Re: [PATCH for-7.1] hw/mips/malta: turn off x86 specific features of PIIX4_PM

[Peter Maydell]

On Mon, 8 Aug 2022 at 18:57, BB <shentey@gmail.com> wrote:
> Am 8. August 2022 14:15:40 MESZ schrieb Igor Mammedov <imammedo@redhat.com>:
> >On Wed, 3 Aug 2022 19:26:30 +0200
> >While refactoring we should keep migration stream compatible with older
> >QEMU versions (we must not regress widely x86 code path). Which might be
> >tricky in this case.
>
> Does this particular fix make future compatibility harder or easier or is it 
> that hard already? IIUC it omits the hotplug bits in the vm state for Malta 
> which is what one would expect there, right?

This patch's fix only affects Malta. It is (I suspect but have
not tested) a migration compat break on Malta, but we don't
care about cross-version migration compat for that board anyway.
Migration compat matters (to a first approximation) only for
those boards which have versioned machine types (eg pc-7.0,
pc-7.1, etc). For all other machine types we retain compat
only if it's easy.

thanks
-- PMM