On Fri, Feb 19, 2016 at 08:59:44AM +0100, Greg Kurz wrote: > On Fri, 19 Feb 2016 11:11:47 +1100 > David Gibson <da...@gibson.dropbear.id.au> wrote: > > > On Thu, Feb 18, 2016 at 12:32:11PM +0100, Greg Kurz wrote: > > > QEMU 2.4 broke the migration of old pseries machine with the addition > > > of configuration sections, which are sent unconditionally. > > > > > > We assume that QEMU 2.3 is more deployed than any newer release (based on > > > the versions currently shipped by most distros). This v3 series hence > > > reverses the logic from v2: it now fully fixes migration of old pseries > > > from/to QEMU 2.3 and provides a manual workaround for the QEMU > > > 2.4/2.4.1/2.5 > > > case. > > > > > > With this series, I could migrate the same pseries-2.3 instance in a full > > > 2.3->2.6->2.5->2.6->2.4->2.6->2.3 cycle. > > > > Sorry, I've lost track slightly here. Does this series apply on top > > of, or instead of your earlier series that peeks for the config > > section? > > > > This v3 series applies instead of the v2 that peeks for the config section.
Ok, thanks for the clarification.
> It was suggested by Laurent during review, and motivated by your decision
> to favor fixing 2.3 over 2.4.
>
> As shown in Laurent's detailed test report, migration from/to 2.3.x now works
> out of the box and 2.4.x/2.5 requires qom-set.
>
> I was also feeling a bit uncomfortable with all these machine properties to
> disable the configuration section, which was explicitly coded to be
> non-optional
> according to the changelog of commit 61964c23. The logic inversion in v3 seem
> to be friendlier with the configuration section design.
>
> Juan, could you share your thoughts ?
With an ack from Juan I'll be happy to merge this to ppc-for-2.6.
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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