Re: [libvirt] [PATCH v5 0/2] qemu: Support for QXL heads

On Fri, May 06, 2016 at 01:27:15PM +0200, Pavel Hrdina wrote: > On Thu, May 05, 2016 at 07:18:51PM -0400, John Ferlan wrote: > > [...] > > > Been sitting on list for a while .... > > > > Obviously I think you know you have to update to top of tree > > > > Would be nice to perhaps add a few intro comments to > > qemuMigratePrepareDomain at least with respect to what the purpose is > > and what "could" be done in the future in the code. Looks like to me > > it's now a shim to qemuProcessPrepareDomain to take care of any of those > > "inconsistencies" between what can be supported in/on the new system > > (perhaps could work in the opposite direction too ;-))... When I'm > > reading code, I'm not necessarily looking at the commit message that > > added which may have that information. > > > > I think you could also update the commit message to point at the > > previous code that was reverted to help understand the history. > > > > ACK for the concept - looks like things are OK to me. > > > > John > > The only issue with this patch is that it breaks migration back to older > libvirt. We generally try to not break migration to old libvirt if you migrate > from new libvirt to old libvirt with the same XML that would be also valid for > the old libvirt. Since there is no change in the XML and we start using the > 'heads' attribute and we now pass that value to qemu you cannot migrate back to > some older libvirt. > > NACK, we need to figure this out. Yep, the major use of QXL is RHEV/oVirt and they explicitly require libvirt to support migration to old versions. So we need to figure this out.

Regards, Daniel -- |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org -o- http://virt-manager.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :|