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From: Paul Brook <paul@codesourcery.com>
Subject: Re: [Qemu-devel] [PATCH] Change virtio-console to
	PCI_CLASS_SERIAL_OTHER
Date: Thu, 28 May 2009 14:20:07 +0100
References: <1243012478.29542.18.camel@blaa>
	<200905281353.50463.paul@codesourcery.com>
	<20090528130419.GC24488@redhat.com>
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To: "Daniel P. Berrange" <berrange@redhat.com>
Cc: Mark McLoughlin <markmc@redhat.com>, Anthony Liguori <aliguori@us.ibm.com>, Dor Laor <dlaor@redhat.com>, ajax@redhat.com, qemu-devel@nongnu.org

> > IMHO think the only sane response is "don't do that". Trying to support
> > migration between different qemu versions just isn't worth the pain.
>
> I think that further more, we shouldn't make a change like altering
> the PCI device class in the stable branch, only in the unstable
> branch. If we restrict the stable branch to bug fixes, then it ought
> to be (more?) practical to support save under 0.10 and restore under
> 0.11, without needing to support the hard problem of save under 0.10
> and restore under 1.00 (or whatever next major release branch is)

0.11 is the next major release series. The current stable releases are 0.10.x.
I agree we shouldn't be making this sort of change on the stable branch, 
precisely because it's reasonable to expect stable releases to be backwards 
compatible.

Paul