On 17/06/2015 13:54, 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.
>
> If you change prog_if migration fails.
No, it doesn't. The guest misbehaves maybe, but the migration format is
not affected.
Paolo
