I think we should invent an MPIC specific property indicating that the
MPIC is to be shared and indicating on one of the users that it's the
"master" (the one doing the initial full setup, the others can then 
spin
on some bit somewhere before going on, unless we decide such a shared
setup, the PIC has to be pre-initialized by some firmware and we skip
all inits in mpic) and indicating which sources belong to which users.

There certainly are way more things then just the MPIC
that both CPUs could do both only one should.  And this
is really the kernel's business, not something to pollute
the device tree with -- well perhaps a global flag (in
/chosen, perhaps) that says "this or that CPU initialises
the shared resources".

It might make sense to have the firmware setup the devices
on these strange strange boards, dunno -- let's worry about
that if/when a board where someone wants that shows up :-)


Segher