[libvirt] [Qemu-devel] [PATCH] [RFC] Add machine type pc-1.0-qemu-kvm for live migrate compatibility with qemu-kvm

[Serge Hallyn]

Quoting Alex Bligh (alex at alex.org.uk):
> 
> On 22 Jul 2014, at 19:43, Alex Bligh <alex at alex.org.uk> wrote:
> 
> > Testing has been light to date (i.e.
> > can I migrate it inbound with -S without anything complaining).

thanks, Alex!

> 
> I've given this quite a bit more testing today.
> 
> It works fine qemu-kvm 1.0 -> qemu-2.0+patch (cirrus vga)
> It works fine qemu-2.0+patch -> qemu-2.0+patch (cirrus vga)
> It doesn't (yet) work qemu-2.0+patch -> qemu-kvm 1.0 (cirrus vga).
> 
> The reason for this is (at least) that I need to emulate the
> broken versioning of the mc146818rtc timer section, as writing
> it correctly confuses qemu-kvm 1.0. Therefore please don't bother
> testing migration back to 1.0 yet.

I don't think that is in any way a problem.  Is migrating to older
versions ever actually expected to work?  In either case I don't
think for this particular case it's a problem.

(The "how to handle this in libvirt" question is more interesting)

-serge