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Re: [Xen-devel] [Patch] use full-size cpumask for vcpu-pin

To: Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>, Juergen Gross <juergen.gross@xxxxxxxxxxxxxx>
Subject: Re: [Xen-devel] [Patch] use full-size cpumask for vcpu-pin
From: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Date: Tue, 10 Aug 2010 15:27:54 +0100
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On 10/08/2010 15:11, "Ian Jackson" <Ian.Jackson@xxxxxxxxxxxxx> wrote:

> Juergen Gross writes ("[Xen-devel] [Patch] use full-size cpumask for
> vcpu-pin"):
>> The reason is the allocation of the cpumap for pinning: the size is only for
>> the ACTUAL number of physical cpus in the system, not the possible number.
>> The solution is to allocate a cpumap for up to NR_CPUS.
> Thanks for this patch.  However, this doesn't seem to be even slightly
> backwards-compatible, because it changes the layout of the physinfo
> sysctl response.

The domctl and sysctl hypercalls do not need to be backward compatible
across major Xen releases. All other hypercalls absolutely do.

 -- Keir

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