sigxcpu.c

#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <signal.h>
#include <getopt.h>
#include <execinfo.h>
#include <native/task.h>

RT_TASK task;

void task_body (void *cookie)

{
    /* Ask Xenomai to warn us upon switches to secondary mode. */
    rt_task_set_mode(0, T_WARNSW, NULL);

    /* A real-time task always starts in primary mode. */

    for (;;) {
        rt_task_sleep(1000000000);
        /* Running in primary mode... */
        printf("Switched to secondary mode\n");
        /* ...printf() => write(2): we have just switched to secondary
           mode: SIGXCPU should have been sent to us by now. */
    }
}

void warn_upon_switch(int sig __attribute__((unused)))

{
    void *bt[32];
    int nentries;

    /* Dump a backtrace of the frame which caused the switch to
       secondary mode: */
    nentries = backtrace(bt,sizeof(bt) / sizeof(bt[0]));
    backtrace_symbols_fd(bt,nentries,fileno(stdout));
}

int main (int argc, char **argv)

{
    int err;

    signal(SIGXCPU, warn_upon_switch);

    err = rt_task_create(&task,"mytask",0,1,T_FPU);

    if (err)
        {
        fprintf(stderr,"failed to create task, code %d\n",err);
        return 0;
        }

    err = rt_task_start(&task,&task_body,NULL);

    if (err)
        {
        fprintf(stderr,"failed to start task, code %d\n",err);
        return 0;
        }

    pause();

    return 0;
}