Re: [patch] x86: 2.6.31-rc7 crash due to buggy flat_phys_pkg_id

From: Ingo Molnar
Date: Tue Aug 25 2009 - 15:27:00 EST

* Ravikiran G Thirumalai <kiran@xxxxxxxxxxxx> wrote:

> On Tue, Aug 25, 2009 at 10:31:30PM +0400, Cyrill Gorcunov wrote:
> >[Ingo Molnar - Tue, Aug 25, 2009 at 08:15:00PM +0200]
> >|
> >
> >I'm definitely not APIC expert but since I was partially involved
> >letme turn in.
> >
> >Original commit which causes problem for vSMP seems to be due
> >to cpu_has_apic bit turned off (ie due to being manually disabled
> >or acpi table broken) so further read apic id will return plain
> >zero (we're talking about 64 bits now). So frnakly I don't understand
> >what is wrong with Ravikiran's patch. In case of apic disabled
> >initial apic value will be used anyway (which is latched but
> >actually may be changed, but it's not our case).
> >
> Exactly my thinking. I hoped the patch I posted solves both cases --
> does not depend on local apic id for the "fix crash on certain UP configs"
> case in the commit here:
> And fixes vsmp too.

Sidenote for .32: i am somewhat worried about the spreading of
various cpu_has_apic checks. We should separate it out more cleanly
and provide an apic-> callback instead and avoid this ugly flaggery.

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