Re: [Qemu-devel] live migration between different qemu versions

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Alexey (alukardd@alukardd.org) wrote:
> Hi David.
> 
> On 2016-01-11 22:51, Dr. David Alan Gilbert wrote:
> >* Alexey (alukardd@alukardd.org) wrote:
> >>Hello.
> >
> >Hi,
> >
> >>I have two servers between which I need have live migration.
> >>
> >>First server have QEMU emulator version 2.3.0
> >>Second server have QEMU emulator version 2.5.0
> >>
> >>Migration command look like this:
> >>/usr/bin/virsh migrate --live DOMAIN_NAME --migrateuri
> >>tcp://second.server
> >>qemu+ssh://second.server/system --verbose
> >>
> >>I got next error on console:
> >>error: operation failed: migration job: unexpectedly failed
> >>
> >>And next error in log on second server:
> >>2016-01-11T15:07:12.888647Z qemu-system-x86_64: Length too large:
> >>/rom@genroms/efi-virtio.rom: 0x32000 > 0x2d000: Invalid argument
> >>2016-01-11T15:07:12.888685Z qemu-system-x86_64: error while loading
> >>state
> >>for instance 0x0 of device 'ram'
> >>2016-01-11T15:07:12.889733Z qemu-system-x86_64: load of migration
> >>failed:
> >>Invalid argument
> >>
> >>In my libvirt domain I have option <rom bar="off"/>.
> >>
> >>I need to do a live migration in any possible way. How can I do this
> >>one?
> 
> >Is the efi-virtio ROM that you're using on the two versions the same
> >identical size?

> No, I have different efi-virtio.rom files, and I try to find a way which
> allows me not to copy the same efi-virtio.rom to all servers.

Right, the error does look like it's just complaining about the ROM size:

  2016-01-11T15:07:12.888647Z qemu-system-x86_64: Length too large:
  /rom@genroms/efi-virtio.rom: 0x32000 > 0x2d000: Invalid argument

It copes with small variations, but as soon as it flips over a 4K (?)
boundary then it has nowhere to put the extra data coming from the
larger ROM.

> >Also, can you post the commandline that you're using please.
> I already done this in my first email: virsh migrate...
> >>/usr/bin/virsh migrate --live DOMAIN_NAME --migrateuri
> >>tcp://second.server
> >>qemu+ssh://second.server/system --verbose

I meant for the QEMU itself; but if we've already found the ROMs are
different sizes, lets fix that first and see how you go.

Dave

> 
> Regards,
> Alexey Mochkin.
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK