Apache NuttX is a mature, real-time embedded operating system (RTOS) https://nuttx.apache.org/
Find a file
Justin Hammond 432ef71ed7 drivers/usbhost: Describe devices to an xHCI controller correctly.
What a controller is told about a device before it will accept it.  A DWC3
core validates these where QEMU's controller does not.

- HCCPARAMS1 says whether context structures are 32 or 64 bytes, and the
  wider form was refused outright with -EIO; the EIC7700X reports
  0x0220fe45 on both of its controllers, so this driver could not have
  driven either.  A wide context is the same fields with reserved space
  after them, so only the stride changes.  Read it at start up and use it
  wherever a context array is walked.
- Contexts must be 64 byte aligned, since every device context base
  address array entry points at one, and the output context came from
  kmm_zalloc().
- The slot context never carried the device speed, which has no valid
  zero, so a validating controller answers Address Device with a parameter
  error.  The speed was already implied by the endpoint context's maximum
  packet size.  The numbering is xHCI's own, hence the mapping.
- The output device context was cleared and never flushed.  That context
  is the controller's to write, so what stays behind is a dirty line of
  zeros written back over the slot state, and the next command against the
  slot is refused with a context state error.  Enumeration reached
  SET_ADDRESS and stopped.
- A buffer copied through an aligned stand-in was copied back using buflen,
  which control transfers deliberately leave zero, so a descriptor read
  copied nothing back and the caller was handed whatever its buffer held
  before.  Keep the requested length separately, and maintain the cache
  over the whole stand-in rather than the part in use.
- A buffer the controller cannot reach is now copied through a stand-in
  rather than refused.  -EFAULT works for a caller with somewhere better
  to put the data, and fails outright for one without: reading a block
  device directly from a user program returned an error where the transfer
  could have gone through a stand-in.

Assisted-by: Claude:claude-opus-5
Signed-off-by: Justin Hammond <justin@dynam.ac>
2026-09-20 22:28:07 +08:00
.github ci: apply Depends-On dependencies to the memory report 2026-09-15 08:47:25 -03:00
arch arch/arm/stm32: implement PTP hardware clock driver (/dev/ptp0) 2026-09-19 18:32:45 -03:00
audio audio: limit the buffer count guard to shared ring requests 2026-08-05 07:58:53 +02:00
binfmt libs/libc/elf, binfmt: Describe the GOT by base and size, not by index. 2026-09-08 16:31:16 -03:00
boards boards: stm32g4: regenerate nucleo-g431kb comp defconfig 2026-09-19 22:41:17 +08:00
cmake cmake: fix undefined function name in parse args error messages 2026-09-11 21:15:22 +08:00
crypto crypto: fix chacha constants under GCC 15. 2026-09-20 08:22:11 -03:00
Documentation docs: document chroot jail root 2026-09-20 22:27:38 +08:00
drivers drivers/usbhost: Describe devices to an xHCI controller correctly. 2026-09-20 22:28:07 +08:00
dummy
fs docs: document chroot jail root 2026-09-20 22:27:38 +08:00
graphics graphics/nxterm: consume SGR escape sequences 2026-08-23 10:46:02 +08:00
include drivers/usbhost: Maintain the cache over xHCI data buffers. 2026-09-20 22:28:07 +08:00
libs libc/atexit: honor registrations made during exit processing 2026-09-14 18:52:46 -03:00
mm mm/iob: fix CONFIG_NET_TIMESTAMPING typo in iob_alloc 2026-09-19 16:36:47 -03:00
net net/pkt: remove unused variable conn in append_timestamping 2026-09-19 18:32:45 -03:00
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: add per-group filesystem jail root 2026-09-20 22:27:38 +08:00
syscall fs: add chroot() syscall 2026-09-20 22:27:38 +08:00
tools tools/imxrt1180: Add a standalone C program for simple AHAB container creation 2026-09-19 22:38:45 +08:00
video video/videomode: Fix EDID parsing and formatting of video mode dumps 2026-08-29 11:09:11 -03:00
wireless wireless/bluetooth: Validate lengths when parsing advertising reports. 2026-09-19 18:30:43 -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 Revert "zbus: Add linker support and documentation for the zbus port" 2026-08-30 10:45:19 -03:00
.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 cmake: reconfigure when .config changes 2026-09-14 18:40:45 -03:00
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

POSIX Badge License Issues Tracking Badge Contributors GitHub Build Badge Documentation Badge MemBrowse

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.