On Mon, 2010-12-13 at 20:54 +0200, Michael S. Tsirkin wrote: > On Mon, Dec 13, 2010 at 11:00:44AM -0700, Alex Williamson wrote: > > On Mon, 2010-12-13 at 19:50 +0200, Michael S. Tsirkin wrote: > > > On Mon, Dec 13, 2010 at 10:43:22AM -0700, Alex Williamson wrote: > > > > So, unfortunately, I stand by my original patch. > > > > > > What about the one that put -1 in saved index for a hotplugged device? > > > > There are still examples that don't work even without hotplug (example 2 > > and example 3 after the reboot). That hack limits the damage, but still > > leaves a latent bug for reboot and doesn't address the non-hotplug > > scenarios. So, I don't think it's worthwhile to pursue, and we > > shouldn't pretend we can use it to avoid bumping the version_id. > > Thanks, > > > > Alex > > I guess when we bump it we tell users: migration is completely > borken to the old version, don't even try it. > > Is there a way for libvirt to discover such incompatibilities > and avoid the migration?
I don't know if libvirt has a way to query this in advance. If a migration is attempted, the target will report: savevm: unsupported version 5 for '0000:00:03.0/rtl8139' v4 And the source will continue running. We waste plenty of bits getting to that point, but hopefully libvirt understands that it failed. Thanks, Alex
