Re: Preempt-RT patch for 2.6.25

[Sven-Thorsten Dietrich <sven@thebigcorporation.com>]

On Fri, 2008-05-02 at 20:02 +0200, Remy Bohmer wrote:
> Hello Steven,
> 
> I was wondering: Is there a preempt-RT-patch planned for 2.6.25?
> I haven't seen one either for any of the 2.6.25-rc kernels at the
> usual place (http://www.kernel.org/pub/linux/kernel/projects/rt/),
> first time in history...
> Am I missing something?


Daniel has done a port, but I think it dropped some archs so its not
complete.


ftp://source.mvista.com/pub/dwalker/rt/patch-2.6.25-rc9-dw1-broken-out.tar.bz2

and updates, possibly:

ftp://source.mvista.com/pub/dwalker/rt/


His bi-sectability changes are pretty key, and I would like to see those
reviewed and incorporated, even if they apply only to x86.

The RT patch queue generally is a mess today. 
Lots of stuff needs to be folded down into the core patches.

The ins and outs of the softirq code need major clean-up.

There are big issues around apic / hardirq threads that we need to
tackle at multiple levels.

(we are seeing the semis acknowledge the IRQ thread model, where IRQs
may stay masked longer than usual)

per-device irq threads, as Jon Masters has mentioned in his blog, may be
one work-around to get past the legacy stuff in x86.

and with the x86 merge, all this should become easier, so that hopefully
we can extricate the IRQ threads changes in a bisectable way, so we can
address the technical issues that stand in the way of upstream, apart
from PREEMPT_RT.

Sven