On Thu, 2014-10-30 at 17:28 +0100, Harald Staub wrote: > On 30.10.2014 11:17, Harald Staub wrote: > > I can confirm that linux-image-3.2.0-4-amd64_3.2.63-2+deb7u1_amd64.deb > > fixes this regression for me. > > But it breaks live migration, probably when the source host runs an > older kernel. > > When libvirt tries to complete the migration, it aborts with: > error: Domain not found: no domain with matching name 'VMNAME' > > On the destination host, in /var/log/libvirt/qemu/VMNAME.log: > kvm: Features 0x300fffe3 unsupported. Allowed features: 0x711fbbe3 > qemu: warning: error while loading state for instance 0x0 of device > '0000:00:03.0/virtio-net' > load of migration failed > > I tried again with the older 3.2.60-1+deb7u3 on the destination host, > this works fine.
Yes, I can see how this (disabling virtio features) would prevent live migration from old to new host kernels. You will probably need a one-time reboot of the guest when migrating to the new host kernel. We could either mention this in the DSA text, or keep UFO enabled even though it doesn't work correctly (in practice, we sort of have to do that as the tap device's feature flags aren't respected by guests - which I think is a QEMU bug). Please let us know whether live migration between two hosts running the new kernel version does work (I think it will). Ben. -- Ben Hutchings The program is absolutely right; therefore, the computer must be wrong.
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