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Re: [Qemu-devel] [PATCH] kvm/apic: fix 2.2->2.1 migration
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From: |
Paolo Bonzini |
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Subject: |
Re: [Qemu-devel] [PATCH] kvm/apic: fix 2.2->2.1 migration |
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Date: |
Fri, 12 Dec 2014 19:42:18 +0100 |
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User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.3.0 |
On 12/12/2014 18:30, Dr. David Alan Gilbert wrote:
> OK, let me just check that I get this....
>
> It gets reset to 0 already in kvm_apic_realize
(before this patch -- after this patch it's only done in reset)
> then we do the common init
Then as part of starting up auxiliary processors we send an INIT
interrupt, that resets the APIC and...
> that sets it to !bsp - so 1 for most CPUs
> then you're adding this so that a specific APIC implementation (kvm)
> can nobble it back to 0 again?
Yes. That's needed because this APIC implementation does not use the
field at all.
> and on the load side it's forced to zero by apic_pre_load.
Yes. That's the common case for the !APIC implementation because it
gets to zero as soon as te OS starts.
Paolo