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Re: [Xen-devel] Re: [Xen-staging] [xen-unstable] Added some more fields

To: Alex Williamson <alex.williamson@xxxxxx>
Subject: Re: [Xen-devel] Re: [Xen-staging] [xen-unstable] Added some more fields to host_cpu.
From: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
Date: Fri, 02 Mar 2007 20:58:41 +0000
Cc: Jimi Xenidis <jimix@xxxxxxxxxxxxxx>, xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>, ewan@xxxxxxxxxxxxx, Hollis Blanchard <hollisb@xxxxxxxxxx>
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Thread-topic: [Xen-devel] Re: [Xen-staging] [xen-unstable] Added some more fields to host_cpu.
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On 2/3/07 20:55, "Alex Williamson" <alex.williamson@xxxxxx> wrote:

>> We have indeed hit this problem and I put a patch in this afternoon to
>> duplicate cpu0's info for any non-existent cpu. Given that the dom0 cpus
>> could be migrating around on arbitrary physical cpus (even across the
>> multiple CPUID invocations that the kernel will have made to build the
>> information for a single 'cpu' in /proc!) this is fine -- x86 multiprocessor
>> systems are supposed to be symmetric (homogeneous CPUs down to the same
>> stepping in some cases) anyway.
>    Cool, I see it in staging.  This is the approach I used to work
> around the problem temporarily, but what happens if cpu0 is hot
> un-plugged?  ISTR x86 Linux doesn't support cpu0 hotplug, but on ia64 we
> can hotplug cpu0.  I'd guess powerpc could too.  Thanks,

Then picking another number than zero would be a good idea. :-)

 -- Keir

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