Re: [Xenomai-help] Sychronize between Linux and Xenomai domain

[Jan Kiszka <jan.kiszka@domain.hid>]

[-- Attachment #1: Type: text/plain, Size: 1161 bytes --]

Li Yi (Adam) wrote:
> Hi,
> 
> Xenomai provides synchronize objects like semaphore and mutex and related
> APIs, e.g: rt_sem_p(), rt_sem_v().
> I think they can only synchonze between Xenomai tasks (e.g, tasks created
> with rt_task_create()).
> 
> Is there any way to synchonize between a "normal" Linux task and a Xenomai
> task?

Either by simply calling a standard sync-mechanism from the RT task so
that it switches over to secondary mode, or by mapping the Linux task to
a Xenomai task as well. The latter is simple too, and you can even leave
its Linux scheduling policy at SCHED_OTHER with latest Xenomai (upcoming
2.2).

> Is there way to synchronize between Linux and Xenomai domain in Kernel
> space? (e.g, a Linux driver and a Xenomai driver)?

Depends on what you have to protect. The easiest way for short code
passages are still spinlocks with hard IRQ protection (under RTDM:
rtdm_lock_xxx). If it's a more complex scenario, please describe it.
There are several patterns available that may fit. They reach from
polling in the non-RT context over virtual IRQs to Linux
(rtdm_nrtsig_xxx) up to RT helper tasks.

Jan


[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 250 bytes --]