ease porting of foreign source code to NuttX.  From Michael
        Jung.
      - libs/libc/unistd/:  Add getuid() and getgid() stubs to match
        MichaelJung's setuid() and setgid().  From Gregory Nutt.
      - libc/libc/unistd/:  Add stubs for geteuid(), getegid(), seteuid(),
        setegid(), setreuid(), and setregid().  NuttX does not currently
        support effective user/group IDs, but these stubs will support
        linkage of applications that expect these POSIX standard interfaces.
        From Gregory Nutt.

    * Symbol Tables:

      - NuttX provides lists of available syscalls and library functions and
        tools to process them.  The lists can be used to build symbol table
        which allows runtime program loading which can reuse functions
        already compiled into NuttX system image.  List processing,
        compilation and linking to the final system image has been possible
        only under manual control until now.  Provided changes add option
        (CONFIG_EXECFUNCS_GENERATE_SYSTEM_SYMTAB) to build complete list of
        available functions and syscalls automatically.  The symbolic table
        is generated in form libsymtab.a which can be reused by application
        or directly pull in when "g_symtab" and "g_nsymbols" variables are
        requested by EXECFUNCS configuration.  I have tried to follow
        mechanisms for library compilation in different kernel protection
        modes but tested only flat no-MMU build. The basic assumption is
        that this library and libraries providing syscall stubs and C-
        library functions are available in user-space context and initial
        application (usually NSH) registers the symbol table through IOCTL.
        The table can be reused then by another applications in their
        address space as kernel allows. Simple for flat or protected mode,
        I am not sure if really support in MMU mode. It is highly probable
        that I have made some mistake, overlooked something, but the
        functionality is optional (should not cause troubles in any mode if
        disabled) and main purpose is to lower memory overhead when more
        applications are loaded on memory constrained system which usually
        use direct kernel calling without protection or address space
        separation. If the table should be provided by kernel to
        applications then makefiles has to be adjusted.  From Pavel Pisa.

    * Tools:

      - tools/:  Change preferred argument of configurations tools to use
        ':' as the delimiter between <board-name> and <config-name>.  This
        is to emphasize that this is not a path; it is configuration
        specification.  The legacy '/' delimiter is still supported but
        not recommend and not advertised.  Updated configurations
        instructions in README.txt files to show ':' delimiter vs '/'
        delimiter.  Update all configuration-related tools to accept ':'
        separator between board and configuration name.  From Gregory Nutt.

    * apps/ General:

      - Makefile:  Added support for application-specific export target.
        Used by nuttx/tools/mkexport.sh.  From Pavel Pisa.
      - apps/builtins:  Move apps/builtins/builtin_forindex.c to
        nuttx/libs/libc/builtin since it is required by kernel logic as
        well.  Other changes account for movement of builtin.h from
        nuttx/include/nuttx/binfmt/built.h to nuttx/include/lib/builtin.h.
        From Gregory Nutt.

    * Examples/Tests: apps/examples:

      - apps/examples/uid:  Demo used to verify PASSWD and GROUP interfaces.
        From Gregory Nutt.
      - apps/examples/webserver/:  Initialilze network and run forever only
        if not built-in app.  Infer from CONFIG_NSH_BUILTIN_APPS if we are a
        NSH built-in app or not.  If built-in app (CONFIG_NSH_BUILTIN_APPS
        defined) then we assume network is initialized prior to webserver
        starting and we exit on webserver failure.  If running standalone
        (CONFIG_NSH_BUILTIN_APPS is undefined) then behavior is unchanged:
        webserver initializes network and runs forever.  From Nathan Hartman.

    * Network Utilities: apps/fsutils:

      - apps/fsutils/passwd:  Handle the improved the format of the
        /etc/passwd file.  It is now a little more similar to other systems.
        From Gregory Nutt.

    * Network Utilities: apps/netutils:

      - apps/netutils/dhcpc:  Add host name support to DHCP client.  From
        Masayuki Ishikawa.

    * Network Utilities: apps/wireless

      - apps/wireless/ieee802154/i8sak:  I8sak improvements:  (1) Adds
        support for getting/setting maxretries and promsicuous mode from
        i8sak, (2) Fixes a build warning and handles a few cases where a
        fault can occur due to not catching missing arguments.  From
        Anthony Merlino.
      - apps/wireless/ieee802154/i8sak:  Allow setting the endpoint PAN ID.
        From Anthony Merlino.
      - apps/wireless/ieee802154/i8sak:  Adds support for energy scan result
        printout.  From Anthony Merlino.
      - apps/wireless/ieee802154/i8shark:  Adds support for intentionally
        suppressing passing the FCS so that Wireshark doesn't try to
        validate it.  From Anthony Merlino.
      - apps/wireless/ieee802154/libmac:  Adds support for getting/setting
        the FCS length  From Anthony Merlino.
      - apps/wireless/gs2200m:  Add UDP support to the GS2200M driver.  From
        Masayuki Ishikawa.
      - apps/wireless/gs2200m:  Add DHCP client handling in ioctl_request().
        From Masayuki Ishikawa.
      - apps/wireless/gs2200m:  ioctl_request() supports SIOCGIFHWADDR.
        From Masayuki Ishikawa.

Bugfixes:
---------
Only the most critical bugfixes are listed here (see the ChangeLog for a
more complete list of bugfixes and for additional, more detailed bugfix
information):

    * Core OS:

      - Priority Inheritance:  Fix a race in telnet with PRIORITY_INHERITANCE
        and SCHED_HPWORK.  Sometimes causes an assertion to fire incorrectly.
        From David S. Alessio.
      - Task Groups:  Correct some naming.  The NuttX task groups have been
        using the acronym 'gid' and also the type 'gid_t' for the the task
        group ID.  That is incorrect.  Than naming is reserved for use with
        group permissions.  So these were all named to grpid and grpid_t so
        that it is clearer that these refer to NuttX task group IDs, and not
        to group permissions.  From Gregory Nutt.
      - Task Termination:  nxtask_signalparent() in task_exithook.c may
        invalidate the group's parent task ID (tg_ppid) too soon.  The
        tg_ppid field is use only to remember the parent tasks ID so that it
        can send the SIGCHLD signal to it.  So it must stay valid until
        SIGCHLD has been sent.  In nxtask_signalparent(), it calls
        nxtask_sigchild() to send SIGCHLD to the parent, then invalidates
        tg_ppid.  That would be okay, except that the SIGCHLD is only sent
        when the last member of the group terminates. That is incorrect;
        tg_ppid can be invalidated too soon and, as a consequence, SIGCHLD
        would never be sent.  Noted by Jeongchan Kim in the Google group:
        https://groups.google.com/forum/#!topic/nuttx/SXd8fVwVKBk  From
        Gregory Nutt.
      - sched_get_rr_interval():  sched_get_rr_interval() should return
        {0,0} if round-robin scheduling is not selected for the task.  From
        Gregory Nutt.
      - SMP Type Collision:  The non-standard, non-portable type cpu_set_t
        was created specifically to support the NuttX internal, SMP
        implementation.  Any resemblance to any other cpu_set_t would be
        purely coincidental.  However it appears that that coincidence has
        occurred.  cpu_set_t has an equivalent, non-standard, non-portable
        type in the GNU C library.  Compilation of libgnat expects this
        non-standard type to be defined.  Who am I to stand in the way of
        progress?  This commit removes the conditioning on CONFIG_SMP so
        that cpu_set_t is typed (as a uint8_t) even if CONFIG_SMP is not
        defined.  Reference:  Bitbucket issue 164.  From Gregory Nutt.
      - Binary Loader:  Change some debug macros from berr() to binfo()
        when dumping module data.  The report of problems is important
        during development but when it enables complete informative output
        about load binaries then the important information can be easily
        overlooked.  The huge output sent to serial terminal slows loading
        significantly as well.  From Pavel Pisa.
      - Power Management:  Fix g_pmcount 16-bits overflow when
        CONFIG_PM_XXENTER_COUNT set big value.  From ligd.
      - Timekeeping:  Fix cases in time conversion that must be >=
        NSEC_PER_SEC, not > NSEC_PER_SEC.  From Gregory Nutt.

    * File System/Block and MTD Drivers:

      - opendir():  opendir() set errno to a negative value in one error
        case.  From Michael Jung.
      - SmartFS:  Update smartfs smart_scan() function.  From Simon Piriou.
      - ProcFS:  Add missing LF to cpuload procfs output  From David Alessio.
      - MMC/SD:  Copy/paste error fix in the SDIO-based block driver for
        MMC.  From Ivan Ucherdzhiev.
      - MMC/SD:  Correct a misplaced #endif in the SDIO-based driver.  From
        Gregory Nutt.

    * Networking/Network Drivers:

      - Ethernet Configuration:  Ethernet packet buffer size cannot be
        permitted to go below 1294 if IPv6 is selected.  From Gregory Nutt.
      - TCP RST:  Fix outgoing RST packet with wrong ack number.  From
        biantao.
      - TCP Close:  Fix TCP close flow; free the connection after all TCP
        close process finished.  From zhangyuan7.
      - UDP Broadcast:  Remove net stack dependency from CONFIG_NET_BROADCAST.
        This change allows us to use CONFIG_NET_BROADCAST without network
        stack (i.e. usrsock application can use broadcast)  From Masayuki
        Ishikawa.
      - UDP:  Fixes a UDP send copy-paste error in the new SO_LINGER code:
        CONFIG_TCP_NOTIFIER to CONFIG_UDP_NOTIFIER.  From Juha Niskanen.
      - TCP and UDP:  Fix errors in the new implementation of SO_LINGER.
        The tcp_drain() and udp_drain() functions were casting the working
        argument to the wrong type, resulting in hangs and abnormal
        behavior.  There is a complexity in the TCP drain logic when the
        remote peer closes the socket before all Tx data has been flushed.
        Sometimes we are not notified of this case and wait the entire
        timeout unnecessarily.  There is a workaround in place in
        tcp_txdrain(), but this really should be revisited.  From Gregory
        Nutt.
      - 6LoWPAN:  Removes unnecessary conversions that were happening due to
        a misunderstanding of byte ordering with EUI-64.  From Anthony
        Merlino.
      - RNDIS:  Fix issue with DEBUGASSERT when using composite device and
        endpoint numbers not being the default.  From Anthony Merlino.

    * Wireless/Wireless Drivers:

      - wireless network devices:  Attach radio to d_buf before registering
        device to handle forwarding case.  When CONFIG_NET_IPFORWARD is
        enabled, and CONFIG_NET_6LOWPAN is being used, a packet that
        attempts to get forwarded on the 6LoWPAN interface will require
        that the radio's buffer be attached to d_buf. Otherwise an assertion
        will fire.  The underlying "radio" in this case is the
        mac802154_netdev.  This behavior has probably not been observed
        because the buffer is normally attached in the periodic txpoll
        worker.  However, in my case, the 6LoWPAN interface was not UP yet,
        and therefore the worker hadn't run yet.  From Anthony Merlino.
      - IEEE 802.15.4 MAC:  Fixes issues with extended address. 1) Extended
        address should be read-only. 2) Extended address should be placed
        in frame in "reverse-canonical" order.  The extended address is a
        read-only attribute and thus an attempt to write the extended
        address should be denied. Instead, the extended address should
        really be either set by the PHY/radio itself, or provided at board
        bring-up time to the radio layer. The MAC layer now pulls in the
        extended address from the radio any time the MAC is reset.  The
        extended address is also supposed to be sent in the frame in
        reverse-canonical order. This is very confusing in the standard and
        it wasn't until I realized it was backwards in Wireshark that I
        researched this further. Searching online I find documents from the
        committee for suggestions/feedback on the future standard.  It isn't
        in the 2015 standard but a newer version of the standard will
        presumably clarify this. It says that the extended address should be
        written in reverse-canonical form, meaning the OUI comes last, not
        first inside the frame.  From Anthony Merlino.
      - IEEE 802.15.4 MAC:  Frame Version should have been 1, but was being
        set to 3 when payload exceeds version 0 capabilities.  Adds warning
        to build to indicate what is noted in the menu for
        CONFIG_MAC802154_NTXDESC  From Anthony Merlino.
      - IEEE 802.15.4 MAC:  Fixes issue where the txdesc's ackreq flag was
        not being set, despite the frame containing a Frame Control field
        with ACKREQ bit set.  From Anthony Merlino.
      - Xbee:  Fix logic to prevent deadlock scenario when there are no
        available IOBs  From Anthony Merlino (2018-12-21).
      - Xbee:  Change assumption about destination address mode for incoming
        frames.  If a short address has been assigned to our radio, then
        assume we were addressed using that.  Otherwise we were addressed
        using our extended address.  From Anthony Merlino.
      - Xbee:  Initialize the short address to the unspecified address and
        query for the extended address on initialization.  From Anthony
        Merlino.
      - Xbee:  Adds CONFIG_XBEE_LOCKUP_WORKAROUND option and corresponding
        logic to workaround an issue where the XBee locks up and stops
        responding.  This typically happens when there is a lot of data
        being received over the link.  When the XBee stops responding, many
        times, querying the XBee kicks it out of this state.  However,
        occasionally the XBee is completely locked up and the XBee has to
        be reset.  This change handles these conditions by periodically
        (if not naturally occurring) querying the XBee.  If during any
        query, the XBee does not respond within a certain number of
        attempts, the XBee is reset.  From Anthony Merlino.
      - Xbee:  Cancel query timeout upon receiving the expected response.
        Add protection for race condition that can cause association
        timeout to continue firing repeatedly  From Anthony Merlino.
      - Xbee:  Detect lockup and reset XBee in xbee_req_data  From Anthony
        Merlino.
      - Xbee:  Fixes one instance of the use of IOBUSER_WIRELESS_MAC802154
        which isn't available without the software MAC layer.  Instead we
        use IOBUSER_WIRELESS_RAD802154 throughout the whole driver since it
        is always available when IEEE 802.15.4 support is enable.  From
        Anthony Merlino.

    * Common Drivers:

      - pipes:  Use inode reference counter instead of device reference
        counter to handle dup().  I found that if I dup() a pipe, the
        reference counter d_refs is not increased.  If I close any of the
        fd, backed by the same pipe, the pipe will be freed.  This causes
        any further usage on the fd referencing a non existent pipe.  This
        change uses the inode reference counter, which is properly
        maintained during dup().  From Yang ChungFan.
      - SPI Bitbang:  Fix build error when the SPI bitbang variable width
        support is enabled.  From Augusto Fraga Giachero.
      - GPIO Lower Half:  Remove limitation when pintype >
        GPIO_INTERRUPT_PIN.  From ligd.

    * ARMv4/ARMv5

      - Classic ARM7/ARM9:  When performing stability test, the application
        would cause kernel crash. When I trace the stack, I find that
        register R1 has been changed, and its value is the same as register
        CPSR.  In up_fullcontextrestore.S, the restoration of R0 and R1 is
        not atomic:  'msr cpsr r1 will enable interrupts and the recovery of
        r0 and r1 may be interrupted and the value or R1 may be changed.
        Fix is to use a single ldmia to restore R0, R1, and return via R15.
        From Loyen Wang.

    * ARMv7-A

      - ARMv7-A:  Fix typo and missing quotation for ARMv7-A.  From Oki
        Minabe.
      - ARMv7-A:  Fix double increment in armv7-a's
        arm_addrenv_destroy_region().  From Oki Minabe.
      - ARMv7-A:  Fix L2 page table mask for ARMv7-A page allocator.  From
        Oki Minabe.

    * ARMv7-M

      - Interrupts.  Removes the architecture-common
        CONFIG_ARCH_INT_DISABLEALL configuration option (but which was
        supported only by ARMv7-M).  In the normal course of things,
        interrupts must occasionally be disabled using the up_irq_save()
        inline function to prevent contention in use of resources that may
        be shared between interrupt level and non-interrupt level logic.
        Now the question arises, if we are using BASEPRI to disable
        interrupts and have high priority interrupts enabled
        (CONFIG_ARCH_HIPRI_INTERRUPT=y), do we disable all interrupts except
        SVCall (we cannot disable SVCall interrupts).  Or do we only disable
        the "normal" interrupts?  If we are using the BASEPRI register to
        disable interrupts, then the answer is that we must disable ONLY the
        "normal interrupts".  That is because we cannot disable SVCALL
        interrupts and we cannot permit SVCAll interrupts running at a
        higher priority than the high priority interrupts (otherwise, they
        will introduce jitter in the high priority interrupt response time.)
        Hence, if you need to disable the high priority interrupt, you will
        have to disable the interrupt either at the peripheral that
        generates the interrupt or at the NVIC.  Disabling global interrupts
        via the BASEPRI register cannot effect high priority interrupts.
        From Gregory Nutt.
      - ARMv7-M Priorities:  In the 'normal' case, the priority of the
        SVCALL interrupt was the same as the priority of the high priority
        interrupt.  This means that SVCALL interrupt processing can defer
        the high priority interrupt and result in the jitter in that
        interrupt response.  Fix is to raise the priority of the high
        priority interrupt above the priority of the SVCALL interrupt.
        Suggested by Nathan Hartman.  From Gregory Nutt.

    * Microchip i.MXRT Drivers:

      - i.MXRT ENC:  Fix some errors in register bit definitions.  Noted by
        Arie de Muijnck.  From Gregory Nutt.
      - i.MXRT LPI2C:  Slave addresses are now correctly shifted when
        sending START.  TX/RX FIFOs now discarded on error to prevent FIFO
        underflow errors.  Fixes error checking to use priv structure and
        removes checking of BBF flag as it is not an error.  From Nicholas
        Chin.

    * Microchip PIC32MZ Drivers:

      - PIC32MZ SPI:  Fix SPI Mode selection.  CKE is the inversion of the
        CPHA.  From Ouss4.

    * Microchip/Atmel SAMD2x/SAML2x Drivers:

      - SAMD2/L2 I2C:  Correct time calculation.  From Bernd Walter.

    * Microchip/Atmel SAM3/SAM4:

      - SAM3/4:  Add missing DMA configuration Kconfig setting.  From Bernd
        Walter.

    * NXP LPC17xx/40xx Drivers:

      - LPC17xx/40xx ADC:  Only use PCLKSEL0 for ADC on LPC176x family.
        From jjlange.
      - LPC17xx/40xx Ethernet:  Set speed back to 10Mbps if 10Mmbps link
        negotiated.  From Augusto Fraga Giachero.
      - LPC17xx/40xx I2C:  Abort I2C transfers if a timeout has occurred.
        If a timeout has occurred in the middle of a I2C transfer, the next
        I2C interrupt should abort any transfers and send a stop condition
        to the corresponding I2C bus.  Failure to do so will result in
        memory corruption / undefined behavior as priv->msgs points to a
        region of memory it doesn't owns anymore after lpc17_40_i2c_start
        returns.  From Augusto Fraga Giachero.
      - LPC17xx/40xx I2C:  Calculate the appropriate timeout for I2C
        transfers.  Depending on the bus frequency and transfer size, I2C
        transactions can take quite a bit, so a fixed timeout is not a
        good solution.  Calculating the timeout at run time poses some
        overhead but still better than aborting long transactions.  From
        Augusto Fraga Giachero.

    * NXP/Freescale Kinetis Drivers:

      - Kinetis I2C:  i2c transfer ensure correct result returned.
        kinetis_i2c_transfer released the mutex then fetched the state,
        this resulted in returning the correct results.  From David
        Sidrane.

    * NXP LPC17xx/40xx Drivers:

      - LPC17xx/40xx CAN:  If BOARD_CCLKSEL_DIVIDER is not equal to 1 on
        LPC178x or LPC40xx then base clock rate is calculated incorrectly
        because CCLK frequency does not correspond to PLL0 clock which is
        used for PCLK.  This  is partially workaround solution.  It would
        be probably better to define BOARD_PCLK_FREQUENCY even for LPC176x
        targets and use that to replace divisor by base_clock in up_dev_s.
        From Pavel Pisa.

    * NXP LPC17xx/40xx Boards:

      - LPC17xx/40xx Ethernet:  Add missing LPC17_40_PHY_CEMENT_DISABLE
        variable to the lpc17xx/40xx Kconfig file.  For some reason this
        setting was not referenced anywhere except in the Ethernet driver.
        From Augusto Fraga Giachero.
      - LPC17xx/40xx Ethernet:  Fix the initialization for DP83848x PHYs.
        The DP83848x requires the RMII mode to be manually enabled through
        the MII_DP83848C_RBR register. Before querying the speed and mode
        it should wait for the link to be established.  From Augusto Fraga
        Giachero.

    * NXP i.MXRT Drivers:

      - i.MXRT LPUART:  Fix some errors in the LPUART register definition
        files.  Correct naming of a function:  up_earlyserialinit() should
        be imxrt_earlyserialinit().  Remove prototypes for non-existent
        serial initialization functions.  From Gregory Nutt.
      - i.MXRT USDHC:  uSDHC typo fixes and command transfer error handling
        modified.  From Ivan Ucherdzhiev.

    * SiLabs EFM32 Drivers:

      - EFM32 OTG host:  Adam Porter's various fixex for STM32 FS/HS
        probably should be applied to EFM32 host which which has very
        similar IP.  From Gregory Nutt.

    * STMicro STM32:

      - STM327F Configuration:  Kconfig add depends on BBSRAM.  From David
        Sidrane.
      - STM32F7 Interrupts:  Fix overwritten IRQ enable.  System boot order
        calls clock_initialize() then up_initialize().  clock_initialize()
        was setting up the alarm IRQ up_initialize is initializing the NVIC.
        This most likely worked in the past due to a bug in the NVIC
        initialization code that failed to clear the Interrupt enables.
      - STM32H7:  Rix BBSRAM name in memory map.  From David Sidrane.
      - STM32H7:  Removed f7 in file path.  From David Sidrane.

    * STMicro STM32 Drivers:

      - STM32H7 BBSRAM:  Fix issues causing no writes and hardfaults.  From
        David Sidrane.
      - STM32H7 BBSRAM:  Convince compiler to perform 32 bit write.  From
        David Sidrane.
      - STM32F7 OTGHS:  Fixes bad preprocessor logic preventing USB OTG HS
        to work when used without external ULPI.  From Anthony Merlino.
      - STM32 OTGH[FS|HS] Host  STM32 host only initiates transfer if
        buflenl > 0.  From Adam Porter.
      - STM32F7/H7/L4 OTG host:  Adam Porter's fix for STM32 FS/HS probably
        should be applied to STM32 F7, H7, and L4 OTG host which are very
        similar.  From Gregory Nutt.
      - STM32/F7/H7/L4:  This change was required to get my devices
        (CDC-MBIM) to enumerate.  Initially the system timed out retrieving
        the USB configuration descriptor.  Ctrl IN requests got nothing but
        NAKs.  I found that the initial SETUP packet and corresponding IN
        transfer were fine; it was the Status OUT phase that was getting the
        NAK.  After receiving a NAK on the Status OUT, the code would loop
        back and issue another ctrl IN, which will always fail because the
        data was already transferred before. Thus the entire transfer would
        'timeout'.  The fix I implemented moves the DATANAK timeout loop to
        only apply to the Status OUT.  Both the ctrl IN and the Status OUT
        need their own retry loops.  From Adam Porter.
      - STM32F7 SDMMC:  If there is only one SDMMC it is slot 0  From David
        Sidrane.
      - STM32F7 USART1:  USART1_RXDMA is dependent on STM32F7_DMA2 not
        STM32F7_DMA1  From Anthony Merlino.
      - STM32H7 DBGMCU:  Memory Map DBGMCU is @ 0x5c001000  From David
        Sidrane.
      - STM32F7 SDMMC:  Fix warning when DMA is not enabled.  From David
        Sidrane.
      - STM32H7 Ethernet:  Fix some errors in Ethernet MAC configuration.
        From Markus Bernet.
      - STM32H7 Ethernet:  Correct stm32h7 mac address filtering.  Correct
        the MAC address 0 register definition and remove the 'receive all'
        flag.  Now the Ethernet driver only receives packets addressed to
        correct MAC.  From Jukka Laitinen.
      - STM32H7 Ethernet:  Correct memory corruption error.  The Ethernet
        driver initialization incorrectly wrote to DMACRXCR instead of
        DMACSR when trying to clear the stopped flags.  This caused
        invalid buffer length in the DMACRXCR, causing DMA to overflow the
        RX buffers when large packets are sent to the device.  From Jukka
        Laitinen.
      - STM32H7 PWR:  Ensure data is flushed on backup domain access
        changes.  From David Sidrane.
      - STM32H7 Serial:  Serial fix undefined with TERMIOS  From David
        Sidrane.
      - STM32H7 UARTs:  Fix UART7/8 typos.  Fix bug in ETH_MACQTXFCR
        configuration.  From Markus Bernet.

    * STMicro STM32 Boards:

      - Multiple STM32 Boards:  If CONFIG_SCHED_CRITMONITOR is selected,
        then make sure that ITM and DWT resources are enabled before
        accessing ITM and DWT registers.  By default, these registers are
        disabled.  Suggested by Juha Niskanen.  From Gregory Nutt.
      - Nucleo-H743ZI:  Correct logic that determines if the RTC driver is
        available.  Find in build testing.  From Gregory Nutt.
      - Nucleo-G071RB:  Fix linker script to avoid .ARM.exidx section
        overlap with .data  From Daniel Pereira Volpato.
      - Modify all linker scripts (all boards, all architectures) to use
        solution from Daniel P. Volpato.  From Alan Carvalho de Assis.
      - Nucleo-L432KC ADC:  Change analog pins definitions and correct DMA
        related issue.  From Daniel P. Carvalho.

    * TI Tiva:

      - Tiva Configuration:  Rename TM4C123GH6PMI identifiers to
        TM4C123GH6PM.  Rationale: In terms of firmware programming, there
        is no functional difference between these parts:  TM4C123GH6PMI7,
        TM4C123GH6PMI7R, TM4C123GH6PMT7, and TM4C123GH6PMT7R.  From a
        programming standpoint, all of the above parts are TM4C123GH6PM,
        which means it doesn't make sense to differentiate between PM and
        PMI. (The PM means 64-LQFP. The I means temperature range -40C to
        +85C. It could be T meaning -40C to +105C. The R means it ships in
        Tape and Reel packaging as opposed to Tray.)  From Nathan Hartman.
      - Tiva Configuration:  Rename TM4C1294NC identifiers to TM4C1294NCPDT.
        Rationale: TM4C1294NC is ambiguous: TM4C1294NCPDT is a 128-TQFP,
        TM4C1294NCZAD is a 212-NFBGA.  The TM4C1294NC part currently
        supported by NuttX is the TM4C1294NCPDT used on the TI EK-TM4C1294XL
        "Connected LaunchPad" (see configs/tm4c1294-launchpad).  To ensure
        the correct part is fully specified, this commit updates all
        TM4C1294NC identifiers to TM4C1294NCPDT.  From Nathan Hartman.
      - Tiva Configuration:  Fix TM4C129XNCZAD part number in Kconfig and
        identifiers.  Rationale: Fully specify that this is the 212-pin BGA
        package (ZAD ending) and for consistency with earlier changes to
        other Tiva TM4C12x part numbers in Kconfig names and identifiers.
        From Nathan Hartman.

    * TI Tiva Drivers:

      - Tiva TM4C 1-Wire:  Fix wrong description on define TIVA_1WIRE_BASE:
        Was "EEPROM and Key Locker" (same as the item above). Now "1-Wire
        Master Module." Make DMACTL symbols visible for TM4C123:  Remove
        "#ifdef CONFIG_ARCH_CHIP_TM4C129" guard around UART DMA Control
        (DMACTL) symbols.  These bits are valid on TM4C123 devices, as well
        as on TM4C129. Also, improve the comment on UART_DMACTL_DMAERR.
        From Nathan Hartman.
      - Tiva GPIO Interrupts:  LM3S, LM4F, TM4C: Fix GPIO IRQ error, ports
        R, S, T.  Preprocessor logic for CONFIG_TIVA_GPIOx_IRQS was setting/
        clearing port Q defines when it should act on ports R, S, T.
        gpioport2irq() was missing handling for port T.  From Nathan
        Hartman.
      - Tiva Timers:  Fix minor errors in tiva_timerlib.c.  Fix incorrect
        preprocessor conditionals related to Kconfig defines:
        CONFIG_TIVA_TIMER32_EDGECOUNT -> CONFIG_TIVA_TIMER16_EDGECOUNT,
        CONFIG_TIVA_TIMER32_TIMECAP -> CONFIG_TIVA_TIMER16_TIMECAP,
        CONFIG_TIVA_TIMER32_PWM -> CONFIG_TIVA_TIMER16_PWM.  From Nathan
        Hartman.
      - Tiva Timers: Fix errors in low-level timer support.
        tiva_gptm_configure() and tiva_gptm_release() were calling
        tiva_emac_periphrdy() instead of tiva_gptm_periphrdy().  Fix
        error in "abcde" description of bit flag defines.  From Nathan
        Hartman.
      - Tiva Timers:  Fix one code error and some comment errors.
        tiva_timer16_setinterval(): Was DEBUGASSERTing on mode !=
        TIMER16_MODE.  Fixed to DEBUGASSERT on mode == TIMER16_MODE.
        From Nathan Hartman.

    * ZiLOG Z80 Boards:

      - z80sim Serial:  Fix uart_dev_t initializer:  pollfds[] is a array of
        pointers and, hence, the NULL initializer must be included in braces.
        Noted by Paul Osmialowski in Issue #160.  From Gregory Nutt.
      - z80sim Interrupts:  Missed a name change up_irqinitialize to
        z80_irq_initialize.  From Gregory Nutt.

    * C Library/Header Files:

      - include/netinet/in.h:  Rename __pad member to sin_zero in struct
        sockaddr_in.  Libwebsockets initializes the 'sin_zero' member of
        sockaddr_in objects to zeros.  Apparently, judging from mailing list
        entries, there are platforms on which not doing this causes
        undefined behavior.  On NuttX compiling respective code is broken,
        as the corresponding member variable is called '__pad'.  Neither in
        the 'nuttx' nor in the 'apps' repository did I find any reference to
        this identifier.  Thus, I believe its a safe bet to just rename it.
        UNIX Network Programming states in this regard:  "The POSIX
        specification requires only three members in the structure:
        sin_family, sin_addr, and sin_port. It is acceptable for a POSIX-
        compliant implementation to define additional structure members, and
        this is normal for an Internet socket address structure. Almost all
        implementations add the sin_zero member so that all socket address
        structures are at least 16 bytes in size."  From Michael Jung.

      - libs/libc/libc.csv:  Correct dependency of setlocale on
        CONFIG_LIBC_LOCALE.  From Pavel Pisa.
      - libs/libc/machine/arm/armv7-m:  Fix build error for ELF.  From
        Masayuki Ishikawa.
      - libs/libc/math.csv:  Correct format of some function entries.  From
        Pavel Pisa.

    * Tools:

      - tools/:  Change all occurrences of /bin/(ba)sh in shell scripts to
        /usr/bin/env bash which appears more portable  From Manuel Stühn.

    * NSH Library: apps/nshlib:

      - apps/nshlib/:  As noted by David S. Alessio, 'cat' should not output
        any additional newline at the end of the cat'ed file content.  This
        additional newline was added to assure that the NSH prompt was
        presented on a new line.  However, that is not the correct behavior
        of 'cat' per the IEEE std:  "The standard output shall contain the
        sequence of bytes read from the input files. Nothing else shall be
        written to the standard output."  Reference:
        https://pubs.opengroup.org/onlinepubs/009695399/utilities/cat.html.
        This commit changes the function nsh_catfile() which underlies the
        'cat' command and well as other NSH commands.  Although this is the
        correct behavior for 'cat' it may not be the correct behavior for
        other commands implemented via nsh_catfile().  That remains to be
        determined.  From Gregory Nutt.

    * System Utilities: apps/system:

      - apps/system/cle/:  ASCII DEL should be treated by Delete-Left.  From
        Dave Marples.
      - apps/system/i2ctool:  (1) Friendlier I2C "knock-knock" uses only
        read request.  While many I2C slave devices have multiple indexed
        registers, some have only one register and it's not indexed.  For
        example, the I2C bus switch TCA9548A has only a Control Register,
        attempting to index to "Reg[0]" alters its contents to 0x00
        disabling all subordinate buses.  This patch fixes that problem by
        simply trying to read something/anything from the slave.  This also
        helps coax out slaves with register files that start from a higher
        index, i.e. the AT24CS0x, FLASH chips with a UUID that appears as a
        2nd I2C slave at (address+8), report their serial number at
        Reg[80]-Reg[8F] and will NAK a read of Reg[0].  (2) Modify get/set
        to prevent write of reg index if not specified  From David Alessio.

    * Network Utilities: apps/netutils:

      - apps/netutils/dhcpd:  Fixes bug where hwaddr was being used instead
        of ipaddr in the ARP update.  This bug seems to have been introduced
        three years ago during a rewrite to remove a direct OS call to arp.
        I'm not sure how others have not run into issues with this.  The
        behavior I was observing was that the DHCPD would go to offer an IP
        address, but then send a ARP request for the IP instead because it
        didn't know where to send the data.  From Anthony Merlino.
      - apps/netutils/netinit/:  Remove warnings.  Unhook PHY notification
        signal handler when cleaning up, if an error occurs after the signal
        handler is put into place.  From Nathan Hartman.

    * Wireless Utilities: apps/wireless:

      - apps/wireless/ieee802154/i8sak:  Fixes conversion from extended
        address to IPv6 address.  From Anthony Merlino.

NuttX-8.2 Release Notes
------------------------

The 133rd release of NuttX, Version 8.2, was made on November 16, 2019,
and is available for download from the Bitbucket.org website.  Note
that release consists of two tarballs:  nuttx-8.2.tar.gz and
apps-8.2.tar.gz.  These are available from:

    https://bitbucket.org/nuttx/nuttx/downloads
    https://bitbucket.org/nuttx/apps/downloads

Both may be needed (see the top-level nuttx/README.txt file for build
information).

Additional new features and extended functionality:
---------------------------------------------------

    * Core OS:

      - Signals:  Add support for SIGPIPE default action.  SIGPIPE uses
        SIG_SIGPIPE_ACTION which terminates process by default.  It also
        could be ignored.  From liuhaitao.
      - Spinlocks:  Remove support for re-entrant spinlocks.  They seemed
        like a good idea, but they are never used.  From Xiang Xiao.
      - Memory Manager:  Remove the assumption that one character equals
        eight bits.  From Xiang Xiao.
      - Power Management:  Historically, the NuttX PM subsystem has
        consisted of two functional components:  (1) an "Upper" part that
        detects state changes based on a random walk driven by activity
        levels, and (2) and "lower" part that implementst the state changes.
        This change decouples that upper activity-based logic from the lower
        random walk logic and allows use of other upper state detection
        logic (such as a custom, application-specific state machine).  From
        Matias Nitsche.
      - boardctl():  Expose power manager function through boardctl()
        interface.  From Xiang Xiao.

    * File System/Block and MTD Drivers:

      - GD25:  Add support for a new FLASH vendor.  From zhangbo_a.
      - GD25:  Add support for GD25 device with 256-Mbit capacity.  From
        YanLin Zhu.
      - GD25:  Add 4-byte address operation for capacity larger than
        128-Mbit.  From YanLin Zhu.
      - GD25:  Add gd25_lock/unlock to case: enable 4-bytes address  From
        ligd.
      - GD5F:  Add gigadevice SPI NAND FLASH driver.  From YanLin Zhu.

    * Networking/Network Drivers:

      - Networking:  Use ntoh() when printing IPv6 addresses so that the
        addresses appear in friendlier host order vs. network order.  From
        Bernd Walter.
      - Netlink:  Implement minimal NETLINK_ROUTE socket functionality that
        can (for now) be use used to obtain a list of network devices, IPv4
        ARP and IPv6 Neighbor tables, and IPv4 and IPv6 routing tables.
        From Gregory Nutt.

    * Wireless/Wireless Drivers:

      - BCM43438A1 Bluetooth:  Add support for the BCM43438A1 Bluetooth
        capability.  From Dave Marples.
      - HCIUART Shim:  Add a serial 'shim' to allow any regular serial port
        to support a Bluetooth H4 interface and to be used to drive a
        Bluetooth device.  From Dave Marples.
      - BCM4343x HCIUART:  BCM4343x HCIUART support.  From Dave Marples.
      - BCM43xxx:  Move drivers/wireless/ieee80211/ to
        drivers/wireless/ieee80211/bcm43xxx/ since the directory only
        contains only BCM43362 and BCM43438 related code.  From Xiang Xiao.
      - GS2200M:  Add reset handler to interface.  Add reset and un-reset
        sequence in driver. From Masayuki Ishikawa.

    * Audio/Audio Drivers:

      - Audio:  Add message type to support audio trigger.  From anchao.

    * Other Common Device Drivers:

      - Altair:  Add support for the altair LTE modem driver.  From Alin
        Jerpelea.
      - MCP2515:  MCP2525 SPI STD-EXT ID fixes.  From DisruptiveNL.
      - OpenAMP:  Brings in the drivers needed to support OpenAMP.  These
        changes were ported from https://github.com/FishsemiCode/nuttx.
        This port was effort of a number of people, I rather arbitrarily
        gave authorship to Guiding Li because he has the largest number of
        fundamental quashed commits from the Xiamoi repository.  From
        Guiding Li.

    * Simulator:

      - Simulator:  Add stack coloration feature.  From ligd.
      - Simulator:  Report PM activity on simulated UART.  From Matias
        Nitsche.
      - Simulator:  Add host ftruncate() support.  From chao.an.
      - Simulator:  Replace all CONFIG_DEV_CONSOLE with USE_DEVCONSOLE for
        arch/sim and compile up_devconsole.c conditionally.  From Xiang
        Xiao.
      - Simulator OpenAMP:  Support OpenAMP between two simulator
        instances.  Please read rpserver/rpproxy section in
        boards/sim/sim/sim/README.txt for more information.  From chao.an.

    * ARMv7-M

      - ARMv7-M:  Add BPIALL register address.  From Dave Marples.
      - ARMv7-M MPU:  Add user peripheral helper

    * Atmel SAMD2/L2 Boards:

      - Arduino-M0:  Add initial board support for the Arduino M0 which is
        based on the SAMD21 chip.  Include nsh and usbnsh configurations.
        From Alan Carvalho de Assis.

    * NXP i.MXRT Drivers:

      - i.MXRT LCD:  Add support for LCD.  Clean up some LCD-related
        interfaces.  From Fabio Balzano.
      - i.MXRT Serial:  This change improves the performance of UART serial
        ports on the IMXRT by enabling the RX & TX FIFOS and transmission on
        the holding register being empty (TDRE) rather than transmission
        being complete (TC).  From Dave Marples.
      - i.MXRT Pin Mux:  This change separates out the pinmux and iomux
        functions cleanly.  For ease of conversion default IOMUX definitions
        have been added into imxrt_iomux.h.  The change effectively does two
        things:  (1) unifies the iomux definitions - previously some pins
        had them, and some didn't. This effectively made it impossible to
        use the pinmuxes without editing the header file in the standard
        distribution tree. And (2) unifies the pin definitions so that every
        pin now has a suffix. This makes it *much* easier to see when a pin
        is in use in your code, because it will always have a definition in
        your board.h file.  From Dave Marples.
      - IMXRT1020-EVK:  Add support for the MIMXRT1021-EVK board.  It
        features nsh, netnsh and usdhc sample configurations.  From Dave
        Marples.

    * NXP i.MXRT Boards:

      - IMXRT1060-EVK:  Add basic LCD support for the board IMXRT1060-EVK.
        From Fabio Balzano.
      - IMXRT1060-EVK:  Added Littlevgl demo configuration into the
        IMXRT1060-EVK board directory.  From Fabio Balzano.

    * NXP/Freescale Kinetis Drivers:

      - Kinetis Ethernet:  Add support for TJA1100 PHY.  From David Sidrane.

    * NXP S31K1xx:

      - S32K1xx:  Support configuration and initialization of the flash
        configuration bytes.  From Gregory

    * NXP S31K1xx Boards:

      - S32K1**EVB:  Create a special FLASH section to hold the FLASH
        configuration bytes.  From Gregory Nutt.
      - S32K146EVB:  Added configuration script and instructions for using
        Thread-Aware OpenOCD for the S32K146 with Eclipse.  From Han
        Raaijmakers.

    * Renesas RX65N:

      - RX65N:  Adds a port of to the Renesas RX65N Micro-controller.  This
        port includes Serial (UART) driver (13 ports) and Ethernet
        driver.  From Anjana.

    * Renesas RX65N Boards:

      - RSK RX65N-2MB:  Add support for the RSK RX65N-2MB board.  From
        Anjana.
      - GR-Rose:  Add support for the GR-Rose board.  From Anjana.

    * Sony CXD56xx

      - CXD56xx CPU FIFO:  Add configurations for CPU FIFO elements.  From
        Alin Jerpelea.
      - CXD56xx Loader:  Update loader and gnssfw ver. 17660.  From Alin
        Jerpelea.
      - CXD56xx SMP:  Add support for SMP.  To run cxd56xx in SMP mode, new
        boot loader which will be released later must be used.  From
        Masayuki Ishikawa.
      - CXD56xx SMP:  Add IRQ routing for SMP in cxd56_irq.c.  In CXD56xx,
        each external interrupt controller can be accessed from a local
        APP_DSP (Cortex-M4F) only.  This change supports IRQ routing for SMP
        by calling up_send_irqreq() in both up_enable_irq() and
        up_disable_irq().  From Masayuki Ishikawa.

    * Sony CXD56xx Drivers:

      - CXD56xx I2C: Add ability to set the i2c frequency to other than just
        100 or 400 Hz.  From Alin Jerpelea.
      - CXD56xx SDHCI:  Reduce power consumption by stopping SD clock.  Re-
        enable SD clock during access to SD card.  Improve GNSS low
        sensitivity with SD card inserted.  From Alin Jerpelea.

    * Sony CXD56xx Spresense Board:

      - CXD56xx Board Common:  Add the Altair LTE modem support on the
        Spresense board.  From Alin Jerpelea.
      - CXD56xx Board Common:  Add Spresense Image Processor.  Enable support
        for accelerated format converter, rotation and so on. using the CXD5602
        image processing accelerator.
      - Spresense:  Add board specific pin configurations of CXD5602 pins to
        fit Spresense board.  From Takayoshi Koizumi.
      - Spresense:  Add a configuration option to select if an extension
        board is attached to the SPresence.  If there is no extension board
        attached, the SPresense may run in a low-power mode by default (as
        determined by the CONFIG_CXD56_CUSTOM_PINCONFIG option).  If an
        extension board is present, then the SPresense will need to run at a
        higher power mode, selected by the new CONFIG_SPRESENSE_EXTENSION
        option.  From Gregory Nutt.
      - Spresense Camera:  Add ISX012 camera initialization and
        configuration.  From Alin Jerpelea.
      - Spresense OS test:  Enable ostest in rndis/defconfig and
        wifi/defconfig. From Masayuki Ishikawa.
      - Spresense:  Add --gc-sections to LDFLAGS and add -ffunction-sections
        and -fdata-sections to ARCHCFLAGS in scripts/Make.defs.   From
        Masayuki Ishikawa.
      - Spresense SMP:  Add smp configuration.  From Masayuki Ishikawa.
      - Spresense SCU:  The SCU has to be initialized at bootup on Spresense
        board because several functions depend on it. Add audio control
        definitions.  Add configuration for the audio implementation.  From
        Alin Jerpelea.
      - Spresense:  Add audio and board audio control implementation.  From
        Alin Jerpelea.
      - Spresense:  Sdd power_control and audio_tone_generator.  Add a simple
        way to control the audio buzzer with defined frequency for user-space
        apps.  From Alin Jerpelea.
      - Spresense:  Add the optional initialization of  GNSS and GEOFENCE at
        boot if the drivers are enabled  From Alin Jerpelea.
      - Spresense:  Add LTE configuration.  From Alin Jerpelea.
      - Spresense:  Enable high current mode for the Spresense Extension
        board on all examples that have SDCARD support.  From Alin Jerpelea.
      - Spresense:  Add lcd examples configuration.  This is a configuration
        for the basic nx examples  From Alin Jerpelea.

    * STMicro STM32:

      - STM32F0/L0/G0:  Add support for STM32G070xx family.  From Daniel
        Pereira Volpato.
      - STM32F0/L0/G0 Power:  Scale dynamic voltage and flash wait states
        properly on STM32G0 chips.  Included preliminary implementation of
        PWR module VOS support.  From Daniel Pereira Volpato.
      - STM32L4R5ZI:  Add support for the STM32L4R5ZI chip type.  From Jussi
        Kivilinna.
      - STM32 L4+ DMA:  Add DMA support for STM32L4+ series.  From Jussi
        Kivilinna.
      - STM32 L4 Clocking:  Enable "Range 1 boost" mode if any PLL freq
        above 80 MHz.  From Jussi Kivilinna.
      - STM32 L4 LPTIM:  Add support for LPTIM timers on the STM32L4 as PWM
        outputs.  From Matias N.
      - STM32 H7 Progmem: Add FLASH progmem support.  From David Sidrane.

    * STMicro STM32 Drivers:

      - STM32 Serial:  Single Wire add pull{up|down|none} via new IOCTL
        command.  From David Sidrane.
      - STM32 F0/L0/G0 Serial:  Single Wire add pull{up|down|none} via
        new IOCTL command.  From David Sidrane.
      - STM32 F0/L0/G0 PWM:  Add PWM support.  From Daniel Pereira Volpato.
      - STM32 G0 TIM:  Support timers available on STM32G070.  Includes TIM1
        PIOs, TIM driver lower-half.  From Daniel Pereira Volpato.
      - STM32 F7 Serial:  Single Wire add pull{up|down|none} via new IOCTL
        command.  From David Sidrane.
      - STM32 H7 BBSRAM:  Exclude BBSRAM from cacheable when
        CONFIG_ARMV7M_DCACHE. ST placed the STM32H7 BBSRAM in the SRAM
        default memory region which is cacheable. This change sets the
        BBSRAM memory range to non-cacheable.  From David Sidrane.
      - STM32 H7 SDMMC:  Add SDMMC support and IDMA as well as interrupt
        driven transmission.  Support pull-ups and SDIO.  From David Sidrane.
      - STM32 H7 Serial:  Single Wire add pull{up|down|none} via new IOCTL
        command.  From David Sidrane.
      - STM32 L4 OTGFS:  Enable OTGFS for STM32L4+ series.  The OTGFS
        peripheral on stm32l4x6 and stm32l4rxxx reference manual is exactly
        the same.  From Jussi Kivilinna.
      - STM32L4 IDLE Loop:  (1) Added BEGIN_IDLE()/END_IDLE() to stop call
        so that we also get notification via LED of the STOP mode, (2) Added
        the stm32l4_clockenable call as previously discussed, and (3) Added
        call to pm_changestate() to inform drivers we're back to running
        after the call to stm32l4_stop() returns.  From Matias N.
      - STM32 L4 Serial:  Single Wire add pull{up|down|none} via new IOCTL
        command.  From David Sidrane.

    * STMicro STM32 Boards:

      - Nucleo-G070RB:  Initial support for board STM32 NUCLEO-G070RB,
        including NSH config.  Enables PWR peripheral and set SYSCLK to
        maximum frequency.  From Daniel Pereira Volpato.
      - Nucleo-G070RB: Enable basic timers.  Add TIMx clock frequencies to
        board.h.  From Daniel Pereira Volpato.
      - Nucleo-G070RB:  Add PWM support and GPIO_TIM3_* mappings.  Add a PWM
        configuration. From Daniel Pereira Volpato.
      - Nucleo-G070RB:  Add button driver support, Add driver support. Add
        GPIO configuration.  From Daniel Pereira Volpato.
      - Nucleo-L476RG:  Add required definitions if libcxx is enabled.  From
        Matias N.
      - Nucleo-L476RG:  Add support for LPTIM timers as PWM outputs.  From
        Matias N.
      - Nucleo-H743ZI:  Added GPIO device driver for user-space apps.  From
        Heiko Demlang.
      - olimex-stm32-e407:  Newer Olimex E407 boards are populated with
        STM32407ZE chips.  From David Alessio.
      - STM32F4-Discovery:  Add support for external DS1307 module.  From
        Alan Carvalho de Assis.
      - STM32F4-Discovery:  Add support for MMCSD_SPI.  This change works
        with STM32F4 Discovery Shield plus microSD click  From Masayuki
        Ishikawa.
      - STM32F4-Discovery:  Add support for gs2200m.  Works with mikroe
        STM32F4 Discovery Shield (slot3)  From Masayuki Ishikawa.

    * TI Tiva:

      - TM4C129ENCPDT:  Add support for Tiva TM4C129ENCPDT.  From Nathan
        Hartman.

    * TI Tiva Boards:

      - TM4C123G-Launchpad: SPI CAN functionality on TM4C123GXL.  From
        DisruptiveNL.

    * Build System:

      - tools/Config.mk:  Eliminate use of the built-in implicit rules.
        From anchao.
      - tools/Config.mk and Makefile.unix:  Support the incremental build
        for configuration change.  From Xiang Xiao.
      - tools/Config.mk:  Support the ability to change the CFLAGS for
        the compilation of a single file.  Set special compiler options as
        follows the rule:  sourcefile + fixed suffix "_[A|C|CPP|CXX]FLAGS".
        For example in apps/examples/hello/Makefile:
        $(SRCDIR)/hello_main.c_CFLAGS = -DTEST.  From Xiang Xiao.
      - Configuration:  Auto-select CONFIG_BUILD_LOADABLE when either
        CONFIG_BUILD_KERNEL or CONFIG_BINFMT_LOADABLE is selected.  From
        Xiang Xiao.

    * Libraries/Header Files:

      - libs/libc:  Add CONFIG_MODLIB_SYSTEM_SYMTAB to generate the symbol
        table for dlopen/insmod.  From Xiang Xiao.
      - getdelim() and getline():  Add implementations of the POSIX
        functions getdelim() and getline().  Because of how the function is
        defined, getline() cannot be used on platforms that use CR-LF lin
        terminations.  From Gregory Nutt.
      - alarm(), setitimer(), and getitimer():  Implement alarm(),
        setitimer() and getitimer() APIs.  From liuhaitao.

    * Tools:

      - tools/mkexport.sh:  Copy the essential build script files too and
        move Make.defs/gnu-elf.ld into scripts like board folder layout.
        From Xiang Xiao.
      - tools/mkexport.sh:  Should export full content for FLAT build even
        with CONFIG_BUILD_LOADABLE.  From Xiang Xiao.
      - tools/testbuild.sh:  Add an option to select the number of CPUs to
        use with 'make'  From Gregory Nutt.
      - tools/indent.sh:  Add a command line option to suppress reformatting
        of comments.  This is useful when comments are already correct
        and/or contain formatted data such as tables or lists.  From Gregory
        Nutt.
      - tools/nxstyle.c:  Add detection of carriage returns.  Improve
        reporting of TABs.  From Gregory Nutt.
      - tools/nxstyle.c:  Add logic to detect if there is a blank line
        following the final right brace.  From Gregory Nutt.
      - tools/nxstyle.c:  Eliminate false alarm errors on comments that are
        to the right of code when the comment terminator is on the same
        line as the last of the comment.  From Gregory Nutt.
      - tools/nxstyle.c:  Eliminate false alarms when checking for
        alignment of comments to the right of code.  Fix check for C++ style
        comments so that strings like http:// and https:// do not generate
        false alarms.  From Gregory Nutt.
      - tools/nxstyle.c:  Eliminate false positive 'Invalid character after
        asterisk in comment block'.  From Gregory Nutt.

    * apps/ Build System:

      - apps/ Build System:  Numerous changes for improvements and general
        clean-up of the apps/ build system.  Too many small and individual
        changes to list here.  Includes many improvements related to loadable
        modules and symbol table generation, removal of duplicated logic,
        renaming of binary directories, use of cygpath, etc.  From Xiang Xiao.
      - apps/Application.mk:  Support the ability to change the CFLAGS for
        the compilation of a single file.  Set special compiler options as
        follows the rule: sourcefile + fixed suffix "_[A|C|CPP|CXX]FLAGS"
        As an example in apps/examples/hello/Makefile:
        $(SRCDIR)/hello_main.c_CFLAGS = -DTEST
        From Xiang Xiao.
      - apps/Application.mk and main.c files:  Change builtin's entry point
        from main to xxx_main by macro expansion.  This change make the
        entry point fully compliant with POSIX/ANSI standard.  From Xiang
        Xiao.

    * Examples/Tests: apps/examples:

      - apps/examples/audio_rttl:  Add a simple RTTL player demo that is
        able to play tunes according to an RTTL song.  From Alin Jerpelea.
      - apps/examples/bmi160:  Add bmi160 example app.  This app will read
        the BM160 data and list it on the NSH console.  From Alin Jerpelea.
      - apps/examples/charger:  Simple charger example that will display on
        the console voltage and current values.  From Alin Jerpelea.
      - apps/examples/netlink_route:  Add test/example of NETLINK_ROUTE
        'get' operations.  From Gregory Nutt.

    * NuttShell:  apps/nshlib:

      - apps/nshlib/: Add rptun cmd for boot remote core.  From ligd.
      - apps.nshlib/:  Add a -t option to the arp command which will enable
        printing the entire ARP table.  From Gregory Nutt.
      - apps/nshlib/:  Add new NSH command, 'pmconfig'.  From ligd.

    * System Utilities:  apps/system:

      - apps/system/cle:  Add basic color support to the CLE editor.
        From Dave Marples.
      - apps/system/i2c:  While many I2C slave devices have multiple
        indexed registers, some have only one register and it's not indexed.
        For example, the I2C bus switch TCA9548A has only a Control
        Register, attempting to index to "Reg[0]" alters its contents to
        0x00 disabling all subordinate buses.  This change fixes that
        problem by simply trying to read something/anything from the slave.
        This also helps coax out slaves with register files that start from
        a higher index, i.e. the AT24CS0x, FLASH chips with a UUID that
        appears as a 2nd I2C slave at (address+8), report their serial
        number at Reg[80]-Reg[8F] and will NAK a read of Reg[0].  Modified
        get/set to prevent write of reg index if not specified.
      - apps/system/i2c:  Added a 'dump' command to issue a single
        transaction to retrieve multiple bytes from an I2C slave and
        register/offset.  From David Alessio.
      - apps/system/spi:  Add options to specify devtype, id for chip
        select.  From David S. Alessio.
      - apps/system/symtab:  Remove system/symtab since the same
        functionality exist in nuttx now.  From Gregory Nutt.
      - apps/system/usrsock_rpmsg:  Add rpmsg based usrsock implementation.
        From Jianli Dong.

    * Network Utilities: apps/netutils:

      - apps/netutils/cjson/:  Update default version to 1.7.12. Previous
        releases raise compilation warnings about redefined true/false.
        From raiden00pl.
      - apps/netutils/netlib/:  Add a function to read the entire ARP table
        using NETLINK_ROUTE protocol.  From Gregory Nutt.
      - apps/netutils/netlib/:  Add support for retrieving a snapshot of the
        IPv6 neighbor table using Netlink sockets.  From Gregory Nutt.
      - apps/netutils/netlib/:  Add a utility function that will return a
        list of all network devices in the UP state.  From Gregory Nutt.
      - apps/netutils/netlib/:  Add function to retrieve routing tables
        using Netlink.  From Gregory Nutt.

Bugfixes:
---------
Only the most critical bugfixes are listed here (see the ChangeLog for a
more complete list of bugfixes and for additional, more detailed bugfix
information):

    * Core OS:

      - Signals:  Fix undefined reference from sig_default.c to
        sched_suspend() if CONFIG_SIG_SIGSTOP_ACTION is not defined.  From
        raiden00pl.
      - waitpid():  Fix a NULL pointer dereference on race without
        DEBUG_ASSERT.  From David Alessio.
      - WD Timers:  Back out a kludge-workaround in wd_start for an SDCC
        compiler problem fix back in Feb 2017.  That workaround now appears
        to conflict with newer GCC versions using (unsupported) warning
        options and SDCC no longer needs the work-around.  From Gregory
        Nutt.
      - clock_systimespec():  Fix early timespec overflow if using 32 bit
        system timer.  From Jens Gräf.
      - Spinlocks:  spin_trylock handle memory barrier and instrumentation
        correctly.  From Xiang Xiao.
      - Power Management:  Fix a problem where a timer cannot start when it
        encounters a very small pmtick.  From ligd.
      - boardctl(BOARDIOC_MKRD):  This change corrects a problem with NSH:
        NSH was calling the OS internal function ramdisk_register() in
        violation of the portable POSIX interface.  This change solves the
        problem by introducing a new boardctl() function BOARDIOC_MKRD
        which moves the RAM disk creation into the OS.  From Gregory Nutt.
      - boardctl(BOARDIOC_ROMDISK):  Add support for the new
        BOARDIOC_ROMDISK command.  This allows applications to create ROMFS
        block drivers without illegal direct calls to romdisk_register.

    * File System/Block and MTD Drivers:

      - SmartFS:  Fix O_CREAT without O_TRUNC truncating existing file.
        Also nothing in POSIX says that O_APPEND should prevent O_TRUNC.
        From Juha Niskanen.
      - SmartFS:  Honor O_APPEND on writes.  Also document pwrite() bug/
        limitation.  From Juha Niskanen.
      - GD25:  spi_devid argument was not used in initialization.  GD25
        driver was always using priv->spi_devid initialized to zero by
        kmm_zalloc(). This change initializes it from the supplied function
        argument.  From Juha Niskanen.
      - MMC/SD:  Set wrbusy after success of all the operations.  Any
        failure could leave wrbusy set when it should not be if the
        operation failed.  From David Sidrane.
      - MMC/SD:  Enter a removed card state On a failure.  If we fail to
        read cardstatus in mmcsd_transferready consider this a hard error
        and set the card to removed.  From David Sidrane.
      - MMC/SD (SDIO): Align DMA buffer for MBURST size.  From David S.
        Alessio.

    * Networking/Network Drivers:

      - Socket close():  Fixed problems noted by Bernd Walter:  Eliminate an
        incomplete test when a disconnection event happens. When a
        disconnection event occurs, the close logic MUST always terminate
        the wait.  The conditional test was not incorrect, however, it
        lacked 'else' logic and would simply ignore that disconnection event
        in some cases.  That is bad because there may not be another
        disconnection event and that can lead to hangs (or at least very,
        very long delays).  From Gregory Nutt.
      - ICMPv6:  Dispatch ICMP_POLL to device's callback list too since
        icmpv6_neighbor stills append the callback into this list.  From
        Gregory Nutt.
      - ICMPv6:  Decouple autoconfig and ICMPv6 socket to avoid an invalid
        Kconfig combination.  From Xiang Xiao.
      - ICMPv6:  cmpv6_autoconfig() error handling must not overwrite
        overwrite the error code.  From Xiang Xiao.
      - TCP/UDP:  Fix a chicken and egg problem by eliminating the check of
        the arp/neighbor tables before packet transmission:
        1. For buffered TCP/UDP case, if CONFIG_NET_ARP_SEND /
           CONFIG_NET_ARP_IPIN / CONFIG_NET_ICMPv6_NEIGHBOR isn't enabled
           and the table doesn't contain the Ethernet address for the
           destination IP address yet, then the logic will skip the real
           transmission and then ARP/neighbor logic can't steal the final
           buffer to generate the ARP/ICMPV6 packet.
        2. For all other case, the TCP layer or user program should already
           contain the retransmit logic, the check is redundant and may
           generate many duplicated packets if ARP/ICMPV6 response is too
           slow because the cursor stop forward.  If user is still concerned
           about the very first packet lost, he could fix the issue by
           enabling CONFIG_NET_ARP_SEND / CONFIG_NET_ICMPv6_NEIGHBOR.
        From Xiang Xiao.
      - UDP sendto():  Add a check for the device that is polling.  In the
        multiple network device case, this check is necessary to prevent
        sending the UDP packet to the wrong device.  From Gregory Nutt.

    * Wireless/Wireless Drivers:

      - MRF24J40:  Correct erroneous isolation of address mode field and
        subsequent bad comparison.  From Gregory Nutt.
      - GS2200M:  Add SPI_SELECT() to _read/write_data() in gs2200m.c
      - BCM43xx Wireless:  In the SDIO interface, the behavior of the DMA
        setup differs, depending on the hardware capability
        SDIO_CAPS_DMABEFOREWRITE.  If this capability is set, then the DMA
        setup much be done before the transfer setup.  Dave Marples
        modified this file for the i.MXRT USDHC which does have the
        SDIO_CAPS_DMABEFOREWRITE.  Xiao Xiang reports that this change
        breaks the Wifi on the Photon which does not report the
        SDIO_CAPS_DMABEFOREWRITE and suggests reverting the change.  In
        reality both changes are correct but must be conditioned on the
        DMA capability of the underlying SDIO device.  From Gregory Nutt.

    * Common Drivers:

      - Various drivers (Cloned logic):  On error, memory was freed, but
        the error was not returned.  It just continued as though no error
        happened.  From Petro Karashchenko.
      - Serial:  Fix data corruption when outputting data in SMP mode  From
        Masayuki Ishikawa.
      - Serial:  serial_io.c used signal numbers, but did not include
        signal.h.  This has no problems but missing signal definitions have
        been seen in certain cases.  From David Sidrane.
      - Serial DMA:  Avoid uart_xmitchars_done() move the tail bigger then
        head.  If ioctl(TCOFLUSH) occurs between uart_xmitchars_dma() and
        uart_xmitchars_done(), TCOFLUSH will reset xmit buffer, then
        uart_xmitchars_done() will move the 'tail' ahead of 'head', then
        sends lots of wrong data.  From ligd.
      - mkfifo():  mkfifo() should return -1 and set errno on failure  From
        raiden00pl.
      - RAMLog: Fix ramlog readers never awakened up when using ramlog as
        syslog or console.  We also make an attempt to avoid the thundering
        herd problem if there are multiple readers/pollers. This change also
        removes forcing CONFIG_RAMLOG_CRLF in nuttx/syslog/ramlog.h as there
        is no point of wasting precious RAM for useless characters.  From
        Juha Niskanen.
      - USB CDC/ACM:  Fix memory leak of RX failsafe timer.  From Juha
        Niskanen.
      - USB HID Keyboard device:  Fix keyboard debounce algorithm used when
        CONFIG_HIDKBD_NODEBOUNCE is undefined.  From Jeff Theusch.
      - USB HID Keyboard:  Change default for CONFIG_HIDKBD_POLLUSEC per
        recommendation of Jeff Theusch.  From Gregory Nutt.
      - VL53L1X IOCTLs:  IOCTL commands for the VL53L1X did not follow the
        sequence.  Noted by Daniel Pereira de Carvalho.  From Gregory Nutt.
      - syslog:  syslog_force does not set errno so do not test against it.
        From Juha Niskanen.
      - syslog:  Fix assertion that assumes re-opened syslog file is the
        same.  Logic in syslog_file_channel() is calling syslog_initialize()
        for the default syslog device as a recovery action after failed
        syslog_dev_initialize().  From Juha Niskanen.

    * Simulator:

      - Simulator HostFS:  Skip '.' and '..' in readdir'  From Xiang Xiao.
      - Simulator HostFS:  Fix warning: 'mapflags' may be used uninitialized
        in this function.  From Xiang Xiao.
      - Simulator Tickless:  Correct the calculation of the Tickless timer
        period.  Fix some missing initialization of globals and missing
        return values.  From Matias N.
      - Simulator:  Add -m32 to HOSTLDFLAGS if enable CONFIG_SIM_M32.  From
        Xiang Xiao.
      - Simulator PM:  Fixes compilation for sim target when enabling power
        management.  From Matias N.
      - Simulator Build:  Fixes missing recursion into sim board directory
        for dependency generation.  From Matias N.
      - Simulator SIMUART:  Remove CONFIG_SIM_UART_DATAPOST for arch/sim.
        It's very dangerous to call NuttX API from simuart_thread.  From
        Xiang Xiao.

    * ARMv7-A

      - ARMv7-A:  Apply Masayuki Ishakawa's change for ARMv7-M to this SMP
        architecture as well.  From Gregory Nutt.

    * ARMv7-M

      - ARMv7-M:  Fix a deadlock in up_sigdeliver() in SMP mode.  In
        previous implementation, up_disable_irq() was called before
        recovering local context. However, I noticed a deadlock happens in
        the following situation. For example, if up_sigdevliver() is in
        progress on CPU0 and CPU1 has called up_cpu_paused to CPU0, hence
        g_cpu_irqlock has been locked by CPU1, in this case, we would see a
        deadlock in later call of enter_critical_section() to restore
        irqcount.  To avoid this situation, we need to call
        enter_critical_section() to break the deadlock.  From Masayuki
        Ishikawa.

    * Atmel SAM3/4 Boards:

      - SAM4CM:  Fix cpustart() implementation.  In Cortex-M, offset 0 in
        vector table stores initial stack pointer and offset 4 stores reset
        vector.  From Masayuki Ishikawa.

    * Atmel SAMA5Dx Boards:

      - SAMA5D4-EK:  Fix bad conditional compilation for
        board_app_initialize().  Should depend only on CONFIG_LIB_BOARDCTL,
        CONFIG_BUILD_KERNEL is irrelevant.  From Gregory Nutt.

    * Microchip i.MXRT:

      - i.MXRT WFI:  WFI needs to be disabled on i.MXRT.  We found the
        reason:  The imxrt1050 is configured to use SYSTICK for the kernel
        timer, but SYSTICK cannot wake up the MCU from low-power modes.
        Disable low-power modes on this MCU until we have support for an
        alternative timer.  Earlier versions of the board (EVK, not EVKB),
        had A0 silicon which by default did not enter low-power mode on a
        WFI.  With this change in place together with the previous one my
        system is stable, just using more power than it should.  From Dave
        Marples.

    * Microchip i.MXRT Drivers:

      - i.MXRT Serial:  TC (Transmission complete) and TDRE (TX Buffer
        Empty) were transposed in imxrt_serial.c.  The end result was that
        for unoptimized code everything worked fine, but optimized code got
        itself into a real mess and continually fired interrupts.  From Dave
        Marples.

    * Microchip i.MXRT Boards:

      - IMXRT1020-EVK:  Make naming of the LED consistent.  In most places
        it is referred to as LED1.  In board.h it is referred to as
        USERLED1.  The i.MXRT1020-EVK hardware user guide (HUG) uses the
        name USERLED.  This command makes all names internally consistent
        and consistent with the HUG.  Noted by Alin Jerpelea.  From Gregory
        Nutt.

    * NXP/Freescale Kinetis Boards:

      - TWR-K60N512:  Suppress errors related to card detect GPIO
        configuration if SDHC support is not enabled.  From Gregory Nutt.

    * NXP LPC17xx/40xx Drivers:

      - lpc17xx/40xx I2C:  Respect the I2C_M_NOSTART flag.  Sending a
        restart condition when not requested will break other drivers that
        depend on this behavior.  From Augusto Fraga Giachero.
      - LPC17xx/40xx Ethernet: Use usleep() instead of up_delay() for large
        wait times.  From Augusto Fraga Giachero.

    * NXP LPC54xx:

      - LPC54 Clocking:  Fix PLL settings.  For the lpc54628 Rev. E board
        the PLL was not configured properly and the board would not boot
        correctly. I checked the startup files from the official IDE and
        inspected the assembly instructions for the libraries used.  From
        Andrei Stefanescu.

    * NXP i.MXRT Boards:

      - IMXRT1060-EVK:  Fix FT5X06 CTRSTn pin configuration, increased
        number of pollwaiters for the FT5X06, tuned resolution during
        pointer dragging.  From Fabio Balzano.

    * On Semiconductor Boards:

      - LC823450:  Fix cpustart() implementation.  In Cortex-M, offset 0 in
        vector table stores initial stack pointer and offset 4 stores reset
        vector.  From Masayuki Ishikawa.
      - LC823450-XGEVK:  Fix build error for posix_spawn.  From Masayuki
        Ishikawa.

    * Sony CXD56xx:

      - CXD56xx Assertions:  Replace some assertions with error return
        values.  From Alin Jerpelea.
      - CXD56xx Interrupts:  Fix hang-up when error interrupt occurs.  From
        Alin Jerpelea.
      - CXD56xx Pin Configuration:  PIN_AP_CLK is used as a port selector of
        SDIO expander on the extension board, and is set output low in
        initialization.  Therefore, this pin cannot be used by the other
        board.  To avoid this restriction, remove this initial operation
        because this pin is pulled down by default on the extension board.
        From Alin Jerpelea.
      - CXD56xx:  Remove duplicate NVIC_SYSH redefinitions.  The NVIC_SYSH
        is already defined in nvicpri.h  From Alin Jerpelea.

    * Sony CXD56xx Drivers:

      - CXD56xx SDHCI:  Fix initial value of semaphore in sdhci driver.
        From Alin Jerpelea.

    * Sony CXD56xx Boards:

      - Spresense:  The SD Card TXS02612 port expander is hosted on the
        Extension board and should not be enabled if the extension board is
        not present.  From Alin Jerpelea.

    * STMicro STM32:

      - STM32 F4 Pin Multiplex:  Ethernet pin ETH_RMII_REF_CLK is an input.
        From Gregory Nutt.
      - STM32 H7 ADC:  Fix typos in ADC register definitions.  From Markus
        Bernet.
      - STM32 H7:  Heap allocation, SRAM and SRAM1 are not continuous  From
        David Sidrane.
      - STM32 H7 CRC:  Add the CRC option in KConfig.  From Eduard Niesner.
      - STM32 H7 RCC: Add PLL3 Support and only enable PLLs if used.  From
        David Sidrane.
      - STM32 L4x6xx RCC:  This fix is needed if HSI clock is selected.
        Otherwise when waking up from STOP mode, the MSI clock is selected
        instead of the HSI clock.  From Matias N.

    * STMicro STM32 Drivers:

      - STM32 USB Host:  There was no relationship between
        CONFIG_STM32_USBHOST and CONFIG_USBHOST, yet they they were used
        interchangeably.  This means that can (and did) get out of synch
        causing link time failures.  This change adds logic to select
        CONFIG_USBHOST when CONFIG_STM32_USBHOST is selected, keeping the
        two settings synchronized.  Furthermore, since CONFIG_STM32_USBHOST
        is the authoritative setting, all occurrences of CONFIG_USBHOST were
        replaced with CONFIG_STM32_USBHOST.  From Gregory Nutt.
      - STM32 SDIO:  SDIO Fix system hang on card eject.  From David Sidrane.
      - STM32 F7 Ethernet:  Large Ethernet packet can leads network halt.
        From Bazooka Joe.
      - STM32F7 OTGHOST:  OTGFS_EPTYPE_INTR should be OTG_EPTYPE_INTR.  From
        Gregory Nutt.
      - STM32 F7 SDMMC: SDMMC Fix system hang on card eject.  From David
        Sidrane.
      - STM32 L4 Firewall:  Correct a test to determine if an address lies
        in FLASH or not.  Improper mask caused test to always fail.  From
        Gregory Nutt.
      - STM32 H7 Ethernet:  Bazooka Joe's fix to the STM32 F7 Ethernet
        driver should be applied to the H7 as well.  The other STM32
        Ethernet drivers already have the change.  From Gregory Nutt.
      - STM32 H7 Ethernet:  Fix ETH_MACMDIOAR_CR_MASK bit mask.  From Markus
        Bernet.
      - STM32 H7 SDMMC: SDMMC Fix system hang on card eject.  From Gregory
        Nutt.
      - STM32 H7 FLASH:  Flash driver BUG fixes.  From David Sidrane.
      - STM32 H7 TIM:  Correct register bit definitions and alternate
        functions.  Fix other copy-paste definitions.  From Daniel Pereira
        Volpato.
      - STM32 L4 SDMMC:  SDMMC Fix system hang on card eject.  From David
        Sidrane.

    * STMicro STM32 Boards:

      - STM32F4-Discovery:  Fix build error for posix_spawn.  From Masayuki
        Ishikawa.

    * TI Tiva:

      - TIVA IRQs:  Fix wrong IRQ vector number.  From Nathan Hartman.
      - Tiva FLASH:  Fix several mistakes in tiva_write(). (1) Fix wrong
        use of && when & was intended. (2) Add compile- time warning
        directive because according to this function's interface, it is
        supposed to support unaligned writes and/or writes of arbitrary
        numbers of bytes to FLASH.  However, this function does NOT support
        that at this time. This needs to be fixed. (3) Fix wrong
        preprocessor conditional.  Was written to use the 32-word write
        buffer only for TM4C1294NCPDT.  This buffer is available on all
        M4C123 and TM4C129 parts. Now conditioned upon
        CONFIG_ARCH_CHIP_TM4C123 or CONFIG_ARCH_CHIP_TM4C129. (4) Add
        comments to document the intent of the above preprocessor logic.
        From Nathan Hartman.

    * Xtensa

      - Xtensa:  Apply Masayuki Ishakawa's change for ARMv7-M to this SMP
        architecture as well.  From Gregory Nutt.

    * Build System:

      - Makefiles:  Change ${shell pwd} to $(CURDIR) since pwd doesn't exist
        on Windows  From Xiang Xiao.
      - tools/Makefile.unix:  Fix build error when issue 'make -B':  "mkdir:
        cannot create directory 'staging': File exists:
        tools/Makefile.unix:269: recipe for target 'staging' failed".  From
        Xiang Xiao.
      - All ARM linker scripts:  Preface all _ebss definitions with '. =
        ALIGN(4)'.  Otherwise, the following .bss section may not be aligned
        properly.  From Gregory Nutt.
      - MIPS Linker Scripts:  The PIC32M* start-up code initializes .bss by
        writing 16 bytes at a time in a loop.  The start (_sbss) alignment
        is only required to be 4 bytes since the write is done with 4 store
        instructions.  From Gregory Nutt.
      - Top-level Kconfig:  Add some protection so that you cannot select an
        architecture-specific header file if the architecture does not
        provide the header file.  From Gregory Nutt.
      - libc Kconfig:  Should select the NuttX float.h file automatically
        if the NuttX math library is selected.  From Gregory Nutt.
      - tools/Makefile.unix:  Make COMMON_DIR work with
        CONFIG_ARCH_BOARD_CUSTOM.  From Xiang Xiao.
      - tools/ Make fragments:  Fix the various minor issue for NUTTXLIBS /
        USERLIBS:  (1) Remove libcxx duplication in FlatLibs.mk and from
        kernel space, (2) Remove libpass1 from KernelLibs.mk since kernel
        build doesn't support the two pass mode, and (3) Remove FSDIR
        related comment since file system cannot be disabled now  From Xiang
        Xiao.

    * C Library/Header Files:

      - getcwd():  Remove stray sched_unlock().  Also fixes several typos.
        From Juha Niskanen.
      - date(), hostname():  Fix portability issue with date, hostname  From
        David Alessio.
      - libs/libxx/Kconfig: Automatically select CONFIG_CLOCK_MONOTONIC when
        CONFIG_LIBCXX is selected.  Removed hardcoded -DCLOCK_MONOTONIC from
        CFLAGS in Make.defs of several configurations.  That definition is
        now automatically adding this define when CONFIG_LIBCXX=y.  From
        Daniel Pereira Volpato.
      - libs/libxx/Kconfig:  CONFIG_LIBC_LOCALE is needed to build libcxx.
        A math library is also needed, however, there are various ways to
        provide a math library so CONFIG_LIBM is not now set.  From Matias
        N.
      - libs/libc/symtab:  Move symbol table generation into libc since the
        address in symbol table should come from userspace binary for
        PROTECTED build, not kernel binary.  From Xiang Xiao.
      - libs/libc/ Kconfig files:  Disable EXECFUNCS_HAVE_SYMTAB for kernel
        build.  The symbol table doesn't have any meaning for kernel build
        since all executable binary should be self contained.  From Xiang
        Xiao.

      - include/sys/time.h:  According to earlier standards, usage of
        select(), FD_CLR, FD_ISSET, FD_SET and FD_ZERO just need include
        headers: sys/time.h, sys/types.h and unistd.h.  So include
        sys/select.h in time.h to compatible with it.  Or mbedtls library
        would build break in calling select() and FD_* related functions.
        From liuhaitao.

    * Tools:

      - tools/configure.sh and configure.c:  Do not remove CONFIG_SIM_M32 if
        host is specified.  From anchao.
      - tools/Directories.mk:  Remove FSDIRS/NOFSDIRS related logic/comments
        since the file system can no longer be disabled now.  From Xiang
        Xiao.
      - tools/Makefile.host:  Add missing binaries from clean target.  From
        Gregory Nutt.
      - tools/mkromfsimg.sh:  Use sed to add const to ROMFS declarations so
        that they lie in FLASH not RAM.  From Bernd Walter.
      - tools/nxstyle.c:  Correct detection of missing blank line following
        a block comment.  From Gregory Nutt.

    * apps/ Build System:

      - Makefiles: Change ${shell pwd} to $(CURDIR) since pwd doesn't exist
        on Windows  From Xiang Xiao.
      - Makefile: Fix warning: jobserver unavailable: using -j1.  Add '+' to
        parent make rule.  From Xiang Xiao.
      - apps/Application.mk:  Correct an error in PATH usage.  Use of
        toolchain path causes make errors.  From Gregory Nutt.

    * apps/tools:

      - tools/mkromfsimg.sh:  Use sed to add const to ROMFS declarations so
        that they like in FLASH not RAM.  From Bernd Walter.

    * Examples: apps/examples:

      - apps/examples/mount:  Replace illegal call to ramdisk_register()
        with a call to boardctl(BOARDIOC_MKRD).  From Gregory Nutt.
      - apps/examples/nxlines/:  Correct nxlines example program name.  From
        Gregory Nutt.
      - apps/examples/nxterm/:  PROGNAME, PRIORITY, STACKSIZE variable
        names did not match declarations in Kconfig file.  From Gregory
        Nutt.
      - apps/examples/romfs:  Remove romfs_testdir.h.  That file is
        regenerated whenever the example is built and so should not be in
        the repository.  From Gregory Nutt.

    * Testing: apps/testing:

      - apps/testing/cxxtest/:  Fix typo error in testing/cxxtest.  From
        Xiang Xiao.
      - apps/testing/unity/:  Fix the error when creating Make.dep.  From
        raiden00pl.

    * NSH Library: apps/nshlib:

      - apps/nshlib:  Remove the inappropriate NSH_BUILTIN_APPS coupling.
        From Xiang Xiao.
      - apps/nshlib/:  The NSH mkrd command was in violation of the NuttX
        portable POSIX interface.  It was calling the internal OS function
        ramdisk_register() directly.  Not only is this a violation of the
        interface specification, but also prevents use of mkrd in PROTECTED
        or KERNEL builds. With this change, the NSH mkrd command now uses
        the BOARDIOC_MKRD boardctl() command.  This command is available in
        all build modes.  The effect of this change is to move the heart of
        the NSH mkrd command into to OS and provide user-space access via
        boardctl().  From Gregory Nutt.
      - apps/nshlib/:  Replace direct calls to romdisk_register() with
        indirect calls via boardioctl(BOARDIOC_ROMDISK).  This not only
        fixes the violation of the portable POSIX OS interface, but also
        permits use of ROM disks in PROTECTED and KERNEL modes.  From
        Gregory Nutt.
      - apps/nshlib/:  Add missing NSH_DISABLE_DMESG from Kconfig.  From
        Juha Niskanen.

    * System Utilities: apps/system:

      - apps/system/cle/:  This change modifies the cle to use the streams
        file interface more consistently and has removed the observed race
        conditions.  It was previously a mix of streams and fileio.  It
        also simplifies the VT100 cursor position handling.  From Dave
        Marples.
      - apps/system/composite:  Remove usb serial loopback test code we can
        achieve the same effect by cat or dd command.  From Xiang Xiao.
      - apps/system/cu/: (1) Fix early exit.  getc(stdin) can return 0 the
        first time around.  (2) Set optind to zero.  getopt() was being
        left in a bad state, causing parsing errors on second use.  (3) Fix
        priority of cu_listen().  (4) Add support for -h.  From David
        Alessio.
      - apps/system/lzf/: Check the protection by CONFIG_SYSTEM_LZF !=
        CONFIG_m (not elf binary) instead of CONFIG_KERNEL_BUILD.  From
        Xiang Xiao.
      - apps/system/spi:  Correctly parse exch txdata args, if any. Should
        always call the board's deselect  From David Alessio.

    * File System Utilities: apps/fsutils:

      - apps/fsutils/passwd/:  Use named semaphore by checking
        CONFIG_FS_NAMED_SEMAPHORES instead of CONFIG_KERNEL_BUILD.  From
        Xiang Xiao.

    * Network Utilities: apps/netutils:

      - apps/netutils/cjson/Makefile:  Fix the error when creating
        Make.dep.  From raiden00pl.

    * Graphics: apps/graphics:

      - apps/graphics/twm4nx/:  Fix a recently introduced error that broke
        all Twm4Nx configurations.  From Gregory Nutt.
      - apps/graphics/traveler/:  Replace direct calls to romdisk_register()
        with indirect calls via boardioctl(BOARDIOC_ROMDISK).  This not only
        fixes the violation of the portable POSIX OS interface, but also
        permits use of ROM disks in PROTECTED and KERNEL modes.  From
        Gregory Nutt.

NuttX-9.0.0 Release Notes
-------------------------

This is the first release of NuttX as Apache NuttX (Incubating) and represents our first major milestone as a Podling of the Apache Software Foundation's Incubator. This release is the culmination of nearly 6 months of hard work and includes several new architectures and drivers, and numerous improvements and bug fixes to the core RTOS, drivers, and networking subsystems.

   * Major Changes to Core OS
       * Bugfixes
          - nxsem_wait_uninterruptible() now returns if the task is canceled.
          - Fix a bug in pthread_condwait() that was improperly re-initializing the mutex.
          - In sched_setpriority(), fix functions called inside a DEBUGASSERT that were eliminated when assertions are disable

   * Compatibility Concerns

        - The configuration option CONFIG_CAN_PASS_STRUCT is now removed.  Previously, it was used (at the cost of breaking standards support) to support older versions of the SDCC compiler that couldn't pass structs/unions as functions' parameters.  A newer version of the compiler has resolved the issue.

   * Major Changes to Build System
       - Add a post-build function that allows extending the build with CPU/board-specific logic.
       - Add build tools to simplify ZDS-II tool usage.
       - mkexport.sh: Deal with ARCHSCRIPT containing multiple files.
       - Various nxstyle improvements.

   * Architectural Support
       * New architecture support
           - Add support for RISCV-64
           - Add support for x86_64 (tested on QEMU)
           - Add support for ELF64
           - Add a port to the NUCLEO-F429ZI board
           - Add support for the STM32H747I-DISCO board
           - Add Z20X board support and bootloader to upload code from the W25 flash to SRAM
           - Add initial support for Litex with softcore CPU VexRiscV SoC
           - Add support for the Digilent ARTY_A7 board to test the Litex port
           - Added initial support for Sipeed Maix Bit board with Kendryte K210 processor
           - New architectural support: ez80f92
           - Flat address x86_64 port of NuttX
           - Support to run NuttX on ESP32 QEMU
           - Initial support for Sipeed Maix Bit board with Kendryte K210 processor
           - Add initial support for Kendryte K210 processor in SMP mode
           - NXP S32K11x (Cortex-M0+) and S32K14x (Cortext-M4F): Add support for NXP automotive boards.
           - XMC 4700 (Cortex-M4F)
       * Architectures with significant improvements
           - ESP32 loadable modules support
           - i.MX RT: FLEXIO clock config logic.
           - Fix the clock configuration for the i.MX RT family
           - i.MX RT: Add ability to run from OCRAM
           - SAMA5D27 peripheral support - USB Host working
           - z20x: Add W25 bootloader
           - i.MX RT: Add USB Device support
           - STM32, STM32F7, STM32H7 add SPI DMATHRESHOLD
           - Improve the simulator timer
           - 64-bit modules on macOS simulator
           - z20x: Add XTP2046 SPI support; add timer support
           - RX65N RTC Driver added
           - NXP Freedom K28F Board SD-Card support
           - STM32H7: support SDRAM via FMC peripheral
           - LM3S6965-ek: Add PROTECTED build support
           - STM32H7: Added IWDG and WWDG, power management (sleep/stop/standby), WKUP pin configuration
           - SAMV71:  Add read UID implementation and move flash functions to RAM
           - i.MX RT: Fix interrupts storm (serial & I2C)
           - Various fixes and cosmetic changes to the CxD56xx architecture
           - Fix SiFive FE310 related code (comments, improve serial irq handling, initial int status)
           - Implement QSPI for STM32H7
           - Improvements for the nRF52 port: I2C, SPI, GPIO support
           - Updates for LPC17xx/40xx serial
           - Adds basic support for Microchip SAM E54 Xplained Pro board
           - Adds an Ethernet driver for the SAME5x family (based on the SAMA5 GMAC driver)
           - Add CDC ECM Ethernet over USB 2.0 High Speed (tested on SAMA5D36-Xplained board)
           - Simulator: Reimplement simulator uart on top of serial driver framework
           - NXP S32K1XX peripheral clock fixes
           - Fix syscall stack alignment on armv7-m
           - Fix flash_erase(page) when page >= 256 for STM32L4 family
           - Add partial support for the NETLINK poll() operation.
           - Add serial DMA support for STM32F7
           - Add AM335x Clock Configuration
           - Add I2C support for AM335x
           - Add configuration to fine tune LPI2C Timeout for iMXRT
           - Add CAN support to AM335x
           - Add I2C support to STM32F0/L0/G0
           - Kinetis LPC SDCard improvements
           - Replace the busy polling with work_queue in the ethernet driver of simulator
           - Fix Xtensa's SMP support to follow same logic from other SMP archs
           - PIC32MZ: SPI transfers can be configured to use DMA.
           - PIC32MZ: Implement cache operations.
   * Driver Support
       * New drivers
           - New driver for the ADS7828 I2C analog to digital converter
           - driver/ioexpander: New driver for PCA9538 I2C I/O expander
           - New driver type for battery monitor ICs.
           - Driver for the BQ769x0 battery monitor IC.
           - Add Support for Quectel EC20 4G LTE Module USB CDC/ACM
           - Add QSPI-based Winbond NOR FLASH driver
       * Drivers with significant improvements
           - Update all the drivers to check return value of nxsem_wait_uninterruptible().
           - MCP9844 shutdown mode support
           - fcntl: add O_CLOEXEC flag, add O_CLOEXEC/FD_CLOEXEC support
           - CDC-ECM Ethernet over USB 2.0 HS
           - smartfs improvements: Handling of duplicate sectors, support fsck to check and repair the smartfs file system, and recover SPI Flash from initial error state.
           - Various fixes for USBDEV driver: Remove unnecessary reset logic, fix descriptor type mismatch when dual speed is enabled, fix invalid/unsupported command processing, and fix string ID calculation.
           - Handle size zero in umm_malloc.c and umm_realloc.c, which causes a system freeze in kernel mode.
           - Fixed compilation issue with poll fds notification.
           - Report POLLHUP and POLLERR in 'revents' regardless the requested 'events' set.
    * Networking
       - Telnet:  Fix/Refine CTRL+C to work on telnet
       - TCP:  Fix of faulty TCP sequence increments
       - netdb:  Fix netdb to query IPv4 and IPv6 addresses regardless the server address type
       - Netlink sockets may be set to non-blocking
       - Improve TUN and SLIP, refine Control+C Handling in Telnet
       - Sockets:  Add socket MSG_DONTWAIT support
       - Network Loopback Driver: Add a configuration option to control packet size
       - Network IOCTLs:  Add FIONBIO network IOCTL support
       - NFS: Support IPv4 and TCP
       - Sockets: Add IP and TCP socket options needed by iperf3
       - Netlink: Add support for asynchronous Netlink responses
       - TCP: Monitor TCP_POLL/TCP_NEWDATA/TCP_BACKLOG per the request like UDP counterpart
       - TCP: Minor design improvement to TCP delayed ACKs
       - DNS IPv4/IPv6 Dual Host Support: When IPv4/IPv6 Dual Stack is enabled, queries both types of addresses regardless of whether the DNS server is accessed via IPv4 or IPv6. As a result, getaddrinfo() may return a mixed (IPv4/IPv6) address list.

    * Applications
       * Improvements
           - Extend netutils and netinit to work with only Netlink sockets enabled
           - Add getprime program to check multi-thread performance
           - Improve zmodem send performance
           - Add simple HTS221, LSM303 and LSM6DSL examples
           - Improve to gs2200m wiki performance
           - Improve telnet server and enable it to listen on both IPv4 and IPv6
           - Improve ntpclient logic
           - Improve wapi to save configuration to file system
           - Improve wapi to skip associate if ssid is invalid
           - Improve cmd_nfsmount to use IPv4 and IPv6
           - Improve ostest for SMP and non-SMP configurations
           - Improve UDP to avoid using standard symbols
           - Improve dhcpd to include configurable timeout and retry count
        * Bugfixes
           - Correct format when printing ARP tablet entries
           - Ensure /bin/ping and ping work at the same time
           - Correct backward conditional logic in dhcpd_leaseexpired()
           - Fix several problems on ftpd
           - Fix dhcpd issue reported on Issue #17
           - Fix sendmail example to run on a local SMTP server
           - Fix buffer overflow on netlib
           - Fix compile errors in loopback mode of the tcpblaster
           - Fix stack corruption in ELF task test
           - Fix errors in NoBlockRecv and BlockRecv tests of usrsocktest
           - Fix ipforward IP Header issue for IPv4
           - Fix wrongly swapped parity options of CU program
           - Fix slcd to avoid using priv->fd before initializing it
           - Fix (tcp, udp)blaster to build on macOS
           - Correct the buffer type of base64 program

NuttX-9.1.0 Release Notes -------------------------

  * Major Changes to Core OS:
      * New Features:
        - PR-977 PR-987 PR-998 PR-995 PR-997 PR-1007 Thread Local Storage (TLS)
          is now a required feature and used by all architectures
          There is detailed information on the implementation and how this
          impacts errno specifically in the Wiki article: Userspace errno and
          TLS
        - PR-957 PR-947 PR-963 PR-969 Provide nx_ versions of many functions
          that are used internally to avoid disrupting errno in userspace
        - PR-965 PR-980 PR-984 ioctl is now always in the variadic form.
          Syscalls in KERNEL builds are also more efficient with this as well now.
          Previously the ioctl prototype was normally defined as:

          int ioctl(int fd, int cmd, unsigned long arg);

          unless the CONFIG_LIBC_IOCTL_VARIADIC was enabled in which case it was

          int ioctl(int fd, int cmd, ...); This form is now the form defined by
          opengroup and is also inline with Linux.  Prior to this change there
          were issues with making ioctl calls on 64-bit arch since the
          implementation assumed that (void *) would be of size long.  There is
          more discussion of this issue in the GitHub issue ticket here:

          https://github.com/apache/incubator-nuttx/issues/959

        - PR-962 PR-964 Add new interface sched_get_stackinfo that simplifies
          interfaces for things like TLS
          There are some security imposed rules for using this interface
              Any thread may query its own stack, A kernel thread may query the
              stack of any other thread Application threads, however, may query
              only the stacks of threads within the same task group, i.e., the
              main thread and any of the child pthreads created with the main
              thread as a parent or grandparent or great-grandparent.

        - PR-1104 Internal function fs_fsopen() no longer affects errno -
        - PR-1123 Move task_init() and task_activate() to be internal functions -
        - PR-1140 Add nxtask_uninit() interface
          This function will undo all operations on a TCB performed by
          task_init() and release the TCB by calling kmm_free(). This is
          intended primarily to support error recovery operations after a
          successful call to task_init() such was when a subsequent call to
          task_activate fails.
        - PR-1134 Add typedef for max_align_t
        - PR-1141 Handle custom stack allocations
          sched_releasetcb() will normally free the stack allocated for a task.
          However, a task with a custom, user-managed stack may be created using
          nxtask_init() followed by nxtask_activate(). If such a custom stack is
          used then it must not be freed in this manner or a crash will most
          likely result.

          This change adds a flag call TCB_FLAG_CUSTOM_STACK that may be passed
          in the the pre-allocated TCB to nxtask_init(). This flag is not used
          internally anywhere in the OS except that if set, it will prevent
          sched_releasetcb() from attempting to free that custom stack.

        * Bug Fixes:
          - Many private architecture interfaces were using 'up_' instead of the
            arch name 'arm_'
            This fix is carried over many PRs such as PR-924.  Many files also
            carried this same error in naming convention and were converted as
            well.

          - PR-1018 PR-1017 PR-1021 PR-1022 PR-1057 PR-1060 PR-1194 Clean up
            internal APIs that were not using the properly naming conventions -
          - PR-857 Wrong value for it_interval field in timespec returned by
            timer_gettime - PR-902 SMP: On task creation do not clone
            uninitialized descriptors
            In SMP mode, there is a possibility that a pthread executing one CPU
            may create a new task while a pthread on another CPU has allocated
            the socket but not yet initialized it. This commit updates the
            socket clone test to assure that the socket is both allocated and
            initialized before it is cloned.
          - PR-911 Use OS signal functions internally to not reset errno that
            applications are using
          - PR-925 sys/stat.h Change the xtime fields to align with POSIX
            standard. Starting from Issue 7 of the POSIX standard the fields
            st_atime, st_mtime and st_ctime have a type of strcut timespec instead
            of time_t.
          - PR-939 openamp: Update to 2020.04.0 - PR-953 lib_vsprintf: Fix issue
            where stack would become corrupt on x86_64
            This function requires traversing the VA_LIST twice.  For some
            architectures like x86 and x86_64 this needs to be cloned first.

  * Major Changes to the Build System:
    Parts of the build system have been refactored to reduce duplication and
    simplify Makefile and Make.defs files across many directories. These changes
    are particularly beneficial for boards.

    Please note that if you develop your own custom boards, you may need to make
    some modifications to keep your board's build scripts up-to-date with the
    rest of NuttX and avoid a broken or defective build. For details, see
    Compatibility Concerns, Changes to Build System, in these release notes.

      * New Features:
        - PR-894 openamp and libmetal can now be downloaded and configured by
          build system - PR-941 Remove 'u' prefix from userspace library in FLAT
          Build so it is the same for all build types - PR-1044 ARM: Remove
          support for old redundant gcc toolchains

          This removes support for the Codesourcery, Atollic, DevKitArm,
          Raisonance, and CodeRed toolchains. Not only are these tools old and
          no longer used but they are all equivalent to the standard ARM EABI
          toolchains. Retaining specific support was not meaningful (and they
          are still supported, but now just as generic EABI toolchains).
        - PR-1148 PR-1149 Improve build time especially on non-Linux platforms
          by providing a C version of incdir.sh

      * Bug Fixes:
        Many small changes to resolve dependency resolution issues that would
        sometimes appear during parallel builds.  Parallel builds should be much
        more reliable now and bugs filed against any issues found.

        - PR-1000 Fix broken support of ZDS-II Toolchain with MSYS

  * Architectural Support:
      * New Architecture Support:
        - PR-879 ARMv8-M support - PR-1051 STM32G474 support

        - Initial architectural support for the STM32G474 family of
          microcontrollers. In terms of peripherals, currently there is basic
          support for the RCC and UART, allowing NuttX to boot to a functional
          NSH prompt on this family. Other peripherals on the SoC are not yet
          supported and/or not tested yet. Contributions to enable other
          peripherals are welcome. This adds support for these variants:

            STM32G474C STM32G474M STM32G474R STM32G474Q STM32G474V

      * Architectures With Significant Improvements:
        - PR-745 The full line of STM32H7 chips are now defined
          This adds support for these variants:

              STM32H743AG STM32H743AI STM32H743BG STM32H743BI STM32H743IG
              STM32H743II STM32H743VG STM32H743VI STM32H743XG STM32H743XI
              STM32H743ZG STM32H753AI STM32H753BI STM32H753VI STM32H753XI
              STM32H753ZI

        - PR-811 i486: Fix corruption of esp register on full context restore
          This resolves a long standing issue with running the x86 port under
          QEMU where it would crash shortly after boot.

        - PR-837 rx65n: Add crashdump support using standby RAM - PR-862
          STM32L4: Expose LPTIM timers - PR-868 STM32L4: Extend clock options and
          power regulation for based on clock settings
            Interface to select the core regulator voltage according to clock
            frequency range Usage of this interface during clock configuration
            according to chosen clock frequency Option to choose a different
            system clock than the main PLL (there is HSI, MSI, HSE and LSE
            available to use) Option to not enable the main PLL which allows for
            reduced power usage when setting one of the above options as system
            clock, to do this you should define STM32L4_BOARD_NOPLL on your
            board header.
        - PR-960 STM32: Add support for ADC features EXTSEL and JEXTSEL
        - PR-1041 STM32H7: Improve IDMA transfer and cache handling
          This resolves an issue where the sdmmc driver crashes at boot when
          using writeback cache.

          This also simplifies the sdmmc driver when the IDMA is in use. There
          is no need to mix IDMA and interrupt based transfers; instead, when
          making unaligned data tranfers, just make IDMA into an internal
          aligned buffer and then copy the data. This method also enables
          multiblock transfers, and transfers from/to data buffers which are not
          aligned on cache boundary.
        - PR-1042 STM32H7: Resolve multiple limitations and bugs with progmem
          especailly for partial memory writes
        - PR-1045 STM32H7: This gives possibility to send arbitrary number of
          bytes from memory to peripheral using DMA also when using write-back
          cache
            It was not possible to DMA to/from AXI sram if
            CONFIG_STM32H7_DMACAPABLE=y When doing TX DMA (e.g. in SPI driver in
            simplex-tx mode), it should not be necessary to align the data
            buffers to the cache line.
        - PR-1103 STM32H7: Resolve clocking and pin configurations bugs that
          could cause SDMMC and ETH to fail in some configurations
        - PR-1104 STM32H7: Use UUID for Ethernet MAC.  This is inline with the
          behaviour of STM32F7
        - PR-1110 STM32H7: Use FDCANSEL to determin FDCAN clock source if
          possible - PR-1165 STM32H7: SPI transaction appears to be completed
          before the data has actually been flushed
          TX DMA completes before the data has been actually sent out from the
          SPI fifo. This is expected, but the exchange should actually wait for
          spi tx to finish instead of dma to the fifo to finish. This replaces
          the dma completion event with the SPI TXC event for detecting end of
          transmission.

        - PR-1203 PR-1204 STM32H7: Enable support for BDMA and enable it for
          SPI6
        - PR-905 x86_64: Resolve linking issue when building with gcc 7 and 9.
        - PR-904 x86_64: Resolve compiler aliasing warnings and RNG
          pointer cast bug - PR-944 x86_64: Change entrypoint to standard
          location 1M
        - PR-971 x86_64: Fix bug in rng implementation using intrinsics
        - PR-973 x86_64: Fix crash on boot when XSAVE and SSE/AVX is enabled
        - PR-974 x86_64: Add support booting NuttX as a Jailhouse Cell
        - PR-919 sim: Add host mmap and perror to allow use of LIBC_MODLIB
          and BINFMT_LOADABLE
        - PR-1198 sim: Use correct errno sign with hostfs interface
        - PR-932 z16: Updated toolchain to ZDS-II 5.2.2
        - PR-970 K210: Add PLL support
        - PR-988 K210: Resolve occasional lock in early boot caused by waiting
          forserial driver to initialize
        - PR-1205 K210: Add basic GPIOHS support - PR-1112 tiva: Add up_idle
          support - PR-1116 NRF52832: Work around chip eratta for SPI Master 1
          Byte transfer anomaly - PR-1130 imxrt: Resolve WFI issue by setting
          the low power mode to remain in run mode
        - PR-1197 cxd56: Fix locking issue in Spresense audio driver causes by
          using semaphore in DMA buffer handling code
        - PR-1221 Add INTx_C macro defintion

  * Driver Support:
      * Bug Fixes:
        - PR-1206 PR-1207 PR-1210 ioctl function should retun ENOTTY when the
          command is not recognized.

      * New Driver Support:
        - PR-795 PR-1001 Initial NuttX audio driver supporting the Spresense
          CXD56
        - PR-975 Support for HDC1008 temperature and humidity sensor
        - PR-1201 Support for the CS4344 stereo audio DAC
        - PR-1145 Support for the FTDI FT232R USB to Serial converter
        - PR-1052 gs2200m: Add max payload size to prevent crashing when
          sending large packets
        - PR-1090 gs2200m: Fix possible packet queue count overflow seen during
          streaming - PR-1127 gs2200m: Resolve possible buffer overrun in packet
          parsing - PR-1167 pty: Return correct number of bytes when
          CONFIG_SERIAL_TERMIOS and OPOST|ONLCR are enabled

      * Drivers With Significant Improvements:
        - PR-887 PR-888 rptun: Add control for independent control of rx and tx
          buffer size
        - PR-917 gs2200m: Receive performance improvement for TCP/UDP
        - PR-1032 gs2200m: Add SPI-DMA support to spresense
        - PR-1046 gs2200m: Add getsockname() support
        - PR-1094 PR-1163 gs2200m: Add flow control support to prevent memory
          starvation in changing network environments
        - PR-1101 gs2200m: Add WPA2-PSK AP mode support, this is now the default
          instead of WEP
        - PR-1115 SPI slave: Improve interface
          Enable enqueue and receive full buffers of data with single call, to
          avoid call overhead when sending / receiving large amounts of data.
          Enable the slave device to leave received data in the controller
          receive buffers and retrieve it from there by polling
        - PR-1196 Audio: Add support for using ap_buffer_info without
          CONFIG_AUDIO_DRIVER_SPECIFIC_BUFFERS and return ENOTTY if provided ioctl
          is not supported
        - PR-1222 audio/cxd56: Add audio buffering feature.

  * Board Support:
      * Significant Improvements:

        - PR-1200 The boards_button_initialize and boards_userled_initialize
          functions now return the number of buttons and leds, thus their
          prototypes have changed from:
            void board_button_initialize(void)
            void board_userled_initialize(void)

            to

            uint32_t board_button_initialize(void)
            uint32_t board_userled_initialize(void).

      * New Board Support:
        - PR-1051 ST Micro B-G474E-DPOW1 Discovery Kit
          Initial support for the ST Micro B-G474E-DPOW1 Discovery Kit with
          STM32G474RE MCU. Currently there is basic support for booting NuttX to
          a functional NSH prompt. Other peripherals on the board are not yet
          supported or not tested yet. Contributions to enable other peripherals
          are welcome. The NSH prompt can be accessed from a host computer via a
          Virtual COM Port over the same Micro-USB Type B connection used for
          programming/debugging.
        - PR-1211  STM32F411-Minimum board (a.k.a. BlackPill)
          Initial support for the BlackPill board which is a low cost STM32F411
          board.  The current support boots NuttX to a functional NSH prompt.

      * Boards With Significant Improvements:
        - PR-949 qemu-intel64: Add nsh configuration for testing QEMU
          virtualization
        - PR-966 qemu-i486: Fix issue where console would not accept input
          because of wrong IRQ number
        - PR-993 stm32h747i-disco: Add support for FMC SDRAM - PR-1029 maix-bit:
          Add knsh configuration for testing Kernel mode under QEMU virtualization
        - PR-1056 stm32h747i-disco: Add support for FAT and SD Card via SDMMC
        - PR-1070 PR-1086 spresense: Add ftpd/ftpc and nxplayer to wifi and rndis
          configurations
        - PR-1084 imxrt1060-evk: Add dns client and renew command to netnsh
          configuration
        - PR-1113 lm3s6965ek: Use proper sysclock for QEMU
          configuration
        - PR-1229 Add support for the inboard joystick
        - PR-1232 Architectural re-organization to the initialization of the
          video stream driver to comply with other NuttX drivers

  * File System:
      * Bug Fixes:
        - PR-918 tmpfs: Calling statfs could cause files to be removed
          recursively - PR-1142 NFS: Use of uint64_t causes issues with gaps in
          data since it must be on a 8 byte boundary
        - PR-1143 Report correct stats for proxied block and MTD drivers

      * Significant Improvements:
        - PR-793 Allow use of genromfs to geneate ROMFS
        - PR-851 Upgrade littlefs to v2.2.1
        - PR-1154 FATFS: Do not rewrite the root directory if it has not been
          changed.
        - PR-1120 PR-1118 Fill in file size for mtd and block inode

  * Networking:
    - PR-807 Netlink: Broadcast link status changes to userspace via
      RTNLGRP_LINK
    - PR-892 Netdb: Multiple DNS Servers
      Adds capability to add multiple nameservers on run-time even when not
      using resolv.conf and reset the list of nameservers back to default
      setting (no nameserver at all or single predefined nameserver in Kconfig).
      This is useful for applications that change their cellular network
      frequently.
    - PR-1015 tcp/conn: Request ARP before 3-way handshake

  * Applications:
      * Improvements:
        - PR-185 PR-828 nshlib
          Add the source command. Avoid use of sh where it is not needed since
          it pollutes the parent environment including the working directory and
          variables.

        - PR-236 littlevgl: Add additional config mappings to the library
        - PR-264 nxplayer: Add max host and filename for http url
        - PR-260 nshlib: Add wget buffer size control with
          CONFIG_NSH_WGET_BUFF_SIZE
        - PR-243 dhcpd: Add ability for daemon to be cancelled
        - PR-238 Remove use the set_errno this is now properly handled by the
          libc and OS
        - PR-233 hdc1008: Add example application for this driver

      * Bug Fixes:
        - PR-282 netlib: Fix pathlen computation for netlib_parseurl and
          netlib_parsehttpurl
        - PR-281 webclient: Check return value of netlib_parseurl correctly
        - PR-278 webclient: Handle http/https redirection correctly
        - PR-277 webclient: Limit the number of http redirects
        - PR-198 webclient: Use getaddrinfo() to get IPv4 address on
          dual stack systems
        - PR-268 ftpd: Fix EPSV mode for IPv4
        - PR-258 nsh: Always try FILE_APPS even if the command is builtin,
          this is a regression introduced in 9.0.0
        - PR-257 gs2200m: Handle packets over 1500 Bytes, previously would
          overflow buffer
        - PR-221 gs2200m: Server sockets were not properly being released by
          the daemon when close was called
        - PR-248 dhcpd: Correct option header check length
        - PR-176 cu: Handle NULL character correctly
        - PR-287 PR-290 examples: Update nxflat and thttpd Makefile's to fix
          a build breakage.

  * Compatibility Concerns -- Changes to Build System:

    If you are building NuttX for a custom board, you may need to make
    some of the following changes in build-related files for your board:

    * Rename EXTRADEFINES to EXTRAFLAGS

      In your custom board's scripts/Make.defs file, rename EXTRADEFINES to
      EXTRAFLAGS.

      For example, these lines:

      ```
      CFLAGS = $(ARCHCFLAGS) $(ARCHWARNINGS) $(ARCHOPTIMIZATION) $(ARCHCPUFLAGS) $(ARCHINCLUDES) $(ARCHDEFINES) $(EXTRADEFINES) -pipe
      ...
      CXXFLAGS = $(ARCHCXXFLAGS) $(ARCHWARNINGSXX) $(ARCHOPTIMIZATION) $(ARCHCPUFLAGS) $(ARCHXXINCLUDES) $(ARCHDEFINES) $(EXTRADEFINES) -pipe
      ...
      CPPFLAGS = $(ARCHINCLUDES) $(ARCHDEFINES) $(EXTRADEFINES)
      ```

      would change as follows:

      ```
      CFLAGS = $(ARCHCFLAGS) $(ARCHWARNINGS) $(ARCHOPTIMIZATION) $(ARCHCPUFLAGS) $(ARCHINCLUDES) $(ARCHDEFINES) $(EXTRAFLAGS) -pipe
      ...
      CXXFLAGS = $(ARCHCXXFLAGS) $(ARCHWARNINGSXX) $(ARCHOPTIMIZATION) $(ARCHCPUFLAGS) $(ARCHXXINCLUDES) $(ARCHDEFINES) $(EXTRAFLAGS) -pipe
      ...
      CPPFLAGS = $(ARCHINCLUDES) $(ARCHDEFINES) $(EXTRAFLAGS)
      ```

      See git commit # 459ad9937377a42785692098ff0d73baaa9551e6 in the main
      NuttX repository.

      If you forget to do this, memory allocations on the heap probably won't
      work and your user tasks won't start.

      To see why, tools/Config.mk assigns a value to KDEFINE such that the
      preprocessor symbol __KERNEL__ will be defined when certain source
      files are compiled. KDEFINE is passed to nested invocations of 'make'
      as EXTRAFLAGS. If your board's scripts/Make.defs still attempts to use
      EXTRADEFINES, the preprocessor symbol __KERNEL__ will not be defined in
      some of the places that it should be. Suppose you're building a FLAT
      build. In this case, include/nuttx/mm/mm.h will not define
      MM_KERNEL_USRHEAP_INIT like it should, which will cause nx_start.c not
      to call up_allocate_heap() at startup. Therefore, any attempt to
      allocate memory on the heap will fail.

    * Rename src/Makefile to src/Make.defs and Modify

      This item pertains only to custom boards that are developed in- tree,
      meaning under the NuttX boards/ subdirectory. Out-of-tree boards are
      not affected.

      If your custom board directory is in-tree and in a board family that
      uses a 'boards/ARCH/FAMILY/common' directory (such as
      boards/arm/stm32/common, boards/arm/cxd56xx/common, etc), then you'll
      need to make two minor changes to your custom board's src/Makefile:

      (1) Rename it from src/Makefile to src/Make.defs, and

      (2) Near the end of that file, replace this line, which usually
          appears at the end:

      ```
      include $(TOPDIR)/boards/Board.mk
      ```

      with these three lines:

      ```
      DEPPATH += --dep-path board
      VPATH += :board
      CFLAGS += $(shell $(INCDIR) $(INCDIROPT) "$(CC)" $(TOPDIR)$(DELIM)arch$(DELIM)$(CONFIG_ARCH)$(DELIM)src$(DELIM)board$(DELIM)board)
      ```

      See git commit # 6ca46520df38854bf660f9be54957cceede39ded in the main
      NuttX repository.

      If you forget to do this, 'make' will report an error, "no rule to make
      libboard.a," and the build will fail.

    * Rename WINTOOL to CONFIG_CYGWIN_WINTOOL

      In your custom board's scripts/Make.defs file, rename any instances of
      WINTOOL to CONFIG_CYGWIN_WINTOOL.

      For example, change this line:

      ```
      ifeq ($(WINTOOL),y)
      ```

      to this:

      ```
      ifeq ($(CONFIG_CYGWIN_WINTOOL),y)
      ```

      See git commit # bd656888f26c92e8832f0e76b395a5ece7704530 in the main
      NuttX repository.

    * Remove INCDIROPT

      In your custom board's src/Make.defs file, remove INCDIROPT from CFLAGS.

      For example, change this line:

      ```
      CFLAGS += $(shell $(INCDIR) $(INCDIROPT) "$(CC)" $(TOPDIR)$(DELIM)arch$(DELIM)$(CONFIG_ARCH)$(DELIM)src$(DELIM)board$(DELIM)board)
      ```

      to this:

      ```
      CFLAGS += $(shell $(INCDIR) "$(CC)" $(TOPDIR)$(DELIM)arch$(DELIM)$(CONFIG_ARCH)$(DELIM)src$(DELIM)board$(DELIM)board)
      ```

      This option, which resolves to -w when CONFIG_CYGWIN_WINTOOL is
      configured, is now appended to INCDIR in tools/Config.mk.

      See git commit # 5eae32577e5d5226e5d3027c169eeb369f83f77d in the main
      NuttX repository.

    * Remove Unnecessary Variables

      In your custom board's scripts/Make.defs file, It is no longer
      necessary to define the following variables unless your build requires
      that you assign special values to them:

      - DIRLINK
      - DIRUNLINK
      - MKDEP
      - ASMEXT
      - OBJEXT
      - LIBEXT
      - EXEEXT

      These variables have been refactored into tools/Config.mk.

      See these git commits in the main NuttX repository:
      9ec9431706fd0eb7c4c4410d84dafff68ff31366 (DIRLINK and DIRUNLINK),
      8b42ee421a41214093c0238e479d73a1099b0e82 (MKDEP), and
      567962bd6263bf8809fb63c739f6ec668c69c416 (ASMEXT, OBJEXT, LIBEXT, EXEEXT)

    * Change ${TOPDIR} to $(TOPDIR)

      In your custom board's scripts/Make.defs file, it is recommended to
      change ${TOPDIR} to $(TOPDIR) for consistency (change curly braces to
      parenthesis).

      See git commit # faf3c0254bb63af89f9eb59beefacb4cba26dd9 in the main
      NuttX repository.

    * Remove Workaround For Missing $(TOPDIR)/Make.defs

      In src/Make.defs or src/Makefile for your custom board or custom apps,
      the workaround for missing $(TOPDIR)/.config and/or
      $(TOPDIR)/Make.defs is no longer needed. To remove the workaround,
      delete the minus sign in front of include .config. This is now handled
      in the main Makefile and, if those files are missing, will print an
      error message with hint to run tools/configure.sh <target>.

      Change this line, located near the top of the file:

      ```
      -include $(TOPDIR)/Make.defs
      ```

      to this:

      ```
      include $(TOPDIR)/Make.defs
      ```

      See git commit # 1a95cce1a3c3ed8b04d1d86b7bd744352cca45a2 in the main
      NuttX repository, and git commit
      # ead498a7883a654b1d542da94a5fab3ce163361e in the apps repository.

    * Simplify ARCHINCLUDES and ARCHXXINCLUDES

      In your custom board's scripts/Make.defs, ARCHINCLUDES and
      ARCHXXINCLUDES can be defined without maintaining two different
      versions conditioned upon CONFIG_CYGWIN_WINTOOL (renamed from WINTOOL).
      Replace syntax similar to the following:

      ```
      ifeq ($(CONFIG_CYGWIN_WINTOOL),y)
      # Windows-native toolchains
        ARCHINCLUDES = -I. -isystem "${shell cygpath -w $(TOPDIR)$(DELIM)include}"
        ARCHXXINCLUDES = -I. -isystem "${shell cygpath -w $(TOPDIR)$(DELIM)include}" -isystem "${shell cygpath -w $(TOPDIR)$(DELIM)include$(DELIM)cxx}"
      else
      # Linux/Cygwin-native toolchain
        ARCHINCLUDES = -I. -isystem $(TOPDIR)$(DELIM)include
        ARCHXXINCLUDES = -I. -isystem $(TOPDIR)$(DELIM)include -isystem $(TOPDIR)$(DELIM)include$(DELIM)cxx
      endif
      ```

      with syntax similar to:

      ```
      ARCHINCLUDES += ${shell $(INCDIR) -s "$(CC)" $(TOPDIR)$(DELIM)include}
      ARCHXXINCLUDES += ${shell $(INCDIR) -s "$(CC)" $(TOPDIR)$(DELIM)include}
      ARCHXXINCLUDES += ${shell $(INCDIR) -s "$(CC)" $(TOPDIR)$(DELIM)include$(DELIM)cxx}
      INCDIR is defined in tools/Config.mk and resolves to a shell script or batch file that constructs the appropriate command line argument string to specify include directories for your compiler.
      ```

      See git commit # 7e5b0f81e93c7e879ce8434d57e8bf4e2319c1c0 in the main
      NuttX repository.

    * Simplify Board Directory Handling With BOARD_DIR

      In your custom board's Make.defs or Makefile, when setting up build
      variables containing paths inside your board directory, a new variable
      BOARD_DIR has been introduced that simplifies the syntax:

      Replace syntax like this:

      ```
      $(TOPDIR)$(DELIM)boards$(DELIM)$(CONFIG_ARCH)$(DELIM)$(CONFIG_ARCH_CHIP)$(DELIM)$(CONFIG_ARCH_BOARD)
      ```

      with this variable:

      ```
      $(BOARD_DIR)
      ```

      For example, change this:

      ```
      ARCHSCRIPT = -T$(TOPDIR)$(DELIM)boards$(DELIM)$(CONFIG_ARCH)$(DELIM)$(CONFIG_ARCH_CHIP)$(DELIM)$(CONFIG_ARCH_BOARD)$(DELIM)scripts$(DELIM)$(LDSCRIPT)
      ```

      to this much simpler syntax:

      ```
      ARCHSCRIPT = -T$(BOARD_DIR)$(DELIM)scripts$(DELIM)$(LDSCRIPT)
      ```

      You may find the old syntax being used for variables like ARCHSCRIPT,
      LDELFFLAGS, LINKCMDTEMPLATE, SCRIPTDIR, USER_LDSCRIPT, or others.

      BOARD_DIR is defined in tools/Config.mk.

      See git commit # e83c1400b65c65cbdf59c5abcf2ae368f540faef in the main
      NuttX repository.


NuttX-10.0.0 Release Notes
------------------------

## Major Changes to Core OS

### New Features

Major changes to the internal, OS timer (wdog) interfaces. The change includes:

 * The wdog timer call backs used to support a variable number of arguments.
Now they support only a single argument ([PR
#1565](https://github.com/apache/incubator-nuttx/pull/1565)). This eliminates
(1) the configuration option `CONFIG_MAX_WDOGPARMS` and the OS interfaces
`wd_create()` and `wd_delete()` *   wdog timer data structures are no longer
pre-allocated. Now they are allocated by the caller of `wd_start()`. This (1)
eliminates the configuration options `CONFIG_PREALLOC_WDOGS` and
`CONFIG_WDOG_INTRESERVE`, (2) eliminates the type `WDOG_ID` which was a pointer
type to `struct wdog_s`, and (3) change the type of the first argument of all
remaining wdog interfaces functions from `WDOG_ID` to `FAR struct wdog_s *`.

Because of these changes, all proprietary drivers maintained by all NuttX users
will require modification. The following summaries the required modifications:

 * Most drivers have a field in structure like `WDOG_ID wdog`; That must be
changed to `struct wdog_s wdog`; That changes the field from a pointer to a
`struct wdog_s` to the `struct wdog_s` storage itself. *   Eliminate all calls
to `wd_create()`. The `WDOG_ID` is not longer managed by the timing subsystem
and the `wd_create()` interface has been removed. *   The `wd_delete()`
interface has also been removed, but more care will need to be exercised:
`wd_delete()` also cancels any running timer so, in many case, calls to
`wd_delete()` should be replaced with calls to `wd_cancel()`. If you are certain
that the timer has never been started, then you must remove the call to
`wd_delete()` altogether. Calling `wd_cancel()` with an un-initialized s`truct
wdog_s` instance may well cause a fatal crash. *   Replace the first parameter
of all remaining wdog function calls from. For example, replace a call like `ret
= wd_cancel(priv->wdog)` where `priv->wdog` was type `WDOG_ID` with the call
`ret = wd_cancel(&priv->wdog)`where `priv->wdog` is now type `struct wdog_s`.

 * [PR-1877](https://github.com/apache/incubator-nuttx/pull/1877) libc:
 Implement "j" modifier for scanf

 * [PR-1864](https://github.com/apache/incubator-nuttx/pull/1864) libc: fs: Add
 relative path support

 * [PR-1863](https://github.com/apache/incubator-nuttx/pull/1863) libc:
 Implement `access()`

 * [PR-1866](https://github.com/apache/incubator-nuttx/pull/1866) libc: uio:
 enable `writev()` for sockets

 * [PR-1853](https://github.com/apache/incubator-nuttx/pull/1853) libc:
 Implement `popcount/popcountl/popcountll`

 * [PR-1850](https://github.com/apache/incubator-nuttx/pull/1850) Add tool for
 parsing the callstack for Trace32

 * [PR-1840](https://github.com/apache/incubator-nuttx/pull/1840) Add POLLPRI
 for exception condition on the file descriptor

 * [PR-1828](https://github.com/apache/incubator-nuttx/pull/1828) Implement
 mkdtemp syscall

 * [PR-1826](https://github.com/apache/incubator-nuttx/pull/1826) libc: Add
 "tm\_zone" member to tm

 * [PR-1824](https://github.com/apache/incubator-nuttx/pull/1824) Implement
 etpriority syscall

 * [PR-1821](https://github.com/apache/incubator-nuttx/pull/1821) Implement
 gettid syscall

 * [PR-1818](https://github.com/apache/incubator-nuttx/pull/1818) Implement
 pipe2 syscall

 * [PR-1779](https://github.com/apache/incubator-nuttx/pull/1779) libc: Minimal
 umask implementation

 * [PR-1758](https://github.com/apache/incubator-nuttx/pull/1758) mm: Add lock
 to protect call to mm\_addregion

 * [PR-1756](https://github.com/apache/incubator-nuttx/pull/1756) libc:
 Implement gethrtime, getrlimit, setrlimit

 * [PR-1658](https://github.com/apache/incubator-nuttx/pull/1658) libc: Add
 stubs for utimes

 * [PR-1615](https://github.com/apache/incubator-nuttx/pull/1615) libc:
 Implement tm::tm\_gmtoff field

 * [PR-1611](https://github.com/apache/incubator-nuttx/pull/1611) libc: Allocate
 file\_struct dynamically

 * [PR-1684](https://github.com/apache/incubator-nuttx/pull/1684) Add gdb script
 for NuttX thread debugging

 * [PR-1607](https://github.com/apache/incubator-nuttx/pull/1607) mm: Implement
 malloc\_usable\_size

 * [PR-1606](https://github.com/apache/incubator-nuttx/pull/1606) sched/pthread:
 Implement pthread\_attr\_detachstate

 * [PR-1600](https://github.com/apache/incubator-nuttx/pull/1600) Implement
 epol\_pwait and EPOLLONESHOT flag

 * [PR-1597](https://github.com/apache/incubator-nuttx/pull/1597) sched: Support
 passing non empty argument to init task

 * [PR-1596](https://github.com/apache/incubator-nuttx/pull/1596) libc: Replace
 all sem\_xxx with \_SEM\_XXX. This insures the correct semaphore interface is
 used by userspace and the kernel.

 * [PR-1517](https://github.com/apache/incubator-nuttx/pull/1517) sched/wdog:
 Change the default value of MAX\_WDOGPARMS from 4 to 2 as wd\_start is two every
 where in the code base. Also bump CONFIG\_MAX\_WDOGPARAMS from 1 to 2 in
 defconfigs to support pthread\_condclockwait()

 * [PR-1486](https://github.com/apache/incubator-nuttx/pull/1486) libc:
 Implement ftw and nftw functions

 * [PR-1567](https://github.com/apache/incubator-nuttx/pull/1567) libc:
 Implement proposed POSIX \_clockwait variants of \_timedwait functions

 * [PR-1411](https://github.com/apache/incubator-nuttx/pull/1411) libxx:
 Integrate latest uclibcxx 0.2.5

 * [PR-1586](https://github.com/apache/incubator-nuttx/pull/1586) libc: Add open
 for text (translated) access support

 * [PR-1584](https://github.com/apache/incubator-nuttx/pull/1584) libc:
 Implement strlcpy function

 * [PR-1580](https://github.com/apache/incubator-nuttx/pull/1580) libc:
 Implement pthread\_conattr\_etclock

 * [PR-1545](https://github.com/apache/incubator-nuttx/pull/1545) sched/wdog: Do
 not dynamically allocate wdog\_s. Reduces overhead and brings it inline with
 work\_s

 * [PR-1534](https://github.com/apache/incubator-nuttx/pull/1534) sched/wdog:
 Replace all callback arguments from uint32\_t to wdparm\_t

 * [PR-1420](https://github.com/apache/incubator-nuttx/pull/1420) libc: Do not
 define localtime\[\_r\] to macro with CONFIG\_LIBC\_LOCALTIME is not defined.

 * [PR-1375](https://github.com/apache/incubator-nuttx/pull/1375) libc: Always
 declare getenv, link/symlink and atexist/on\_exit. Many C++ libraries reference
 these but dont use them

 * [PR-1371](https://github.com/apache/incubator-nuttx/pull/1371) libc: Improve
 stat/readdir to be more POSIX compliant with S\_xxx macro definition as with
 Linux

 * [PR-1369](https://github.com/apache/incubator-nuttx/pull/1369) Initialize the
 idle stack at the arch layer to better support stack coloring and also make it
 compatible with new TLS implementation

 * [PR-1292](https://github.com/apache/incubator-nuttx/pull/1292) pthread/mutex:
 Add PTHREAD\_RECURSIVE\_MUTEX\_INITIALIZER\_NP support

 * [PR-1280](https://github.com/apache/incubator-nuttx/pull/1280) libc:
 Implement fseeko and ftello

 * [PR-1279](https://github.com/apache/incubator-nuttx/pull/1279) libc:
 Implement lstat and realpath

 * [PR-1278](https://github.com/apache/incubator-nuttx/pull/1278) libc:
 Implement pathconf and fpathconf

 * [PR-1269](https://github.com/apache/incubator-nuttx/pull/1269) cstdlib: Add
 missing atox to std namespace

 * [PR-1264](https://github.com/apache/incubator-nuttx/pull/1264) sched/pthread:
 Prohibit the use of pthread\_cleanup API's by kernel threads

 * [PR-1440](https://github.com/apache/incubator-nuttx/pull/1440) libc: Add the
 UUID libc functions

 * [PR-1308](https://github.com/apache/incubator-nuttx/pull/1308) libc: Add
 support for \_SC\_NPROCESSORS\_CONF/\_SC\_NPROCESSORS\_ONLN to sysconf

 * [PR-1305](https://github.com/apache/incubator-nuttx/pull/1305) libc:
 Implement WNOHANG for waitpid and waitid

 * [PR-1237](https://github.com/apache/incubator-nuttx/pull/1237) libc: Add
 minimal support for locale\_t operation: suplocale, freelocale, newlocale,
 userlocale

 * [PR-1317](https://github.com/apache/incubator-nuttx/pull/1317) sched/task:
 Unify task initialization

 * [PR-1187](https://github.com/apache/incubator-nuttx/pull/1187) sched: Unify
 main thread and pthread behavior

 * [PR-2263](https://github.com/apache/incubator-nuttx/pull/2263) libc/stdio:
 Preallocate stdin, stdout, stderr

 * [PR-2053](https://github.com/apache/incubator-nuttx/pull/2053)  *
 [PR-2040](https://github.com/apache/incubator-nuttx/pull/2040) serial/termios:
 Support custom baudrate setting

### Bug Fixes

 * [PR-1911](https://github.com/apache/incubator-nuttx/pull/1911) init\_section
 was not being emitted resulting in C++ static constructors not being called.

 * [PR-1889](https://github.com/apache/incubator-nuttx/pull/1889) Fix build
 error for ::setbuf if CONFIG\_STDIO\_DISABLE\_BUFFERING is set

 * [PR-1619](https://github.com/apache/incubator-nuttx/pull/1619) Fix inverted
 errno in mq\_open

 * [PR-1595](https://github.com/apache/incubator-nuttx/pull/1595) epoll\_wait()
 must loop until "maxevents" to fille output evs array

 * [PR-1519](https://github.com/apache/incubator-nuttx/pull/1519) libc: Replace
 index/rindex from macro to function to protect against side effects with
 conflicting local variables

 * [PR-1514](https://github.com/apache/incubator-nuttx/pull/1514) Remove usage
 for user-space memalign() from kernel/driver code. Instead use the proper
 kernel memory interface.

 * [PR-1512](https://github.com/apache/incubator-nuttx/pull/1512) /  *
 [PR-1510](https://github.com/apache/incubator-nuttx/pull/1510) /  *
 [PR-1507](https://github.com/apache/incubator-nuttx/pull/1507) Remove usage for
 user-space malloc()/zalloc()/free() from kernel/driver code. Instead use the
 proper kernel memory interface.

 * [PR-1496](https://github.com/apache/incubator-nuttx/pull/1496) libc: Change
 ctype macro to normal function to resolve macro evaluation side effects

 * [PR-1463](https://github.com/apache/incubator-nuttx/pull/146) libc: Replace
 all malloc/free with lib\_malloc/lib\_free inside libc

 * [PR-1365](https://github.com/apache/incubator-nuttx/pull/1365) up\_assert
 should not call exit() directly because it is only callable from userspace

 * [PR-1336](https://github.com/apache/incubator-nuttx/pull/1336) syscall: Fix
 prctl PR\_SET\_NAME failure if called without pid argument

 * [PR-1289](https://github.com/apache/incubator-nuttx/pull/1289) Clear the
 error indicator with rewind()

 * [PR-1254](https://github.com/apache/incubator-nuttx/pull/1254) libc: mkstemp
 only look at the trailing X's instead of the first X

 * [PR-1311](https://github.com/apache/incubator-nuttx/pull/1311) libc: Move
 double\_t typedef from sys/types.h to math.h

 * [PR-1328](https://github.com/apache/incubator-nuttx/pull/1328) Make sure that
 pthread\_cleanup functions are only called from userspace

 * [PR-1318](https://github.com/apache/incubator-nuttx/pull/1318)
 nxsched\_release\_tcb should release stack in kernel build, fixes memory leak

 * [PR-2951](https://github.com/apache/incubator-nuttx/pull/2951) sched: Fix
 deadlock in nxtask\_exit() for SMP

 * [PR-2229](https://github.com/apache/incubator-nuttx/pulls/2229)  *
 [PR-2298](https://github.com/apache/incubator-nuttx/pulls/2298)  *
 [PR-2279](https://github.com/apache/incubator-nuttx/pulls/2279)  *
 [PR-2272](https://github.com/apache/incubator-nuttx/pulls/2272)  *
 [PR-2264](https://github.com/apache/incubator-nuttx/pulls/2264)  *
 [PR-1992](https://github.com/apache/incubator-nuttx/pulls/1992)  *
 [PR-2022](https://github.com/apache/incubator-nuttx/pulls/2022) sched: SMP
 fixups that caused locking and removal of some no longer required workarounds

 * [PR-1993](https://github.com/apache/incubator-nuttx/pull/1993) libc: Skip
 close stdin/stdout/stderr in fclose

 * [PR-1997](https://github.com/apache/incubator-nuttx/pull/1997) libc: Remove
 all calls to fclose with stdin/stdout/stderr with fclose



## Major Changes to Documentation

 * [PR-1763](https://github.com/apache/incubator-nuttx/pulls/1763) Add
 quickstart documentation

 * [PR-1677](https://github.com/apache/incubator-nuttx/pull/1677) Add simulator,
 drivers, and contributing instructions for new users

 * [PR-1675](https://github.com/apache/incubator-nuttx/pull/1675) Add quickstart
 documentation from NuttX Companion

 * [PR-1673](https://github.com/apache/incubator-nuttx/pull/1673) Update all the
 links in the documentation to point to nuttx.apache.org or the Apache NuttX
 wiki instead of old nuttx.org resources

 * [PR-1501](https://github.com/apache/incubator-nuttx/pull/1501) Port all the
 existing documentation from HTML files to Sphinx based documentation along with
 a bunch of updates and improvments

 * [PR-1433](https://github.com/apache/incubator-nuttx/pull/1433) Convert README
 documentation to Markdown

## Major Changes to the Build System

### New Features

 * [PR-1786](https://github.com/apache/incubator-nuttx/pull/1786) Support
 building external code into the OS

 * [PR-1396](https://github.com/apache/incubator-nuttx/pull/1396) Make C/C++
 search path common so all boards support uClibc++/libc++ automatically

 * [PR-1682](https://github.com/apache/incubator-nuttx/pull/1682) configure.sh
 can now list configurations with "-L" option

 * [PR-2023](https://github.com/apache/incubator-nuttx/pull/2023) tools: Remove
 WSL configuration. This is just Linux now.

### Bug Fixes

 * [PR-1713](https://github.com/apache/incubator-nuttx/pull/1713) Fix export
 target: libboard was missing KERNEL flag.

 * [PR-1470](https://github.com/apache/incubator-nuttx/pull/1470) Fix Make.dep
 not updated by .config changes

 * [PR-1345](https://github.com/apache/incubator-nuttx/pull/1786) Enhance export
 target: make BIN directory configurable, export post build script, use LDNAME
 instead of LDSCRIPT

 * [PR-1332](https://github.com/apache/incubator-nuttx/pull/1332) Include
 incdir.c in the export target

 * [PR-1995](https://github.com/apache/incubator-nuttx/pull/1995) Fix issue
 where wrong extension was generated for mkconfig in WSL builds

 * [PR-1949](https://github.com/apache/incubator-nuttx/pull/1949) Fix issue in
 make export where nuttx-names.dat was not being generated

 * [PR-1682](https://github.com/apache/incubator-nuttx/pull/1682): Fix issue
 where windows style paths might not be handled correctly breaking Cygwin builds

## Architectural Support

### New Architecture Support

 * [PR-1847](https://github.com/apache/incubator-nuttx/pull/1847) ARM: Initial
 support for ARMV6M to support CortexM0+

 * [PR-1397](https://github.com/apache/incubator-nuttx/pull/1379): EOSS3:
 Initial support for the QuickLogic EOS S3 SoC

### Architectures With Significant Improvements

#### cxd56xx

 * [PR-1753](https://github.com/apache/incubator-nuttx/pull/1753) cxd56xx: Use
 spinlock in gpioint to improve SMP performance

 * [PR-1650](https://github.com/apache/incubator-nuttx/pull/1650) cxd56xx: Use
 spinlock in rtc to improve SMP performance

 * [PR-1621](https://github.com/apache/incubator-nuttx/pull/1621) cxd56xx: Use
 spinlock in serial to improve SMP performance

 * [PR-1569](https://github.com/apache/incubator-nuttx/pull/1569) cxd56xx: Add
 SMP support to cxd56\_farapi.c

 * [PR-1689](https://github.com/apache/incubator-nuttx/pull/1689) cxd56xx: Use
 spinlock in uart to improve SMP performance

#### ESP32

 * [PR-1422](https://github.com/apache/incubator-nuttx/pull/1422) ESP32: Add SPI
 driver (Master & Slave)

 * [PR-1435](https://github.com/apache/incubator-nuttx/pull/1435) ESP32: Add I2C
 driver

 * [PR-1491](https://github.com/apache/incubator-nuttx/pull/1491) ESP32: Add SPI
 Flash driver

 * [PR-1525](https://github.com/apache/incubator-nuttx/pull/1525) ESP32: Add
 Ethernet driver

 * [PR-1610](https://github.com/apache/incubator-nuttx/pull/1610) ESP32: Improve
 SPI transmision (DMA, IOMUX, software CS)

 * [PR-1630](https://github.com/apache/incubator-nuttx/pull/1630) ESP32: Add
 support for HW RNG

 * [PR-1830](https://github.com/apache/incubator-nuttx/pull/1830) ESP32: Add
 Power Management of Force-Sleep

 * [PR-1754](https://github.com/apache/incubator-nuttx/pull/1754) ESP32: Add
 support for external SPIFLASH

 * [PR-1613](https://github.com/apache/incubator-nuttx/pull/1613) ESP32: Add
 function for switching CPU from 80MHz to 240MHz

PR-1712 ESP32: Add support for external MMCSD card over SPI

#### IMXRT

 * [PR-1868](https://github.com/apache/incubator-nuttx/pull/1868) IMXRT: Add ADC
 driver

#### Kinetis

 * [PR-1624](https://github.com/apache/incubator-nuttx/pull/1624) Kinetis:
 USBHOST improvements to avoid race condition durring freeing for queue head
 structure by using Async Advance Doorbell.

PR-1516 Kinetis K28: Add support for USB High Speed Host

PR-1531 Kinetis K28: Add USB state change notifiers in notifier work queue

PR-1456 Kinetis K28: Reworked USB driver for setup out data phase



#### NRF52

 * [PR-1418](https://github.com/apache/incubator-nuttx/pull/1418) NRF52: Add
 Timer and RTC drivers

 * [PR-1432](https://github.com/apache/incubator-nuttx/pull/1422) NRF52: Add
 timer lowerhalf

 * [PR-1635](https://github.com/apache/incubator-nuttx/pull/1635) NRF52: Add
 support for RTC event handling

 * [PR-1636](https://github.com/apache/incubator-nuttx/pull/1636) NRF52: Add
 support for PPI peripheral

 * [PR-1681](https://github.com/apache/incubator-nuttx/pull/1681) NRF52: Add
 support for GPIOTE task mode

 * [PR-1726](https://github.com/apache/incubator-nuttx/pull/1726) NRF52: Extend
 systimer support

 * [PR-1773](https://github.com/apache/incubator-nuttx/pull/1773) NRF52: Add ADC
 and PWM support

 * [PR-1915](https://github.com/apache/incubator-nuttx/pull/1915) NRF52: Add
 serial termios support (no flow control)

 * [PR-1907](https://github.com/apache/incubator-nuttx/pull/1907) NRF52: Add
 basic error handing for i2c in polling mode to support i2ctool. Still not
 handled in DMA mode.

 * [PR-1839](https://github.com/apache/incubator-nuttx/pull/1839) NRF52: Add
 missing SPI callback register hooks to support drivers like mmcsd

 * [PR-1646](https://github.com/apache/incubator-nuttx/pull/1646) NRF52: Better
 differentiation between NRF52840 and NRF52832

PR-1685 NRF52: Add ARM system reset support. Add UID support.

PR-1674 NRF52: Add LFCLK/HFCLK support for selecting oscillator sources.

#### RISCV

 * [PR-1858](https://github.com/apache/incubator-nuttx/pull/1858) RISCV: Add
 missing CSR macros listed in RISC-V spec V1.10.

PR-1314 rv32im: Add schedulesigaction.c, SYS\_save\_context handling, skip ECALL
instruction when calling up\_swint()

#### RX65N

 * [PR-1622](https://github.com/apache/incubator-nuttx/pull/1622) RX65N: Add
 I2C(RIIC) support

 * [PR-1894](https://github.com/apache/incubator-nuttx/pull/1894) RX65N: Add USB
 device support

 * [PR-1899](https://github.com/apache/incubator-nuttx/pull/1899) RX65N: Add DTC
 driver

PR-1910 RX65N: Add SPI driver support

#### SAMD5E5

 * [PR-1515](https://github.com/apache/incubator-nuttx/pull/1515) SAMD5E5: Add
 Watchdog timer support

 * [PR-1574](https://github.com/apache/incubator-nuttx/pull/1574) SAMD5E5: Add
 USB host support

 * [PR-1594](https://github.com/apache/incubator-nuttx/pull/1594) SAMD5E5:
 Freerun timer, oneshot timer and tickless support

 * [PR-1816](https://github.com/apache/incubator-nuttx/pull/1816) SAMD5E5: Add
 MTD progmem support and NVM USER PAGE IOTCLs

#### SAMA5D2

PR-1412 SAMA5D27: Implement system reset to support nsh reboot command

PR-1393 SAMA5D2x: Implement SDMMC peripheral support

#### S32K

PR-1339 S32K: Extend FlexTimer support and add support for PWM

PR-1337 S32K: Allow FlexCAN to use to NETDEV\_LATEINIT to handle the case where
both FlexCAN and ENET are used

#### SIM
 * [PR-1914](https://github.com/apache/incubator-nuttx/pull/1914) SIM: SIGUSR1
 handling now uses NuttX interrupt logic

 * [PR-1859](https://github.com/apache/incubator-nuttx/pull/1859) ESIM: Add
 host timer and improve the oneshot timer logic

 * [PR-1767](https://github.com/apache/incubator-nuttx/pull/1767) SIM: Allow
 access to tty interfaces for better termios support

 * [PR-1655](https://github.com/apache/incubator-nuttx/pull/1655) SIM: Add
 support for Linux HCI Socket as a NuttX BLE adapter. Full NuttX BLE stack can
 be run against any Linux Bluetooth adapter in sim.

 * [PR-1558](https://github.com/apache/incubator-nuttx/pull/1558) SIM: Add
 support for Stack Smashing Protector.

 * [PR-1392](https://github.com/apache/incubator-nuttx/pull/1392) SIM: Make
 uClibc++ and libcxx work on sim platform

 * [PR-1460](https://github.com/apache/incubator-nuttx/pull/1460) SIM: Call
 sched\_note\_cpu\_\* when scheduler instrumentation is enabled

#### STM32

 * [PR-1865](https://github.com/apache/incubator-nuttx/pull/1865) STM32F4: Add
 support for STM32F412CE fixing I2C2/I2C3 and USART1 alt

 * [PR-1506](https://github.com/apache/incubator-nuttx/pull/1506) STM32: Add
 support for single wire UART push/pull mode

 * [PR-1572](https://github.com/apache/incubator-nuttx/pull/1572) STM32F2/F4:
 Add options for I-Cache and D-Cache to be enabled/disable. Previously they were
 always enabled.

 * [PR-1287](https://github.com/apache/incubator-nuttx/pull/1286) STM32F7:
 Refactor the FMC driver to support STM32F7 family and add support to the
 STM32F46G-DISCO board

 * [PR-1275](https://github.com/apache/incubator-nuttx/pull/1275) STM32: Allow
 SysTick to be a tickless clock source option

 * [PR-1268](https://github.com/apache/incubator-nuttx/pull/1268) STM32: Add
 support for STM32F412 with UART / SPI / CAN / I2C / DMA

 * [PR-1250](https://github.com/apache/incubator-nuttx/pull/1250) STM32L4: Add
 support for booting into DFU mode

### Bug Fixes

#### ARM

 * [PR-1562](https://github.com/apache/incubator-nuttx/pull/1562) ARM: Save
 tcb-adj\_stack\_size should be saved without tls overhead

 * [PR-1900](https://github.com/apache/incubator-nuttx/pull/1900) ARM: Fix false
 reporting for stack usage for unaligned stacks

#### AVR

 * [PR-1410](https://github.com/apache/incubator-nuttx/pull/1410) avr: Implement
 missing double\_t type, CONFIG\_STACK\_ALIGNMENT, linker emulation flags

#### CXD56xx

 * [PR-1930](https://github.com/apache/incubator-nuttx/pull/1930) cxd56xx: Fix
 handle\_irqreq() in cxd56\_cpupause.c

 * [PR-1789](https://github.com/apache/incubator-nuttx/pull/1789) cxd56xx: Fix
 deadlock issue in up\_txinit() in SMP mode.

 * [PR-1620](https://github.com/apache/incubator-nuttx/pull/1620) cxd56xx: Fix
 IRQ control in cxd56\_dmac.c

 * [PR-1253](https://github.com/apache/incubator-nuttx/pull/1253) cxd56xx: Fix
 audio cxd56\_stop where a deadlock could be hit if the worker thread took too
 long to turn on AMP

 * [PR-1950](https://github.com/apache/incubator-nuttx/pull/1950) cxd56xx: Fix
 deadlock and tcb corruption in SMP mode

#### ESP32

 * [PR-1908](https://github.com/apache/incubator-nuttx/pull/1908) ESP32: Fix
 task signal process preemption

 * [PR-1941](https://github.com/apache/incubator-nuttx/pull/1941) ESP32: Fix
 interrupt clearing of edge interrupt due to issuing in masking interrupt state

#### IMXRT

 * [PR-1527](https://github.com/apache/incubator-nuttx/pull/1527) IMXRT: Fix
 kconfig so that IMXRT\_ENET\_NRXBUFFERS can be set

 * [PR-1455](https://github.com/apache/incubator-nuttx/pull/1455) IMXRT: Fix
 auto-negotiation for KSZ8081 PHY

#### Kinetis

 * [PR-1273](https://github.com/apache/incubator-nuttx/pull/1273) Kinetis: Fix
 issue in ethernet driver where buffers were blindly initialized and could cause
 the TX of the MAC to be in a bad state. Also resolves an issue with interrupts
 being throttled in the NVIC.

#### NRF52

 * [PR-1928](https://github.com/apache/incubator-nuttx/pull/1928) NRF52: Fix PPI
 group disable and add group clear

 * [PR-1885](https://github.com/apache/incubator-nuttx/pull/1885) NRF52: Fix SPI
 driver structures when SPI\_EXCHANGE is not set

 * [PR-1799](https://github.com/apache/incubator-nuttx/pull/1799) NRF52: Fix
 SPI\_MASTER entry in kconfig

 * [PR-1787](https://github.com/apache/incubator-nuttx/pull/1787) NRF52: Fix
 base address for SPIM{1,2,3}

 * [PR-1777](https://github.com/apache/incubator-nuttx/pull/1777) NRF52: Handle
 case where rx or tx buffer could be 0 but data would still be transferred. Also
 error if more than max data is requested.

 * [PR-1770](https://github.com/apache/incubator-nuttx/pull/1770) NRF52: Fix bug
 where SPI cmddata was not properly mapped for SPIM 0,2,3

#### RISC-V

 * [PR-1909](https://github.com/apache/incubator-nuttx/pull/1909) RISC-V: MIE
 instead of MPIE register was being used in up\_schedule\_sigaction for storing
 interrupt state

#### SIM

 * [PR-1903](https://github.com/apache/incubator-nuttx/pull/1903) SIM: Fix
 complication issue for WPCAP in Cygwin build

 * [PR-1888](https://github.com/apache/incubator-nuttx/pull/1888) SIM: Fix
 EOVERFLOW returned when CONFIG\_SIM\_M32 is set

 * [PR-1709](https://github.com/apache/incubator-nuttx/pull/1709) SIM: Fix
 up\_cpu\_start initialization for macOS with SMP enabled

#### STM32

 * [PR-1898](https://github.com/apache/incubator-nuttx/pull/1898) STM32F7: Fixes
 data loss bug in UART5 with TX DMA

 * [PR-1841](https://github.com/apache/incubator-nuttx/pull/1841) STM32: Remove
 broken overdriver support

 * [PR-1719](https://github.com/apache/incubator-nuttx/pull/1719) STM32:
 Lowputc: Ensure USART is disabled before attempting to configuring it

 * [PR-1714](https://github.com/apache/incubator-nuttx/pull/1714) STM32H7: Fix
 I2C driver interrupt storm

 * [PR-1556](https://github.com/apache/incubator-nuttx/pull/1556) STM32: Fix IO
 compentation support in STM32F7 and remove incorrect reference in STM32F0/L0/G0

 * [PR-1529](https://github.com/apache/incubator-nuttx/pull/1529) STM32: Fix
 initialization bug in ADC that prevented adc\_reset() from working correctly

 * [PR-1561](https://github.com/apache/incubator-nuttx/pull/1561) STM32: Make
 sure that core over-drive is enabled for all chips that support it and operating
 at 180MHz. Some were enabled at 180MHz but may have not been stable without
 over-drive not configured.

 * [PR-1553](https://github.com/apache/incubator-nuttx/pull/1553) STM32F7: Fix
 possible interrupt blocking in serial TXDMA ISR

 * [PR-1544](https://github.com/apache/incubator-nuttx/pull/1544) STM32: Make
 sure IO compensation cell is configured prior to call to
 rcc\_enableperipherals() causing syscfg is accessed before it is enabled

 * [PR-1380](https://github.com/apache/incubator-nuttx/pull/1380) STM32F7: Fix
 tickless driver where th compare register could be set to a value that has
 just passed preventing expiration

 * [PR-1252](https://github.com/apache/incubator-nuttx/pull/1252) STM32L4: Fix
 48MHz MSI clock selection that could cause boot to hang

 * [PR-1310](https://github.com/apache/incubator-nuttx/pull/1310) STM32L4:
 Configure flash wait states earlier to prevent corruption of execution state

 * [PR-1248](https://github.com/apache/incubator-nuttx/pull/1248) STM32L4: Fix
 oneshot timer so that a minimum period is set otherwise it will never be
 triggered.

 * [PR-1247](https://github.com/apache/incubator-nuttx/pull/1247) STM32L47x/8x:
 Set additional registers required to place a pin in analog mode

 * [PR-1246](https://github.com/apache/incubator-nuttx/pull/1246) STM32L4: Fix
 issue where clock divider for serial baud rate was not set correctly

#### Miscellaneous

 * [PR-1912](https://github.com/apache/incubator-nuttx/pull/1912) Fix
 up\_interrupt\_contex() in case of SMP - Make sure the operation is atomic in
 case of SMP

## Driver Support

### Bug Fixes

 * [PR-1896](https://github.com/apache/incubator-nuttx/pull/1896) spi\_xx25xx
 EEPROM: return the number of bytes written instead of 0 or error

 * [PR-1891](https://github.com/apache/incubator-nuttx/pull/1891) serial: Don't
 mangle PID when ISIG is changed

 * [PR-1856](https://github.com/apache/incubator-nuttx/pull/1856) pipe: In case
 of empty pipe with no writers, return EOF instead of EAGAIN

 * [PR-1836](https://github.com/apache/incubator-nuttx/pull/1836) stmpe811: Fix
 incorrect GPIO interrupt register logic

 * [PR-1741](https://github.com/apache/incubator-nuttx/pull/1741) mmcsd\_sdio:
 Properly arm the write completion detection

 * [PR-1370](https://github.com/apache/incubator-nuttx/pull/1370) can: Fix
 incorrect usage of nxsem\_getvalue which caused fifo->rx\_sem to increase with
 teach received msg

 * [PR-1452](https://github.com/apache/incubator-nuttx/pull/1452) lcd: Fix
 memory leak when board\_graphics\_setup fail



### New Driver Support

 * [PR-1797](https://github.com/apache/incubator-nuttx/pull/1797) leds: WS2812
 LED controller (aka Adafruit NeoPixel)

 * [PR-1851](https://github.com/apache/incubator-nuttx/pull/1851) kbd: Add
 support for SolderParty BlackBerry Q10 Keyboard

 * [PR-1618](https://github.com/apache/incubator-nuttx/pull/1618) BQ27426 fuel
 gauge

 * [PR-1276](https://github.com/apache/incubator-nuttx/pull/1276) Add support
 for the ST7735 TFT Controller

 * [PR-1233](https://github.com/apache/incubator-nuttx/pull/1233) usbhost: Add
 support for CDC-MBIM USB host driver

### Drivers With Significant Improvements

 * [PR-1816](https://github.com/apache/incubator-nuttx/pull/1816) stmpe811: Add
 SPI support for touch screen controller

 * [PR-1800](https://github.com/apache/incubator-nuttx/pull/1800) vfs: Add
 `FIOCLEX/FIONCLEX` ioctl support

 * [PR-1798](https://github.com/apache/incubator-nuttx/pull/1798) mmcsd: Allow
 setting `IDMODE_CLOCK` via kconfig

 * [PR-1587](https://github.com/apache/incubator-nuttx/pull/1587) BCH: Delay the
 sector flush to avoid multiple erase/write operations in sequence write

 * [PR-1577](https://github.com/apache/incubator-nuttx/pull/1577) rwbuffer:
 Avoid allocating memory for the temporary erase buffer by the FTL driver

 * [PR-1466](https://github.com/apache/incubator-nuttx/pull/1466) Altair Modem:
 Add board specific logic, Fix issue that SPI4 RX frequency violated AC Spec,
 Fix priority of SPI transfer task is too low, Modify timeout value for RX ready

 * [PR-1471](https://github.com/apache/incubator-nuttx/pull/1471) ramlog: Add
 option to overwrite buffer

 * [PR-1547](https://github.com/apache/incubator-nuttx/pull/1547) usbhub: Make
 sure to enumerate hubs that report protocol = 1 (High Speed Hub)

 * [PR-1374](https://github.com/apache/incubator-nuttx/pull/1374) gpio: Extend
 gpio\_pintype\_e for pulldown/up and opendrain

 * [PR-1249](https://github.com/apache/incubator-nuttx/pull/1249) bmp280: Add
 support for reading temperature

 * [PR-1299](https://github.com/apache/incubator-nuttx/pull/1299) mpu60x0: Add
 I2C support for the MPU60x0 sensor driver

 * [PR-1325](https://github.com/apache/incubator-nuttx/pull/1325) can: expose
 NART/ABOM and RTR settings via ioctls

 * [PR-1520](https://github.com/apache/incubator-nuttx/pull/1520) note: Move
 note driver from syslog to drivers/note

 * [PR-1288](https://github.com/apache/incubator-nuttx/pull/1288) / PR-1449
 note: Add sched\_note\_syscall\_enter/leave hooks for syscall instrumentation

 * [PR-1259](https://github.com/apache/incubator-nuttx/pull/1259) note: Add
 buffering support for syscall instrumentation

 * [PR-1256](https://github.com/apache/incubator-nuttx/pull/1256) note: Add
 hooks for note driver for interrupt instrumentation

Board Support -------------

### **Significant Improvements**

 * [PR-1618](https://github.com/apache/incubator-nuttx/pull/1618) metro-m4: Add
 support for: SmartFS initialization, AT24 EEPROM, GPIO dev, BQ27426 gauge
 initialization

 * [PR-1727](https://github.com/apache/incubator-nuttx/pull/1729) b-g474e-dpow1:
 Add support for FLASH bootloader

 * [PR-1683](https://github.com/apache/incubator-nuttx/pull/1683) cxd56xx: Add
 wifi\_smp configuration

 * [PR-1668](https://github.com/apache/incubator-nuttx/pull/1668) sim: Add new
 configuration for SMP

 * [PR-1644](https://github.com/apache/incubator-nuttx/pull/1644)
 stm32f746g-disco: Move serial console from USART6 to USART1 which is attached
 to the USB virtual COM port.

 * [PR-1464](https://github.com/apache/incubator-nuttx/pull/1464) cxd56xx: Add
 new GNSS functions, support for lower PWM frequency,
 CONFIG\_CPUFREQ\_RELEASE\_LOCK, high speed ADC, HPADC input gain configuration,
 eMMC device, frame buffer support

 * [PR-1405](https://github.com/apache/incubator-nuttx/pull/1405)
 stm32f4discovery: Add ELF support to wifi configuration

 * [PR-1402](https://github.com/apache/incubator-nuttx/pull/1402) imxrt1060: Add
 buttons support to iMXRT1060

 * [PR-1590](https://github.com/apache/incubator-nuttx/pull/1590) sim: Add
 duktape configuration

 * [PR-1532](https://github.com/apache/incubator-nuttx/pull/1532) sim: Add
 cromfs configuration

 * [PR-1335](https://github.com/apache/incubator-nuttx/pull/1335) cxd56xx:
 Enable basic snapshop camera example

### New Board Support

 * [PR-1664](https://github.com/apache/incubator-nuttx/pull/1664) NRF52: Add
 support for NRF52832 MakerDiary MDK board

 * [PR-1633](https://github.com/apache/incubator-nuttx/pull/1633) NRF52: Add
 support for Sparkfun NRF52832 Breakout Board

 * [PR-1728](https://github.com/apache/incubator-nuttx/pull/1728) SAMA5D27: Add
 support for Giant Board

 * [PR-1397](https://github.com/apache/incubator-nuttx/pull/1397) EOSS3: Initial
 support for the QuickLogic EOS S3 SoC QuickFeather board

 * [PR-1268](https://github.com/apache/incubator-nuttx/pull/1268) STM32: Add
 support for nucleo-f412zg board

File System -----------

### **Bug Fixes**

 * [PR-1796](https://github.com/apache/incubator-nuttx/pull/1796) vfs: Fix
 memory leak calling `pseudorename`

 * [PR-1794](https://github.com/apache/incubator-nuttx/pull/1794) vfs: Fix issue
 where opendir would remove the trailing whitespace or /

 * [PR-1793](https://github.com/apache/incubator-nuttx/pull/1793) vfs: Make sure
 that rename of mount point uses pseudorename. Previously mv on a mountpoint
 would return err 88.

 * [PR-1737](https://github.com/apache/incubator-nuttx/pull/1737) vfs: reuse
 file\_dup2 direction in file\_dup to prevent segfault issue

 * [PR-1490](https://github.com/apache/incubator-nuttx/pull/1490) Ensure that
 filesystems can all support paths that end with '/'

 * [PR-1546](https://github.com/apache/incubator-nuttx/pull/1546) ROMFS: Fix
 issue with how hard links are followed for ROMFS

 * [PR-1442](https://github.com/apache/incubator-nuttx/pull/1442) SmartFS: Fix
 file size corruption when opening with overwriting mode

 * [PR-1431](https://github.com/apache/incubator-nuttx/pull/1431) nxffs: Fix
 scan good block slowly and scan an invalid block

PR-1295 fs: for setfd correct the return value

### **Significant Improvements**

 * [PR-1554](https://github.com/apache/incubator-nuttx/pull/1554) CROMFS: Add
 support for hard links

 * [PR-1499](https://github.com/apache/incubator-nuttx/pull/1499) FAT: Add
 support for UTF8 long filename

 * [PR-1479](https://github.com/apache/incubator-nuttx/pull/1479) vfs: Add file
 descriptor based events support eventfd()

 * [PR-1582](https://github.com/apache/incubator-nuttx/pull/1482) vfs: Add
 epoll\_create1() support

 * [PR-1579](https://github.com/apache/incubator-nuttx/pull/1579) vfs: Do not
 check CONFIG\_NFILE\_STREAMS for mkdir/rename/rmdir/fs\_unlink

 * [PR-1355](https://github.com/apache/incubator-nuttx/pull/1355) vfs: Implement
 statvfs and fstatvfs

 * [PR-1323](https://github.com/apache/incubator-nuttx/pull/1323) vfs: Add
 chmod/fchmod/utimes function prototypes

Networking ----------

### **Bug Fixes**

 * [PR-1267](https://github.com/apache/incubator-nuttx/pull/1267) SocketCAN:
 When timestamped frame was received while in CAN2.0B mode the frame got dropped.

 * [PR-1446](https://github.com/apache/incubator-nuttx/pull/1446) usrsock: Fix
 recv() cannot peek data

### **Significant Improvements**

 * [PR-1666](https://github.com/apache/incubator-nuttx/pull/1666) Bluetooth:
 Bluetooth sockets now use Linux sockaddr types of sockaddr\_l2 sockaddr\_hci
 sockaddr\_rc. There are slight breaking changes here that may require
 applications to be updated, but this brings the interface inline with Linux.

 * [PR-1581](https://github.com/apache/incubator-nuttx/pull/1581) Socket: Add
 SOCK\_CLOEXEC/SOCK\_NONBLOCK support

 * [PR-1443](https://github.com/apache/incubator-nuttx/pull/1443) usrsock: Add
 flag argument to sendto/recvfrom interface in usrsock

 * [PR-1238](https://github.com/apache/incubator-nuttx/pull/1238) SocketCAN: Add
 support for SocketCAN interface API

Applications ------------

### **Significant Improvements**

 * [PR-409](https://github.com/apache/incubator-nuttx-apps/pull/409) wamr:
 Update version to 09-29-2020 that supports NuttX directly and remove patches

 * [PR-407](https://github.com/apache/incubator-nuttx-apps/pull/407) ipcfg: Add
 IPv4 configuration file access helper

 * [PR-406](https://github.com/apache/incubator-nuttx-apps/pull/406) wamr: Add
 configs for heap pool and custom name sections

 * [PR-404](https://github.com/apache/incubator-nuttx-apps/pull/404) timer: Add
 supplying timer dev path to example

 * [PR-403](https://github.com/apache/incubator-nuttx-apps/pull/402)
 nxplayer/nxrecorder: Add channel map support

 * [PR-396](https://github.com/apache/incubator-nuttx-apps/pull/396) wamr: Add
 missing options to kconfig

 * [PR-395](https://github.com/apache/incubator-nuttx-apps/pull/395) dhcpc: Try
 to get hostname via syscall first

 * [PR-391](https://github.com/apache/incubator-nuttx-apps/pull/391) wapi: Add
 option to assocated directly via bssid

 * [PR-390](https://github.com/apache/incubator-nuttx-apps/pull/390) wapi: App
 option to scan partial channel

 * [PR-387](https://github.com/apache/incubator-nuttx-apps/pull/387) wamr: Add
 support for WAMR web assembly interpreter

 * [PR-337](https://github.com/apache/incubator-nuttx-apps/pull/337) docs:
 Convert all README files to markdown

 * [PR-333](https://github.com/apache/incubator-nuttx-apps/pull/333) webclient:
 Add hooks for TLS, extra request headers, PUT method, report status code,
 improved error handling

 * [PR-329](https://github.com/apache/incubator-nuttx-apps/pull/329) gpio: Add
 support for new GPIO pin types

 * [PR-317](https://github.com/apache/incubator-nuttx-apps/pull/317) nshlib:
 Call symlink if user pass -s for ln command

 * [PR-315](https://github.com/apache/incubator-nuttx-apps/pull/315) c++:
 Support uClibc++ and libcxx in examples/testing

 * [PR-314](https://github.com/apache/incubator-nuttx-apps/pull/314) camera: Add
 a simple camera snapshot example

 * [PR-378](https://github.com/apache/incubator-nuttx-apps/pull/378) wasm3:
 Initial WebAssembly runtime support

 * [PR-374](https://github.com/apache/incubator-nuttx-apps/pull/374) bluetooth:
 Use the new l2cap socket address type

 * [PR-373](https://github.com/apache/incubator-nuttx-apps/pull/373) duktape:
 Add duktape to global search path so it can be used as a library

 * [PR-372](https://github.com/apache/incubator-nuttx-apps/pull/372) quickjs:
 Add support for QuickJS interpreter

 * [PR-367](https://github.com/apache/incubator-nuttx-apps/pull/367) nsh: Accept
 the command line arguments like sh

 * [PR-365](https://github.com/apache/incubator-nuttx-apps/pull/365) duktape:
 Add console, print, alert support

 * [PR-364](https://github.com/apache/incubator-nuttx-apps/pull/364) cu:
 Refactor cu and add support for "-c" to disable \\n to \\r\\n conversion

 * [PR-362](https://github.com/apache/incubator-nuttx-apps/pull/362) libuv: Add
 support for libuv library

 * [PR-352](https://github.com/apache/incubator-nuttx-apps/pull/352) duktape:
 Add initial support for duktape

 * [PR-346](https://github.com/apache/incubator-nuttx-apps/pull/364) wget:
 Enable URL from command line, can be used with ifup, hooks for HTTPS

 * [PR-302](https://github.com/apache/incubator-nuttx-apps/pull/302) lvgl: Use
 the latest version 7.0.2

 * [PR-300](https://github.com/apache/incubator-nuttx-apps/pull/300) note: Add
 support for decoding interrupt and syscall instrumentation

 * [PR-299](https://github.com/apache/incubator-nuttx-apps/pull/299) nxrecorder:
 Add O\_TRUNC when creating a file

 * [PR-296](https://github.com/apache/incubator-nuttx-apps/pull/296) bmp280: Add
 support for BMP180 to BMP280 application

 * [PR-294](https://github.com/apache/incubator-nuttx-apps/pull/294) can: Add
 cansend and candump utilities for interacting with SocketCAN

### Bug Fixes

 * [PR-411](https://github.com/apache/incubator-nuttx-apps/pull/411) wgetjson:
 Fix build breakage

 * [PR-405](https://github.com/apache/incubator-nuttx-apps/pull/405) nxplayer:
 Fix missing "%d" in a sscanf call

 * [PR-400](https://github.com/apache/incubator-nuttx-apps/pull/400) dhcpc:
 Handle case where gethostname() might be empty

 * [PR-399](https://github.com/apache/incubator-nuttx-apps/pull/399) build: Fix
 build system issue where compiler would only compile first assembly file

 * [PR-393](https://github.com/apache/incubator-nuttx-apps/pull/393) build: Fix
 build system issue where ARCHCPUFLAGS in cxx command was lost

 * [PR-392](https://github.com/apache/incubator-nuttx-apps/pull/392) wapi: Make
 wapi more robust in failure cases

 * [PR-383](https://github.com/apache/incubator-nuttx-apps/pull/383) ntpclient:
 Fix NTP daemon state in case of DNS failure

 * [PR-344](https://github.com/apache/incubator-nuttx-apps/pull/344) gs2200m:
 Fix freeing of uninitialized memory

 * [PR-335](https://github.com/apache/incubator-nuttx-apps/pull/335) ntp: Fix
 malformated authentication headers in NTP packet

 * [PR-331](https://github.com/apache/incubator-nuttx-apps/pull/331) telnetd:
 Fix buffer overflow issue clearing socket address

 * [PR-312](https://github.com/apache/incubator-nuttx-apps/pull/312) build: Make
 sure to include incdir when running make export

 * [PR-377](https://github.com/apache/incubator-nuttx-apps/pull/377) readline:
 Fix stack overflow when application name is too long

 * [PR-359](https://github.com/apache/incubator-nuttx-apps/pull/259) nshlib: Fix
 memory corrupt in nsh\_parse if pthread\_create() failed

 * [PR-354](https://github.com/apache/incubator-nuttx-apps/pull/354) dhcpd: Fix
 member name for "ds\_pid"

## Security Issues Fixed In This Release

## Compatibility Concerns

## Changes to Build System

### In Apps, Change `$(TOPDIR)` to `$(APPDIR)`

In the 'apps' repo, Makefiles are now using `$(APPDIR)` instead of `$(TOPDIR)`.

In your custom app's Makefile, it is recommended to change `$(TOPDIR)` to
`$(APPDIR)`.

Replace this line:

include $(TOPDIR)/Make.defs

With this:

include $(APPDIR)/Make.defs

See  * [PR-326](https://github.com/apache/incubator-nuttx-apps/pull/326), git
commit #
`[deaa6c5b7bf8445b4a300691525f60aa506be0d7](https://github.com/apache/incubator-nuttx-apps/commit/deaa6c5b7bf8445b4a300691525f60aa506be0d7)`
in the NuttX 'apps' repository.

### Custom Boards Don't Need `ARCHINCLUDES` and `ARCHXXINCLUDES` Definitions

As part of an effort to unify support for uClibc++ and libc++, the C/C++ include
search path definitions `ARCHINCLUDES` and `ARCHXXINCLUDES` are now defined in
one central place in `tools/Config.mk`. It is no longer necessary to define
these in every board's `scripts/Make.defs`. Boards included in the NuttX
repository have been updated, but if you are building NuttX for a custom board
and are using C++, you may want to make the following changes:

In your board's configuration, ensure that you have enabled either
`CONFIG_UCLIBCXX` or `CONFIG_LIBCXX` as appropriate.

In your custom board's `scripts/Make.defs` file, remove lines like these:

CINCPATH := ${shell $(INCDIR) -s "$(CC)" $(TOPDIR)$(DELIM)include} CXXINCPATH :=
${shell $(INCDIR) -s "$(CC)" $(TOPDIR)$(DELIM)include$(DELIM)cxx} ARCHINCLUDES
+= $(CINCPATH) ARCHXXINCLUDES += $(CINCPATH) $(CXXINCPATH)

In case your `scripts/Make.defs` uses different names, such as `ARCHINCLUDESXX`
instead of `ARCHXXINCLUDES`, you'll need to find all uses of that variable and
update them to use `ARCHXXINCLUDES`.

See  * [PR-1396](https://github.com/apache/incubator-nuttx/pull/1396), git
commit
#[d32e9c38dfb0659a7f3c0cf586ba1584cd7eb3d6](https://github.com/apache/incubator-nuttx/commit/d32e9c38dfb0659a7f3c0cf586ba1584cd7eb3d6)
in the main NuttX repository.

See also  * [PR-1399](https://github.com/apache/incubator-nuttx/pull/1399), git
commit
#[6abd03d53ff9164fb17ea4aca701a49fbbf751c0](https://github.com/apache/incubator-nuttx/commit/6abd03d53ff9164fb17ea4aca701a49fbbf751c0).

### Custom Boards Don't Need `HOSTCC` and `HOSTCFLAGS` Definitions

The NuttX build system uses several binary utilities that it compiles and runs
on the host computer. To build these binaries, it needs to know the host C
compiler and C flags. Previously, every board's `scripts/Make.defs` file had to
provide this information via `HOSTCC` and `HOSTCFLAGS` Definitions. As part of
an effort to simplify the build system, these definitions are now automatically
provided by logic in `tools/Config.mk`. Boards included in the NuttX repository
have been updated, but if you are building NuttX for a custom board, you may
want to make the following changes:

In your custom board's `scripts/Make.defs` file, remove lines like these:

HOSTCC = gcc HOSTCFLAGS = -Wall -Wstrict-prototypes -Wshadow -Wundef -g -pipe

Sometimes they may look like this:

ifeq ($(CONFIG\_WINDOWS\_NATIVE),y)
  HOSTCC = mingw32-gcc.exe
else
  HOSTCC = gcc
endif

Note: These changes are OPTIONAL.

You may still set these definitions in your board's scripts/Make.defs, and your
definitions will override the ones in tools/Config.mk.

Also, you may override these definitions for a single run by providing them on
the make command line. This is useful if, for example, you wish to build debug
versions of these host binaries: define HOSTCFLAGS with -g on the command line.

See  * [PR-1398](https://github.com/apache/incubator-nuttx/pull/1398), git
commit
#[ee875b2a260cb4cc532b8ca303c2515e24c39b4e](https://github.com/apache/incubator-nuttx/commit/ee875b2a260cb4cc532b8ca303c2515e24c39b4e)
in the main NuttX repository.

### Removal of Unused `ARCHCCVERSION` and `ARCHCCMAJOR`

The ARCHCCVERSION and ARCHCCMAJOR variables are unused. Historically they were
defined in many boards' scripts/Make.defs. These were removed from all boards in
the NuttX repository, but if you are building NuttX for a custom board, you may
want to remove this unnecessary boilerplate.

In your custom board's `scripts/Make.defs` file, remove lines like these:



ARCHCCVERSION = ${shell $(CC) -v 2>&1 | sed -n '/^gcc version/p' | sed -e
's/^gcc version \\(\[0-9\\.\]\\)/\\1/g' -e 's/\[-\\ \].\*//g' -e '1q'}
ARCHCCMAJOR = ${shell echo $(ARCHCCVERSION) | cut -d'.' -f1}

See  * [PR-1344](https://github.com/apache/incubator-nuttx/pull/1344), git
commit
#[f5311de6b42466ab5c6ef299dab0ecc417131bbe](https://github.com/apache/incubator-nuttx/commit/f5311de6b42466ab5c6ef299dab0ecc417131bbe)
in the main NuttX repository.

### Custom Boards May Not Need `EXTRA_LIBS` and `EXTRA_LIBPATHS` Definitions

The `EXTRA_LIBS` and `EXTRA_LIBPATHS` make variables were previously defined in
many boards' `scripts/Make.defs` files. These are now defined in a more central
location: `arch/*/src/*/Toolchain.defs`. Your board's `scripts/Make.defs`
usually includes this file. Boards included in NuttX have been updated, but if
you are building NuttX for a custom board, you may need to update your board's
`scripts/Make.defs` file to ensure you build with the correct definitions.

If you have lines like these:

EXTRA\_LIBPATHS = -L "${shell dirname "$(LIBSUPXX)"}" EXTRA\_LIBS = -lsupc++

You may want to do one of the following:

*   If they are redundant to the definitions provided in the included
`arch/*/src/*/Toolchain.defs`, remove these lines, or *   If they contain
additional needed libraries and paths not present in
`arch/*/src/*/Toolchain.defs`, remove any redundant definitions and change the
assignment '`=`' to '`+=`'.

See  * [PR-1404](https://github.com/apache/incubator-nuttx/pull/1404), git
commit
#[4910d43ab0fc360dbddb1f8a31db2a3ee383b46d](https://github.com/apache/incubator-nuttx/commit/4910d43ab0fc360dbddb1f8a31db2a3ee383b46d)
in the main NuttX repository.

### Custom Boards May Not Need CC, CXX, CPP, LD, STRIP, AR, NM, OBJCOPY, and
OBJDUMP Definitions

These `make` variables were previously defined in many boards' scripts/Make.defs
files with copy-paste duplication spanning many hundreds of files. These are now
defined in a more central location: `arch/*/src/*/Toolchain.defs`. Your board's
`scripts/Make.defs` usually includes this file. Boards included in NuttX have
been updated, but if you are building NuttX for a custom board, you may need to
update your board's `scripts/Make.defs` file to ensure you build with the
correct definitions.

If you have lines that define `CC`, `CXX`, `CPP`, `LD`, `STRIP`, `AR`, `NM`,
`OBJCOPY`, and `OBJDUMP`, such as these:

CC = $(CROSSDEV)gcc CXX = $(CROSSDEV)g++ CPP = $(CROSSDEV)gcc -E -P -x c LD =
$(CROSSDEV)ld STRIP = $(CROSSDEV)strip --strip-unneeded AR = $(ARCROSSDEV)ar rcs
NM = $(ARCROSSDEV)nm OBJCOPY = $(CROSSDEV)objcopy OBJDUMP = $(CROSSDEV)objdump



You may want to do one of the following:

*   If they are redundant to the definitions provided in the included
`arch/*/src/*/Toolchain.defs`, remove these lines, or *   If they are different
from the definitions in `arch/*/src/*/Toolchain.defs`, leave them as-is and they
will take precedence.

See  * [PR-1426](https://github.com/apache/incubator-nuttx/pull/1426), git
commit
#[b329e2377dd8816f37ad0408279926829efdf85d](https://github.com/apache/incubator-nuttx/commit/b329e2377dd8816f37ad0408279926829efdf85d)
in the main NuttX repository.

### Consolidated ARCROSSDEV and CROSSDEV

The `ARCROSSDEV` and `CROSSDEV` variables always had identical values. Therefore
`ARCROSSDEV` has been removed and `CROSSDEV` is used instead. Boards included in
NuttX have been updated, but if you are building NuttX for a custom board, you
may need to update your board's build scripts to use the `CROSSDEV` variable.

See  * [PR-1439](https://github.com/apache/incubator-nuttx/pull/1439), git
commit
#[5efa93ec26fd8a3fd85b24a2008bb743f96027fb](https://github.com/apache/incubator-nuttx/commit/5efa93ec26fd8a3fd85b24a2008bb743f96027fb)
in the main NuttX repository.

NuttX-10.1.0 Release Notes
------------------------

# What's New In This Release

## Highlights

* Better separation between kernel and userspace.
* Heap and stack management improvements.
* More closely follow POSIX and Linux interfaces.
* Symmetric Multi-Processing (SMP) performance improvements and bug fixes.
* Networking improvements and bug fixes.
* Added support for many microcontrollers and boards, and improved support for many existing ones.
* Many added and improved drivers.
* Build system improvements to deliver faster builds.
* Thousands of NuttX files converted to Apache 2.0 License with permission of their authors.
* Improved listing of 3rd party licenses used in NuttX (see LICENSE, NOTICE, and DISCLAIMER-WIP files).

## Major Changes to Core OS

### New Features
* [#2324](https://github.com/apache/incubator-nuttx/pull/2324) audio: libsamplerate: add initial audio Sample Rate Converter
* [#2820](https://github.com/apache/incubator-nuttx/pull/2820) arch, boards, drivers, include, sched, wireless: Change spinlock APIs.
* [#2885](https://github.com/apache/incubator-nuttx/pull/2885) Ensure the kernel component don't call userspace API

### Bug Fixes
* [#1852](https://github.com/apache/incubator-nuttx/pull/1852) sysconf: add _SC_PAGESIZE sysconf support
* [#1922](https://github.com/apache/incubator-nuttx/pull/1922) sched: nxtask_start should call entry point directly for kernel thread
* [#1994](https://github.com/apache/incubator-nuttx/pull/1994) libc: Don't fclose and fopen file in freopen
* [#2005](https://github.com/apache/incubator-nuttx/pull/2005) Fix note_syscall_leave_s to avoid unaligned access
* [#2043](https://github.com/apache/incubator-nuttx/pull/2043) sched: Add SCHED_INSTRUMENTATION_HIRES support
* [#2044](https://github.com/apache/incubator-nuttx/pull/2044) sched: Add note_syscall args support
* [#2071](https://github.com/apache/incubator-nuttx/pull/2071) pollnotify: we should send poll events before semaphore incrementes.
* [#2076](https://github.com/apache/incubator-nuttx/pull/2076) libc: math: Make this friendly with libcxx
* [#2111](https://github.com/apache/incubator-nuttx/pull/2111) LIBCXX related fixes
* [#2147](https://github.com/apache/incubator-nuttx/pull/2147) sched: Use nx_close() inside OS
* [#2176](https://github.com/apache/incubator-nuttx/pull/2176) syscall/syscall.csv: Increase number of arguments for prctl()
* [#2204](https://github.com/apache/incubator-nuttx/pull/2204) sched: irq: Fix enter_critical_section() in an irq handler for SMP
* [#2218](https://github.com/apache/incubator-nuttx/pull/2218) sched: signal.h: fix compile failed when open TTY_SIGINT
* [#2229](https://github.com/apache/incubator-nuttx/pull/2229) sched/sched/sched_waitid.c: Allow WNOHANG
* [#2236](https://github.com/apache/incubator-nuttx/pull/2236) sched/task/task_exithook.c: Remove a redundant assignment
* [#2243](https://github.com/apache/incubator-nuttx/pull/2243) libcxx: Update [0001-libcxx-Port-to-NuttX-https-nuttx.apache.org](http://0001-libcxx-Port-to-NuttX-https-nuttx.apache.org)-RTOS.patch
* [#2255](https://github.com/apache/incubator-nuttx/pull/2255) sys/epoll: sync the epoll define with linux
* [#2256](https://github.com/apache/incubator-nuttx/pull/2256) unistd/sched_sporadic: correct the disable value
* [#2261](https://github.com/apache/incubator-nuttx/pull/2261) sched/timer: add support of CLOCK_MONOTONIC
* [#2262](https://github.com/apache/incubator-nuttx/pull/2262) sched/init: init the default home directory to environment
* [#2285](https://github.com/apache/incubator-nuttx/pull/2285) libc/stdlib: Fix range check in strtoul(l)
* [#2326](https://github.com/apache/incubator-nuttx/pull/2326) libc: Enhance getopt function
* [#2407](https://github.com/apache/incubator-nuttx/pull/2407) libc: machine: arch: Support armv8-m relocation
* [#2418](https://github.com/apache/incubator-nuttx/pull/3447) libc: Change OK/ERROR from macro to enum
* [#2420](https://github.com/apache/incubator-nuttx/pull/2420) sched/signal: Remove redundant checks
* [#2437](https://github.com/apache/incubator-nuttx/pull/2765) sched/sched/sched_waitpid.c: Fix return value
* [#2449](https://github.com/apache/incubator-nuttx/pull/2449) mm/circbuf: fix the problem of dividing by zero
* [#2450](https://github.com/apache/incubator-nuttx/pull/2450) unistd/getopt: remove number of arguments limit
* [#2451](https://github.com/apache/incubator-nuttx/pull/2451) libc: pthread_mutexattr_getprotocol: modify prototype
* [#2455](https://github.com/apache/incubator-nuttx/pull/2455) sched/sched/sched_waitpid.c: Discard the correct child entry
* [#2475](https://github.com/apache/incubator-nuttx/pull/2475) sched/sched_waitid.c: Fix two bugs when CONFIG_SCHED_CHILD_STATUS is enabled
* [#2487](https://github.com/apache/incubator-nuttx/pull/2487) sched: clock/time: add CLOCK_BOOTTIME definition
* [#2492](https://github.com/apache/incubator-nuttx/pull/2492) procfs: make array const to reduce memory use
* [#2494](https://github.com/apache/incubator-nuttx/pull/2494) sched: Fix SMP
* [#2509](https://github.com/apache/incubator-nuttx/pull/2509) libc: net: implement ether_aton/ether_aton_r
* [#2517](https://github.com/apache/incubator-nuttx/pull/2517) sched: spinlock: Introduce SP_WFE() and SP_SEV()
* [#2518](https://github.com/apache/incubator-nuttx/pull/2518) sched: Don't forward gettid to getpid directly
* [#2530](https://github.com/apache/incubator-nuttx/pull/2530) libc: Implement posix_fallocate
* [#2533](https://github.com/apache/incubator-nuttx/pull/2533) sched: Make the number of queue/signal used by irq handler configurable
* [#2534](https://github.com/apache/incubator-nuttx/pull/2534) libc: Implement getppid
* [#2538](https://github.com/apache/incubator-nuttx/pull/2538) sched: pthread: Fix potential bugs in pthread_condclockwait.c
* [#2574](https://github.com/apache/incubator-nuttx/pull/2574) libc: dumpbuffer: dump buffer enhancement
* [#2580](https://github.com/apache/incubator-nuttx/pull/2580) sched: arch & sched: task: Fix up_exit() and nxtask_exit() for SMP
* [#2585](https://github.com/apache/incubator-nuttx/pull/2585) libc: netdb: Move hostbuffer out of the stack
* [#2602](https://github.com/apache/incubator-nuttx/pull/2740) sched: Add include/sys/poll.h
* [#2604](https://github.com/apache/incubator-nuttx/pull/2604) libc: Add b64_ntop and b64_pton implementation
* [#2616](https://github.com/apache/incubator-nuttx/pull/2616) libc/dumpvbuffer: update the vector ptr correctly
* [#2624](https://github.com/apache/incubator-nuttx/pull/2624) sched: implement the default test-and-set semantics
* [#2627](https://github.com/apache/incubator-nuttx/pull/2627) OS internal function should indicate the error by return negative value
* [#2630](https://github.com/apache/incubator-nuttx/pull/2630) libc: net: implement socketpair
* [#2631](https://github.com/apache/incubator-nuttx/pull/2631) sched: mqueue: simplify the mqueue reailize
* [#2650](https://github.com/apache/incubator-nuttx/pull/2650) libc: ctype/iscntrl: correct the control character function
* [#2653](https://github.com/apache/incubator-nuttx/pull/2653) sched: Don't call sched_lock()/unlock() in nx_waitid()/waitpid() for SMP
* [#2668](https://github.com/apache/incubator-nuttx/pull/2668) Kernel module should prefer functions with nx/kmm prefix
* [#2675](https://github.com/apache/incubator-nuttx/pull/2675) libc: Add placement new and new[] function
* [#2693](https://github.com/apache/incubator-nuttx/pull/2693) libxx: use built-in __aeabi_atexit() if LIBSUPCXX is enabled
* [#2694](https://github.com/apache/incubator-nuttx/pull/2694) libc/machine/arch: fix build break if enable armv8 ELF
* [#2719](https://github.com/apache/incubator-nuttx/pull/2719) sched/task: setup the scheduling policy to task
* [#2726](https://github.com/apache/incubator-nuttx/pull/2726) sched: sched: Remove sched_lock/unlock from nxsched_set_affinity()
* [#2737](https://github.com/apache/incubator-nuttx/pull/2737) sched: task: Fix a potential bug in nxtask_assign_pid()
* [#2740](https://github.com/apache/incubator-nuttx/pull/2740) sched/timer: get the previous reload value correctly
* [#2741](https://github.com/apache/incubator-nuttx/pull/2741) libc: unistd/fpathconf: enhance fpathconf
* [#2742](https://github.com/apache/incubator-nuttx/pull/2742) libc: pthread/cond: enhance pthread_cond_destroy
* [#2744](https://github.com/apache/incubator-nuttx/pull/2744) sched: task: Fix comments and label in nxtask_assign_pid()
* [#2765](https://github.com/apache/incubator-nuttx/pull/2765) sched: pthread: Return get_errno instead the hardcode value
* [#2767](https://github.com/apache/incubator-nuttx/pull/2767) sched/wqueue/notifier: protect the work notifier with critical section
* [#2797](https://github.com/apache/incubator-nuttx/pull/2797) sched: group: Fix group_kill_children() for SMP
* [#2849](https://github.com/apache/incubator-nuttx/pull/2849) mqueue: Add _MQ_OPEN, _MQ_CLOSE and _MQ_UNLINK macro
* [#2855](https://github.com/apache/incubator-nuttx/pull/2855) libs: Remove the duplicated _NX_ and _MQ_ macro
* [#2865](https://github.com/apache/incubator-nuttx/pull/2865) libc: :machine:risc-v:unifying elf relocation code
* [#2872](https://github.com/apache/incubator-nuttx/pull/2872) sched: pthread: Fix pthread cmdline issue
* [#2881](https://github.com/apache/incubator-nuttx/pull/2881) libc: Move stack check stuff from libc/stdlib/ to libc/assert/
* [#2904](https://github.com/apache/incubator-nuttx/pull/2904) libc: unistd/getcwd: enhance getcwd when buf is NULL
* [#2906](https://github.com/apache/incubator-nuttx/pull/2906) mm: umm_heap: valloc: support valloc (LEGACY)
* [#2910](https://github.com/apache/incubator-nuttx/pull/2910) libc/hex2bin: fix handling of segment offsets
* [#2919](https://github.com/apache/incubator-nuttx/pull/2919) sched: fix fd leak in dlopen
* [#2938](https://github.com/apache/incubator-nuttx/pull/2938) libs: misc: Remove critical section in lib_filesem.c for SMP
* [#2942](https://github.com/apache/incubator-nuttx/pull/2492) mtd: progmem: Add up_progmem_read callback guarded by ARCH_HAVE_PROGMEM_READ
* [#2946](https://github.com/apache/incubator-nuttx/pull/2946) sched: task: Call nxtask_flushstreams() without critical section
* [#2960](https://github.com/apache/incubator-nuttx/pull/2960) sched: signal: sigdeliver: fix system block when kill signal to idle in SMP
* [#2980](https://github.com/apache/incubator-nuttx/pull/2980) include: Add iso646.h for alternative spellings
* [#2981](https://github.com/apache/incubator-nuttx/pull/2981) sched: Remove all group id related stuff
* [#3033](https://github.com/apache/incubator-nuttx/pull/3033) unistd: Fix getpriority not handling invalid input value
* [#3080](https://github.com/apache/incubator-nuttx/pull/3080) sched: semaphore: Remove a redundant critical section in nxsem
* [#3083](https://github.com/apache/incubator-nuttx/pull/3083) libc: stdio/lib_clearerr: Did not clear stream buffer flags in clearerr
* [#3086](https://github.com/apache/incubator-nuttx/pull/3086) mm: improve the memory manager modularity and reduce the information explosion
* [#3111](https://github.com/apache/incubator-nuttx/pull/3111) sched: Sporadic scheduler: Fix time calculation and compile errors when assertions are enabled:
* [#3115](https://github.com/apache/incubator-nuttx/pull/3115) libc: time: localtime: fix race condition
* [#3121](https://github.com/apache/incubator-nuttx/pull/3121) mm/heap: Move semaphore related declaration to private header
* [#3123](https://github.com/apache/incubator-nuttx/pull/3123) sched: pthread: Remove a redundant critical section in pthread_condclockwait.c
* [#3131](https://github.com/apache/incubator-nuttx/pull/3131) mm: Minor fix for heap manager
* [#3159](https://github.com/apache/incubator-nuttx/pull/3159) mm: mm_heap: Remove critical section in mm_sem.c
* [#3170](https://github.com/apache/incubator-nuttx/pull/3170) libc: Move getopt() variables into TLS
* [#3196](https://github.com/apache/incubator-nuttx/pull/3196) sched/signal: Implement SA_NODEFER
* [#3228](https://github.com/apache/incubator-nuttx/pull/3228) mm/mm_heap: fix compile failed when open DEBUG_MM
* [#3244](https://github.com/apache/incubator-nuttx/pull/3244) libdsp: Improvements for libdsp and support for fixed16 libdsp implementation
* [#3247](https://github.com/apache/incubator-nuttx/pull/3247) sched: Move the default Task Stack size to Stack menu
* [#3251](https://github.com/apache/incubator-nuttx/pull/3251) libc: update pthread_once according to the specification
* [#3253](https://github.com/apache/incubator-nuttx/pull/3253) libc pthread: Fix pthread_rwlock_init return error
* [#3268](https://github.com/apache/incubator-nuttx/pull/3268) libdsp/fixed16: add open-loop handler
* [#3272](https://github.com/apache/incubator-nuttx/pull/3272) libc: Implement getopt_long() and getopt_long_only()
* [#3280](https://github.com/apache/incubator-nuttx/pull/3280) libc: Correct some getopt() logic
* [#3289](https://github.com/apache/incubator-nuttx/pull/3289) sched: task: Fix to initialize the task-specific data
* [#3294](https://github.com/apache/incubator-nuttx/pull/2418) libc: getopt(): Fix Use of Pointer before NULL check
* [#3299](https://github.com/apache/incubator-nuttx/pull/3299) libc: getopt_common(): Correct handling of unsupported long options.
* [#3308](https://github.com/apache/incubator-nuttx/pull/3308) libc: getopt_long(): Add support for required argument format
* [#3445](https://github.com/apache/incubator-nuttx/pull/3445) libc: update stream getoffset to handle write case
* [#3447](https://github.com/apache/incubator-nuttx/pull/2450) libc: correct zoneinfo genromfs source directory

## Major Changes to the Build System

### New Features
* [#1834](https://github.com/apache/incubator-nuttx/pull/1834) License/authorship handling scripts
* [#2107](https://github.com/apache/incubator-nuttx/pull/2107) build: Makefile should reference CONFIG_HOST_xxx
* [#2392](https://github.com/apache/incubator-nuttx/pull/2392) configure.sh: support custom board build config with absolute path
* [#2824](https://github.com/apache/incubator-nuttx/pull/2824) build/esp32: Create Flash size configuration and a new DOWNLOAD make target
* [#3317](https://github.com/apache/incubator-nuttx/pull/3317) tols: Update python scripts to py3 and lint all of them againt Black

### Bug Fixes
* [#1890](https://github.com/apache/incubator-nuttx/pull/1890) make/expression: improving up asm/C/C++ compile times(make with multi-jobs only)
* [#1940](https://github.com/apache/incubator-nuttx/pull/1940) cygwin build - path issue fix for Renesas arch
* [#2032](https://github.com/apache/incubator-nuttx/pull/2032) build: Change .external_dummy to dummy
* [#2101](https://github.com/apache/incubator-nuttx/pull/2101) build: Add $(OBJS) and $(BIN) to CLEAN macro to clean objects also in subdirectories
* [#2192](https://github.com/apache/incubator-nuttx/pull/2192) build: Move __NuttX__ definition to tools/[Config.mk](http://Config.mk)
* [#2221](https://github.com/apache/incubator-nuttx/pull/2221) tools: Avoid messing the final binary nuttx.(bin,hex,...) compilation msg
* [#2335](https://github.com/apache/incubator-nuttx/pull/2335) build: Parallelize depend file generation
* [#2380](https://github.com/apache/incubator-nuttx/pull/2380) tools: Fix nuttx-gdbinit for armv7-m with FPU
* [#2404](https://github.com/apache/incubator-nuttx/pull/2404) Update checkrelease script to check [readme.md](http://readme.md) instead of .txt
* [#2411](https://github.com/apache/incubator-nuttx/pull/2411) tools: Add 'handle SIGUSR1' to nuttx-gdbinit for the NuttX sim SMP
* [#2432](https://github.com/apache/incubator-nuttx/pull/2432) build system: add missing --obj-path to MKDEP
* [#2557](https://github.com/apache/incubator-nuttx/pull/2557) tools/version.sh: Fix the version retrieved from GIT
* [#2561](https://github.com/apache/incubator-nuttx/pull/2561) tools: Fix version.sh
* [#2642](https://github.com/apache/incubator-nuttx/pull/2642) tools/version.sh: Fix the version retrieved from git-tag
* [#2673](https://github.com/apache/incubator-nuttx/pull/2673) tools: esp32: add a gdb script to show backtrace
* [#2679](https://github.com/apache/incubator-nuttx/pull/2679) tools: esp32: btdecode.sh: Script to decode the Xtensa backtrace.
* [#2701](https://github.com/apache/incubator-nuttx/pull/2701) tools: gdbinit: add support for reporting total and used stack size
* [#2729](https://github.com/apache/incubator-nuttx/pull/2729) tools: esp32: backtrace.gdbscript: Add comments
* [#2803](https://github.com/apache/incubator-nuttx/pull/2803) tools: esp32: Remove some duplicated output
* [#2882](https://github.com/apache/incubator-nuttx/pull/2882) tools: esp32: refine the QEMU image generation.
* [#2895](https://github.com/apache/incubator-nuttx/pull/2895) tools: esp32: fix warnings from ShellCheck
* [#2930](https://github.com/apache/incubator-nuttx/pull/2930) tools: version.sh: If the version is not available, use 0.0.0
* [#2982](https://github.com/apache/incubator-nuttx/pull/2982) tools: nxstyle: Verify relative path in the file header
* [#3004](https://github.com/apache/incubator-nuttx/pull/3004) tools: esp32XX: Delete the Makefile that downloads IDF.
* [#3012](https://github.com/apache/incubator-nuttx/pull/3012) tools: esp32xx: Few fixes/improvements to the post build scripts
* [#3017](https://github.com/apache/incubator-nuttx/pull/3017) tools: esp32: [Config.mk](http://Config.mk): Revert part of "Don't abort make when QEMU script fails"
* [#3094](https://github.com/apache/incubator-nuttx/pull/3094) tools: version.sh: Fix PATCH including extra version

## Architectural Support

### New Architectures
* [#1995](https://github.com/apache/incubator-nuttx/pull/1995) arch: Add custom arch chip build support
* [#2161](https://github.com/apache/incubator-nuttx/pull/2161) Added Support for more TI Tiva Microcontrollers: TM4C123GH6PZ, TM4C123GH6PGE, TM4C129ENCPDT, and TM4C129ENCZAD.
* [#2566](https://github.com/apache/incubator-nuttx/pull/2566) arch/risc-v: Add BL602 support
* [#2974](https://github.com/apache/incubator-nuttx/pull/2974) STM32L5 Architecture Support
* [#3001](https://github.com/apache/incubator-nuttx/pull/3001) arch:riscv64:basic porting for C906
* [#3023](https://github.com/apache/incubator-nuttx/pull/3023) Remove nr5m100 and gap8 support

### Architectures with significant improvements

#### ARM
* [#2042](https://github.com/apache/incubator-nuttx/pull/2042) Fix interrupt stack handlings for ARM SMP
* [#2061](https://github.com/apache/incubator-nuttx/pull/2061) Refactor arm interrupt stack related code
* [#2309](https://github.com/apache/incubator-nuttx/pull/2309) Fix armv7-a L2CC and apply the code to the sabre-6quad board
* [#2876](https://github.com/apache/incubator-nuttx/pull/2876) arm: ARMv6-M vector table offset register support
* [#2932](https://github.com/apache/incubator-nuttx/pull/2932) arch: armv6-m: Apply armv7-m signal handling logic
* [#2944](https://github.com/apache/incubator-nuttx/pull/2944) armv8-m: Fix EXC_RETURN for non-secure usage
* [#2990](https://github.com/apache/incubator-nuttx/pull/2990) arch/armv7-m: Adds dwt helper functions for controlling watchpoints i…

#### BL602
* [#2614](https://github.com/apache/incubator-nuttx/pull/2614) bl602: Update register maps and lower half drivers
* [#2633](https://github.com/apache/incubator-nuttx/pull/2633) BL602: Add support for system reset modes
* [#2655](https://github.com/apache/incubator-nuttx/pull/2655) arch/risc-v/bl602 : add pwm onshot watchdog driver
* [#2659](https://github.com/apache/incubator-nuttx/pull/2659) arch/risc-v/bl602 : add spiflash(hardware sf controller)
* [#2669](https://github.com/apache/incubator-nuttx/pull/2669) risc-v/bl602 : add gpioirq、 i2c(master) driver.
* [#2804](https://github.com/apache/incubator-nuttx/pull/2804) arch/risc-v/bl602: spi_master support.
* [#2809](https://github.com/apache/incubator-nuttx/pull/2809) arch:risc-v:bl602: enable FPU for this target.
* [#2836](https://github.com/apache/incubator-nuttx/pull/2836) :risc-v:bl602:add support for elf file apps
* [#2991](https://github.com/apache/incubator-nuttx/pull/2991) risc-v/bl602: Add wifi and ble support

#### CXD56XX
* [#2750](https://github.com/apache/incubator-nuttx/pull/2750) arch: cxd56xx: Add i2c bitbang lower driver
* [#2830](https://github.com/apache/incubator-nuttx/pull/2830) Driver-specific spinlock for cxd56_serial.c

#### ESP32
* [#1893](https://github.com/apache/incubator-nuttx/pull/1893) Add ESP32 WiFi adapter and driver
* [#1942](https://github.com/apache/incubator-nuttx/pull/1942) Implement BASIC reset logic
* [#1945](https://github.com/apache/incubator-nuttx/pull/1945) Added Timer Support
* [#1958](https://github.com/apache/incubator-nuttx/pull/1958) When PSRAM is enabled allow drivers and tasks to allocate memory from a separate internal memory
* [#1978](https://github.com/apache/incubator-nuttx/pull/1978) Add power management of deep-sleep
* [#2074](https://github.com/apache/incubator-nuttx/pull/2074) Add real-time timer support for WiFi
* [#2138](https://github.com/apache/incubator-nuttx/pull/2138) Add Partition and OTA device
* [#2199](https://github.com/apache/incubator-nuttx/pull/2199) SPI Flash driver uses global sem for all MTD
* [#2224](https://github.com/apache/incubator-nuttx/pull/2224) Add SPI Flash hardware encryption I/O support
* [#2234](https://github.com/apache/incubator-nuttx/pull/2234) Include cache workaround to PSRAM
* [#2242](https://github.com/apache/incubator-nuttx/pull/2242) Watchdog support (MWDTs)
* [#2269](https://github.com/apache/incubator-nuttx/pull/2269) Add high memory support to work with PSRAM
* [#2294](https://github.com/apache/incubator-nuttx/pull/2294) Refactor ESP32 Wi-Fi driver
* [#2296](https://github.com/apache/incubator-nuttx/pull/2296) added support to automonitor by capture
* [#2474](https://github.com/apache/incubator-nuttx/pull/2474) Optimize IRAM usage based on esp-idf
* [#2514](https://github.com/apache/incubator-nuttx/pull/2514) allows the rtc wdt to be configured in bootloader and used later
* [#2515](https://github.com/apache/incubator-nuttx/pull/2515) Added support for RTC WDT
* [#2550](https://github.com/apache/incubator-nuttx/pull/2550) enables started flag if the wdt was turned on in bootloader
* [#2613](https://github.com/apache/incubator-nuttx/pull/2613) Added driver api to reload counter instantly
* [#2716](https://github.com/apache/incubator-nuttx/pull/2716) Add AES hardware accelerator driver
* [#2721](https://github.com/apache/incubator-nuttx/pull/2613) Add efuse driver
* [#2831](https://github.com/apache/incubator-nuttx/pull/2831) Writeback PSRAM data when mapping SPI Flash address to ESP32's address bus
* [#2840](https://github.com/apache/incubator-nuttx/pull/2840) Add esp32_gpio_matrix_in/out to replace ROM functions
* [#2858](https://github.com/apache/incubator-nuttx/pull/2858) Fix a memory leak when discarding a large packet.
* [#2939](https://github.com/apache/incubator-nuttx/pull/2939) Refactor ESP32 WiFi driver to support station and softAP coexistence
* [#2947](https://github.com/apache/incubator-nuttx/pull/2947) esp32_ummap: write back spiram cache before calling Cache_Flush
* [#2965](https://github.com/apache/incubator-nuttx/pull/2965) Add more flash options to esptool
* [#2979](https://github.com/apache/incubator-nuttx/pull/2979) Add support for I2C tracing
* [#2983](https://github.com/apache/incubator-nuttx/pull/2983) Extract memory layout definitions to a separate header
* [#2999](https://github.com/apache/incubator-nuttx/pull/2999) Add WPA2 Enterprise and WPA3 support
* [#3003](https://github.com/apache/incubator-nuttx/pull/3003) Re-organise the different heap regions
* [#3048](https://github.com/apache/incubator-nuttx/pull/3048) timer driver refactor
* [#3233](https://github.com/apache/incubator-nuttx/pull/3233) Bugfixes and Improvements for SPI DMA Exchange function

#### ESP32C3
* [#2870](https://github.com/apache/incubator-nuttx/pull/2870) Support for ESP32-C3 GPIO Driver
* [#2875](https://github.com/apache/incubator-nuttx/pull/2875) risc-v/esp32c3: Add support for Main System Watchdog Timer
* [#2901](https://github.com/apache/incubator-nuttx/pull/2901) esp32c3: Add system reset.
* [#2965](https://github.com/apache/incubator-nuttx/pull/2965) ESP32XX: Add more flash options to esptool
* [#3006](https://github.com/apache/incubator-nuttx/pull/3006) esp32-c3: Adds timer driver
* [#3007](https://github.com/apache/incubator-nuttx/pull/3007) risc-v/esp32-c3: complements serial driver
* [#3028](https://github.com/apache/incubator-nuttx/pull/3028) ESP32-C3: Add I2C drive
* [#3029](https://github.com/apache/incubator-nuttx/pull/3029) esp32-c3: Adds termios support
* [#3040](https://github.com/apache/incubator-nuttx/pull/3040) riscv/esp32c3: Add ESP32-C3 WLAN netcard driver
* [#3126](https://github.com/apache/incubator-nuttx/pull/3126) risc-v/esp32-c3: Add support to SPI Flash
* [#3160](https://github.com/apache/incubator-nuttx/pull/3160) riscv/esp32c3: Add standard C atomic function

#### IMX6
* [#2595](https://github.com/apache/incubator-nuttx/pull/2595) Add imx_enet driver

#### IMXRT
* [#2212](https://github.com/apache/incubator-nuttx/pull/2212) imxrt: adds support for WDOG1
* [#2354](https://github.com/apache/incubator-nuttx/pull/2354) imxrt: Added support for DP83825I PHY
* [#2461](https://github.com/apache/incubator-nuttx/pull/2461) imxrt: Added NETDEV_LATEINIT option for Ethernet
* [#2471](https://github.com/apache/incubator-nuttx/pull/2471) imxrt: Support serial single-wire mode and fix parity settings
* [#2929](https://github.com/apache/incubator-nuttx/pull/2929) imxrt: changes to FlexCAN driver support

#### NRF52
* [#2148](https://github.com/apache/incubator-nuttx/pull/2148) nrf52_wdt: split into low-level API and watchdog driver lower-half
* [#2149](https://github.com/apache/incubator-nuttx/pull/2149) nrf52832: add errata mitigation code for various RADIO issues
* [#2182](https://github.com/apache/incubator-nuttx/pull/2182) nrf52: support configuring no console/serial
* [#2189](https://github.com/apache/incubator-nuttx/pull/2189) nrf52_spi: support unconnected MISO/MOSI pins
* [#2207](https://github.com/apache/incubator-nuttx/pull/2207) nrf52: add POWER register definitions; support enabling DC/DC regulator
* [#2270](https://github.com/apache/incubator-nuttx/pull/2270) nRF52 SPI improvements
* [#2440](https://github.com/apache/incubator-nuttx/pull/2440) nrf52 ADC: minor fixes
* [#2674](https://github.com/apache/incubator-nuttx/pull/2674) nrf52_i2c: add support for I2C_M_NOSTOP and I2C_M_NOSTART flags
* [#2705](https://github.com/apache/incubator-nuttx/pull/2705) nrf52: Add a static copy buffer for i2c NOSTART transfers
* [#2712](https://github.com/apache/incubator-nuttx/pull/2712) nRF52: support stack coloration
* [#2717](https://github.com/apache/incubator-nuttx/pull/2717) I2C bitbang driver (and nRF52 implementation)
* [#2735](https://github.com/apache/incubator-nuttx/pull/2735) nRF52: add support for building SoftDevice BLE controller
* [#2756](https://github.com/apache/incubator-nuttx/pull/2756) nrf52: add stackcheck support

#### RP2040
* [#2916](https://github.com/apache/incubator-nuttx/pull/2916) rp2040: Raspberry Pi Pico SMP support
* [#2927](https://github.com/apache/incubator-nuttx/pull/2927) rp2040: Fix LDFLAGS for boot stage2
* [#2952](https://github.com/apache/incubator-nuttx/pull/2952) rp2040: Add I2C driver support
* [#2986](https://github.com/apache/incubator-nuttx/pull/2986) rp2040: Add SPI driver support
* [#3002](https://github.com/apache/incubator-nuttx/pull/3002) rp2040: SPI driver DMA transfer support
* [#3057](https://github.com/apache/incubator-nuttx/pull/3057) rp2040: Fix SPI halfword DMA transfer

#### S32K1XX
* [#2900](https://github.com/apache/incubator-nuttx/pull/2900) s32k1xx: Support ramfunc

#### STM32
* [#2010](https://github.com/apache/incubator-nuttx/pull/2010) arch/arm/src/stm32h7/stm32_spi.c: fixed build issue when SPI is configured
* [#2095](https://github.com/apache/incubator-nuttx/pull/2095) arch: stm32: fix otghs logic to support interface requests
* [#2177](https://github.com/apache/incubator-nuttx/pull/2177) FLASH waiting cycles are configured based on HCLK.
* [#2180](https://github.com/apache/incubator-nuttx/pull/2180) stm32 - Add register mappings for STM32G474 VREFBUF
* [#2194](https://github.com/apache/incubator-nuttx/pull/2194) stm32 - Add register mappings for STM32Gxxxxx-family DAC
* [#2273](https://github.com/apache/incubator-nuttx/pull/2273) stm32/stm32_spi: Add SPI register definitions for STM32G47xxx
* [#2288](https://github.com/apache/incubator-nuttx/pull/2288) stm32: Add DMAMUX register mappings and request IDs
* [#2325](https://github.com/apache/incubator-nuttx/pull/2325) arch/arm/src/stm32/stm32_serial.c: for flowcontrol use common idiom for enabling/disabling RX interrupts
* [#2473](https://github.com/apache/incubator-nuttx/pull/2473) STM32 - Add ADC register definitions for STM32G4 family
* [#2477](https://github.com/apache/incubator-nuttx/pull/2477) STM32 FLASH latency is calculated based on Vin
* [#2985](https://github.com/apache/incubator-nuttx/pull/2985) stm32 Ethernet hardening

#### STM32F7
* [#2209](https://github.com/apache/incubator-nuttx/pull/2209) stm32f7/stm32_serial.c: fix console re-initialisation if DMA enabled
* [#3489](https://github.com/apache/incubator-nuttx/pull/3489) stm32f7: Freeze tickless timer during debug halt.

#### STM32H7
* [#2880](https://github.com/apache/incubator-nuttx/pull/2880) stm32h7: add definitions for DAC
* [#2955](https://github.com/apache/incubator-nuttx/pull/2955) stm32h7:Add DBGMCU missing from master
* [#2994](https://github.com/apache/incubator-nuttx/pull/2994) stm32h7: Allow custom clock configuration to use stdclockconfig
* [#3143](https://github.com/apache/incubator-nuttx/pull/3143) stm32h7: DMA BDMA does not auto disabled on completion
* [#3207](https://github.com/apache/incubator-nuttx/pull/3207) usbhost: Add usb host tracing strings to stm32h7
* [#3458](https://github.com/apache/incubator-nuttx/pull/3458) stm32h7: Adds stm32_dbgmcu.h to match stm32f7 port
* [#3461](https://github.com/apache/incubator-nuttx/pull/3461) stm32h7: Expose flash lock, unlock, and write protect functions to boards

#### STM32L4
* [#2068](https://github.com/apache/incubator-nuttx/pull/2068) STM32L4: Improvements on ADC driver
* [#2178](https://github.com/apache/incubator-nuttx/pull/2178) STM32L4 ADC driver: extenal event configuration
* [#2220](https://github.com/apache/incubator-nuttx/pull/2220) STM32L4 TIMER: Add some helper functions
* [#2232](https://github.com/apache/incubator-nuttx/pull/2232) STM32L4 ADC: Add injected channel support.

#### STM32L5
* [#3090](https://github.com/apache/incubator-nuttx/pull/3090) stm32l5: Optional LSE xtal drive strength ramp-up

#### Renesas RX65N
* [#2469](https://github.com/apache/incubator-nuttx/pull/2469) USB Host Driver Support

#### Risc-V
* [#2470](https://github.com/apache/incubator-nuttx/pull/2470) risc-v: Introduce basic setjmp support
* [#2918](https://github.com/apache/incubator-nuttx/pull/2918) risc-v: up_sigdeliver missing fpu contexts.

#### RV64
* [#2928](https://github.com/apache/incubator-nuttx/pull/2928) rv64:add API up_copyfullstate for later FPU support
* [#3018](https://github.com/apache/incubator-nuttx/pull/3018) rv64:c906:enable DP FPU support
* [#3073](https://github.com/apache/incubator-nuttx/pull/3073) rv64:c906:demo protect build without the PMP
* [#3087](https://github.com/apache/incubator-nuttx/pull/3087) rv64: keep the stack to be 16bytes aligned
* [#3098](https://github.com/apache/incubator-nuttx/pull/3098) rv64:fix 64bit data type and instruction for FPU handlers
* [#3203](https://github.com/apache/incubator-nuttx/pull/3203) rv64:c906:add risc-v PMP and change mem map for protect build.

#### Xtensa
* [#1933](https://github.com/apache/incubator-nuttx/pull/1933) Add support to PSRAM using SPIRAM interface
* [#2014](https://github.com/apache/incubator-nuttx/pull/2014) Add the optional interrupt stack to the Xtensa architecture
* [#2352](https://github.com/apache/incubator-nuttx/pull/2352) Print the bakctrace on assertions
* [#2504](https://github.com/apache/incubator-nuttx/pull/2504) Get full backtrace from interrupts.
* [#3015](https://github.com/apache/incubator-nuttx/pull/3015) hostfs: Make host_stat populate st_size

### Minor changes

* [#1904](https://github.com/apache/incubator-nuttx/pull/1904) xtensa: ESP32: Fixed the type of cpuint variables in esp32_emac.c
* [#1943](https://github.com/apache/incubator-nuttx/pull/1943) xtensa: ESP32: Fix and clean some corners of GPIOs configuration.
* [#1947](https://github.com/apache/incubator-nuttx/pull/1947) xtensa: esp32: Fix crash on startup
* [#1948](https://github.com/apache/incubator-nuttx/pull/1948) xtensa: ESP32: Fixes the GPIO's function mask test
* [#1960](https://github.com/apache/incubator-nuttx/pull/1960) xtensa: xtensa.h: Include sys/types.h needed if STACK_COLORATON is enabled
* [#1968](https://github.com/apache/incubator-nuttx/pull/1968) arm: kinetis: freedom-k64f: Declare missing NUM_BUTTONS
* [#1990](https://github.com/apache/incubator-nuttx/pull/1990) arm: kinetis: flexcan fixed compile error
* [#2120](https://github.com/apache/incubator-nuttx/pull/2120) arm: stm32h7: Fix missing 'ret' reported by Frank-Christian Kruegel
* [#2159](https://github.com/apache/incubator-nuttx/pull/2159) xtensa: esp32: Fix SPI master DMA RX buffer memcpy size erro
* [#2160](https://github.com/apache/incubator-nuttx/pull/2160) arm: stm32l4/stm32l4_adc.c: fix copy-paste mistake with CONFI
* [#2210](https://github.com/apache/incubator-nuttx/pull/2210) arm: stm32/stm32_adc.c: do not allow negative ref count
* [#2214](https://github.com/apache/incubator-nuttx/pull/2214) xtensa: esp32: Fix rt-timer issues
* [#2233](https://github.com/apache/incubator-nuttx/pull/2233) xtensa: esp32: Fix the memory regions with regards to the range used by the ROM
* [#2240](https://github.com/apache/incubator-nuttx/pull/2240) arm: nrf52 GPIO/GPIOTE: better expose pin interrupt capability
* [#2284](https://github.com/apache/incubator-nuttx/pull/2284) arm: stm32h7/stm32_dmamux.h: Fix errors in bitfield definitions
* [#2286](https://github.com/apache/incubator-nuttx/pull/2286) arm: stm32f0l0g0/stm32_dmamux.h: Fix errors in bitfield definitions
* [#2287](https://github.com/apache/incubator-nuttx/pull/2287) arm: stm32h7/stm32_dmamux.h: Add missing CCR SPOL defines
* [#2300](https://github.com/apache/incubator-nuttx/pull/2300) arm: sam34: compile error on SAM34 TWI
* [#2316](https://github.com/apache/incubator-nuttx/pull/2844) risc-v: minor fix
* [#2330](https://github.com/apache/incubator-nuttx/pull/2330) xtensa: esp32/esp32_tim.c: Fix build when debug is enabled.
* [#2336](https://github.com/apache/incubator-nuttx/pull/2336) arm: stm32l4: correct macros STM32L4_CAN_MCR_OFFSET, etc... to match defines
* [#2344](https://github.com/apache/incubator-nuttx/pull/2344) xtensa: esp32/esp32_gpio.c: Fix GPIO IRQ assert condition
* [#2351](https://github.com/apache/incubator-nuttx/pull/2351) xtensa: esp32: Fix issues of force-sleep
* [#2355](https://github.com/apache/incubator-nuttx/pull/2355) xtensa: esp32_himem: Fix issue that was preventing to map all free memory
* [#2361](https://github.com/apache/incubator-nuttx/pull/2361) arm: nrf52 GPIO: minor fixes
* [#2364](https://github.com/apache/incubator-nuttx/pull/2364) arm: stm32h7: Fix bug where more than CONFIG_MM_REGIONS would be allocated
* [#2372](https://github.com/apache/incubator-nuttx/pull/2372) rv64: Fix SCN/PRI.PTR definitions
* [#2373](https://github.com/apache/incubator-nuttx/pull/2373) risc-v: Don't use non existent "saved_status"
* [#2423](https://github.com/apache/incubator-nuttx/pull/2423) xetnsa: Couple of Xtensa fixes
* [#2448](https://github.com/apache/incubator-nuttx/pull/2448) arm: stm32/stm32h7: fix the configuration of PWM outputs when subsequent channels are not enabled
* [#2454](https://github.com/apache/incubator-nuttx/pull/2454) xtensa: esp32/esp32-core: Fix #ifdef warning and update MM_SECTIONS
* [#2483](https://github.com/apache/incubator-nuttx/pull/2483) arm: stm32: convert all STM32G47X specific code to generic STM32G4 series code
* [#2519](https://github.com/apache/incubator-nuttx/pull/2519) arm: imxrt: replace clock_systimespec with clock_systime_timespec
* [#2536](https://github.com/apache/incubator-nuttx/pull/2536) xtensa: esp32: fixes enable int function and gets apb clk frequency through function
* [#2546](https://github.com/apache/incubator-nuttx/pull/2546) arm: imxrt: imxrt_usdhc.c: fixed no DMA build error
* [#2551](https://github.com/apache/incubator-nuttx/pull/2551) arm: stm32h7x3xx_memorymap.h invalid address map for fdcan
* [#2554](https://github.com/apache/incubator-nuttx/pull/2554) xtensa: Esp32 wifi fixes
* [#2555](https://github.com/apache/incubator-nuttx/pull/2555) xtensa: esp32/esp32_spiflash.c: Writeback PSRAM data before invalidating the cache
* [#2559](https://github.com/apache/incubator-nuttx/pull/2559) risc-v: Remove duplicated declaration for up_irq_save and up_irq_restore
* [#2560](https://github.com/apache/incubator-nuttx/pull/2560) risc-v: Move csr.h to common place
* [#2568](https://github.com/apache/incubator-nuttx/pull/2568) risc-v: Move CSR register bit definition to csr.h
* [#2569](https://github.com/apache/incubator-nuttx/pull/2569) risc-v: Reuse the common up_schedule_sigaction implementation
* [#2570](https://github.com/apache/incubator-nuttx/pull/2570) arm: stm32g4: Fix incorrect FLASH wait states
* [#2573](https://github.com/apache/incubator-nuttx/pull/2573) xtensa: esp32: Bump NAME_MAX where CONFIG_ESP32_WIFI_SAVE_PARAM=y
* [#2584](https://github.com/apache/incubator-nuttx/pull/2584) xtensa: esp32_wifi_adapter.c: file mode for open doesn't make sense for O_RDONLY
* [#2589](https://github.com/apache/incubator-nuttx/pull/2589) risc-v: fix redefined CSR_INSTRET
* [#2612](https://github.com/apache/incubator-nuttx/pull/2612) arm: kinetis: S32K/Kinetis: Fix RTC settime prescaler
* [#2612](https://github.com/apache/incubator-nuttx/pull/2612) arm: S32K/Kinetis: Fix RTC settime prescaler
* [#2647](https://github.com/apache/incubator-nuttx/pull/2647) xtensa: esp32: Fix ESP32 serial UART tx ready check error
* [#2666](https://github.com/apache/incubator-nuttx/pull/2666) xtensa: esp32: Fix ESP32 SPI3 slave ops data error
* [#2676](https://github.com/apache/incubator-nuttx/pull/2676) arm: stm32412: Fixes pinmap CAN1
* [#2689](https://github.com/apache/incubator-nuttx/pull/2689) arm: tiva: Fix lm3s_ethernet.c with DEBUGASSERT
* [#2700](https://github.com/apache/incubator-nuttx/pull/2700) arm: nRF52 various minor fixes
* [#2708](https://github.com/apache/incubator-nuttx/pull/2708) xtensa: esp32: Fix ESP32 I2C driver issues
* [#2709](https://github.com/apache/incubator-nuttx/pull/2709) xtensa: esp32: Fix ESP32 SPI driver issues
* [#2722](https://github.com/apache/incubator-nuttx/pull/2722) arm: stm32f412:Replaced Kludged pinmap with one for SoC.
* [#2725](https://github.com/apache/incubator-nuttx/pull/2725) arm: nRF52: FIX wrong bitmask for DRIVE setting
* [#2727](https://github.com/apache/incubator-nuttx/pull/2727) xtensa: esp32_free_cpuint: Fix an assertion
* [#2728](https://github.com/apache/incubator-nuttx/pull/2728) xtensa: esp32_dma_init: Fix a dubious assertion
* [#2731](https://github.com/apache/incubator-nuttx/pull/2731) xtensa: esp_allocateheap.c: Correct ROM memory boundaries in SMP case
* [#2752](https://github.com/apache/incubator-nuttx/pull/2752) xtensa: esp32/esp32_spiflash.c: Fix the value of the page start address when invalidating the cache
* [#2755](https://github.com/apache/incubator-nuttx/pull/2755) xtensa: esp32: Fix compile errors with CONFIG_SMP=y
* [#2757](https://github.com/apache/incubator-nuttx/pull/2757) xtensa: esp32/esp32_wifi_adapter.c: Print debug output only when DEBUG_WIRLESS* are enabled
* [#2758](https://github.com/apache/incubator-nuttx/pull/2758) xtensa: Kconfig: Reduce the default value of the internal memory
* [#2759](https://github.com/apache/incubator-nuttx/pull/2759) xtensa: esp32/psram: Fix missing configs
* [#2761](https://github.com/apache/incubator-nuttx/pull/2761) risc-v: Remove unused and undefined file section "Public Variables"
* [#2763](https://github.com/apache/incubator-nuttx/pull/2763) arm: imx6: Apply the latest imxrt/imxrt_enet.c to imx6/imx_enet.c
* [#2771](https://github.com/apache/incubator-nuttx/pull/2771) arm: imx6: Update imx6 enet
* [#2772](https://github.com/apache/incubator-nuttx/pull/2771) arm: imx6 enet with TCP_WRITE_BUFFERS
* [#2777](https://github.com/apache/incubator-nuttx/pull/2777) arm: imx6: Fix a compile error with CONFIG_DEBUG_ASSERTIONS=y
* [#2779](https://github.com/apache/incubator-nuttx/pull/2779) arm: samv7/sam_mcan.c: fix some mismatches caused by renaming
* [#2782](https://github.com/apache/incubator-nuttx/pull/2782) arm: nRF52 fixes
* [#2788](https://github.com/apache/incubator-nuttx/pull/2788) risc-v: Don't declare riscv_addregion if CONFIG_MM_REGIONS is < 1.
* [#2791](https://github.com/apache/incubator-nuttx/pull/2791) arm: stm32f7/stm32_qspi.c: Fix warning of format strings
* [#2792](https://github.com/apache/incubator-nuttx/pull/2792) arm: [imxrt] Fix FlexCAN tx dropping frames
* [#2793](https://github.com/apache/incubator-nuttx/pull/2316) risc-v: Remove nx_start prototype from riscv_internal.h
* [#2795](https://github.com/apache/incubator-nuttx/pull/2795) arm: stm32f412:Corrected Pin count
* [#2796](https://github.com/apache/incubator-nuttx/pull/2796) xtensa: esp32: Fix cache issue detected by DEBUG_ASSERTION
* [#2799](https://github.com/apache/incubator-nuttx/pull/2799) RV64: handle relocation type R_RISCV_CALL_PLT in PIC build.
* [#2805](https://github.com/apache/incubator-nuttx/pull/2805) arm: imxrt1060 iperf
* [#2812](https://github.com/apache/incubator-nuttx/pull/2812) xtensa: esp32_spiflash.c: Fix preprocessor condition
* [#2813](https://github.com/apache/incubator-nuttx/pull/2813) xtensa: esp32: Add extern modifier to ROM function declaration
* [#2815](https://github.com/apache/incubator-nuttx/pull/2815) riscv: Fix files names in headers that were still using the old 'up_' prefix
* [#2832](https://github.com/apache/incubator-nuttx/pull/2832) xtensa: esp32: Fix the issue of WiFi internal malloc from PSRAM
* [#2844](https://github.com/apache/incubator-nuttx/pull/2844) risc-v: LiteX: Make Arty-A7 example work
* [#2867](https://github.com/apache/incubator-nuttx/pull/2867) arm: lpc17xx_40xx/lpc17_40_i2c.c: Propagate I2C I/O errors
* [#2886](https://github.com/apache/incubator-nuttx/pull/2886) arm: pic32mz: Chip does not have ANSEL register on port K
* [#2889](https://github.com/apache/incubator-nuttx/pull/2889) arm: pic32mx7 cannot perform context switch
* [#2892](https://github.com/apache/incubator-nuttx/pull/2892) risc-v: esp32-c3: Don't reserve any vectors for any special use.
* [#2893](https://github.com/apache/incubator-nuttx/pull/2893) risc-v: esp32-c3: Build serial driver only when selected
* [#2903](https://github.com/apache/incubator-nuttx/pull/2903) xtensa: esp32: xtensa_user: Implement a few more instructions
* [#2912](https://github.com/apache/incubator-nuttx/pull/2912) risc-v: esp32-c3: Fix CPU interrupts freeing on WDT driver
* [#2917](https://github.com/apache/incubator-nuttx/pull/2917) arm: Add 'select ARM_HAVE_WFE_SEV' to ARCH_CHIP_RP2040
* [#2920](https://github.com/apache/incubator-nuttx/pull/2920) risc-v: esp32-c3: Configure clock and call board initialize at startup
* [#2923](https://github.com/apache/incubator-nuttx/pull/2923) ez80: fix several bugs in emac driver
* [#2931](https://github.com/apache/incubator-nuttx/pull/2931) arm: kinetis: [FlexCAN] Fix TX drop #2792 and correctly set CAN timings to non-zero
* [#2931](https://github.com/apache/incubator-nuttx/pull/2931) arm: s32k1xx: [FlexCAN] Fix TX drop #2792 and correctly set CAN timings to non-zero
* [#2943](https://github.com/apache/incubator-nuttx/pull/2943) arm: stm32x7:lse ensure it is started
* [#2951](https://github.com/apache/incubator-nuttx/pull/2951) arm: stm32_wwdg debug log formatting
* [#2967](https://github.com/apache/incubator-nuttx/pull/2967) arm: STM32F7 lse static values directly from Kconfig
* [#2968](https://github.com/apache/incubator-nuttx/pull/2968) xtensa: esp32: Change I2C SCL default pin to a valid one
* [#2972](https://github.com/apache/incubator-nuttx/pull/2972) risc-v: esp32-c3: Fix GPIO pin function configuration
* [#2976](https://github.com/apache/incubator-nuttx/pull/2976) xtensa: ESP32: Fix I2C Kconfig bringing the character driver as a dependency
* [#2977](https://github.com/apache/incubator-nuttx/pull/2977) xtensa: ESP32: Fix GPIO pin function configuration
* [#2996](https://github.com/apache/incubator-nuttx/pull/2996) arm: stm32h747xi: Fix missing IO_CONFIG setting
* [#3008](https://github.com/apache/incubator-nuttx/pull/3008) risc-v: esp32-c3: free cpu in case it was preallocated in wdt driver
* [#3013](https://github.com/apache/incubator-nuttx/pull/3013) risc-v: bl602:fix bl602_flash_erase to erase the wrong block
* [#3034](https://github.com/apache/incubator-nuttx/pull/3034) arm: imx6: Fix an error message in imx_enet.c
* [#3051](https://github.com/apache/incubator-nuttx/pull/3051) risc-v: Internal functions should be prefixed with riscv_ not up
* [#3075](https://github.com/apache/incubator-nuttx/pull/3075) arm: Fix syscall number out of swi range in thumb mode
* [#3079](https://github.com/apache/incubator-nuttx/pull/3079) arm: kinetis: [FlexCAN] Correct reset state for CTRL1 register
* [#3079](https://github.com/apache/incubator-nuttx/pull/3079) arm: s32k1xx: [FlexCAN] Correct reset state for CTRL1 register
* [#3088](https://github.com/apache/incubator-nuttx/pull/3088) arm: samv7: Fix sam_putreg() parameter type
* [#3092](https://github.com/apache/incubator-nuttx/pull/3092) xtensa: xtensa: esp32_allocateheap.c: Don't allocate ROM regions when running in QEMU.
* [#3116](https://github.com/apache/incubator-nuttx/pull/3116) arm: stm32l5: Enable SPI support and license clearing
* [#3119](https://github.com/apache/incubator-nuttx/pull/2976) xtensa: sp32: Fix buffer size word-alignment for DMA transfers
* [#3125](https://github.com/apache/incubator-nuttx/pull/3125) risc-v: Internal functions should be prefixed with "riscv_"
* [#3130](https://github.com/apache/incubator-nuttx/pull/3145) xtensa: esp32: Fix SPI polling mode when DMA is also enabled.
* [#3135](https://github.com/apache/incubator-nuttx/pull/3135) rv64:c906:colorize the idle stack area;minor fixes.
* [#3145](https://github.com/apache/incubator-nuttx/pull/3145) xtensa: esp32_part_ioctl: Return -ENOTTY for unknown commands
* [#3162](https://github.com/apache/incubator-nuttx/pull/3162) arm: STM32 USB OTGFSDEV: Fix handling of SETUP OUT longer than 64 bytes
* [#3167](https://github.com/apache/incubator-nuttx/pull/3167) arm: stm32h7:SPI Fix 16 bit SPI mode
* [#3174](https://github.com/apache/incubator-nuttx/pull/3174) arm: Use macro defined swi range in dispatch_syscall
* [#3178](https://github.com/apache/incubator-nuttx/pull/3178) arm: tiva:cc13x0_adi3_refsys fix typo
* [#3198](https://github.com/apache/incubator-nuttx/pull/3198) arm: Stm32h7 fix heap clobber
* [#3199](https://github.com/apache/incubator-nuttx/pull/3199) xtensa: ESP32: Fix math for DMA buffer length rounding
* [#3200](https://github.com/apache/incubator-nuttx/pull/3200) xtensa: esp32: Fix DMA burst mode being unintendedly disabled
* [#3219](https://github.com/apache/incubator-nuttx/pull/3219) risc-v: bl602: fix _heap_start not word aligned
* [#3220](https://github.com/apache/incubator-nuttx/pull/3220) arm: Fix indexing for stm32h7 usbhost tracing
* [#3248](https://github.com/apache/incubator-nuttx/pull/3248) xtensa: esp32: remove extra initial newline on syslog call
* [#3283](https://github.com/apache/incubator-nuttx/pull/3283) rv64:add memory clobber to inline asm for syscall.
* [#3285](https://github.com/apache/incubator-nuttx/pull/3285) arm: Remove .cpu directive from assemble file
* [#3293](https://github.com/apache/incubator-nuttx/pull/3293) arm: armv6-m: Remove cpsid and cpsie from exception_common
* [#3307](https://github.com/apache/incubator-nuttx/pull/3307) arm: Replace the hardcode syscall number with macro
* [#3310](https://github.com/apache/incubator-nuttx/pull/3310) arm: armv8-m: Merge ite instruction to the previous one
* [#3311](https://github.com/apache/incubator-nuttx/pull/3311) arm: fix the potential corruption in initialization
* [#3313](https://github.com/apache/incubator-nuttx/pull/3313) arm: Replace "b lr" or "mov pc, lr" with "bx lr"
* [#3315](https://github.com/apache/incubator-nuttx/pull/3315) arm: Move setjmp/longjmp to libc/machine
* [#3326](https://github.com/apache/incubator-nuttx/pull/3326) arm: Update the old arm architecture with the recent fix
* [#3440](https://github.com/apache/incubator-nuttx/pull/3440) arm: Change all spsr_cxsf to spsr
* [#3448](https://github.com/apache/incubator-nuttx/pull/3448) arm: armv7-a: Remove the special process of the nest level
* [#3451](https://github.com/apache/incubator-nuttx/pull/3451) arm: Remove g_irqtmp, g_undeftmp and g_aborttmp
* [#3452](https://github.com/apache/incubator-nuttx/pull/3452) risc-v: esp32-c3: Refactors and fixes issues on serial driver.
* [#3457](https://github.com/apache/incubator-nuttx/pull/3457) arm: stm32h7: Actually use the AXI SRAM as the main heap as the documentation describes in PROTECTED mode.
* [#3459](https://github.com/apache/incubator-nuttx/pull/3459) arm: stm32h7: Fixes build error in stm32_sdmmc.c without DCACHE
* [#3473](https://github.com/apache/incubator-nuttx/pull/3473) xtensa: esp32: move common XTAL and RUN_IRAM configs to ESP32 KConfig
* [#3486](https://github.com/apache/incubator-nuttx/pull/3486) xtensa: esp32: Improve SPI polling to use the entire HW buffer
* [#3492](https://github.com/apache/incubator-nuttx/pull/3492) risc-v: riscv_initialize.c: Add telnet_initialize to riscv's up_initialize
* [#2868](https://github.com/apache/incubator-nuttx/pull/2868) xtensa: Fix xtensa stack coloring

## Simulator

### New Features
* [#2129](https://github.com/apache/incubator-nuttx/pull/2129) add "nimble" config, to test nimBLE on top of bthcisock
* [#2130](https://github.com/apache/incubator-nuttx/pull/2130) rpproxy/rpserver: force use 'CONFIG_SIM_M32' for 64bit system.
* [#2158](https://github.com/apache/incubator-nuttx/pull/2158) linux I2C bus support in sim
* [#2164](https://github.com/apache/incubator-nuttx/pull/2164) add LVGL configuration which uses the X11 framebuffer and mouse
* [#2198](https://github.com/apache/incubator-nuttx/pull/2198) support LCD emulation over X11; correctly decouple LCD/FB from X11/NX
* [#2579](https://github.com/apache/incubator-nuttx/pull/2579) make it conditional with FS_FAT
* [#2599](https://github.com/apache/incubator-nuttx/pull/2599) names: add writev/readv into name list
* [#2619](https://github.com/apache/incubator-nuttx/pull/2619) hci: reuse the reserved fields of hci buffer
* [#2690](https://github.com/apache/incubator-nuttx/pull/2690) support sim vfork
* [#2696](https://github.com/apache/incubator-nuttx/pull/2696) hcitty: add hcitty adapter
* [#2720](https://github.com/apache/incubator-nuttx/pull/2720) board/sim: Support NuttX BLE stack through uart shim driver
* [#3093](https://github.com/apache/incubator-nuttx/pull/3093) add heap policy and asan logic to support mm debug on sim platform
* [#3152](https://github.com/apache/incubator-nuttx/pull/3152) add dlsym to [nuttx-names.in](http://nuttx-names.in)
* [#3224](https://github.com/apache/incubator-nuttx/pull/3224) boards/sim: remove dsptest configuration
* [#3231](https://github.com/apache/incubator-nuttx/pull/3231) add the simulated lower-half FOC device
* [#3478](https://github.com/apache/incubator-nuttx/pull/3478) refactor signal handling

### Bug Fixes
* [#2109](https://github.com/apache/incubator-nuttx/pull/2109) Revert "arch/sim: Make the SIGUSR1 host signal use the NuttX irq logic"
* [#2246](https://github.com/apache/incubator-nuttx/pull/2246) boards/sim/sim/sim/src/sim_touchscreen.c: add missing nx_disconnect
* [#2259](https://github.com/apache/incubator-nuttx/pull/2259) boards/sim: add atexit(2) into naming list
* [#2441](https://github.com/apache/incubator-nuttx/pull/2441) sim: fix input handling and add simulated buttons support from mouse
* [#2597](https://github.com/apache/incubator-nuttx/pull/2597) Revert "board/sim: Remove the too strict warning"
* [#3176](https://github.com/apache/incubator-nuttx/pull/3176) sim: fix signal deliver calling error on sim platform
* [#3205](https://github.com/apache/incubator-nuttx/pull/3205) sim: do not exit simulator on up_assert (just let the task exit)

## Documentation

### New Features
* [#1955](https://github.com/apache/incubator-nuttx/pull/1955) Add documentation for note filters and task trace guides
* [#1959](https://github.com/apache/incubator-nuttx/pull/1959) Documentation for the Timer Driver
* [#2268](https://github.com/apache/incubator-nuttx/pull/2268) Documentation for Watchdog Timer Driver
* [#2334](https://github.com/apache/incubator-nuttx/pull/2334) [CONTRIBUTING.md](http://CONTRIBUTING.md): talk about preferred commit message format
* [#2408](https://github.com/apache/incubator-nuttx/pull/2408) Documentation: support versioned docs
* [#2543](https://github.com/apache/incubator-nuttx/pull/2543) Documentation: how to use auto monitor feature to keep the chip alive
* [#2818](https://github.com/apache/incubator-nuttx/pull/2818) Documentation: introduce hardware platforms documentation
* [#2819](https://github.com/apache/incubator-nuttx/pull/2819) Documentation: document nRF52832 Sparkfun board (improve MDK board a bit)
* [#3022](https://github.com/apache/incubator-nuttx/pull/3022) hostfs: Document the backends and restrictions
* [#3127](https://github.com/apache/incubator-nuttx/pull/3127) Documentation: add ESP32 and DevKitC docs
* [#3138](https://github.com/apache/incubator-nuttx/pull/3138) Addind CMake based C++ project example in documentation
* [#3490](https://github.com/apache/incubator-nuttx/pull/3490) Documentation/esp32: Add supported peripherals

### Improvements
* [#2021](https://github.com/apache/incubator-nuttx/pull/2021) Correct the links in Documentation folder
* [#2024](https://github.com/apache/incubator-nuttx/pull/2024) Fix broken documentation links
* [#2026](https://github.com/apache/incubator-nuttx/pull/2026) Documentation: Remove all tail spaces from *.rst and *.html
* [#2027](https://github.com/apache/incubator-nuttx/pull/2027) Documentation: Reorganize some section
* [#2031](https://github.com/apache/incubator-nuttx/pull/2031) Documentation/quickstart/debugging.rst: rewrite JTAG/OpenOCD section
* [#2045](https://github.com/apache/incubator-nuttx/pull/2045) Documentation: Misc fixups for broken links, errors, warnings
* [#2051](https://github.com/apache/incubator-nuttx/pull/2051) Documentation/quickstart/debugging: rewrite SWD sentence
* [#2106](https://github.com/apache/incubator-nuttx/pull/2106) documentation: change non-working URL
* [#2329](https://github.com/apache/incubator-nuttx/pull/2329) Documentation/components/drivers/character/pwm: fix pwm.c location
* [#2362](https://github.com/apache/incubator-nuttx/pull/2362) Documentation improvements
* [#2390](https://github.com/apache/incubator-nuttx/pull/2390) Documentation: improve debugging section
* [#2485](https://github.com/apache/incubator-nuttx/pull/2485) Documentaiton: merge quickstart to getting started
* [#2563](https://github.com/apache/incubator-nuttx/pull/2563) update Documentation/components/drivers/character/watchdog.rst
* [#3144](https://github.com/apache/incubator-nuttx/pull/3144) CI: remove linkcheck when building docs
* [#3180](https://github.com/apache/incubator-nuttx/pull/3180) documentation: improve boardctl() docs
* [#3194](https://github.com/apache/incubator-nuttx/pull/3194) Documentation: add syslog user API and other minor improvements
* [#3271](https://github.com/apache/incubator-nuttx/pull/3271) docs and comments: Update stale references to COPYING
* [#3470](https://github.com/apache/incubator-nuttx/pull/3470) Documentation: migrate ESP32 README to docs

## Driver Support

### New Driver Support
* [#1936](https://github.com/apache/incubator-nuttx/pull/1936) note: Add task trace support
* [#1989](https://github.com/apache/incubator-nuttx/pull/1989) sensors: Support fxos8700cq motion I2C sensor
* [#2091](https://github.com/apache/incubator-nuttx/pull/2091) usbdev: add Android Debug Bridge driver
* [#2166](https://github.com/apache/incubator-nuttx/pull/2166) lcd: Add LCD character driver: allows interacting with LCD directly from userspace
* [#2216](https://github.com/apache/incubator-nuttx/pull/2216) rc: support infrared remote control
* [#2282](https://github.com/apache/incubator-nuttx/pull/2282) audio: cxd56: add initial audio SRC implementation
* [#2301](https://github.com/apache/incubator-nuttx/pull/2301) analog: support for MAX1161X family of I2C 12 bit ADC chips
* [#2429](https://github.com/apache/incubator-nuttx/pull/2429) audio: add simple wm8994 codec driver
* [#2628](https://github.com/apache/incubator-nuttx/pull/2628) efuse: Add generic efuse driver for NuttX
* [#2736](https://github.com/apache/incubator-nuttx/pull/2736) console: Add generic support to LWL Console
* [#2829](https://github.com/apache/incubator-nuttx/pull/2829) sensor: add fakesensor driver
* [#3230](https://github.com/apache/incubator-nuttx/pull/3230) motor: add generic upper-half driver for Field Oriented Control (FOC)
* [#3474](https://github.com/apache/incubator-nuttx/pull/3474) sensors: Adds driver for hyt271 sensore module

### Bug Fixes
* [#2036](https://github.com/apache/incubator-nuttx/pull/2036) serial: break from read after closing
* [#2039](https://github.com/apache/incubator-nuttx/pull/2039) sensors: add unified management for sensor
* [#2070](https://github.com/apache/incubator-nuttx/pull/2070) bluetooth: support HCI/L2CAP sockets, support HCI RAW channel
* [#2139](https://github.com/apache/incubator-nuttx/pull/2139) lcd: Ssd1306 cleanup
* [#2142](https://github.com/apache/incubator-nuttx/pull/2776) note: Add task name record for task trace
* [#2146](https://github.com/apache/incubator-nuttx/pull/2146) pipes: nx_pipe syscall takes three params, also use nx_close
* [#2175](https://github.com/apache/incubator-nuttx/pull/2175) wireless: gs2200m: Check disassociation from AP and enable rejoin
* [#2188](https://github.com/apache/incubator-nuttx/pull/2200) lcd_dev: put header in correct location; fix missing const
* [#2200](https://github.com/apache/incubator-nuttx/pull/2200) lcd: Minor fixes to ssd1306 i2c driver
* [#2201](https://github.com/apache/incubator-nuttx/pull/2512) wireless: gs2200m: Add function to get IWNWID / IWFREQ / IWSENS information
* [#2208](https://github.com/apache/incubator-nuttx/pull/2208) lcd: add optional putarea()/getarea() operations
* [#2215](https://github.com/apache/incubator-nuttx/pull/2215) sensors: add new feature about sensor driver model
* [#2223](https://github.com/apache/incubator-nuttx/pull/2223) audio: cxd56: cleanup for the spresense audio implementation
* [#2315](https://github.com/apache/incubator-nuttx/pull/2370) sensors: add common circular buffer management
* [#2318](https://github.com/apache/incubator-nuttx/pull/2318) sensors: update l3gd20 sensor driver with new sensor driver model
* [#2343](https://github.com/apache/incubator-nuttx/pull/2343) serial: Prevent RX stall
* [#2345](https://github.com/apache/incubator-nuttx/pull/2345) mtd/mtd_progmem.c: fix progmem_log2 parameter type to match prototype
* [#2369](https://github.com/apache/incubator-nuttx/pull/2369) sensors: support custom types of sensor
* [#2370](https://github.com/apache/incubator-nuttx/pull/2370) rc: fix bug about lirc_read
* [#2383](https://github.com/apache/incubator-nuttx/pull/2383) USB: Do not try to print NULL format strings for verbose trace messages when disabled
* [#2398](https://github.com/apache/incubator-nuttx/pull/2398) rptun: fix rptun rpmsg_unregister_callback fault
* [#2445](https://github.com/apache/incubator-nuttx/pull/2445) audio: Make audio_null play at real speed
* [#2488](https://github.com/apache/incubator-nuttx/pull/2488) crypto/arc4random: rename getrandom to arc4random_buf
* [#2490](https://github.com/apache/incubator-nuttx/pull/3482) leds: ws2812: make frequency selection more flexible
* [#2497](https://github.com/apache/incubator-nuttx/pull/2497) crypto/random_pool.c: fix getrandom() when thread calling it gets can…
* [#2508](https://github.com/apache/incubator-nuttx/pull/2508) leds/ws2812: optimize reset bytes
* [#2512](https://github.com/apache/incubator-nuttx/pull/2488) wireless/bluetooth: change the tx thread stack size to DEFAULT_TASK_STACKSIZE
* [#2564](https://github.com/apache/incubator-nuttx/pull/2564) audio: uninitialize usermq to NULL when the device has not
* [#2571](https://github.com/apache/incubator-nuttx/pull/2571) bluetooth: Fix bt_buff lifecycle
* [#2607](https://github.com/apache/incubator-nuttx/pull/2607) wireless: bluetooth: minor fix to bluetooth stack
* [#2609](https://github.com/apache/incubator-nuttx/pull/2609) wireless: bluetooth: fix minor issue in bt uart driver
* [#2611](https://github.com/apache/incubator-nuttx/pull/2611) wireless/bluetooth: Fix vairous issues found in bt uart shim driver
* [#2617](https://github.com/apache/incubator-nuttx/pull/2617) serial: should include <signal.h> explicitly
* [#2621](https://github.com/apache/incubator-nuttx/pull/2621) syslog: Added formatted timestamps in syslog.
* [#2636](https://github.com/apache/incubator-nuttx/pull/2636) pipes: pty shouldn't call nx_pipe and then file_detach in kernel space
* [#2664](https://github.com/apache/incubator-nuttx/pull/2664) can: fix RTR ioctl and support timeout
* [#2691](https://github.com/apache/incubator-nuttx/pull/2383) wireless: bluetooth: add more hci event definitions
* [#2692](https://github.com/apache/incubator-nuttx/pull/2692) syslog: Prepend Process ID to syslog message
* [#2697](https://github.com/apache/incubator-nuttx/pull/2697) syslog: Added printing of log priority in syslog
* [#2698](https://github.com/apache/incubator-nuttx/pull/2698) syslog: Added color output to syslog.
* [#2704](https://github.com/apache/incubator-nuttx/pull/2704) wireless: bluetooth: minor fix for bluetooth driver
* [#2707](https://github.com/apache/incubator-nuttx/pull/2707) drivers: wireless: Fix ASSERT() in _read_data_len() in gs2200m.c
* [#2710](https://github.com/apache/incubator-nuttx/pull/2710) syslog: Re-arranged syslog fields.
* [#2711](https://github.com/apache/incubator-nuttx/pull/2711) sensors: bmp280: minor fixes
* [#2715](https://github.com/apache/incubator-nuttx/pull/2715) sensors: bmp280: convert to sensor interface (and minor sensor change)
* [#2738](https://github.com/apache/incubator-nuttx/pull/2738) wireless: gs2200m: Print error massages with wlerr()
* [#2747](https://github.com/apache/incubator-nuttx/pull/2747) wireless: gs2200m: Fix _read_data()
* [#2775](https://github.com/apache/incubator-nuttx/pull/2775) mtd: w25qxxxjv.c : W25Q256's sector count is 8192
* [#2776](https://github.com/apache/incubator-nuttx/pull/2776) net/encx24j600.c: Correct setting of ifstate
* [#2798](https://github.com/apache/incubator-nuttx/pull/2798) wireless: gs2200m: Change retry condition in gs2200m_hal_write()
* [#2801](https://github.com/apache/incubator-nuttx/pull/2801) mtd:w25qxxxjv.c: use different protect bits and address lengts
* [#2850](https://github.com/apache/incubator-nuttx/pull/2850) audio: Introduce a driver-specific spinlock to cxd56.c
* [#2907](https://github.com/apache/incubator-nuttx/pull/2711) sensors: driver model update
* [#2950](https://github.com/apache/incubator-nuttx/pull/2950) audio: pcm_decode: add RAW format support
* [#2961](https://github.com/apache/incubator-nuttx/pull/2961) syslog_rpmsg: fix system crash when open CONFIG_SCHED_HAVE_PARENT
* [#2989](https://github.com/apache/incubator-nuttx/pull/2989) mmcsd: Fixes race condition in event wait logic of SDMMC driver
* [#3000](https://github.com/apache/incubator-nuttx/pull/3000) sensors: fakesensor support batch
* [#3020](https://github.com/apache/incubator-nuttx/pull/3020) syslog: add option to prefix process name
* [#3047](https://github.com/apache/incubator-nuttx/pull/3047) mmcsd: Stuck in 1-bit mode, Removed CONFIG_ARCH_HAVE_SDIO_DELAYED_INVLDT
* [#3050](https://github.com/apache/incubator-nuttx/pull/3050) syslog: Added support for multiple syslog channels.
* [#3110](https://github.com/apache/incubator-nuttx/pull/3110) can: Add CAN FD flags to CAN header
* [#3118](https://github.com/apache/incubator-nuttx/pull/3118) sensors: qencoder.c - Remove bad sninfo() format string
* [#3163](https://github.com/apache/incubator-nuttx/pull/3163) USBDEV: RNDIS: Fix occasional disconnections due to race condition
* [#3185](https://github.com/apache/incubator-nuttx/pull/3185) USBDEV RNDIS: Fix unaligned access caused by 4f66624
* [#3195](https://github.com/apache/incubator-nuttx/pull/3195) serial: Don't comment out ws_[x|y]pixel field from winsize struct
* [#3201](https://github.com/apache/incubator-nuttx/pull/3201) timers: rtc/rpmsg: support server and client to set time each other
* [#3214](https://github.com/apache/incubator-nuttx/pull/3214) can: Fix TX ID bits 18-20 of mcp2515 can driver
* [#3215](https://github.com/apache/incubator-nuttx/pull/3215) syslog: Drop extra carriage return from syslog calls
* [#3226](https://github.com/apache/incubator-nuttx/pull/3226) syslog: Added multi device support in syslog_device.
* [#3269](https://github.com/apache/incubator-nuttx/pull/3269) motor: Add support for motor debug messages
* [#3453](https://github.com/apache/incubator-nuttx/pull/3453) syslog: Fix in syslog_intbuffer flushing
* [#3454](https://github.com/apache/incubator-nuttx/pull/3454) syslog: Proper uninit of syslog_device.
* [#3475](https://github.com/apache/incubator-nuttx/pull/3214) input: Add INPUT_TOUCHSCREEN config
* [#3482](https://github.com/apache/incubator-nuttx/pull/3482) input: Rename config from INPUT classes

## Board Support

### New Board Support
* [#2054](https://github.com/apache/incubator-nuttx/pull/2054) configure.sh: update custom board config build support
* [#2463](https://github.com/apache/incubator-nuttx/pull/2463) boards: Added Teensy-4.x BSP
* [#2503](https://github.com/apache/incubator-nuttx/pull/2503) Re-organise ESP32 boards and introduce two more(ESP-WROVER-KIT and the ESP32-Ethernet-Kit)
* [#2506](https://github.com/apache/incubator-nuttx/pull/2506) stm32: add stm32g43x support and nucleo-g431rb board
* [#2838](https://github.com/apache/incubator-nuttx/pull/2838) Add initial support for ESP32-C3 and ESP32-C3 DevKit board
* [#2877](https://github.com/apache/incubator-nuttx/pull/2877) Support for Raspberry Pi Pico
* [#3129](https://github.com/apache/incubator-nuttx/pull/3129) boards/stm32: add initial support for b-g431b-esc1 board
* [#3217](https://github.com/apache/incubator-nuttx/pull/3217) board: Add support for nucleo-h743i2
* [#3234](https://github.com/apache/incubator-nuttx/pull/3234) boards/stm32/common: add support for IHM07M1 and IHM08M1 boards

### Boards With Significant Improvements

#### ARM

#### BL602
* [#2764](https://github.com/apache/incubator-nuttx/pull/2764) boards: bl602evb flash and debug notes

#### C906
* [#3027](https://github.com/apache/incubator-nuttx/pull/3027) board:rv64:c906:support the ELF apps

#### CXD56
* [#1939](https://github.com/apache/incubator-nuttx/pull/1939) Add cxd56xx intstack for SMP
* [#3016](https://github.com/apache/incubator-nuttx/pull/3016) spresense:rndis_smp
* [#3024](https://github.com/apache/incubator-nuttx/pull/3024) Spesense CPU activity LED support
* [#3084](https://github.com/apache/incubator-nuttx/pull/3084) cxd56_gnss: Add missing include header for cxd56_gnss.c
* [#3085](https://github.com/apache/incubator-nuttx/pull/3085) cxd56_cpu1signal: Fix an issue that gnss does not work

#### ESP32
* [#2507](https://github.com/apache/incubator-nuttx/pull/2507) boards/arm/stm32: add common and stm32f103-minimum support for WS2812
* [#2753](https://github.com/apache/incubator-nuttx/pull/2753) esp32: Enable renew for "wapi" configs
* [#2864](https://github.com/apache/incubator-nuttx/pull/2864) Add wapi_smp to test Wi-Fi in SMP mode
* [#2883](https://github.com/apache/incubator-nuttx/pull/2883) This commit implements I2C support for ESP32 (wrover kit)
* [#2888](https://github.com/apache/incubator-nuttx/pull/2888) This commit enables BMP180 suport for ESP32
* [#2971](https://github.com/apache/incubator-nuttx/pull/2971) esp32: Add board config to support MCP2515
* [#3071](https://github.com/apache/incubator-nuttx/pull/3071) ESP32: Mount TMPFS on board bring up
* [#3095](https://github.com/apache/incubator-nuttx/pull/3095) ESP32: Allow a BSS section to reside in external memory
* [#3117](https://github.com/apache/incubator-nuttx/pull/3117) xtensa/esp32: Use Polling instead of DMA for transfers below threshold
* [#3139](https://github.com/apache/incubator-nuttx/pull/3139) xtensa/esp32: Support esp32 wireless ioctl cmd
* [#3154](https://github.com/apache/incubator-nuttx/pull/3154) ESP32: Add Button support via BOOT button on GPIO0
* [#3164](https://github.com/apache/incubator-nuttx/pull/3164) xtensa/esp32: Adds oneshot timer driver.
* [#3190](https://github.com/apache/incubator-nuttx/pull/3190) risc-v/esp32c3: Support ESP32-C3 wireless ioctl cmd
* [#3192](https://github.com/apache/incubator-nuttx/pull/3192) esp32-devkitc: Make nsh the entry-point of the ostest config
* [#3211](https://github.com/apache/incubator-nuttx/pull/3211) esp32-devkitc: Add GPIO board support
* [#3270](https://github.com/apache/incubator-nuttx/pull/3270) xtensa/esp32: Refactor register access functions on SPI driver
* [#3303](https://github.com/apache/incubator-nuttx/pull/3303) esp32-devkitc: Add BMP180 sensor support

#### ESP32C3
* [#2879](https://github.com/apache/incubator-nuttx/pull/2879) risc-v/esp32c3: Enable stdio buffering for esp32c3-devkit NSH config
* [#2897](https://github.com/apache/incubator-nuttx/pull/2897) boards/esp32c3: Add tmpfs mounting when bringing up
* [#3074](https://github.com/apache/incubator-nuttx/pull/3074) esp32c3-devkit: Use nx_mount to avoid overriding errno
* [#3261](https://github.com/apache/incubator-nuttx/pull/3261) esp32-c3: Add support to RNG peripheral

#### IMX6
* [#2997](https://github.com/apache/incubator-nuttx/pull/2997) boards: sabre-6quad: Add netnsh_smp configuration

#### IMXRT
* [#2004](https://github.com/apache/incubator-nuttx/pull/2004) FlexCAN driver for i.MX RT1060 MCU
* [#2526](https://github.com/apache/incubator-nuttx/pull/2526) boards/arm/imxrt/teensy-4.x: CDC-ACM console support
* [#2588](https://github.com/apache/incubator-nuttx/pull/2588) teensy-4.x Support for ST7789 controller

#### KINETIS
* [#1969](https://github.com/apache/incubator-nuttx/pull/1969) freedom-k64f: Init PWM only if enabled
* [#1977](https://github.com/apache/incubator-nuttx/pull/1977) freedom-k64f: Support raw binary firmware format
* [#1980](https://github.com/apache/incubator-nuttx/pull/1980) freedom-k64f: Add renew DHCP client for netnsh
* [#1982](https://github.com/apache/incubator-nuttx/pull/1982) freedom-k64f: Add I2C initial support
* [#1999](https://github.com/apache/incubator-nuttx/pull/1999) freedom-k64f: Register on board sensor driver
* [#2020](https://github.com/apache/incubator-nuttx/pull/2020) freedom-k64f: Declare k64_i2cdev_initialize function
* [#2030](https://github.com/apache/incubator-nuttx/pull/2030) freedom-k64f: Fix k64_buttons.c
* [#2037](https://github.com/apache/incubator-nuttx/pull/2037) freedom-k64f: Add demo configuration
* [#2047](https://github.com/apache/incubator-nuttx/pull/2047) freedom-k64f: Add I2C to demo image
* [#2847](https://github.com/apache/incubator-nuttx/pull/2847) board/freedom-k64f: Add usbdev support with cdcacm example

#### LPC17XX_40XX
* [#3239](https://github.com/apache/incubator-nuttx/pull/3239) board/arm/lpc17xx_40xx/mbed: Add userleds driver support

#### NRF52
* [#2706](https://github.com/apache/incubator-nuttx/pull/2706) board/nrf52-feather: Add simple i2c test configuration

#### RP2040
* [#2884](https://github.com/apache/incubator-nuttx/pull/2884) Update raspi-pico
* [#2894](https://github.com/apache/incubator-nuttx/pull/2894) boards: raspberrypi-pico: Add nshsram defconfig for SRAM build
* [#3014](https://github.com/apache/incubator-nuttx/pull/3014) BMP180 sensor support to RP2040
* [#3021](https://github.com/apache/incubator-nuttx/pull/3021) add INA219 support
* [#3030](https://github.com/apache/incubator-nuttx/pull/3030) boards/raspberrypi-pico: Support ENC28J60 SPI ethernet board
* [#3067](https://github.com/apache/incubator-nuttx/pull/3067) boards/raspberrypi-pico: Pico Display Pack (ST7789 LCD) support

#### SAM34
* [#2464](https://github.com/apache/incubator-nuttx/pull/2464) Added: MT29F2G Nand Flash block driver for sam4s-xplained-pro

#### STM32
* [#2433](https://github.com/apache/incubator-nuttx/pull/2433) Add 2.4 Inch TFT LCD Shield ILI9341 for nucleo-l152re, 8080 MCU 8-bit
* [#2505](https://github.com/apache/incubator-nuttx/pull/2505) boards/arm/stm32/stm32f103-minimum: cleanup
* [#3053](https://github.com/apache/incubator-nuttx/pull/3053) Nucleo-F446RE: added support for CAN driver
* [#3064](https://github.com/apache/incubator-nuttx/pull/3064) boards: refactor for nucleo-f446re and nucleo-f302r8 boards
* [#3097](https://github.com/apache/incubator-nuttx/pull/3097) Add configuration for testing the Sporadic Scheduler.
* [#3222](https://github.com/apache/incubator-nuttx/pull/3222) stm32/stm32_serial: add support for TX DMA and some improvements
* [#3223](https://github.com/apache/incubator-nuttx/pull/3223) stm32/stm32_pwm: add interfaces to access RCR register and TRGO
* [#3225](https://github.com/apache/incubator-nuttx/pull/3225) stm32/stm32_adc: various improvements for ADC
* [#3232](https://github.com/apache/incubator-nuttx/pull/3232) stm32/stm32_foc.c: add the lower-half FOC device support

#### STM32F4
* [#2553](https://github.com/apache/incubator-nuttx/pull/2553) boards: stm32f4discovery: Add adb configuration
* [#2699](https://github.com/apache/incubator-nuttx/pull/2699) boards/stm32f4discovery: Add a LWL board profile and improve the README.txt
* [#3052](https://github.com/apache/incubator-nuttx/pull/3052) Add support to LCD ST7789 on STM32F4Discovery
* [#3056](https://github.com/apache/incubator-nuttx/pull/3056) Add LCD1602 Backpack to common board

#### STM32F7
* [#3218](https://github.com/apache/incubator-nuttx/pull/3218) Integration of pysimCoder with NUTTX

#### STM32H7
* [#2353](https://github.com/apache/incubator-nuttx/pull/2353) Fix of the OTG FS HOST for nucleo-h743zi

#### STM32L4
* [#2009](https://github.com/apache/incubator-nuttx/pull/2842) Added STM32L432KC DAC support
* [#2837](https://github.com/apache/incubator-nuttx/pull/2837) Add missing I2C3 support on nucleo-l432kc board
* [#2842](https://github.com/apache/incubator-nuttx/pull/2842) board: nucleo-l432kc: Add missing i2c_master_s definition

#### TIVA
* [#2684](https://github.com/apache/incubator-nuttx/pull/2684) boards: lm3s6965-ek: Add iperf to discover/defconfig

#### XTENSA

### **Minor Board Changes**
* [#2558](https://github.com/apache/incubator-nuttx/pull/2558) boards: Remove CINCPATH and CXXINCPATH

#### ARM
* [#2079](https://github.com/apache/incubator-nuttx/pull/2079) Stm32 oled fixes pr
* [#2360](https://github.com/apache/incubator-nuttx/pull/2360) stm32/stm32ldiscovery: modernize board init little bit
* [#2500](https://github.com/apache/incubator-nuttx/pull/2500) stm32/common: devpath not long enough for apa102 and veml6070

#### CXD56
* [#2193](https://github.com/apache/incubator-nuttx/pull/2193) cxd56xx: Remove HOSTCC and HOSTCFLAGS from Make.defs

#### Xtensa
* [#2127](https://github.com/apache/incubator-nuttx/pull/2127) esp32: Added Userled support
* [#2802](https://github.com/apache/incubator-nuttx/pull/2802) ESP32: Refactor of POSTBUILD action
* [#3263](https://github.com/apache/incubator-nuttx/pull/3263) esp32: Move the WLAN initialisation to the common directory.
* [#3288](https://github.com/apache/incubator-nuttx/pull/3288) esp32-wrover-kit: Don't use User GPIO Subsystem to control LED
* [#3442](https://github.com/apache/incubator-nuttx/pull/3442) esp32 boards: BUTTON_BOOT should use PULLUP instead PULLDOWN

## File System

### Significant Improvements
* [#2598](https://github.com/apache/incubator-nuttx/pull/2598) fs/epoll: add asynchronous epoll control support
* [#2841](https://github.com/apache/incubator-nuttx/pull/2841) fs: procfs meminfo improvements
* [#2957](https://github.com/apache/incubator-nuttx/pull/2957) fs: mqueue: add poll support
* [#3045](https://github.com/apache/incubator-nuttx/pull/3045) fs: Allocate file/socket dynamically
* [#3212](https://github.com/apache/incubator-nuttx/pull/3212) fs/lfs: Update version to 2.4.0

### Bug Fixes
* [#2073](https://github.com/apache/incubator-nuttx/pull/2073) fs: epoll_create: modify return value for epoll_create1
* [#2260](https://github.com/apache/incubator-nuttx/pull/2260) fs: eventfd: remove the unique minor limit
* [#2317](https://github.com/apache/incubator-nuttx/pull/2317) fs: flashback to release all file descriptors in group to increase debugging time.
* [#2339](https://github.com/apache/incubator-nuttx/pull/2339) Revert "fs/nxffs: Fix scan good block slowly and scan an invalid block"
* [#2532](https://github.com/apache/incubator-nuttx/pull/2532) fs/unionfs: remove excessive protection to avoid deadlock
* [#2540](https://github.com/apache/incubator-nuttx/pull/2540) fs: Skip call fs_checkfd if fd < 3 in fs_fdopen
* [#2572](https://github.com/apache/incubator-nuttx/pull/2572) fs: spiffs fixes
* [#2606](https://github.com/apache/incubator-nuttx/pull/2606) fs: Fix inode lock at umount2
* [#2618](https://github.com/apache/incubator-nuttx/pull/2618) fs: remove INODE_IS_SPECIAL() use INODE_IS_PSEUDODIR instead
* [#2638](https://github.com/apache/incubator-nuttx/pull/2618) fs: fs_dupfd2 should return OK if fd1 equals fd2
* [#2639](https://github.com/apache/incubator-nuttx/pull/2639) fs: Let files_allocate return -EMFILE instead ERROR
* [#2640](https://github.com/apache/incubator-nuttx/pull/2640) fs: Remove _files_close and reuse file_close
* [#2643](https://github.com/apache/incubator-nuttx/pull/2643) fs: Fix the race condition in file_dup
* [#2648](https://github.com/apache/incubator-nuttx/pull/2648) fs: Remove the special hack for pty in nx_vopen
* [#2660](https://github.com/apache/incubator-nuttx/pull/2660) fs: Reimplement file_open to not depend on nx_open
* [#2661](https://github.com/apache/incubator-nuttx/pull/2661) fs: file_dup2 shouldn't hold the file list lock
* [#2662](https://github.com/apache/incubator-nuttx/pull/2662) fs/inode/fs_files.c: fix DEBUGASSERT in romfs
* [#2667](https://github.com/apache/incubator-nuttx/pull/2667) fs: Make nx_vxxx and file_vxxx as internal functions
* [#2724](https://github.com/apache/incubator-nuttx/pull/2724) fs/tmpfs: Iterate the entry reversely in readdir
* [#2739](https://github.com/apache/incubator-nuttx/pull/2739) fs/readdir: Must reserve a byte for the NUL terminator
* [#2810](https://github.com/apache/incubator-nuttx/pull/2810) fs: eventfd: Convert the indent under EVENT_FD_VFS_PATH option to tab
* [#2852](https://github.com/apache/incubator-nuttx/pull/2852) fs: Merge fs_poll into poll_fdsetup
* [#2854](https://github.com/apache/incubator-nuttx/pull/2854) fs: Don't call _NX_SETERRNO in fopen and fdopen
* [#2861](https://github.com/apache/incubator-nuttx/pull/2861) fs: change geometry sizes from size_t to uint32_t
* [#2913](https://github.com/apache/incubator-nuttx/pull/2913) fs/lfs: lfs_file_sync() when littlefs_open
* [#2956](https://github.com/apache/incubator-nuttx/pull/2956) fs/mount: fix mount cmd break out when meet stat error
* [#3042](https://github.com/apache/incubator-nuttx/pull/3042) fs: vfs : Do some adjustments for epoll
* [#3060](https://github.com/apache/incubator-nuttx/pull/3060) fs: find_blockdriver: Don't ferr() on MTDs
* [#3069](https://github.com/apache/incubator-nuttx/pull/3069) fs/mmap: Clarify MAP_PRIVATE dependency on CONFIG_FS_RAMMAP
* [#3070](https://github.com/apache/incubator-nuttx/pull/3070) fs/mmap: Return EACCES for incompatible file descriptors
* [#3105](https://github.com/apache/incubator-nuttx/pull/3105) fs/epoll: correct the return value of epoll_ctl(2)
* [#3137](https://github.com/apache/incubator-nuttx/pull/3137) fs/littlefs: Suppport the duplication function
* [#3444](https://github.com/apache/incubator-nuttx/pull/3444) fs/romfs: fix open zero-byte file fail issue
* [#3491](https://github.com/apache/incubator-nuttx/pull/3491) fs: vfs: adjust the error code of write to be consistent with read

## Networking

### Significant Improvements
* [#2414](https://github.com/apache/incubator-nuttx/pull/2414) net: tcp: implement the fast retransmit
* [#2415](https://github.com/apache/incubator-nuttx/pull/2415) net: gmp: add MULTICAST_TTL support
* [#2417](https://github.com/apache/incubator-nuttx/pull/2417) net: wireless: add country code control support
* [#2548](https://github.com/apache/incubator-nuttx/pull/2548) net: tcp: optimize TCP handshake performance
* [#2695](https://github.com/apache/incubator-nuttx/pull/2695) netpacket: if_addr: add interface address header
* [#2899](https://github.com/apache/incubator-nuttx/pull/2899) net: socket: Unify socket into file system to avoid the code duplication
* [#2964](https://github.com/apache/incubator-nuttx/pull/2964) net: socket_rpmsg: add socket rpmsg support
* [#3025](https://github.com/apache/incubator-nuttx/pull/3025) net: Add sendmsg and recvmsg to syscall list
* [#3081](https://github.com/apache/incubator-nuttx/pull/3081) tcp_send_buffered.c: improve tcp write buffering
* [#3113](https://github.com/apache/incubator-nuttx/pull/3113) net: usrsock: add send multi-elements support
* [#3257](https://github.com/apache/incubator-nuttx/pull/3257) net: tcp: support bind the same port with different domain

### Bug Fixes
* [#1589](https://github.com/apache/incubator-nuttx/pull/1589) net: tcp: fix tcp socket close timeout if loss wireless connection
* [#2075](https://github.com/apache/incubator-nuttx/pull/2075) net: TCP-stack fix for stalled tcp sockets due to broken keepalive
* [#2121](https://github.com/apache/incubator-nuttx/pull/2121) net: devif: devif_callback.c: remove harmful debug check
* [#2257](https://github.com/apache/incubator-nuttx/pull/2257) net: callback: remove the assert check of conn instance
* [#2332](https://github.com/apache/incubator-nuttx/pull/2332) net/tcp: Rectified keepalive fix
* [#2412](https://github.com/apache/incubator-nuttx/pull/2413) net/icmp: add sanity check to avoid wild data length
* [#2413](https://github.com/apache/incubator-nuttx/pull/2413) net/tcp: correct the available iobs count if throttle is enabled
* [#2416](https://github.com/apache/incubator-nuttx/pull/2416) net/tcp: fallback to unthrottle pool to avoid deadlock
* [#2421](https://github.com/apache/incubator-nuttx/pull/2421) net/neighbor/neighbor_ethernet_out.c: fix build error without ICMPv6
* [#2465](https://github.com/apache/incubator-nuttx/pull/2465) net/procfs: handle opendir("/proc/net/") correctly
* [#2466](https://github.com/apache/incubator-nuttx/pull/2466) net/igmp: add sanity check to handle allocate fail
* [#2467](https://github.com/apache/incubator-nuttx/pull/2467) net/sockopt: Try usrsock further if the protocol not available
* [#2489](https://github.com/apache/incubator-nuttx/pull/2489) net: tcp: send the ACK in time after obtain ahead buffer from iobs
* [#2688](https://github.com/apache/incubator-nuttx/pull/2688) net: Remove duplicate forward references
* [#2774](https://github.com/apache/incubator-nuttx/pull/2774) net/ip: do not drop the udp packet from IP layer
* [#2811](https://github.com/apache/incubator-nuttx/pull/2811) net/local: Add an option to specify the prefix of named pipe
* [#2869](https://github.com/apache/incubator-nuttx/pull/2869) netdb.h: Add NI_MAXHOST and NI_MAXSERV
* [#2911](https://github.com/apache/incubator-nuttx/pull/2911) net: fix a few DP83848C and DP83825I constants
* [#2959](https://github.com/apache/incubator-nuttx/pull/2959) net: socket: move si_send/recv into sendmsg/recvmsg
* [#2978](https://github.com/apache/incubator-nuttx/pull/2978) telnet: fix crash about telnet client connect
* [#3037](https://github.com/apache/incubator-nuttx/pull/3037) Revert "net: tcp: Add DEBUGASSERT() in psock_tcp_send()"
* [#3043](https://github.com/apache/incubator-nuttx/pull/3043) net: local: Remove local_send.c since nobody use it now
* [#3044](https://github.com/apache/incubator-nuttx/pull/3044) net: fix local_sendmsg return length
* [#3062](https://github.com/apache/incubator-nuttx/pull/3062) net: tcp_sendfile.c: Remove an unused copy of CONFIG_NET_TCP_SPLIT_SIZE
* [#3099](https://github.com/apache/incubator-nuttx/pull/3099) net: tcp: dup: do not start the tcp monitor if unestablished
* [#3100](https://github.com/apache/incubator-nuttx/pull/3100) net: tcp: correct the port byte order
* [#3101](https://github.com/apache/incubator-nuttx/pull/3101) net: arp: add timeout to avoid infinite send wait
* [#3103](https://github.com/apache/incubator-nuttx/pull/3103) net: tcp: reset the connection ref count before tcp_free()
* [#3104](https://github.com/apache/incubator-nuttx/pull/3104) net: dev: check the available address further
* [#3106](https://github.com/apache/incubator-nuttx/pull/3106) net: if: remove the macro expansion of the public structure
* [#3221](https://github.com/apache/incubator-nuttx/pull/3221) net: tcp: tcp_send_buffered.c: Fix non-blocking I/O
* [#3254](https://github.com/apache/incubator-nuttx/pull/3254) net: arp: Fix arp
* [#3319](https://github.com/apache/incubator-nuttx/pull/3319) tcp_netpoll.c: Fix a performance issue with CONFIG_NET_TCP_WRITE_BUFFERS

# Security Issues Fixed In This Release

# Compatibility Concerns

## Changes to Build System

### Change CFLAGS, CPPFLAGS, CXXFLAGS, and AFLAGS from Recursive to Simple Assignment

[PR-1890](https://github.com/apache/incubator-nuttx/pull/1890)
(commit [2caf3a69e3d60ec550980f7ba897c732e7a39df7](https://github.com/apache/incubator-nuttx/pull/1890/commits/2caf3a69e3d60ec550980f7ba897c732e7a39df7))
attempts to speed up compilation time for concurrent builds by changing
assignment to makefile variables `*CFLAGS*`, `*CPPFLAGS*`, `*CXXFLAGS*`, and
`*AFLAGS*` from recursive `=` to simple `:=`. This causes these compile
options to be expanded only once during the build.

If you are using NuttX on a custom board not in the NuttX repository, you may
want to make a similar change to your `Make.defs` files. Change these
recursive assignments:

```
CFLAGS = $(ARCHCFLAGS) $(ARCHWARNINGS) $(ARCHOPTIMIZATION) $(ARCHCPUFLAGS) $(ARCHINCLUDES) $(ARCHDEFINES) $(EXTRAFLAGS) -pipe
CXXFLAGS = $(ARCHCXXFLAGS) $(ARCHWARNINGSXX) $(ARCHOPTIMIZATION) $(ARCHCPUFLAGS) $(ARCHXXINCLUDES) $(ARCHDEFINES) $(EXTRAFLAGS) -pipe
CPPFLAGS = $(ARCHINCLUDES) $(ARCHDEFINES) $(EXTRAFLAGS)
AFLAGS = $(CFLAGS) -D__ASSEMBLY__
```

to simple assignments:

```
CFLAGS := $(ARCHCFLAGS) $(ARCHWARNINGS) $(ARCHOPTIMIZATION) $(ARCHCPUFLAGS) $(ARCHINCLUDES) $(ARCHDEFINES) $(EXTRAFLAGS) -pipe
CXXFLAGS := $(ARCHCXXFLAGS) $(ARCHWARNINGSXX) $(ARCHOPTIMIZATION) $(ARCHCPUFLAGS) $(ARCHXXINCLUDES) $(ARCHDEFINES) $(EXTRAFLAGS) -pipe
CPPFLAGS := $(ARCHINCLUDES) $(ARCHDEFINES) $(EXTRAFLAGS)
AFLAGS := $(CFLAGS) -D__ASSEMBLY__
```

### Not Necessary to Define `__NuttX__` in Make.defs

[PR-2192](https://github.com/apache/incubator-nuttx/pull/2192)
(commit [9208176f600d0d04446531909bf05710716a5ee4](https://github.com/apache/incubator-nuttx/commit/9208176f600d0d04446531909bf05710716a5ee4))
refactors definition of the `__NuttX__` preprocessor symbol to
`tools/Config.mk`, so it is no longer necessary to define it in each board's
`Make.defs` file.

If you are using NuttX on a custom board not in the NuttX repository, you may
want to make a similar change to your Make.defs files.

Remove lines like this:

```
ARCHDEFINES = -D__NuttX__
```

Or remove -D__NuttX__ from lines like this:

```
CXXFLAGS += $(ARCHDEFINES) $(EXTRAFLAGS) -pipe -std=c++11 -D__NuttX__
```