Hi Eric,
On Fri, 2014-03-28 at 14:07 -0600, Eric Blake wrote:
> On 03/28/2014 10:32 AM, Cédric Bosdonnat wrote:
> > From: Cédric Bosdonnat <cedric.bosdonnat@xxxxxxx>
> >
> > pm-is-supported is the only thing needed in pm-utils, better get rid of
> > it since systemd is heavily used for libvirt.
> > ---
> > src/util/virnodesuspend.c | 34 ++++++++++++++++++++--------------
> > 1 file changed, 20 insertions(+), 14 deletions(-)
>
> You also need to modify libvirt.spec.in to drop the dependency.
Oh, yes, I forgot about this one.
> >
> >
> > + if (virFileReadAll("/sys/power/state", 1024, &buf) < 0)
> > + goto cleanup;
> > +
> > + states = virStringSplit(buf, " ", 0);
> > +
> > + canSuspend = (virStringArrayHasString(states, "mem") ||
> > + virStringArrayHasString(states, "standby"));
> > + canHibernate = virStringArrayHasString(states, "disk");
>
> pm-is-supported checks a bit more than what your replacement checks.
>
> For suspend, it declares yes if any of these succeed:
> grep -q mem /sys/power/state
> [ -c /dev/pmu ] && pm-pmu --check
> grep -q standby /sys/power/state
The only missing bit here is the /dev/pmu one and that one is a powermac
only thing... so probably not something really bothering us.
> For hibernate, it requires that BOTH of these succeed:
> [ -f /sys/power/disk ]
> grep -q disk /sys/power/state
Oh... I overlooked the /sys/power/disk check, I'll add it.
> For hybrid, it requires that all three succeed:
> [ -f /sys/power/disk ] && \
> grep -q disk /sys/power/state && \
> grep -q suspend /sys/power/disk
Same here.
> as well as having fallback code to fake a hybrid sleep by joining the
> other two states.
>
>
> > +
> > switch (target) {
> > case VIR_NODE_SUSPEND_TARGET_MEM:
> > - cmd = virCommandNewArgList("pm-is-supported", "--suspend", NULL);
> > + *supported = canSuspend;
> > break;
> > case VIR_NODE_SUSPEND_TARGET_DISK:
> > - cmd = virCommandNewArgList("pm-is-supported", "--hibernate", NULL);
> > + *supported = canHibernate;
> > break;
> > case VIR_NODE_SUSPEND_TARGET_HYBRID:
> > - cmd = virCommandNewArgList("pm-is-supported", "--suspend-hybrid", NULL);
> > + *supported = canSuspend && canHibernate;
>
> I'm not sure if your simpler checks will cause us to declare an action
> unsupported on systems where it was previously declared supported by
> pm-is-supported. I think the idea makes sense, but I'd like a second
> opinion that we aren't hurting ourselves by doing fewer checks than what
> we are replacing.
>
I'm not a power management expert either, so any other opinion is highly
appreciated. In the version I have here the hybrid case checks whether
/sys/class/rtc/rtc0/wakealarm is writeable.
--
Cedric
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