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Date: Thu, 19 Sep 2013 19:19:10 +0200
From: Paolo Bonzini <pbonzini@redhat.com>
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Subject: Re: [Qemu-devel] [RFC] Enabling x2apic on most (all?) x86 CPU models
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To: Eduardo Habkost <ehabkost@redhat.com>
Cc: Igor Mammedov <imammedo@redhat.com>, Bandan Das <bsd@redhat.com>, =?ISO-8859-1?Q?Andreas_F=E4rber?= <afaerber@suse.de>, Gleb Natapov <gleb@redhat.com>, qemu-devel@nongnu.org

Il 19/09/2013 18:58, Eduardo Habkost ha scritto:
>> > 
>> > I disagree, since this would also affect TCG. I would prefer to add
>> > x2apic only to models that really have it and would be open to generally
>> > enabling it for kvm_enabled() in instance_init/registration (so that
>> > users can disable it via ,-x2apic or soon QMP).
> This won't affect TCG because features not supported by TCG are removed
> automatically, and "enforce" doesn't even work on TCG mode (yet).
> 
> I believe we agreed that we don't want to make the semantics of CPU
> model names change depending if KVM or TCG are enabled[1], so I am
> trying to avoid making the default depend on kvm_enabled().

I agree.  I don't think it would matter much if one day TCG starts
supporting x2apic (it's probably only a few hours work) and old CPUs
started showing x2apic.

Paolo