Re: Hardware state saving & X

[Pavel Machek <pavel-AlSwsSmVLrQ@public.gmane.org>]

Hi!

> > > Well, it depends on what X (and in general userspace) needs to know on a 
> > > power-state transition. Alan, how does/will X behave differently for each 
> > > power state that we can enter? 
> > 
> > Different scripts should run on apm -s (BIOS saves most of hw state)
> > and S3 (we have to save most of hw state).
> 
> The fact that different behavior exists is completely obvious (refer to 
> the question and documentation). The question was *how* it was different 
> from a userpsace perspective. I.e. what exactly is saved, and what isn't. 
> 
> Under APM, the BIOS handles the state transition, but it does not know 
> each device initimately, so the OS still has to handle some of the device 
> state. 

I guess you answered yourself ;-). X is hardware driver. On some
machines, video is handled by bios during apm -s. That's not the case
during S3. Therefore X wants to know if it should do hardware saving
or not.

[Of course, X might want to save allways (simulated console switch).]

> Video devices have an int10 call to save/restore state, which is what the 
> APM BIOS uses.

Could you elaborate? I'm not aware of int10 call doing that... That
would solve S3 video problems, right? I was told that we can't call
int10 at all from real mode because pci might not yet be intialized
during acpi_wakeup.S; but it works on machines I have here.

								Pavel
-- 
When do you have a heart between your knees?
[Johanka's followup: and *two* hearts?]


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