State of PREEMPT_RT in PPC arch

State of PREEMPT_RT in PPC arch

[Ryan]

Hi,

We have a MPC7448 based board with 2.6.21 ported (ppc arch). We want
to apply the PREEPMT_RT patch to the existing kernel and drivers.
Well, it turns out to be a difficult task since the ppc arch doesn't
seem to support the RT patch very well. Has anyone had a working
2.6.21+ kernel with RT patch for the ppc arch? Is the ppc arch just
dying?

I may have two choices. One is to move to the powerpc arch that is
actively developed and has proven working RT patches from the
community. This will force us to migrate our drivers to a newer kernel
and a new arch, which is certainly not trivial. The other is to back
port an existing and working RT patch to the ppc arch of 2.6.21,
which, at least for now, seems quite difficult and may not be merited
for future.

I'm soliciting comments from the community. Thanks in advance for
sharing your thoughts.

-Ryan.

Re: State of PREEMPT_RT in PPC arch

[Wolfram Sang]

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> I'm soliciting comments from the community. Thanks in advance for
> sharing your thoughts.

Mainline your driver and you are free from such problems :)

-- 
Pengutronix e.K.                           | Wolfram Sang                |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |

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Re: State of PREEMPT_RT in PPC arch

[Ryan]

On Thu, Feb 18, 2010 at 5:15 AM, Wolfram Sang <w.sang@pengutronix.de> wrote:
>
> > I'm soliciting comments from the community. Thanks in advance for
> > sharing your thoughts.
>
> Mainline your driver and you are free from such problems :)

Shouldn't it be the opposite way? That is, get drivers working first
then mainline them? I even don't have a working driver with RT patch.
Thanks for the response though. At least it shows that such emails are
not completely ignored.

I feel the linuxppc-dev mailing list is full of development patches
and discussions about them, kinda dedicated to active developers. Is
there a place that users or not-so-active developers can post
technical questions and get some relatively quick answers or comments?
I think there used to be such a mailing list but I couldn't remember
it.

-Ryan.

Re: State of PREEMPT_RT in PPC arch

[Wolfram Sang]

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On Thu, Feb 18, 2010 at 09:34:28PM -0800, Ryan wrote:
> On Thu, Feb 18, 2010 at 5:15 AM, Wolfram Sang <w.sang@pengutronix.de> wrote:
> >
> > > I'm soliciting comments from the community. Thanks in advance for
> > > sharing your thoughts.
> >
> > Mainline your driver and you are free from such problems :)
> 
> Shouldn't it be the opposite way? That is, get drivers working first
> then mainline them? I even don't have a working driver with RT patch.

If you have problems getting your driver to mainline, the lists are there to
help. Of course, this implies working with a recent kernel (which also answers
your initial question a bit). Most people don't want to supprt old kernels like
2.6.2x in their freetime. You can get commercial support for such tasks (be it
my employer or other consultants on this list).

> and discussions about them, kinda dedicated to active developers. Is
> there a place that users or not-so-active developers can post
> technical questions and get some relatively quick answers or comments?

The list was apropriate. As all people are busy by default, getting no response
is not that exceptional. If you need a fast response, you should consider
commercial support.

Regards,

   Wolfram

-- 
Pengutronix e.K.                           | Wolfram Sang                |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |

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Re: State of PREEMPT_RT in PPC arch

[Ryan]

Hi Wolfram,

On Fri, Feb 19, 2010 at 12:54 AM, Wolfram Sang <w.sang@pengutronix.de> wrote:
>
> The list was apropriate. As all people are busy by default, getting no response
> is not that exceptional. If you need a fast response, you should consider
> commercial support.

I appreciate your comments.

-Ryan.