On 11/25/09 15:09, Michael S. Tsirkin wrote:
We were discussing features that are (mostly) not user-visible.
It is clear that if you have a user-visible change you have
a different machine, so you can not migrate.
Now if you fix a bug by changing savevm format, without user visible
changes you *also* can not migrate, but this does not make it into
feature or make it a good fit for machine description.
Well, it does fit into the machine description IMHO. When you want
migrate to a old qemu version you need to know what the old qemu version
understands, and the machine description for old qemu is a natural fit.
We still could make the use of this information optional though, so
savevm/migration could use either the most recent savevm format
(ignoring DeviceState->savevm_version) or the savevm format matching the
machine type (using DeviceState->savevm_version) depending on what the
user chooses.
cheers,
Gerd
