[patch 3/4] powerpc/mpic: dont reset affinity for secondary MPIC on boot

[Benjamin Herrenschmidt]

On Fri, 2008-11-28 at 20:51 +0100, Arnd Bergmann wrote:
> plain text document attachment
> (0003-powerpc-mpic-don-t-reset-affinity-for-secondary-MPI.patch)
> Kexec/kdump currently fails on the IBM QS2x blades when the kexec happens
> on a CPU other than the initial boot CPU.  It turns out that this is the
> result of mpic_init trying to set affinity of each interrupt vector to the
> current boot CPU.
> 
> As far as I can tell,  the same problem is likely to exist on any
> secondary MPIC, because they have to deliver interrupts to the first
> output all the time. There are two potential solutions for this: either
> not set up affinity at all for secondary MPICs, or assume that a single
> CPU output is connected to the upstream interrupt controller and hardcode
> affinity to that per architecture.
> 
> This patch implements the second approach, defaulting to the first output.
> Currently, all known secondary MPICs are routed to their upstream port
> using the first destination, so we hardcode that.
> 
> Signed-off-by: Arnd Bergmann <arnd at arndb.de>

Acked-by: Benjamin Herrenschmidt <benh at kernel.crashing.org>