Apache NuttX is a mature, real-time embedded operating system (RTOS) https://nuttx.apache.org/
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Jacob Dahl 58181135ab arch/arm/src/imxrt: Fix FlexCAN TX timeout aborting live mailboxes.
imxrt_txtimeout_work() had four defects that together let one expired frame
take the interface down permanently.

It aborted mailbox RXMBCOUNT + mbi while the deadline it consulted belongs to
RXMBCOUNT + 1 + mbi, so every abort landed one mailbox low and mbi == 0 wrote
CAN_TXMB_ABORT into the buffer reserved for the ERR005829 workaround, while
the highest TX mailbox was never aborted at all.

Its expiry test read `now.tv_sec > d.tv_sec || now.tv_usec > d.tv_usec`, which
declares any deadline that crosses a second boundary expired: in that case the
deadline's microsecond field is always the smaller of the two. The `now` it
compared against was a struct timespec cast to a struct timeval, so writing
tv_usec wrote over tv_nsec and tv_sec was whatever the cast happened to line
up with.

imxrt_txdone() cancelled the watchdog but left txmb[].deadline set, so a
retired mailbox looked expired forever and the next watchdog expiry on any
other mailbox aborted whatever frame had since been loaded there.

The walk ran to TXMBCOUNT, which counts the reserved mailbox as well, so its
last iteration addressed mailbox TOTALMBCOUNT - one past the ring, and
mb_address[] one past its end. Only txmb[] never being written that far kept
it in bounds. TXMBRINGSIZE now names the ring size that the rest of the driver
already assumes.

Aborting a frame that is already on the wire raises a bit error, so the
transmit error counter climbs and the node goes error passive. Since
imxrt_txmb_next() only hands out a mailbox above every pending one, a mailbox
left in DATAORREMOTE also pins the allocator at TOTALMBCOUNT and transmit
never recovers.

Measured on an ARK FMU-v6XRT with a DroneCAN GNSS node on the bus, offering
736 frames/s (9% of a 1 Mbit/s bus) from the PX4 uavcan driver: before, the
interface transmitted 0 frames/s with ECR[TXERRCNT] pinned at 128 and
ESR1[FLTCONF] error passive, and stayed dead across a reboot. After, 734
frames/s, 0.1% loss, TXERRCNT 0, error active.

Assisted-by: Claude:claude-opus-5
Signed-off-by: Jacob Dahl <dahl.jakejacob@gmail.com>
2026-08-27 01:04:57 +08:00
.github build(deps): bump docker/setup-buildx-action from 4.2.0 to 4.3.0 2026-08-24 15:30:16 +08:00
arch arch/arm/src/imxrt: Fix FlexCAN TX timeout aborting live mailboxes. 2026-08-27 01:04:57 +08:00
audio audio: limit the buffer count guard to shared ring requests 2026-08-05 07:58:53 +02:00
binfmt sched: add supplementary group IDs (setgroups/getgroups/initgroups) 2026-08-12 16:06:03 -03:00
boards boards: fix lvglterm defconfig 2026-08-26 17:25:34 +08:00
cmake sched,fs,docs: support setuid sudo helper 2026-08-18 15:57:52 +08:00
crypto tools: fix stale archive members surviving a Kconfig-driven CSRCS change 2026-07-28 21:26:03 -03:00
Documentation include/nuttx: Add link-time iterable sections infrastructure 2026-08-27 01:04:05 +08:00
drivers drivers/serial: correct the USART9 console label 2026-08-27 01:01:51 +08:00
dummy build: add initial cmake build system 2023-07-08 13:50:48 +08:00
fs nuttx/atomic: replace atomic_fetch_xxx with atomic_xxx just like zephyr 2026-08-24 13:20:45 +08:00
graphics graphics/nxterm: consume SGR escape sequences 2026-08-23 10:46:02 +08:00
include include/nuttx: Add link-time iterable sections infrastructure 2026-08-27 01:04:05 +08:00
libs arch/tricore: drop illd dependence for atomic 2026-08-25 10:07:25 +08:00
mm cmake: Use NUTTX(_DIR/_BIN_DIR) instead CMAKE(_SRC_DIR/_BIN_DIR) 2026-08-09 11:13:08 -03:00
net net/local: fix SCM_RIGHTS pointer and memory corruption 2026-08-21 02:19:10 +08:00
openamp cmake: Use NUTTX(_DIR/_BIN_DIR) instead CMAKE(_SRC_DIR/_BIN_DIR) 2026-08-09 11:13:08 -03:00
pass1 tools: fix stale archive members surviving a Kconfig-driven CSRCS change 2026-07-28 21:26:03 -03:00
sched nuttx/atomic: replace atomic_fetch_xxx with atomic_xxx just like zephyr 2026-08-24 13:20:45 +08:00
syscall sched: add supplementary group IDs (setgroups/getgroups/initgroups) 2026-08-12 16:06:03 -03:00
tools include/nuttx: Add link-time iterable sections infrastructure 2026-08-27 01:04:05 +08:00
video tools: fix stale archive members surviving a Kconfig-driven CSRCS change 2026-07-28 21:26:03 -03:00
wireless nuttx/atomic: replace atomic_fetch_xxx with atomic_xxx just like zephyr 2026-08-24 13:20:45 +08:00
.asf.yaml github: master branch protection tune. 2025-05-07 18:37:13 -05:00
.codespell-ignore-lines arch/arm: Reserve r10 via ARCHCFLAGS and hoist the PIC module flags. 2026-07-24 23:09:08 +08:00
.codespellrc arch/arm/rp23xx: Add hardware TRNG driver for /dev/random. 2026-07-25 15:06:56 +08:00
.editorconfig .editorconfig: fix character encoding property specification 2025-11-28 19:12:13 +08:00
.gitignore boards/risc-v/eic7700x: Adopt the common board layout. 2026-08-19 01:40:57 +08:00
.gitmessage docs/contributing: Add a commit message template 2025-06-03 17:33:24 +08:00
.pre-commit-config.yaml pre-commit: enable codespell checks 2025-05-05 12:34:39 +08:00
.yamllint
AUTHORS AUTHORS: add Jorge Guzman 2026-08-25 08:43:13 -04:00
CMakeLists.txt include/nuttx: Add link-time iterable sections infrastructure 2026-08-27 01:04:05 +08:00
CONTRIBUTING.md contributing: Add requirement for 'Assisted-by' commit field 2026-07-12 09:42:28 +08:00
INVIOLABLES.md
Kconfig include/nuttx: Add link-time iterable sections infrastructure 2026-08-27 01:04:05 +08:00
LICENSE libs/libdsp: Add Matrix operations 2026-07-11 14:55:59 -03:00
Makefile !boards: enforce secure ROMFS passwd and TEA key setup 2026-07-09 22:41:11 +08:00
NOTICE
README.md ci/testing: Add MemBrowse Integration 2026-06-18 12:07:41 -03:00
ReleaseNotes Documentation: move ReleaseNotes 2023-09-26 20:41:00 +08:00

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Apache NuttX is a real-time operating system (RTOS) with an emphasis on standards compliance and small footprint. Scalable from 8-bit to 64-bit microcontroller environments, the primary governing standards in NuttX are POSIX and ANSI standards. Additional standard APIs from Unix and other common RTOSs (such as VxWorks) are adopted for functionality not available under these standards, or for functionality that is not appropriate for deeply-embedded environments (such as fork()).

For brevity, many parts of the documentation will refer to Apache NuttX as simply NuttX.

Getting Started

First time on NuttX? Read the Getting Started guide! If you don't have a board available, NuttX has its own simulator that you can run on terminal.

Documentation

You can find the current NuttX documentation on the Documentation Page.

Alternatively, you can build the documentation yourself by following the Documentation Build Instructions.

The old NuttX documentation is still available in the Apache wiki.

Supported Boards

NuttX supports a wide variety of platforms. See the full list on the Supported Platforms page.

Contributing

If you wish to contribute to the NuttX project, read the Contributing guidelines for information on Git usage, coding standard, workflow and the NuttX principles.

License

The code in this repository is under either the Apache 2 license, or a license compatible with the Apache 2 license. See the License Page for more information.