POSIX sapi_platform backend: real-time bring-up for a PREEMPT_RT Linux host (ADR-018, ADR-035). More...

#include "safeapi/posix_backend/sapi_posix_backend.h"

Include dependency graph for sapi_posix_backend_platform.c:

Functions
static sapi_status_t	backend_realtime_init (uint32_t rt_priority)
const sapi_platform_backend_t *	sapi_posix_backend_platform (void)
	The POSIX sapi_platform backend (ADR-035): real-time bring-up via mlockall() + SCHED_FIFO, best-effort, on Linux; a no-op returning SAPI_STATUS_OK on any other POSIX host. Register it (directly or via sapi_posix_backend_register_all()) and call sapi_platform_realtime_init() through the framework rather than reaching for a backend symbol - see safeAPIFreamwork's docs/architecture/ADR-035-platform-realtime-init.md.

Variables
static const sapi_platform_backend_t	s_posix_platform_backend = { backend_realtime_init }

Detailed Description

POSIX sapi_platform backend: real-time bring-up for a PREEMPT_RT Linux host (ADR-018, ADR-035).

Locks the process image resident (mlockall) so cyclic execution is free of demand-paging jitter, pre-faults the current thread stack, and raises the calling thread to SCHED_FIFO at the requested priority. Every step is best-effort per REQ-OAL-PLATFORM-001: an unprivileged host, a kernel without an RT scheduler, or a bounded lockable-memory limit each degrade to a logged WARNING, never a hard failure, and the function still returns SAPI_STATUS_OK.

RLIMIT_MEMLOCK interaction (the reason this is not just mlockall(MCL_CURRENT | MCL_FUTURE)): with a bounded RLIMIT_MEMLOCK, MCL_FUTURE forces every later mapping - including each new thread's stack - to be locked, so the next pthread_create() fails with EAGAIN and the process cannot start its timer/task threads at all (observed on a stock Ubuntu VM: 8 MiB memlock cap, 8 MiB default thread stack). When the limit is not RLIM_INFINITY this backend locks the current footprint only (MCL_CURRENT) and says so; a privileged / memlock=unlimited deployment still gets MCL_CURRENT | MCL_FUTURE.

On any non-Linux POSIX host the whole thing is a no-op that returns OK.

Definition in file sapi_posix_backend_platform.c.

Macro Definition Documentation

◆ _GNU_SOURCE

#define _GNU_SOURCE

Definition at line 6 of file sapi_posix_backend_platform.c.

Function Documentation

◆ backend_realtime_init()

sapi_status_t backend_realtime_init ( uint32_t rt_priority )

static

Local makros Local types declarations Local function declarations

Definition at line 81 of file sapi_posix_backend_platform.c.

◆ sapi_posix_backend_platform()

const sapi_platform_backend_t * sapi_posix_backend_platform ( void )

The POSIX sapi_platform backend (ADR-035): real-time bring-up via mlockall() + SCHED_FIFO, best-effort, on Linux; a no-op returning SAPI_STATUS_OK on any other POSIX host. Register it (directly or via sapi_posix_backend_register_all()) and call sapi_platform_realtime_init() through the framework rather than reaching for a backend symbol - see safeAPIFreamwork's docs/architecture/ADR-035-platform-realtime-init.md.

Global variables declarations Global functions

Definition at line 73 of file sapi_posix_backend_platform.c.

Variable Documentation

◆ s_posix_platform_backend

const sapi_platform_backend_t s_posix_platform_backend = { backend_realtime_init }

static

Local variables declarations

Definition at line 67 of file sapi_posix_backend_platform.c.

Functions

Variables