[Xenomai-help] Three questions about RTDM

[Xenomai-help] Three questions about RTDM

[Alessio Igor Bogani]

Hi all, Hi Jan,

I apologize for my (very) bad english.

I have three simple questions about RTDM:

1) Where may I find a more detailed documentation about RTDM? 

2) Now I'm attempting to write a simple device driver with RTDM: Can
someone show me a standard GNUMakefile/Makefile to compile it?

3) Device driver written with RTDM must be released under GPL?
Or, as like Xenomai, the developer is free to choose the license that
prefer for his/her sw based on it?

Thanks in advance.

Bye,
Alessio

Re: [Xenomai-help] Three questions about RTDM

[Jan Kiszka]

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Alessio Igor Bogani wrote:
> Hi all, Hi Jan,
> 
> I apologize for my (very) bad english.
> 
> I have three simple questions about RTDM:
> 
> 1) Where may I find a more detailed documentation about RTDM? 

More detailed than what? Have you already discovered the online docs on
www.xenomai.org?

> 
> 2) Now I'm attempting to write a simple device driver with RTDM: Can
> someone show me a standard GNUMakefile/Makefile to compile it?

Take a look at the heartbeat example on

www.rts.uni-hannover.de/mitarbeiter/kiszka/rtaddon

This works for 2.6 kernels and Xenomai 2.0.x. I still need to update it
for Xenomai 2.1, where compilation melts down to simple out-of-tree
kernel module generation. Does anyone else here have a generic Makefile
for all kernel and Xenomai versions at hand?

> 
> 3) Device driver written with RTDM must be released under GPL?
> Or, as like Xenomai, the developer is free to choose the license that
> prefer for his/her sw based on it?
> 

For me, an RTDM driver using the official RTDM API would be no derived
work, thus would not necessarily have to be GPL. But I cannot speak for
all other developers involved in the APIs you may have to use in your
driver (moreover, RTDM is also not only my own work). Actually, this
does not solely depend on RTDM, this is a linux kernel issue as you put
your module inside this GPL'ed system. As long as there are no urging
needs (non-extractable IP inside the driver core that must be kept
closed), I would recommend no one theses days to develop binary-only
kernel modules anymore (this is also one reason why you shouldn't write
closed-source RT kernel application modules, BTW).

If you just prefer another open source license, release your driver
under both GPL and that other license. But if you plan to keep it
closed, I can only recommend to ask a lawyer about legal pros and cons
of this approach.

Jan


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Re: [Xenomai-help] Three questions about RTDM

[Alessio Igor Bogani]

Hi Jan,

Thank for your reply.

[...]
> > 1) Where may I find a more detailed documentation about RTDM? 
> 
> More detailed than what? Have you already discovered the online docs on
> www.xenomai.org?

Yes i have already discovered online docs.
IMVHO API Reference is indispensable but not sufficient.
I would be very happy to see for RTDM something similar to Xenomai's
Native-API-Tour.

> > 2) Now I'm attempting to write a simple device driver with RTDM: Can
> > someone show me a standard GNUMakefile/Makefile to compile it?
> 
> Take a look at the heartbeat example on
> 
> www.rts.uni-hannover.de/mitarbeiter/kiszka/rtaddon
> 
> This works for 2.6 kernels and Xenomai 2.0.x. I still need to update it
> for Xenomai 2.1, where compilation melts down to simple out-of-tree
> kernel module generation. Does anyone else here have a generic Makefile
> for all kernel and Xenomai versions at hand?

Google is a great friend. ;-)

I have already seen heartbeat example.
Mysteriously heartbeat.ko module resulted is dependent from
latency_rt.ko module (present in testsuite\klatency in Xenomai package)
for a reason that i don't understand. :-(
How can resolve this problem?

Thank you very much!

Bye,
Alessio

Re: [Xenomai-help] Three questions about RTDM

[Jan Kiszka]

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Alessio Igor Bogani wrote:
> Hi Jan,
> 
> Thank for your reply.
> 
> [...]
>>> 1) Where may I find a more detailed documentation about RTDM? 
>> More detailed than what? Have you already discovered the online docs on
>> www.xenomai.org?
> 
> Yes i have already discovered online docs.
> IMVHO API Reference is indispensable but not sufficient.
> I would be very happy to see for RTDM something similar to Xenomai's
> Native-API-Tour.

Would be nice - just takes /someone/ to write it... :-/

Maybe this paper can provide a few further hints meanwhile:

ftp://ftp.realtimelinuxfoundation.org/pub/events/rtlws-2005/JanKiszka.pdf

> 
>>> 2) Now I'm attempting to write a simple device driver with RTDM: Can
>>> someone show me a standard GNUMakefile/Makefile to compile it?
>> Take a look at the heartbeat example on
>>
>> www.rts.uni-hannover.de/mitarbeiter/kiszka/rtaddon
>>
>> This works for 2.6 kernels and Xenomai 2.0.x. I still need to update it
>> for Xenomai 2.1, where compilation melts down to simple out-of-tree
>> kernel module generation. Does anyone else here have a generic Makefile
>> for all kernel and Xenomai versions at hand?
> 
> Google is a great friend. ;-)
> 
> I have already seen heartbeat example.
> Mysteriously heartbeat.ko module resulted is dependent from
> latency_rt.ko module (present in testsuite\klatency in Xenomai package)
> for a reason that i don't understand. :-(
> How can resolve this problem?

Due to which symbol? Which Xenomai version precisely? Indeed very
strange. Something must be broken in your build.

> 
> Thank you very much!
> 
> Bye,
> Alessio
> 

Jan


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Re: [Xenomai-help] Three questions about RTDM

[Alessio Igor Bogani]

Hi Jan,

[RTDM Docs]
> > I would be very happy to see for RTDM something similar to Xenomai's
> > Native-API-Tour.
> 
> Would be nice - just takes /someone/ to write it... :-/

Ok :-)

> Maybe this paper can provide a few further hints meanwhile:
> 
> ftp://ftp.realtimelinuxfoundation.org/pub/events/rtlws-2005/JanKiszka.pdf

Wow! Can you put this document in Technical articles section in
Xenomai's site? I think that this document could be useful for others. 

[heartbeat example]
> > Mysteriously heartbeat.ko module resulted is dependent from
> > latency_rt.ko module (present in testsuite\klatency in Xenomai package)
> > for a reason that i don't understand. :-(
> > How can resolve this problem?
> 
> Due to which symbol? Which Xenomai version precisely? Indeed very
> strange. Something must be broken in your build.

Xenomai 2.0.3

Heartbeat.ko is loaded but not start and rtdm_task_init() return a -11
error code (EAGAIN?). If i load latency_rt.ko before to load
heartbeat.ko this work perfectly.
I suppose that heartbeat.ko should do start a timer, or not?

Bye,
Alessio

Re: [Xenomai-help] Three questions about RTDM

[Jan Kiszka]

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Alessio Igor Bogani wrote:
> Hi Jan,
> 
> [RTDM Docs]
>>> I would be very happy to see for RTDM something similar to Xenomai's
>>> Native-API-Tour.
>> Would be nice - just takes /someone/ to write it... :-/
> 
> Ok :-)
> 
>> Maybe this paper can provide a few further hints meanwhile:
>>
>> ftp://ftp.realtimelinuxfoundation.org/pub/events/rtlws-2005/JanKiszka.pdf
> 
> Wow! Can you put this document in Technical articles section in
> Xenomai's site? I think that this document could be useful for others. 

Yes, this should be done indeed.

@All: How to include this in the SVN and later the website? As PDF only
or also in source code form (it's latex).

> 
> [heartbeat example]
>>> Mysteriously heartbeat.ko module resulted is dependent from
>>> latency_rt.ko module (present in testsuite\klatency in Xenomai package)
>>> for a reason that i don't understand. :-(
>>> How can resolve this problem?
>> Due to which symbol? Which Xenomai version precisely? Indeed very
>> strange. Something must be broken in your build.
> 
> Xenomai 2.0.3
> 
> Heartbeat.ko is loaded but not start and rtdm_task_init() return a -11
> error code (EAGAIN?). If i load latency_rt.ko before to load
> heartbeat.ko this work perfectly.
> I suppose that heartbeat.ko should do start a timer, or not?

RTDM does not know any abstraction for the system timer. That's intended
because only the native skin currently controls it at API level, all
others via a module parameter. So, to test heartbeat, you just have to
load any skin or application that starts the timer. "insmod xeno_posix"
does this job e.g.

Jan



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