Re: [linux-pm] Re: Hibernate after alarm wakes from STR

[Nigel Cunningham <nigel@nigel.suspend2.net>]

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Hi.

On Wednesday 11 July 2007 20:09:04 Rafael J. Wysocki wrote:
> On Wednesday, 11 July 2007 05:14, Nigel Cunningham wrote:
> > On Wednesday 11 July 2007 11:59:48 Matthew Garrett wrote:
> > > On Wed, Jul 11, 2007 at 11:39:37AM +1000, Nigel Cunningham wrote:
> > > 
> > > > Yeah, that is a bit confusing. At the moment, I'm doing the suspend to 
ram 
> > > > platform dependent preparation and cleanup in this scenario. That's 
> > > > definitely the right thing to do in the case where we write an image, 
then 
> > > > suspend to ram, wake and continue working without running running out 
of 
> > > > battery (writing the image is redundant in that case). Where we end up 
> > > > properly powering down after suspending to ram, I believe we don't run 
the 
> > > > pm_ops->finish after doing the atomic restore when resuming the image.
> > > 
> > > I'm not convinced this can work terribly well. It's not unlikely that 
> > > hardware will need different state stored over different types of 
> > > suspend. Can you separate out the saving of kernel memory and userspace 
> > > memory, then resume/suspend/save the new kernel state without touching 
> > > the userspace state?
> > 
> > Yeah, we could redo and resave the atomic copy, but it doesn't seem to be 
> > necessary at the moment; it has been working reliably, regardless of which 
> > combination of events occurs. If/when I come across a case where we have 
> > problems, I'll give resaving the atomic copy a go.
> > 
> > (Thinks some more). Ah, I think we're already doing the right thing, if 
I'm 
> > recalling the order of actions right. If I'm remembering correctly, prior 
to 
> > the atomic copy, we do hibernation prep, then after the atomic copy, 
> > hibernation cleanup. Then, if suspending to ram, we do the 
prep/enter/cleanup 
> > after the image has finished writing. If we lose power from suspend to 
ram, 
> > it doesn't matter because we're just doing a normal resume then, with the 
> > hibernation cleanup post atomic restore machine the prep that was done 
prior 
> > to the atomic copy.
> > 
> > To summarise:
> > 
> > Hibernate + STR + full wake.
> >  Hibernation prep
> >  (Atomic copy)
> >  Hibernation cleanup
> >  STR prep
> >  STR enter
> >  STR cleanup		
> >  Remove hibernation image
> > 
> > Hibernate + STR + poweroff + hibernate resume:
> > 
> >  Hibernation prep
> >  (Atomic copy)
> >  Hibernation cleanup
> >  STR prep
> >  STR enter
> >  <power out> or <STR wake + power off> (STR prep/enter no longer matters)
> >  (Fresh boot)
> >  Atomic restore
> >  Hibernation cleanup (matching prep at start)
> >  Remove hibernation image
> 
> Yes, I think that this is the right ordering, but for some graphics adapters
> we need to do some tricks from the user space before 'STR prep' and after
> 'STR cleanup', which is theoretically possible with uswsusp.

Yeah. I haven't done it yet, but intend to implement that using userui.

Regards,

Nigel
-- 
Nigel Cunningham
Christian Reformed Church of Cobden
103 Curdie Street, Cobden 3266, Victoria, Australia
Ph. +61 3 5595 1185 / +61 417 100 574
Communal Worship: 11 am Sunday.

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