Re: [PATCH] - UV fix for size of hub mappings

From: Ingo Molnar
Date: Sat Sep 27 2008 - 16:02:30 EST



* Jack Steiner <steiner@xxxxxxx> wrote:

> > x2apic support is available in tip/master, so it would be nice to
> > glue UV to generic x2apic support properly and remove duplication
> > and fixmes.
>
> Good point. I'll send the fixes to you early next week. Recently, I've
> been focused on a distro release which is still waiting for the x2apic
> code. However, I don't need to wait to fix this upstream...

great!

> > For example, do we really need apic_x2apic_uv_x, or could we use
> > apic_x2apic_cluster?
>
> Unfortunately, we really need a uv genapic. IPIs on large UV systems
> can't use an x2apic model. Because of the size of our large systems,
> APICIDs in the cpu MSRs are not globally unique. We have a special
> feature in the UV chipset that must be used for on large systems for
> IPIs. Small & medium sized system can and do use the x2apic genapic.

not a problem really - it's not really complex or intrusive, we just
want to make sure all unnecessary duplication is eliminated.

Ingo
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