* Igor Mammedov (imamm...@redhat.com) wrote: > On Wed, 4 Mar 2020 12:27:48 -0500 > Igor Mammedov <imamm...@redhat.com> wrote: > > > Migration from QEMU(v4.0) fails when using 3.1 or older machine > > type. For example if one attempts to migrate > > QEMU-2.12 started as > > qemu-system-ppc64 -nodefaults -M pseries-2.12 -m 4096 -mem-path /tmp/ > > to current master, it will fail with > > qemu-system-ppc64: Unknown ramblock "ppc_spapr.ram", cannot accept > > migration > > qemu-system-ppc64: error while loading state for instance 0x0 of device > > 'ram' > > qemu-system-ppc64: load of migration failed: Invalid argument > > > > Caused by 900c0ba373 commit which switches main RAM allocation to > > memory backends and the fact in 3.1 and older QEMU, backends used > > full[***] QOM path as memory region name instead of backend's name. > > That was changed after 3.1 to use prefix-less names by default > > (fa0cb34d22) for new machine types. > > *** effectively makes main RAM memory region names defined by > > MachineClass::default_ram_id being altered with '/objects/' prefix > > and therefore migration fails as old QEMU sends prefix-less > > name while new QEMU expects name with prefix when using 3.1 and > > older machine types. > > > > Fix it by forcing implicit[1] memory backend to always use > > prefix-less names for its memory region by setting > > 'x-use-canonical-path-for-ramblock-id' > > property to false. > > > > 1) i.e. memory backend created by compat glue which maps > > -m/-mem-path/-mem-prealloc/default RAM size into > > appropriate backend type/options to match old CLI format. > > > > Fixes: 900c0ba373 > > Signed-off-by: Igor Mammedov <imamm...@redhat.com> > > Reported-by: Lukáš Doktor <ldok...@redhat.com> > > > ping, > > so we don't forget to merge it
I'm queueing this. > > --- > > CC: ldok...@redhat.com > > CC: marcandre.lur...@redhat.com > > CC: dgilb...@redhat.com > > --- > > softmmu/vl.c | 3 +++ > > 1 file changed, 3 insertions(+) > > > > diff --git a/softmmu/vl.c b/softmmu/vl.c > > index 5549f4b619..1101b1cb41 100644 > > --- a/softmmu/vl.c > > +++ b/softmmu/vl.c > > @@ -2800,6 +2800,9 @@ static void create_default_memdev(MachineState *ms, > > const char *path) > > object_property_set_int(obj, ms->ram_size, "size", &error_fatal); > > object_property_add_child(object_get_objects_root(), > > mc->default_ram_id, > > obj, &error_fatal); > > + /* Ensure backend's memory region name is equal to mc->default_ram_id > > */ > > + object_property_set_bool(obj, false, > > "x-use-canonical-path-for-ramblock-id", > > + &error_fatal); > > user_creatable_complete(USER_CREATABLE(obj), &error_fatal); > > object_unref(obj); > > object_property_set_str(OBJECT(ms), mc->default_ram_id, > > "memory-backend", > > -- Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK