On Tue, 21 Jul 2026 at 20:01, Michael Tokarev <[email protected]> wrote: > > On 7/15/26 16:18, Tao Ding wrote: > > Add ucr2 from imx_serial to vmstate, and increment the version_id. > > > > Migrating on sabrelite can reproduce this issue: > > 1. Prepare the U-Boot required for sabrelite. (according to sabrelite.rst) > > 2. Compile qemu > > $ mkdir build && cd build && ../configure --target-list="arm-softmmu" > > && make -j4 > > 3. Start sabrelite and prepare for migration > > $ ./build/qemu-system-arm -M sabrelite \ > > -smp 1 -m 1G -display none -serial null -serial mon:stdio \ > > -kernel ~/u-boot > > 4. Enter qemu monitor after uboot. (ctrl + a + c) > > (qemu) stop > > (qemu) xp /4wx 0x021e8084 > > 021e8084: 0x00004027 0x00000784 0x00008000 0x00000a01 > > (qemu) migrate -d file:vmstate > > (qemu) q > > > > Load the migrated vmstate, before repairing: > > > > $ ./build/qemu-system-arm -M sabrelite \ > > -smp 1 -m 1G -display none -serial null -serial mon:stdio \ > > -kernel ~/u-boot -incoming file:vmstate > > > > (ctrl + a + c) > > QEMU 11.0.50 monitor - type 'help' for more information > > (qemu) xp /4wx 0x021e8084 > > 021e8084: 0x00000004 0x00000784 0x00008000 0x00000a01 > > (qemu) q > > > > It can be found that the data for address 0x021e8084 (register of usr2 in > > imx_serial of sabrelite) > > is not the data before the migration. > > > > After being repaired: > > $ ./build/qemu-system-arm -M sabrelite \ > > -smp 1 -m 1G -display none -serial null -serial mon:stdio \ > > -kernel ~/u-boot -incoming file:vmstate > > (ctrl + a + c) > > QEMU 11.0.50 monitor - type 'help' for more information > > (qemu) xp /4wx 0x021e8084 > > 021e8084: 0x00004027 0x00000784 0x00008000 0x00000a01 > > > > Signed-off-by: Tao Ding <[email protected]> > > > Somehow, this grow Cc: qemu-stable@ in the final version which was > applied as v11.1.0-rc0-68-g8833ff95eaf. I don't think this is a > good candidate for the stable series, since this fix changes the > migration stream format, which is very difficult to do in the stable > series.
On the other hand it goes from "migration doesn't work" to "migration works" for a typical guest :-) But I agree it's probably better to avoid migration breaks in stable branches unless they're fixing something really critical. -- PMM
