Re: Re: standby to disk transition

[Nigel Cunningham <nigel@suspend2.net>]

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Hi.

On Tuesday 14 March 2006 07:24, Pavel Machek wrote:
> On Po 13-03-06 13:33:18, Dave Jones wrote:
> > On Mon, Mar 13, 2006 at 10:13:32AM +0100, Pavel Machek wrote:
> >  > On Po 13-03-06 04:07:59, Adam Belay wrote:
> >  > > On Mon, Mar 13, 2006 at 09:50:42AM +0100, Pavel Machek wrote:
> >  > > > On Po 13-03-06 03:48:11, Adam Belay wrote:
> >  > > > > The timeout feature could be done using the ACPI alarm
> >  > > > > interface, but there's no reliable way of knowing how long the
> >  > > > > system can remain in a suspend state on the x86 mobile platform,
> >  > > > > so waking up at the right time would be tricky if not
> >  > > > > impossible.
> >  > > >
> >  > > > Make it an hour... System should be able to stay suspended for an
> >  > > > hour. IIRC Apple did something like this? I'd just be slightly
> >  > > > worried about machine waking up itself just when you hit the
> >  > > > turbulence in the airplane, or something like that.
> >  > >
> >  > > Hmm, but let's say the battery is 40% charged.  Then it's not very
> >  > > clear if it will last an hour.  All of a sudden the issue becomes
> >  > > system specific, or it may even depend on things like whether
> >  > > wake-on-lan is enabled, right?
> >  >
> >  > 40% battery should still last 10+ hours in suspend-to-RAM, unless
> >  > something is wrong.
> >  >
> >  > You *could* wakeup every minute or so to check the battery state; some
> >  > PDAs actually do that.
> >
> > if suspend-to-disk is fast enough, you could just *always* write
> > to disk, even if we're doing S3.  If power runs out, you then have a
> > valid resume image on-disk.  iirc, this is what Windows does.
>
> Yep, I call that suspend-to-both. It is planned, but not really
> trivial, and I'm a little busy. If someone wants to help....

Actually it is really easy to do Pavel, so long as your code already has the 
error handling that allows it to back out nicely. Just enter S3 at the point 
where you'd otherwise power down, then on resume act like an error occured at 
the last moment and back out.

Regards,

Nigel

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