[libvirt] [PATCH] Add support for disabling S3 and S4 states

Daniel P. Berrange berrange at redhat.com
Mon Jul 30 14:48:11 UTC 2012


On Mon, Jul 30, 2012 at 02:43:33PM +0200, Martin Kletzander wrote:
> On 07/30/2012 02:33 PM, Daniel P. Berrange wrote:
> > On Mon, Jul 30, 2012 at 02:25:04PM +0200, Martin Kletzander wrote:
> >> There a two new elements in <features> implemented, which control what
> >> ACPI sleeping states will be advertised. The default is to have both
> >> states enabled, so this means no change for current machines.
> > 
> >> diff --git a/docs/schemas/domaincommon.rng b/docs/schemas/domaincommon.rng
> >> index b7562ad..859cb26 100644
> >> --- a/docs/schemas/domaincommon.rng
> >> +++ b/docs/schemas/domaincommon.rng
> >> @@ -2788,6 +2788,16 @@
> >>                <empty/>
> >>              </element>
> >>            </optional>
> >> +          <optional>
> >> +            <element name="disable_s3">
> >> +              <empty/>
> >> +            </element>
> >> +          </optional>
> >> +          <optional>
> >> +            <element name="disable_s4">
> >> +              <empty/>
> >> +            </element>
> >> +          </optional>
> >>          </interleave>
> >>        </element>
> >>      </optional>
> > 
> > This is not very nice design.  With this if an app wants to request
> > S3, and have an error if it is not supported, they can't do that.
> > 
> 
> I'm sorry, but I don't quite understand what do you mean. If the guest
> wants to go to S3, there is (of course) no difference between the state
> not being supported or the support being disabled. If an application
> wants to request the guest to go to S3 through libvirt, then it will get
> an appropriate message (disabled/not supported). Having one more option
> means just setting the QEMU parameter to the default value (0).

I'm talking about the host mgmt's POV. An application creating a guest
may want to guarantee that S3 is available to the guest. With your
proposal, there is no way they can do that - since there is no explicit
element in the XML to request S3. So the mgmt app may get a guest with
S3, or it may not - it has no way of being sure. The only thing a mgmt
app can do is forcably disable S3 .

Daniel
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