Re: [linux-pm] [RFC] Add some hooks to generic suspend code

[Pavel Machek <pavel@ucw.cz>]

Hi!

> > > While consolidating the powermac suspend to ram and suspend to disk
> > > implementations to properly use the new framework in kernel/power, among
> > > others, I ended up with the need of adding various callbacks to
> > > kernel/power/main.c. Here is a patch adding & documenting those.
> > > 
> > > The reasons I need them are:
> > > 
> > > 	/* Call before process freezing. If returns 0, then no freeze
> > > 	 * should be done, if 1, freeze, negative -> error
> > > 	 */
> > > 	int (*pre_freeze)(suspend_state_t state);
> > > 
> > > I'm using that one for calling my "old style" notifiers (they are beeing phased
> > > out but I still have a couple of drivers using them). The reason I do that here
> > > is because that's how my APM emulation hooks, and that code interacts with userland
> > > (to properly signal things like X of the suspend process), so I need to do that
> > > before we freeze processes.
> > 
> > This should not be needed in future, right? Could it be marked
> > deprecated or something?
> 
> Not really ... I need to notify userland before we freeze processes.

Why do you need it? Do you initiate suspend without userland asking
you to?

Anyway, it should not be arch-dependend. We need one good mechanism of
notifying userland, not one per architecture.

> > > 	/* called after unfreezing userland */
> > > 	void (*post_freeze)(suspend_state_t state);
> > > 
> > > That one is the mirror of pre-freeze, gets called after userland has been re-enabled,
> > > it also calls my old-style notifiers, which includes APM emulation, which is important
> > > for sending the APM wakeup events to things like X.
> > 
> > Could this be marked deprecated, too?
> > 
> > Alternatively, proper way of notifying X (etc) should be created, and
> > done from generic code....
> 
> Sure, ideally. However, existing X knows how to deal with APM events,
> and thus APM emulation is an important thing to get something that
> works. Pne thing I should do is consolidate PPC APM emu with ARM one as
> I think Russell improve my stuff significantly.

Perhaps we need apm emulation on i386, too?
									Pavel
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