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Date: Thu, 18 Feb 2016 12:06:39 +0530
From: Amit Shah <amit.shah@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH v2 3/3] migration: allow to suppress
 configuration section submission
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To: David Gibson <david@gibson.dropbear.id.au>
Cc: Laurent Vivier <lvivier@redhat.com>, Juan Quintela <quintela@redhat.com>, qemu-devel@nongnu.org, "Dr. David Alan Gilbert" <dgilbert@redhat.com>, qemu-ppc@nongnu.org, Greg Kurz <gkurz@linux.vnet.ibm.com>

On (Thu) 18 Feb 2016 [13:50:25], David Gibson wrote:
> On Wed, Feb 17, 2016 at 05:06:43PM +0100, Greg Kurz wrote:
> > Since the addition of the configuration section in QEMU 2.4, it is impossible
> > to migrate a pseries-2.3 machine back to QEMU 2.3.
> > 
> > This patch makes it possible thanks to a new machine property which allows to
> > disable configuration section submission.
> > 
> > To disable submission, just add:
> > 
> > -machine suppress-config-section=on
> > 
> > Alternatively, if the target QEMU version isn't known at startup, this can
> > be done later from the QEMU monitor with:
> > 
> > qom-set /machine suppress-config-section on
> > 
> > This property won't be automatically set for pseries-2.3 because it would
> > then break backward migration to QEMU 2.4. If automatic behaviour is needed,
> > it is up to the tooling to handle this.
> 
> As noted elsewhere, I'd actually be ok with enabling it for
> pseries-2.3.  Basically we have to chose whether to work against qemu
> 2.3 or 2.4 out of the box, we can't have both, and it sounds like qemu
> 2.3 is more widely deployed than qemu 2.4.
> 
> > 
> > Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
> 
> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
> 
> I'm not sure whose tree these need to go in via.

I'd like to see Juan's ack, and I'm fine if you take it via your tree.



		Amit