On 11/02/2016 17:33, Michael S. Tsirkin wrote: >> They won't start unless the QEMU command-line is changed, because >> they are using a feature QEMU won't support anymore. Why is that >> a problem? > > We don't support installing one machine type, then switching.
Uhm, we definitely support people using qemu directly with no -M option at all with installed VMs. That's the same as switching machine types every time a new QEMU is released. At least RHEV supports switching machine types, even RHEL6->RHEL7. There are constraints on when to do that because it affects the whole datacenter, but it is done routinely because each RHEV release only supports two machine types IIRC. Paolo
