Apache NuttX is a mature, real-time embedded operating system (RTOS) https://nuttx.apache.org/
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Marco Casaroli aae62ceaae !Documentation: Describe the fork()/vfork() split.
Documentation/guides/fork_vfork_migration.rst is new.  It says what changed
and why, gives the two primitives as a table, states plainly what breaks, and
answers "which replacement do I want?" from the reader's own reason for having
called fork() -- posix_spawn() or vfork() to run a program, pthread_create()
for a second flow of control that shares memory, fork() itself for an
independent copy.  It also documents the two configuration symbols, what an
architecture has to implement to gain real fork(), and the one visible
consequence of moving the vfork() suspension into the kernel: a waitpid()
after a child that _exit()s can only report status where
CONFIG_SCHED_CHILD_STATUS is enabled.

reference/user/01_task_control.rst gains an entry for fork() and rewrites the
one for vfork(), which described NuttX's limitations rather than the
interface's contract.  standards/posix.rst moves fork() from "No" to "Cond."
and vfork() from "Yes" to "Cond.", both being conditional on the configuration
now.  implementation/memory_configurations.rst no longer lists fork() as
unimplementable in the presence of address environments, which was the whole
point of that section's wish list.  Three long-standing typos in that file are
corrected while touching it, since codespell checks the whole of any file a
patch modifies.

BREAKING CHANGE: this commit carries no code; it is the migration guide for
the fork() withdrawal in the commit before it, and is marked so that every
commit in the series carries the marker CONTRIBUTING.md 1.13 requires.  The
quick fixes are in Documentation/guides/fork_vfork_migration.rst.

Assisted-by: Claude Code:claude-opus-5
Signed-off-by: Marco Casaroli <marco.casaroli@gmail.com>
2026-08-10 08:57:30 -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 !sched/arch/libc: Give fork() and vfork() their real, separate semantics. 2026-08-10 08:57:30 -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 cmake: Use NUTTX(_DIR/_BIN_DIR) instead CMAKE(_SRC_DIR/_BIN_DIR) 2026-08-09 11:13:08 -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 !Documentation: Describe the fork()/vfork() split. 2026-08-10 08:57:30 -03:00
drivers cmake: Use NUTTX(_DIR/_BIN_DIR) instead CMAKE(_SRC_DIR/_BIN_DIR) 2026-08-09 11:13:08 -03:00
dummy
fs cmake: Use NUTTX(_DIR/_BIN_DIR) instead CMAKE(_SRC_DIR/_BIN_DIR) 2026-08-09 11:13:08 -03:00
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 !sched/arch/libc: Give fork() and vfork() their real, separate semantics. 2026-08-10 08:57:30 -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 pre-commit: enable codespell checks 2025-05-05 12:34:39 +08:00
.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 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.