[Xenomai-help] Down interruptible

[Xenomai-help] Down interruptible

[Iwan Budi Kusnanto]

Hello all
why rt_sem_p does not have behaviour like down_interruptible (that
receive a signal while being blocked on a semaphore to give up the
"down"/"p" operation).Is that a bad design?
sem_wait (posix skin)have behaviour like that.

In what situation we must use posix skin?
In what situation we must use native skin?

thx


-- 
Iwan Budi Kusnanto

Re: [Xenomai-help] Down interruptible

[Jan Kiszka]

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Iwan Budi Kusnanto wrote:
> Hello all
> why rt_sem_p does not have behaviour like down_interruptible (that
> receive a signal while being blocked on a semaphore to give up the
> "down"/"p" operation).Is that a bad design?
> sem_wait (posix skin)have behaviour like that.

rt_sem_p() does have the desired property. If you observed anything
different in practice, it would be a bug and we would be happy to hear
more details (used versions, testcase code, etc.).

Just note that signal delivery breaks the determinism of the target
application.

> 
> In what situation we must use posix skin?
> In what situation we must use native skin?

There are no technical reasons to pick any of them, it's purely a design
question of your application (/me being in hurry and can't go into
details ATM).

Jan


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Re: [Xenomai-help] Down interruptible

[Philippe Gerum]

On Mon, 2007-09-03 at 11:26 +0700, Iwan Budi Kusnanto wrote:
> Hello all
> why rt_sem_p does not have behaviour like down_interruptible (that
> receive a signal while being blocked on a semaphore to give up the
> "down"/"p" operation).Is that a bad design?
> sem_wait (posix skin)have behaviour like that.

rt_sem_p automatically switches the pending thread to secondary mode
upon signal receipt, so that it can process this signal from a regular
Linux context, then -EINTR is returned to the caller.

> 
> In what situation we must use posix skin?
> In what situation we must use native skin?
> 

The native skin resembles traditional RTOS interfaces; if you know about
VxWorks, VRTX, pSOS and the like, it should sound familiar.
OTOH, choosing the POSIX interface has the advantage of keeping all
options open to move away from Xenomai, since it aims at conforming to
the opengroup's specs.

> thx
> 
> 
-- 
Philippe.