[Xenomai-help] Xenomai and reading of linux files?

[Xenomai-help] Xenomai and reading of linux files?

[Jens Köhler]

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Hello,

I like to port a rtai application  to xenomai. The rtai application has a
user space part and a kernel module. Both communication together by rtai
queues and a shared memory.
Do I need for xenomai still queues? Or is it f.i. possible to read or write
linux files from xenomai application without problems?

Thanks and regards,
Jens

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Re: [Xenomai-help] Xenomai and reading of linux files?

[Gilles Chanteperdrix]

Jens Köhler wrote:
> Hello,
> 
> I like to port a rtai application  to xenomai. The rtai application has a
> user space part and a kernel module. Both communication together by rtai
> queues and a shared memory.
> Do I need for xenomai still queues? Or is it f.i. possible to read or write
> linux files from xenomai application without problems?

reading and writing will work, but will cause the thread which does it
to switch to secondary mode (if it is a real-time thread), so it may not
be what you want.

-- 
                                                 Gilles.

Re: [Xenomai-help] Xenomai and reading of linux files?

[Jens Köhler]

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2009/3/6 Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>

>  Jens Köhler wrote:
> > Hello,
> >
> > I like to port a rtai application  to xenomai. The rtai application has a
> > user space part and a kernel module. Both communication together by rtai
> > queues and a shared memory.
> > Do I need for xenomai still queues? Or is it f.i. possible to read or
> write
> > linux files from xenomai application without problems?
>
> reading and writing will work, but will cause the thread which does it
> to switch to secondary mode (if it is a real-time thread), so it may not
> be what you want.
>
> --
>                                                 Gilles.


Hi Gilles,

thank you for your fast answer. I need in periodic real time task data from
user space. Then I have to use a msg_queue!?
How can I check if my real time task/ thread runs accidentally in secondary
mode?

Thanks,
Jens

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Re: [Xenomai-help] Xenomai and reading of linux files?

[Gilles Chanteperdrix]

Jens Köhler wrote:
> 2009/3/6 Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>
> 
>>  Jens Köhler wrote:
>>> Hello,
>>>
>>> I like to port a rtai application  to xenomai. The rtai application has a
>>> user space part and a kernel module. Both communication together by rtai
>>> queues and a shared memory.
>>> Do I need for xenomai still queues? Or is it f.i. possible to read or
>> write
>>> linux files from xenomai application without problems?
>> reading and writing will work, but will cause the thread which does it
>> to switch to secondary mode (if it is a real-time thread), so it may not
>> be what you want.
>>
>> --
>>                                                 Gilles.
> 
> 
> Hi Gilles,
> 
> thank you for your fast answer. I need in periodic real time task data from
> user space. Then I have to use a msg_queue!?

Xenomai allows real-time in user-space (as RTAI does, by the way), so
the problem is not user-space versus kernel-space, the problem is
primary mode versus secondary mode.

> How can I check if my real time task/ thread runs accidentally in secondary
> mode?

See:
http://www.xenomai.org/documentation/branches/v2.4.x/html/api/group__task.html#g915e7edfb0aaddb643794d7abc7093bf

And for an introduction on xenomai native api, see:
http://www.xenomai.org/documentation/branches/v2.3.x/pdf/Native-API-Tour-rev-C.pdf

-- 
                                                 Gilles.