Hi! We had a few examples when a bugfix required for a stable series but it can't be applied because it breaks migration. One recent example is https://bugs.launchpad.net/ubuntu/+source/qemu/+bug/2131822 - the fix has been cherry-picked for 10.0.x but had to be reverted.
I wonder if we can, sometimes, introduce additional machine types for stable series. In this case, it might've been an intermediate 10.0.4 machine type, which is between 10.0 and 10.1 - with this additional change included. If this machine is known to both 10.1-tobe and 10.0.4+, all migration should work fine in both directions. It is exactly the same situation and solution which has been implemented by ubuntu in the end, but using their own, distribution-specific, machine types. Why can't we do the same in upstream qemu? And yes, that would be a very rare case. Thanks, /mjt
