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From: Philippe Gerum <rpm@xenomai.org>
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Date: Tue, 04 Oct 2011 17:41:24 +0200
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Subject: Re: [Xenomai-help] Xenomai-forge: SEGFAULT is pSOS skin
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To: Ronny Meeus <ronny.meeus@domain.hid>
Cc: xenomai-help <xenomai@xenomai.org>

On Mon, 2011-09-26 at 22:01 +0200, Ronny Meeus wrote:

<snip>

> Next to this I also adapted the task priority automatically using
> following algorithm:
> static int check_task_priority(u_long *psos_prio)
> {
>         if (*psos_prio < 1 || *psos_prio > 255) /* In theory. */
>                 return ERR_PRIOR;
>         /* Do not change priorities <=10 and >= 240.
>          * Priorities in between are divided by 4 */
>         if (*psos_prio > 240)
>                 *psos_prio = 70 + *psos_prio - 240;
>         else if (*psos_prio > 10)
>                 *psos_prio = 11 + ((*psos_prio-10)/4);
> 
>         if ((int)(*psos_prio) >= threadobj_max_prio - 1) /* In practice. */
>                 panic("current implementation restricts pSOS "
>                       "priority levels to range [1..%d]",
>                       threadobj_max_prio - 2);
> 
>         return SUCCESS;
> }
> 
> It also works well for our application.
> Please share your thoughts.

Since we cannot generalize the priority mapping rules, a better way may
be to allow your own code to be called by the pSOS emulator when such
mapping is required. So I have committed a tentative solution, defining
psos_task_normalize_priority() as a weak function, which receives the
pSOS priority, and should return the POSIX one.

A default implementation is provided by the emulator which does a
trivial 1:1 mapping.

-- 
Philippe.