2.6.28-rt on PowerPC

[Benjamin Herrenschmidt]

> This is trivially solved by converting arch/powerpc/sysdev/ipic.c
> back to spinlocks (ipic_lock).
> 
> Assuming that converting-back is automatic, there are few other
> chained interrupt controllers you might want to convert-back:
> 
> arch/powerpc/sysdev/i8259.c (i8259_lock)
> arch/powerpc/sysdev/mpic.c (mpic_lock)
> arch/powerpc/sysdev/qe_lib/qe_ic.c (qe_ic_lock)

Except that a bunch of those can be both primary and chained... It's
simply not a solution to have to "convert" interrupt controller code to
use a different locking scheme depending on whether they are chained or
primary...

Cheers,
Ben.