Re: [Qemu-devel] [RFC PATCH 0/4] Fix subsection ambiguity in the migration format

[Christoph Hellwig]

On Sun, Jul 31, 2011 at 11:43:08PM +0300, Dor Laor wrote:
> /me caught off guard. I wonder why it wasn't converted to VMSTATE before?  
> virtio is one of the key devices, it's not just random forgotten one that 
> might not care about migration.

It just shows the extent of incomplete transitions in qemu.  Given how
much burden incomplete transitions have on software projects we should
try to minimize them in qemu.  That is if people add a new API we need
to have a clear roadmap when it's going to be finished, and more importantly
what the consequence of not finishing it are instead of leaving it half
done.  I think the way the Linux kernel handles API transitions is something
qemu could borrow from. For most of them it's simply expected to do a simple
conversion of all users of an API to the new equivalent, maybe it in
simplistic and dumb way, but at least a transition.  Combined with a
deprectation schedule for unused drivers that seems to do wonders, although
of course even the Linux kernel is slacking in some areas.