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Date: Fri, 18 Jan 2013 17:50:45 -0200
From: Marcelo Tosatti <mtosatti@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH] define qemukvm-1.2 machine type
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To: Cole Robinson <crobinso@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>, Anthony Liguori <aliguori@us.ibm.com>, qemu-devel@nongnu.org

On Fri, Jan 18, 2013 at 11:04:04AM -0600, Cole Robinson wrote:
> >> Thanks for the analysis Paolo, here's the final patch I used:
> >>
> >> http://pkgs.fedoraproject.org/cgit/qemu.git/tree/0004-Fix-migration-compat-with-qemu-kvm.patch
> >>
> >> Thanks,
> >> Cole
> > 
> > Cole,
> > 
> > version_id and minimum_version_id should be changed to 2, as the comment
> > indicates.

Problem is it uses acpi_load_old, when reading from qemu-kvm 1.2 (which
advertises format as V2), which reads 4*16 bits (instead of 16 bits)
for en/sts fields. So it can corrupt incoming migration data.

> But won't that mean we have to carry that patch forever, and while we carry
> that patch we can never migrate from Fedora qemu to an upstream qemu instance?
> I'd like to avoid carrying any incompatibility forward, if possible.

No useful ideas :(