signal from rt-task to linux-task

Paolo Mantegazza mantegazza at
Fri Jun 13 16:24:13 CEST 2003

Kay-Ulrich Scholl wrote:
> Hi,
> I want to synchronize a linux-process with a rt-task.
> the linux process has to wait(sleep) within a read function of a device driver
> (It waits there for data from an rt-task).
> I want to provide the data  by the rt-task and then wake up the
> linux task.
> Using pthread_cond /mutex will freeze the whole linux-part (I only want
> the single linux process to sleep).
> Using linux queues doesn't work within rt-tasks.

What do you mean when you say rt-task?

- Linux kernel thread under RTAI?
- An RTAI proper light kernel task?
- A Linux process/thread executing in hard real time mode (user space)?

Generally speaking recall that you can use anything of RTAI everywhere
in kernel/user space alike ((NEW)LXRT mode), but there can be
communication solutions for simple specific cases of rt_tasks in kernel
space and Linux tasks that can use just FIFOs. If so your Linux task can
simply wait to read on a fifo that is written by the rt_task.


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