Apache NuttX is a mature, real-time embedded operating system (RTOS) https://nuttx.apache.org/
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Marco Casaroli 8f69f27b4d boards/esp32-devkitc: Let ostest finish on the knsh configuration.
A full ostest run never reached the end on esp32-devkitc:knsh.  It stopped in
the barrier test:

  barrier_test: ERROR thread 6 create, status=12
  ostest_main: Exiting with status 256

The cause is the interaction of two settings that are each reasonable on their
own.  CONFIG_TLS_ALIGNED is set and CONFIG_TLS_LOG2_MAXSTACK is 13, so every
pthread stack must start on an 8 KiB boundary.  The barrier threads take the
2 KiB default stack, so each one occupies an 8 KiB aligned slot.  Eight of them
do not fit the 96 KiB user heap of a protected build once the tests before them
have fragmented it, and up_create_stack() fails:

  up_create_stack: ERROR: Failed to allocate stack, size 2048

The flat build has the same two settings and passes, because its heap is
320 KiB against 96 KiB here.

So this lowers the barrier thread count for this configuration only.  Four
threads still test a barrier, and they leave margin:  six was the most that
ever started, so six would pass with none.

The user heap cannot grow far.  User data has to sit in the MMU governed window
of SRAM2, which is 128 KiB in total, and the kernel holds the first 32 KiB of
it.

Verified on an ESP32-DevKitC V4, ESP32-D0WD-V3 revision 3.1.  All four threads
reach the barrier and ostest reports "Exiting with status 0".

Assisted-by: Claude Opus 5 (1M context) <noreply@anthropic.com>
Signed-off-by: Marco Casaroli <marco.casaroli@gmail.com>
2026-08-11 09:52:16 -03:00
.github build(deps): bump docker/login-action from 4.5.1 to 4.6.0 2026-08-05 12:38:32 +02:00
arch arch/mips: Add support for loadable ELF modules 2026-08-11 09:46:46 -03:00
audio audio: limit the buffer count guard to shared ring requests 2026-08-05 07:58:53 +02:00
binfmt cmake: Use NUTTX(_DIR/_BIN_DIR) instead CMAKE(_SRC_DIR/_BIN_DIR) 2026-08-09 11:13:08 -03:00
boards boards/esp32-devkitc: Let ostest finish on the knsh configuration. 2026-08-11 09:52:16 -03:00
cmake cmake: Use NUTTX(_DIR/_BIN_DIR) instead CMAKE(_SRC_DIR/_BIN_DIR) 2026-08-09 11:13:08 -03:00
crypto tools: fix stale archive members surviving a Kconfig-driven CSRCS change 2026-07-28 21:26:03 -03:00
Documentation boards/arm/stm32l4/b-l475e-iot01a: Add a QEMU nsh configuration. 2026-08-10 22:46:31 +08:00
drivers cmake: Use NUTTX(_DIR/_BIN_DIR) instead CMAKE(_SRC_DIR/_BIN_DIR) 2026-08-09 11:13:08 -03:00
dummy
fs fs/romfs: fix node cache overflow in directories with >256 entries 2026-08-11 10:53:19 +08:00
graphics tools: fix stale archive members surviving a Kconfig-driven CSRCS change 2026-07-28 21:26:03 -03:00
include !sched/arch/libc: Give fork() and vfork() their real, separate semantics. 2026-08-10 08:57:30 -03:00
libs arch/mips: Add support for loadable ELF modules 2026-08-11 09:46:46 -03:00
mm cmake: Use NUTTX(_DIR/_BIN_DIR) instead CMAKE(_SRC_DIR/_BIN_DIR) 2026-08-09 11:13:08 -03:00
net net/igmp: fix checksum validation that always dropped valid IGMP packets 2026-08-07 16:36:42 +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 !sched/arch/libc: Give fork() and vfork() their real, separate semantics. 2026-08-10 08:57:30 -03:00
syscall !sched/arch/libc: Give fork() and vfork() their real, separate semantics. 2026-08-10 08:57:30 -03:00
tools cmake: Use NUTTX(_DIR/_BIN_DIR) instead CMAKE(_SRC_DIR/_BIN_DIR) 2026-08-09 11:13:08 -03:00
video tools: fix stale archive members surviving a Kconfig-driven CSRCS change 2026-07-28 21:26:03 -03:00
wireless cmake: Use NUTTX(_DIR/_BIN_DIR) instead CMAKE(_SRC_DIR/_BIN_DIR) 2026-08-09 11:13:08 -03:00
.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 git: Specify multiple build directories in .gitignore. 2026-05-20 03:06:58 +08:00
.gitmessage docs/contributing: Add a commit message template 2025-06-03 17:33:24 +08:00
.pre-commit-config.yaml
.yamllint
AUTHORS AUTHORS: add Eren Terzioglu 2026-05-20 15:17:00 +08:00
CMakeLists.txt cmake: Use NUTTX(_DIR/_BIN_DIR) instead CMAKE(_SRC_DIR/_BIN_DIR) 2026-08-09 11:13:08 -03:00
CONTRIBUTING.md contributing: Add requirement for 'Assisted-by' commit field 2026-07-12 09:42:28 +08:00
INVIOLABLES.md
Kconfig sched/misc/assert: Add CONFIG_SCHED_DUMP_TASKS and CONFIG_SCHED_DUMP_STACK 2026-06-09 08:04:54 -04:00
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

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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.