I am developing a set of applications which write to and read from a
rt_pipe. The writing app is in plain linux userspace, the reading app is a
periodic Xenomai task. I am using xenomai 2.6.3 on kernel 3.4.6 (32 bit).
The problem I have is that the Xenomai task gets this warning when it tries
to read the pipe:
"errno 11 -EWOULDBLOCK" and the bytes the userspace app sent never arrive
at the Xenomai task.
The Xenomai task creates the pipe this way:
ret = rt_pipe_create(&cmd_fifo_fd, "cmd_fifo", 0, 30);
The userspace app opens and writes to the pipe this way:
fd = open("/dev/rtp0", O_RDWR);
wr = write(fd, "Debug", sizeof("Debug"));
The Xenomai task becomes periodic like this:
ret = rt_task_create(&main_task, "mytask", 0, 99, T_FPU | T_JOINABLE);
ret = rt_task_start(&main_task, &Periodic_routine, NULL);
Each time the Xenomai periodic task 'wakes', it checks the pipe in a
non-blocking fashion (this is a requirement).
Here is most of the periodic code which reads the pipe:
void Periodic_routine(void *cookie) {
RTIME next;
rt_task_set_mode(0, T_WARNSW, NULL);
next = rt_timer_read();
while (1) {
next += 2000000000;
retval = rt_task_sleep_until(next);
retval = rt_pipe_read(&cmd_fifo_fd, msg, 6, TM_NONBLOCK);
}
}
Yet the rt_pipe_read() above always returns errno 11 -EWOULDBLOCK and never
gets any bytes from the pipe, no matter how many times the periodic task
wakes up.
-CSmith
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