* Jason Wang (jasow...@redhat.com) wrote: > > > On 2016年10月17日 17:01, Dr. David Alan Gilbert wrote: > > * Stefan Weil (s...@weilnetz.de) wrote: > > > On 10/14/16 10:25, Dr. David Alan Gilbert wrote: > > > > * Stefan Weil (s...@weilnetz.de) wrote: > > > > > Instead of allocating a VMStateDescription for each NIC instance, > > > > > the code now uses a single constant VMStateDescription for all > > > > > instances. That implies that the name field is always the same. > > > > Doesn't this break migration compatibility? > > > > > > > > You might be able to get around that (in the forward direction only) > > > > by adding an entry to qdev_alias_table but I'm not sure. > > > > > > > > Dave > > > I'm not an expert for migration (never used it myself). > > > > > > Is migration compatibility a must, even for non default settings > > > like the NICs implemented by eepro100.c? I assume that applications > > > which use migration will usually run with an e1000 NIC. > > > > > > Or can we break migration compatibility and add that information > > > to the release notes? > > We normally keep migration compatibility for all devices > > in the forward direction unless it's something really obscure; > > I don't think an e100 is. > > > > > How does e1000 handle migration if QEMU was started with a > > > e1000-82544gc NIC and migrated to a e1000-82545em NIC? > > That's not required to work; you're required to have the same device > > configuration on the destination as the source. > > > > $ qemu-system-x86_64 -nographic -device e1000-82544gc > > (qemu) migrate "exec:cat > t.mig" > > > > $ qemu-system-x86_64 -nographic -device e1000-82545em -incoming "exec:cat > > t.mig" > > qemu-system-x86_64: get_pci_config_device: Bad config data: i=0x2 read: c > > device: f cmask: ff wmask: 0 w1cmask:0 > > qemu-system-x86_64: error while loading state for instance 0x0 of device > > '0000:00:04.0/e1000' > > qemu-system-x86_64: load of migration failed: Invalid argument > > > > Now, note that what's happening here is that e1000 is doing a similar > > trick to what you're doing - i.e. all devices end up getting > > migrated as 'e1000' in the device string (0000:00:04.0/e1000). > > > > The scheme you end up with is OK, but the problem is it's just > > different from what we have now, so existing streams > > with device names like '0000:00:04.0/i82550' won't load. > > > > Dave > > > > Can we bump the version here? Or just use v1 for the fixing.
The problem isn't the version of the contents of the section, it's the naming of the devices. I think you can work around it by adding aliases for the old names. Dave > Thanks -- Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
