Re: Hibernation considerations

Rafael J. Wysocki
2007-07-17T21:38:34Z

On Tuesday, 17 July 2007 23:27, Jeremy Maitin-Shepard wrote:
> david@lang.hm writes:
>
> [snip]
>
> >> How do you guarantee that no tasks are scheduled when you get back to the
> >> hibernated kernel?
>
> > just don't schedule any userspace tasks. all you need to do is to execute the
> > ACPI sleep functions. you normally do that after stopping userspace
> > anyway.
>
> What does "stopping userspace" mean? You already said it does not mean
> disabling interrupts. But using the freezer is also not an option,
> since the avoidance of that is the main reason for the kexec approach in
> the first place.
>
> [snip]
>
> >> Well, not exactly. If your battery runs out of power while you're suspended,
> >> but you have the image saved, it's still better to restore from the image,
> > even
> >> if something may not work correctly after the restore, than to risk a loss of
> >> data.
>
> > if things don't work correctly you are still risking the loss of data, the user
> > just doesn't know it.
>
> It should be possible on any system to do a hibernate followed by a
> shutdown (and then resume properly, without any problems). Thus, for
> handling suspend to both, you resume as if the system had been shutdown,
> rather than resuming as if the system came from S4.

Exactly.

Greetings,
Rafael

--
"Premature optimization is the root of all evil." - Donald Knuth