Re: [Xenomai] RTDM-native mainlining - status?

[Philippe Gerum <rpm@xenomai.org>]

On 06/14/2015 10:46 AM, Gilles Chanteperdrix wrote:
> 
> Michael Haberler wrote:
>>
>>> Am 13.06.2015 um 09:19 schrieb Gilles Chanteperdrix
>>> <gilles.chanteperdrix@xenomai.org>:
>>>
>>>
>>> Michael Haberler wrote:
>>>> I hope I do not overlook some boundary condition - but assuming that
>>>> building out-of-tree RTDM support is significantly less invasive and
>>>> version-dependent than patching a kernel, that scheme could enormously
>>>> widen the range of platforms we could deploy with good results, and at
>>>> the
>>>> same time lower maintenance requirements.
>>>
>>> No, alas a Linux driver is always version-dependent, so, the driver
>>> would
>>> contain some wrappers to handle differences between version. But this is
>>> not something new, everybody maintaining out-of-tree Linux kernel code
>>> has
>>> been doing it for a very long time. We do it for Xenomai, even Linux
>>> developers are doing it for the driver backport project.
>>
>> certainly, but if the problem scope changes from "patch a specific kernel
>> version for full Xenomai support" to "maintain the API and support library
>> for a set of out-of-tree drivers on top of a stock kernel from elsewhere"
>> we're in a different (my guess: easier and more widely applicable)
>> ballgame
> 
> There should not be a need for a support library, since RTDM uses the
> usual driver API open, read, write, ioctl, I would expect an RTDM native
> driver to work with the plain Linux version of these calls.
> 
>>
>> I would really be interested in exploring this route with a simple
>> example, like this GPIO RTDM driver, and try to make this work with say a
>> vanilla or RT-PREEMPT kernel - if only to gauge feasibility, effort and
>> results
>>
>> what would you recommend as a starting point?
> 
> Well, RTDM native is not part of Xenomai (yet), so, the first step would
> be to to try and compile it. The last commits in the git date back from
> 2007, so, some adaptation will be needed to get it running with the latest
> kernels.
> 
> https://git.xenomai.org/rtdm-native.git/
> 

And changes to the RTDM API brought in by the transition to xenomai 3 too.


-- 
Philippe.