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Phase 1: build the NuttX runtime against NuttX 12 headers with GCC 15 - #2

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NevynUK merged 5 commits into
MergeManagedCodefrom
Phase1
Oct 14, 2026
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Phase 1: build the NuttX runtime against NuttX 12 headers with GCC 15#2
NevynUK merged 5 commits into
MergeManagedCodefrom
Phase1

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@NevynUK NevynUK commented Oct 14, 2026

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Part of bringing the Mono runtime into the NuttX 12-based Meadow.OS (Meadow.OS MergeManagedCode, phase 1). The NuttX target was written against Meadow's old NuttX 7 headers. This makes it build cleanly against NuttX 12.12 with arm-none-eabi-gcc 15.3, keeping the existing -Wno-error=incompatible-pointer-types for HOST_NUTTX as decided.

This branch starts from meadow-3.0 (f980b4c), which is left untouched because Legacy builds it by name.

Commits

  1. Fix type mismatches exposed by NuttX 12 headers; drop the sys/random.h override. NuttX 12 makes int32_t long int (from __INT32_TYPE__), so five definitions written with int no longer matched their gint32/gboolean/int32_t declarations. GCC 14+ makes those hard errors; each definition now matches its declaration. The h_errno static asserts are skipped on NuttX: NuttX numbers those codes differently, and GetHostErrorCodes is never returned to managed code. The getrandom override no longer compiled because NuttX 12 has the POSIX three-argument call.
  2. Retire the NuttX 7 header workarounds.
    • Removed the errno override and -DO_CLOEXEC=0.
    • Cut nuttx-compat.h down to what NuttX 12 still lacks.
    • Fixed a latent bug: the fallback IFF_ALLMULTI (1 << 8) was NuttX's IFF_NAT.
    • pal_config.h now enables O_CLOEXEC, pipe2, chmod, aligned_alloc, pthread_condattr_setclock, utimensat and timespec stat times. Each was checked against the NuttX 12 headers and user-space libraries.
  3. Sentinel handle for dlopen(NULL). NuttX faults on a NULL file name. This replaces the NuttX libc patch the old firmware carried.
  4. Real-time signals SIGRTMIN + 1/2/3 for suspend, restart and abort, instead of 20/21/22, which are SIGTSTP/SIGTTIN/SIGTTOU on NuttX 12. Suspend stays cooperative.
  5. MONO_BUILD_DIR option in build-nuttx.sh, and a prototype for nxsock_close_notify.

Tested

  • Clean Release and Debug builds, 358/358 targets, via Meadow.OS build-mono.sh against the NuttX 12.12 headers. All the archives the OS link needs are produced.
  • All 86 remaining incompatible-pointer-types warnings were reviewed. Each is 32-bit int/long aliasing, which is harmless on ARM.
  • No hardware test: nothing is linked into the OS yet (agreed for phase 1).

Merge this before the Meadow.OS phase 1 PR. Meadow.OS's MONO_RUNTIME_COMMIT will then be moved to the merge commit.

🤖 Generated with Claude Code

NevynUK and others added 5 commits October 14, 2026 14:56
@NevynUK @claude
nuttx: fix type mismatches exposed by NuttX 12 headers; drop sys/rand…
05460ac 
…om.h override

NuttX 12 takes int32_t from the compiler's __INT32_TYPE__, which is
'long int' for arm-none-eabi GCC, where the old NuttX 7 headers used
'int'.  gint32 and gboolean follow int32_t, so definitions written with
'int' no longer match prototypes written with gint32/gboolean/int32_t.
GCC 14 and later report these as hard errors (conflicting types).

Make each definition match its declaration:
- sgen_client_binary_protocol_sweep_begin/end: full_sweep is gboolean,
  as declared by sgen-protocol-def.h.
- ves_icall_RuntimeType_GetFunctionPointerTypeModifiers: position is
  gint32, as declared in icall-def.h.
- mono_regression_test_step: returns int, as declared by the public
  MONO_API prototype in mini-runtime.h.
- SystemNative_Select: maxFd is int32_t, as declared in pal_networking.h.

NuttX also numbers the h_errno codes differently (NO_DATA 2, TRY_AGAIN
4).  The static asserts that require them to match GetHostErrorCodes are
skipped on NuttX; GetHostErrorCodes values are never returned to managed
code, which receives resolver errors through the EAI_* conversion.

Remove the sys/random.h override.  It wrapped NuttX 7's two-argument
void getrandom() in a POSIX-style function; NuttX 12 declares the POSIX
ssize_t getrandom(void *, size_t, unsigned int) itself, so the wrapper's
two-argument call no longer compiles.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
@NevynUK @claude
nuttx: retire the NuttX 7 header workarounds
c7dd57f 
The NuttX/Cortex-M7 target was first written against Meadow's NuttX 7
headers.  Meadow.OS now builds against NuttX 12, which provides most of
what those workarounds supplied, and some of the workarounds are wrong
there.

- Remove the errno.h override.  NuttX 12 already defines errno as
  (*__errno()), a per-thread lvalue in user space; the override also
  redirected set_errno() to a firmware helper that is no longer used.
- Stop passing -DO_CLOEXEC=0; NuttX 12 supports O_CLOEXEC.
- Reduce nuttx-compat.h to what NuttX 12 still lacks: the INT32_C family
  (now taken from the compiler, so they match __INT32_TYPE__), the dlmalloc
  mallinfo and page-size settings, _POSIX_HOST_NAME_MAX and IFF_ALLMULTI.
  The declarations of realpath, readlink, lstat, mkdtemp, posix_memalign,
  srand48/lrand48 and the math helpers are dropped, as are the SA_RESTART,
  _POSIX_VERSION and stale CONFIG_C99_BOOL8 definitions.  IFF_ALLMULTI is
  now 0: the old Linux value (1 << 8) is IFF_NAT on NuttX, so interfaces
  with NAT enabled were being reported as multicast-capable.  The other
  IFF_* fallbacks are removed; NuttX numbers those flags differently.
- Set HAVE_MKDTEMP for NuttX in configure.cmake instead of forcing it in
  the compat header.
- pal_config.h: NuttX 12 has F_DUPFD_CLOEXEC, O_CLOEXEC, pipe2, chmod,
  fchmod, aligned_alloc, pthread_condattr_setclock, utimensat, futimens,
  <sys/poll.h> and timespec st_atim/st_mtim/st_ctim.  Enable them and
  correct the comments that described NuttX 7.
- Correct the toolchain file's note on int32_t: NuttX 12 takes it from
  __INT32_TYPE__ ('long int' with arm-none-eabi GCC), so 'int *' and
  'int32_t *' mixes are -Wincompatible-pointer-types warnings (downgraded
  from errors in CMakeLists.txt for HOST_NUTTX).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
@NevynUK @claude
nuttx: use a sentinel handle for dlopen(NULL)
535eae3 
mono_dl_open (NULL, ...) asks for a handle on the main program, which
reaches dlopen (NULL, flags) through mono_dl_open_file ().  NuttX's
dlopen () does not accept NULL: it duplicates the file name, which faults
on NULL.

On NuttX return a static sentinel for a NULL file name.  Symbol lookups
through it return NULL and closing it does nothing, which matches a
statically linked image with no exported dynamic symbol table; P/Invokes
are resolved by the host's PINVOKE_OVERRIDE callback.  This replaces the
patch to NuttX's lib_dlopen.c that the NuttX 7 firmware carried.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
@NevynUK @claude
nuttx: use real-time signals for thread suspend, restart and abort
ae2e81b 
The NuttX 7 firmware only had signals 0-31, so the suspend, restart and
abort signals were fixed at 20, 21 and 22.  NuttX 12 supports signals up
to 63, reserves no real-time signals, and numbers 20-22 as SIGTSTP,
SIGTTIN and SIGTTOU.

Use SIGRTMIN + 1 (suspend), SIGRTMIN + 2 (restart) and SIGRTMIN + 3
(abort).  They stay fixed rather than searched for, so traces compare
between runs.  Suspend remains cooperative on NuttX (CMakeLists.txt).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
@NevynUK @claude
nuttx: allow an external build directory; declare nxsock_close_notify
a76e66e 
build-nuttx.sh: take the build directory from MONO_BUILD_DIR when it is
set, so that several NuttX checkouts can build this runtime without
sharing one build directory inside the runtime tree.  The default is
unchanged (build-nuttx-<type>).

pal_networking.h: declare nxsock_close_notify (), which the Meadow.OS
firmware calls from its close() wrapper.  It had no prototype
(-Wmissing-prototypes).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
@NevynUK NevynUK mentioned this pull request Oct 14, 2026
Merged
@NevynUK
NevynUK merged commit c668e4a into MergeManagedCode Oct 14, 2026
NevynUK added a commit to WildernessLabs/Meadow.OS that referenced this pull request Oct 14, 2026
@NevynUK @claude
Point MONO_RUNTIME_COMMIT at the merged runtime phase 1
69100f2 
WildernessLabs/runtime#2 merged Phase1 into the runtime's MergeManagedCode
as c668e4a3aea; the tree is unchanged (5cf48371256).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
@NevynUK NevynUK mentioned this pull request Oct 16, 2026
Merged
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