[Xenomai-help] Getting the current RT-state of a task

[Xenomai-help] Getting the current RT-state of a task

[Johan Borkhuis]

I am building an OS-abstraction layer for our application, and for this 
I would like to know the RT-status of a task.
Using the rt_task_set_mode function it is possible to switch between RT 
and non-RT (using T_PRIMARY). But I would like to know what the state is 
of the current task. I did not find a function to retrieve the RT-state 
of a task; is a function available that will return the status of a task?

For the moment I am using the code shown below. Does this code work:

    rt_task_set_mode(0,0, &var);
    if(var&T_PRIMARY)
    {   /* Primary mode */
        ....
    }
    else
    {   /* Secondary mode */
        ....
    }

I would like to use this for a printf-implementation, where the text is 
printed if the task is non-RT or send to a logging task is the task is 
RT. I would like to call this code from Xenomai tasks, but also from 
plain Linux tasks. Is this possible?

Kind regards,
    Johan Borkhuis

Re: [Xenomai-help] Getting the current RT-state of a task

[Philippe Gerum]

On Mon, 2007-06-25 at 09:46 +0200, Johan Borkhuis wrote:
> I am building an OS-abstraction layer for our application, and for this 
> I would like to know the RT-status of a task.
> Using the rt_task_set_mode function it is possible to switch between RT 
> and non-RT (using T_PRIMARY). But I would like to know what the state is 
> of the current task. I did not find a function to retrieve the RT-state 
> of a task; is a function available that will return the status of a task?
> 

rt_task_inquire(), check the status field for XNRELAX; if set, your task
runs in secondary mode. Note: this method is currently an ugly hack,
because you should be allowed to check for something like T_SECONDARY
there instead, but unfortunately, you can't for obscure historical
reasons. Cleanup of that mess is pending.

> For the moment I am using the code shown below. Does this code work:
> 

Not as you would expect, because rt_task_set_mode() will send the caller
to the primary domain, but a current glitch in the implementation even
forgets to set the T_PRIMARY bit in the returned mask.

>     rt_task_set_mode(0,0, &var);
>     if(var&T_PRIMARY)
>     {   /* Primary mode */
>         ....
>     }
>     else
>     {   /* Secondary mode */
>         ....
>     }
> 
> I would like to use this for a printf-implementation, where the text is 
> printed if the task is non-RT or send to a logging task is the task is 
> RT. I would like to call this code from Xenomai tasks, but also from 
> plain Linux tasks. Is this possible?
> 

A library doing exactly this is pending, and due for merge before -rc1
is out. If you want to use it on top of 2.3.x, you may want to adapt it
locally:
http://www.rts.uni-hannover.de/rtaddon/patches/xenomai/librtutils.patch

> Kind regards,
>     Johan Borkhuis
> 
> 
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> Xenomai-help mailing list
> Xenomai-help@domain.hid
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-- 
Philippe.