On Thu, Mar 21, 2013 at 02:42:23PM +0100, Paolo Bonzini wrote: > Il 21/03/2013 14:38, Stefan Hajnoczi ha scritto: > > There already is a guest RAM cloning mechanism: fork the QEMU process. > > Then you have a copy-on-write guest RAM. > > > > In a little more detail: > > > > 1. save non-RAM device state > > 2. quiesce QEMU to a state that is safe for forking > > 3. create an EventNotifier for live savevm completion signal > > 4. fork and pass completion EventNotifier to child > > 5. parent continues running VM > > 6. child performs vmsave of copy-on-write guest RAM > > 7. child signals completion EventNotifier and terminates > > 8. parent raises live savevm completion QMP event > > Forking a threaded program is not so easy, but it could be done if the > child is very simple and only uses syscalls to communicate back with the > parent:
On Linux you should be able to use clone(2) to spawn a thread with copy-on-write memory. Too bad it's not portable because it gets around the messy fork issues. Stefan
