Re: [Qemu-devel] Re: Live migration protocol, device features, ABIs and other beasts

[Gerd Hoffmann]

> >   And this is also the trivial part to describe: I want a
> > machine like the one in qemu-0.11.
>
> Yes, but there might be a ton of reasons to want a
> machine like the one in qemu 0.11.
> The need to migrate to old qemu is very rare,
> it is a completely separate decision
> one might take long after starting qemu,

Doesn't work.  If you have a qemu 0.11 machine, a virtio nic and your 
guest uses MSI-X you simply can't migrate to qemu 0.10.  End of story.

If you want to be able to migrate to 0.10 you have to start in 0.10 
compat mode with MSI-X disabled.  So IMHO it does makes sense to tie the 
savevm format to -M pc-<version>.

cheers,
  Gerd