On the Linux port, tasks are pthreads that cannot be forcibly paused;
the scheduler "unschedules" a task only by selecting a different next
task, and the outgoing task keeps running until it next blocks itself
in event_wait (e.g. via vPortYield). If the scheduler later switches
back into such a task (event_signal) before it ever parked in
event_wait, that wake is never consumed and event_triggered stays
latched. The task's next voluntary block then returns immediately
instead of blocking (e.g. vTaskDelay(100ms) returning in 0ms), which
desynchronizes kernel and port scheduling state.
Clear the outgoing task's pending event when switching to a different
task, under s_port_mutex and atomically with the scheduling decision.
Any latched-but-unconsumed wake is stale at that point; a legitimate
wake can only be delivered later, once the scheduler selects the task
again as next_thread.
Add event_clear() to the wait_for_event helper to support this.
Verified: minimal repros (busy-wait with another ready task, and
pthread-blocked task) now measure 92-101 ms for vTaskDelay(100ms)
instead of 0 ms; linux_freertos kernel test app 18/18 pass; the
previously failing esp_linenoise host test suite passes 34/34.
Rework the syscall interposition architecture so FreeRTOS works
standalone (without VFS) and VFS optionally overrides with strong
symbols. All kernel FDs are registered with VFS via
esp_vfs_register_fd_with_local_fd, so the application only sees
VFS-allocated FD numbers, preventing numerical collisions between
kernel FDs and VFS-internal FD slots.
FreeRTOS side:
- Create linux_port_coop_internal.h with LINUX_COOP_IO_LOOP,
LINUX_COOP_RESOLVE, linux_coop_yield and FD state table functions
- Export cooperative I/O primitives (freertos_linux_coop_read/write/
open/close/fcntl/select/pread/pwrite/readv/writev/recv/send/
recvfrom/sendto/recvmsg/sendmsg/connect/accept/pselect/poll/
socket/socketpair/pipe/pipe2/dup/dup2/syscalls_init)
- Define weak POSIX symbols calling through to the cooperative
primitives; keep nanosleep/sleep/usleep as strong (not FD-related)
- Refactor freertos_linux_coop_syscalls.h into a pure public API header
VFS side:
- Register the Linux host FS with esp_vfs_register_fs_with_id() as a
proper VFS driver; register stdin/stdout/stderr at init (priority 99)
- Rewrite vfs_linux.c with strong POSIX symbols dispatching through
esp_vfs_*
- Add strong overrides for FD-creating syscalls (open, pipe, pipe2,
socket, socketpair, dup, dup2, accept) that register returned FDs
with VFS
- Add strong overrides for FD-translating syscalls (readv, writev,
recv, send, recvfrom, sendto, recvmsg, sendmsg, connect, pselect,
poll) that translate VFS FD to kernel FD
- Delete vfs_coop_syscalls.c (absorbed into FreeRTOS weak + VFS strong)
- Update CMakeLists.txt: remove vfs_coop_syscalls.c, add linker hook
* Added port layer from the FreeRTOS POSIX port, added
additional port code for ESP-IDF.
* Created another hello world example using that POSIX
port in tools/test_apps.
* Removed old linux app
