Gerd Hoffmann wrote:
On 12/18/09 15:35, Anthony Liguori wrote:
I know this series carries a good bit of risk but I'd like to bring it
in 0.12.0. Because this has a guest visible change to the PCI devices,
we cannot carry it in stable-0.12 post release and I think the
functionality it brings it's very important.
The guest visible change automatically raises the question:
Do we need to do something for -M pc-0.11? Like loading the pci roms
via fw_cfg too so the guest doesn't see the new pci rom bar?
Yes, we do. We can fix that problem as a stable-0.12 update though.
Right now, migration with pc-0.11 is broken in other areas too.
Oh, and while thinking about compatibility issues: What about
migration? I think we have to save rom_offset in case $pcidevice has
a rom bar, otherwise your roms are gone after migration. Which you
wouldn't notice until reboot though.
It's really unclear to me the best way to handle live migration. The
rom_offset is not enough because unfortunately it's not stable after
invocations of qemu. I think we're going to have to actually save the
some contents with the PCIDevices.
For 0.13, we need to change the way that we migrate memory to fix this
problem properly.
Is 0.11 -> 0.12 migration supposed to work? That could become quite
nasty too. But maybe that is impossible anyway due to the switch to
seabios?
In theory, it should work. SeaBIOS should not be a guest visible change
because the guest should not depend on what BIOS we're using. While
it's probably debatable about whether that's true, what's really
important is whether it's actually functional. IOW, can we migrate,
reboot Windows, and not have Windows freak out about the underlying
machine changing.
If we can make the migration work, I suspect it won't be until 0.12.3 or
0.12.4.
Regards,
Anthony Liguori
