Re: [PATCH 8/9] x86/apic: match destination id with destinationmode

From: Ingo Molnar
Date: Sat Jun 27 2009 - 13:02:21 EST



* Eric W. Biederman <ebiederm@xxxxxxxxxxxx> wrote:

> Ingo Molnar <mingo@xxxxxxx> writes:
>
> > The question here is whether this should layer on top of
> > Jeremy's IO-APIC driverization patches. I think it should.
>
> The patch is a bad hack that is totally misdocumented. A bit like
> the Xen apic changes in that respect.
>
> I haven't seen Jeremy's IO-APIC driverization patches.
>
> I am stumped why we need any driverization in this area. x86_64
> and has had for years a mechanism that is perfectly fine for
> abstracting this. i386 also has had something similar and last I
> looked we just about had that code merged.

We have the local apic abstracted out into struct apic on both
32-bit and 64-bit, but not the IO-APIC methods.

> Xen doesn't have ioapics so it doesn't need us faking writes to
> ioapics. Xen either needs to parse the ioapic tables itself or
> Xen needs a proper interface to be given the table information.
>
> I this patch can be replaced by a 2 line change to the apic mode
> logic to force us into physflat mode on moorestown.

Yes, probably. I havent looked deeply into all the merits yet, there
were so many other structural problems with these patches.

Ingo
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