Re: apm_emulation regression

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

On Thu, 2007-12-13 at 12:40 +0100, Johannes Berg wrote:
> > > That basically means X will break. That's why X broke on the latest
> > > ubuntu until I whacked some new scripts in them to force console
> > > switching, among other things. Possibly other apps that relied
> > > on /dev/apm_bios to be notified of system suspend/resume broke as well.
> > 
> > Ah. I guess I never noticed because I had the scripts to do console
> > switching all along.
> 
> Actually, it just occurred to me that the *kernel* does a console switch
> when we use /sys/power/state, so maybe that is why I never had a problem
> rather than userspace doing a console switch (which it only started
> doing very recently)

The kernel console switching can be disabled and -is- by some distros.
For example, the problem I was having was when testing Gutsy before it
was final, the script to console switch wasn't in the right place for
powermac and didn't work. X wouldn't be suspended properly and the
machine would lockup.

In general, we should try to fix that, as other things might rely
on /dev/apm_bios doing the right thing.

Ben.