[Spice-devel] migration and qemu/spice versions

[Gerd Hoffmann]

On 09/06/11 11:54, Yonit Halperin wrote:
> Hi,
> I'm working on the changes discussed in the thread "changing the timing
> of spice client linking in migration (RHBZ #725009)".
> In order to be backward compatible with respect to spice-server and qemu
> we need
> (1) new qemu calling the old switch_host if the server is old (instead
> of spice_server_migrate_end)

New qemu can just call spice_server_migrate_start() and check the return 
value.  If it succeeds just go on with seamless migration, otherwise 
(return value < 0) fallback to switch-host.

> (2) new spice-server using the old switch host (and not the new
> migration mechanism) if qemu is old.

Old qemu which can't handle seamless migration will never ever call 
spice_server_migrate_start().

cheers,
   Gerd