* Peter Maydell (peter.mayd...@linaro.org) wrote: > On 7 August 2018 at 16:05, Juan Quintela <quint...@redhat.com> wrote: > > Peter Maydell <peter.mayd...@linaro.org> wrote: > >> So it's better to use a needed-always subsection, which will give > >> the desired behaviour: > >> * new QEMU -> new QEMU: state is always migrated > >> * old QEMU -> new QEMU: migration doesn't fail, and guest > >> will work assuming it didn't care about this corner of the > >> device's functionality (the device will end up with state > >> as it was at reset, or possibly special-cased via > >> pre_load/post_load hooks for the "section not present" case) > > > > we break by definiton new QEMU -M <old machine type> into old QEMU. > > Is that supposed to work? I always thought that we never > supported migration back to an older QEMU version like that.
Downstream we do a lot of hard work to keep that working for versioned machine types; using subsections makes this a lot easier and if it's done right in the first place then it works upstream as well. > In any case, for all the devices here the machine types are > not versioned. Right. Dave > thanks > -- PMM -- Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
