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Date: Tue, 26 Jul 2016 10:00:49 +0200
From: Igor Mammedov <imammedo@redhat.com>
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Subject: Re: [Qemu-devel] [PULL 26/28] apic: Use apic_id as apic's migration
 instance_id
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To: Amit Shah <amit.shah@redhat.com>
Cc: Eduardo Habkost <ehabkost@redhat.com>, Peter Maydell <peter.maydell@linaro.org>, Paolo Bonzini <pbonzini@redhat.com>, qemu-devel@nongnu.org, Richard Henderson <rth@twiddle.net>

On Tue, 26 Jul 2016 10:41:38 +0530
Amit Shah <amit.shah@redhat.com> wrote:

> On (Wed) 20 Jul 2016 [12:08:32], Eduardo Habkost wrote:
> > From: Igor Mammedov <imammedo@redhat.com>
> > 
> > instance_id is generated by last_used_id + 1 for a given device type
> > so for QEMU with 3 CPUs instance_id for APICs is a seti of [0, 1, 2]
> > When CPU in the middle is hot-removed and migration started
> > APICs with instance_ids 0 and 2 are transferred in migration stream.
> > However target starts with 2 CPUs and APICs' instance_ids are
> > generated from scratch [0, 1] hence migration fails with error
> >   Unknown savevm section or instance 'apic' 2
> > 
> > Fix issue by manually registering APIC's vmsd with apic_id as
> > instance_id, in this case instance_id on target will always
> > match instance_id on source as apic_id is the same for a given
> > cpu instance.
> > 
> > Reported-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
> > Signed-off-by: Igor Mammedov <imammedo@redhat.com>
> > Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> > Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
> > Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>  
> 
> After these patches, the static checker complains about missing
> sections:
> 
> Section "apic-common" does not exist in dest
> Section "apic" does not exist in dest
> Section "kvm-apic" does not exist in dest
It works for me, could you post reproducing commands?

> 
> This will break migration from older versions.
> 
> 		Amit