Platform numbers

Benjamin Herrenschmidt benh at
Sat Jul 9 13:45:23 EST 2005

On Fri, 2005-07-08 at 11:52 -0500, Olof Johansson wrote:
> On Fri, Jul 08, 2005 at 10:45:06PM +1000, Michael Ellerman wrote:
> > Hi y'all,
> > 
> > Are the platform numbers in asm-ppc64/processor.h private to Linux? Or do 
> > firmware/hardware know about them?
> > 
> > For pseries/pmac/maple it looks like we just assign them based on OF 
> > properties. For iSeries we check in the naca. I don't see where BPA gets 
> > assigned?
> > 
> > The reason I ask is PLATFORM_MAPLE is currently 0x0500 which means we can't 
> > (easily) do any bit mask based trickery on platform numbers.
> They are just local to Linux and you can change them if you see a need
> to. Only thing to think about is the LPAR bit (0x1).

No, they are not local. Think about kexec, and firmwares that directly
pass a flattened device-tree
> Only challenge with going with bitmap is that the number of possible
> platforms are quite a bit lower, I'm not sure how quickly that will hurt
> us. We'll have other, bigger, headaches before we run out of platform
> bits anyway.

Yes, but I think we should kill the platform number. We should replace
it with a "HV type" (native, iseries, rpa, xen, ...) and have the
ppc_md.probe() function use the device-tree to identify the platform.

There are bits & pieces here or there that will need to be fixed for
that approach to work though. Like gross hacks in the interrupt tree


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