Re: [libvirt] [PATCH 00/22] qemu: Store default CPU in domain XML

On Thu, 2019-10-03 at 16:00 +0200, Jiri Denemark wrote: > When starting a domain without a CPU model specified in the domain XML, > QEMU will choose a default one. Which is fine unless the domain gets > migrated to another host because libvirt doesn't perform any CPU ABI > checks and the virtual CPU provided by QEMU on the destination host can > differ from the one on the source host. > > With QEMU 4.2.0 we can probe for the default CPU model used by QEMU for > a particular machine type and store it in the domain XML. This way the > chosen CPU model is more visible to users and libvirt will make sure > the guest will see the exact same CPU after migration. > > https://bugzilla.redhat.com/show_bug.cgi?id=1598151 > https://bugzilla.redhat.com/show_bug.cgi?id=1598162 Unfortunately this will break all ppc64 guests that have been defined without specifying a CPU model, because it will result in something like <cpu mode='custom' match='exact' check='partial'> <model fallback='allow'>power8</model> </cpu> being added to the domain XML, which in turn at runtime will cause error: internal error: Unknown CPU model power8