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.