Re: [Qemu-devel] [RFC] qemu-ga: Introduce guest-hibernate command

[Amit Shah <amit.shah@redhat.com>]

On (Fri) 09 Dec 2011 [10:22:25], Luiz Capitulino wrote:
> On Thu, 08 Dec 2011 21:18:00 -0600
> Michael Roth <mdroth@linux.vnet.ibm.com> wrote:
> 
> > On 12/08/2011 12:52 PM, Luiz Capitulino wrote:
> > > This is basically suspend to disk on a Linux guest.
> > >
> > > Signed-off-by: Luiz Capitulino<lcapitulino@redhat.com>
> > > ---
> > >
> > > This is an RFC because I did it as simple as possible and I'm open to
> > > suggestions...
> > >
> > > Now, while testing this or even "echo disk>  /sys/power/state" I get several
> > > funny results. Some times qemu just dies after printing that message:
> > >
> > >   "Guest moved used index from 20151 to 1"
> > >
> > > Some times it doesn't die, but I'm unable to log into the guest: I type
> > > username&  password but the terminal kind of locks (the shell doesn't run).
> > >
> > > Some times it works...

...

> > It doesn't seem to tell us much...but there's a bunch of successful 
> > reads before the final virtio_queue_notify, and that notify takes quite 
> > a bit longer than the previous ones. I can only speculate at this point, 
> > but I would guess this is when the guest has completed loading the saved 
> > memory from disk and it attempting to restore the previous state..
> > 
> > In the kernel there's a virtio_pci_suspend() PM callback that seems to 
> > get called around this time and restores the PCI config from 
> > virtio_pci_resume(). Could that be switching us to an older vring and 
> > throwing the QEMU side out of whack?
> 
> Not sure. But Amit has confirmed that it's a virtio bug and he's working
> on it. Right Amit?

Yes.  You can try the series at

https://lkml.org/lkml/2011/12/6/479

in the guest kernel to see it all work.

		Amit