On 17/06/2015 13:45, Michael S. Tsirkin wrote:
>> > Where, in the specific case of migration?
> Just look at hour compat flags.
>
> For example (intentionally using serial here):
> {\
> .driver = "pci-serial",\
> .property = "prog_if",\
> .value = stringify(0),\
> },\
> {\
> .driver = "pci-serial-2x",\
> .property = "prog_if",\
> .value = stringify(0),\
> },\
> {\
> .driver = "pci-serial-4x",\
> .property = "prog_if",\
> .value = stringify(0),\
> },\
>
> apparently some clients check the specific prog if
> value, completely breaking if the value was incorrect.
> So we fixed it for new machine types but not old ones.
That has nothing to do with migration.
Paolo
