Re: Hibernation considerations

Rafael J. Wysocki
2007-07-20T10:59:42Z

On Friday, 20 July 2007 06:40, Al Boldi wrote:
> Rafael J. Wysocki wrote:
> > On Wednesday, 18 July 2007 16:29, Alan Stern wrote:
> > >
> > > Never mind. It seems clear that this approach will suffer the same
> > > drawback as the proposal for removing the freezer from the
> > > suspend-to-RAM pathway. Namely, device drivers will have to be changed
> > > to prevent user I/O requests from proceeding while devices are supposed
> > > to be quiescent or in a low-power state.
> >
> > I agree.
> >
> > > If a driver fails to handle this properly, its device could be
> > > reactivated in order to service a user request before the memory
> > > snapshot is made. This could easily ruin the snapshot.
> >
> > That's why I've been saying for quite some time that we first need to take
> > care of the drivers. :-)
> >
> > IMO we've reached the point at which, whatever we want to do next, the
> > drivers are in the way.
>
> Correct, but only if we want ACPI support.

No, in general.

> Granted, we need a separation of
> the hibernate/suspend PM functions, but in the absence of ACPI, all we need
> right now are dump/restore routines for the crashkernel.

IMO you aren't right, but I guess there's no point in trying to convince you.

> Next, we should be looking into reducing the kexec'd kernel environment size,
> which currently, at 16MB, is way too big, and even at 1MB would be
> problematic for small systems.
>
> So, ACPI should really be the least of our worries, and the reason why people
> are fixating on ACPI is probably because they have nothing else to fixate
> on.

Yeah, right. Please read the $subject message again. And sorry, but IMO your
previous replies to it haven't addressed any of the original points.

Greetings,
Rafael

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