Re: [Qemu-devel] [PATCH v5 30/45] Postcopy: Postcopy startup in migration thread

[Dr. David Alan Gilbert]

* Paolo Bonzini (address@hidden) wrote:
> 
> 
> On 26/03/2015 12:05, Dr. David Alan Gilbert wrote:
> >>> > > +    qemu_system_wakeup_request(QEMU_WAKEUP_REASON_OTHER);
> >>> > > +    *old_vm_running = runstate_is_running();
> >> > 
> >> > I think that needs some explanation.  Why are you doing a wakeup on
> >> > the source host?
> > This matches the existing code in migration_thread for the end of precopy;
> > Paolo's explanation of what it does is here:
> > https://lists.gnu.org/archive/html/qemu-devel/2014-08/msg04880.html
> 
> The more I look at it, the more I'm convinced it's working by chance or
> not working at all.

Do you mean in general or in the postcopy case?

> Here we probably need to do only the notifier_list_notify +
> qapi_event_send_wakeup.

Do you mean a :
   wakeup_reason = QEMU_WAKEUP_REASON_OTHER;
   notifier_list_notify(&wakeup_notifiers, &wakeup_reason);
   wakeup_reason = QEMU_WAKEUP_REASON_NONE;
   qapi_event_send_wakeup(&error);

which I guess would need wrapping up in vl.c

(It's not really clear to me what this stuff does even with
your previous explanation; if it's to do with migrating
something suspended-to-ram I guess a postcopy is possible
but it doesn't seem that sensible to use postcopy for a
machine with a CPU that isn't running).

Dave

> 
> Paolo
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK