Re: 256 apic id for amd64

[Andi Kleen]

On Fri, Jan 07, 2005 at 04:26:57PM -0800, James Cleverdon wrote:
> Already done, although not dividing along AMD vs. Intel lines.  
> phys_pkg_id() indirects through the subarch table.  See 
> genapic_cluster.c and genapic_flat.c for details.
> 
> We may need a third subarch for AMD's Extended APIC mode boxes.

I'm not convinced we do. Things seem to work with BSP APIC-ID = 0.
Is there any real reason to not just require that?

> 
> Can you suggest some heuristics for detecting such a system and 
> discerning it from a clustered APIC box?  (Hopefully, without using MPS 
> or ACPI table ID string lookups.)

Early PCI scan would work in the worst case. All Opterons have a builtin
northbridge with a specific ID.  There is already other code that 
checks for these.

-Andi

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