Re: Hibernation considerations

Rafael J. Wysocki
2007-07-15T22:30:44Z

On Sunday, 15 July 2007 14:58, Dr. David Alan Gilbert wrote:
> * Rafael J. Wysocki (rjw@sisk.pl) wrote:
>
> > (5) Hibernation should be transparent from the applications' point of view
> >
> > Generally, applications should not notice that hibernation took place.
> > [Note that I don't regard all processes as applications and I think that
> > there may be processes which need to handle the hibernation in a special
> > way.] Ideally, for example, if some audio is being played when a
> > hibernation starts, the audio player should be able to continue playing the
> > same audio after the restore from the point in which it has been
> > interrupted by the hibernation. Also, the CPU affinities and similar
>
> That would be _so_ embarrassing in a library; I'd rather the audio
> player had the opportunity to consider whether restarting was a good idea.
>
> > (6) State of devices from before hibernation should be restored, if possible
> >
> > If possible, during a restore devices should be brought back to the same
> > state in which they were before the corresponding hibernation. Of course
> > in some situations it might be impossible to do that (eg. the user
> > connected the hibernated system to a different IP subnet and then
> > restored), but as a general rule, we should do our best to restore the
> > state of devices, which is directly related to point (5) above.
>
> Or the user unplugs their flash drive after hibernation rather than before.
>
> Two things which I think would be nice to consider are:
> 1) Encryption - I'd actually prefer if my luks device did not
> remember the key accross a hibernation; I want to be forced to
> reenter the phrase. However I don't know what the best thing
> to do to partitions/applications using the luks device is.

Encryption is possible with both the userland hibernation (aka uswsusp) and
TuxOnIce (formerly known as suspend2). Still, I don't consider it as a "must
have" feature for a framework to be generally useful (many users don't use it
anyway).

> 2) Some level of debugging needs to be available so that users can
> provide something so you can see why something hasn't hibernated
> or why (as in the case of this tosh laptop) it still takes power
> during hibernation.

I agree.

Greetings,
Rafael

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