layout: page released: true apache: false title: 7.31 date: 2019-07-27 summary: > Release v7.31

artifact-root: “https://bitbucket.org/nuttx/nuttx/downloads/” checksum-root: "" key-file: ""

source-os-dist: - “nuttx-7.31.tar.gz” source-app-dist: - “apps-7.31.tar.gz”


{% include JB/setup %}

NuttX-7.31 Release Notes

The 131st release of NuttX, Version 7.31, was made on July 22, 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 busses 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 segements.
    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 failues 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.