Re: [linux-pm] Re: Hibernation considerations

Oliver Neukum
2007-07-20T21:33:25Z

Am Freitag 20 Juli 2007 schrieb Alan Stern:
> On Fri, 20 Jul 2007, Oliver Neukum wrote:
>
> > Am Freitag 20 Juli 2007 schrieb Alan Stern:
> > > Some drivers need the ability to schedule.  Some will need the ability
> > > to allocate memory (although GFP_ATOMIC is probably sufficient).  Some
> > > will need timers to run.
> >
> > Some will have to request firmware. It can add up to some megabytes.
> > In addition, if we don't freeze, some drivers, eg. video drivers, can
> > do allocations in the megabyte range.
> >
> > It seems to me that without the freezer we will end up with many drivers
> > needing a two step notification process. Furthermore there are requirements
> > on the order of shutting down system facilities, eg. device addition must
> > be stopped before drivers allocate firmware.
>
> These are really separate issues, since they refer to things that have
> to happen well before the memory snapshot is captured.
>
> We already have a pre-suspend notification available for drivers that
> need to allocate large amounts of memory.

Is that facility fine grained enough?

> You are correct about the need to delay/stop device addition. I don't
> know how this can be done in general; each code path calling
> device_add() may have to be treated individually.

What about the old API? Do we have to block module loading?
What happens if a scsi error handler is woken? If it cannot be woken,
how are errors handled?

Regards
Oliver