Apache NuttX is a mature, real-time embedded operating system (RTOS) https://nuttx.apache.org/
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zhekunren c8f6c8b72d net/tcp/tcp_send: Remove work_available check when updating retransmit timer
The condition work_available(&conn->work) && tx_unacked != 0
prevented tcp_update_retrantimer from being called when the work
queue was still busy, leaving conn->timer stale or zero on
subsequent sends. This caused the RTT estimation to compute a
false RTT (m = rto - 0 = rto), creating a positive feedback loop
that inflated the RTO to extreme values (e.g., 232 half-seconds
= ~116 seconds).

Fix: remove the work_available check so that tcp_update_retrantimer
is always called when there is unacknowledged data. The decision to
re-queue the work is handled internally by tcp_update_timer.

Signed-off-by: zhekunren <zhekunren@qq.com>
2026-08-05 10:56:59 +02:00
.github ci: Build the documentation from its lock file. 2026-08-04 17:28:41 -03:00
arch arch/risc-v: add LDO source for Espressif devices 2026-08-04 23:31:56 +08:00
audio audio: limit the buffer count guard to shared ring requests 2026-08-05 07:58:53 +02:00
binfmt fs/binfmt: close symlink TOCTOU and harden setuid/setgid exec hygiene 2026-08-01 15:32:03 -03:00
boards boards/arm/stm32h7/linum-stm32h753bi: add an nxdoom configuration 2026-08-04 10:30:04 +08:00
cmake cmake: Omit default priority ELF symbol. 2026-07-27 14:30:42 +08:00
crypto tools: fix stale archive members surviving a Kconfig-driven CSRCS change 2026-07-28 21:26:03 -03:00
Documentation Documentation/audio: document the audio upper half interface 2026-08-05 07:58:53 +02:00
drivers drivers/sensors/mpu6050: deliver samples from the data ready interrupt 2026-08-04 17:40:28 -03:00
dummy build: add initial cmake build system 2023-07-08 13:50:48 +08:00
fs fs: enforce path search and unify inode permission helpers 2026-08-02 18:48:40 -03:00
graphics tools: fix stale archive members surviving a Kconfig-driven CSRCS change 2026-07-28 21:26:03 -03:00
include video/rgbcolors: Fix RGBTO8 to use the high bits of each component. 2026-08-04 21:17:48 -03:00
libs libc/dlfcn: Count opens so a library can be shared. 2026-08-04 11:12:49 -03:00
mm mm/ubsan: fix signed inline value decoding 2026-07-30 12:52:17 +02:00
net net/tcp/tcp_send: Remove work_available check when updating retransmit timer 2026-08-05 10:56:59 +02:00
openamp tools: fix stale archive members surviving a Kconfig-driven CSRCS change 2026-07-28 21:26:03 -03:00
pass1 tools: fix stale archive members surviving a Kconfig-driven CSRCS change 2026-07-28 21:26:03 -03:00
sched sched/semaphore: Clear mutex blocking bit after timeout 2026-08-04 11:14:33 -03:00
syscall sched/group: add getresuid, getresgid, setreuid, and setregid 2026-07-30 09:48:10 +08:00
tools arch/arm/rtl8721f: bring up minimal NSH (P1) 2026-07-30 17:04:14 +08:00
video tools: fix stale archive members surviving a Kconfig-driven CSRCS change 2026-07-28 21:26:03 -03:00
wireless tools: fix stale archive members surviving a Kconfig-driven CSRCS change 2026-07-28 21:26:03 -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 feat: add a GitHub action to lint the YAML files 2020-12-15 09:52:04 -06:00
AUTHORS AUTHORS: add Eren Terzioglu 2026-05-20 15:17:00 +08:00
CMakeLists.txt cmake: Do not link an executable to detect the compiler. 2026-07-25 22:52:39 +08:00
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 Remove the double blank line from source files 2022-02-20 20:10:14 +01:00
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.