Re: [ACPI] Radeon S3/resume: VGA ROM POST from kernel

[Pavel M. <pa...@uc...>]

Hi!

> Pavel> Agreed, I like this patch.
> 
> Cool... Let's see if it's still like that when I've explained how it
> works.

:-))))

> Pavel> If you are adding comment with function name, you should at least
> Pavel> explain what the function does... or not add the comment at all.
> 
> Sure. Ditto for acpi_restore_state from the stock kernel sources that
> I started with:-)

Okay, I'll fix that.

> >> testl	$1, video_flags - wakeup_code
> >> jz	1f
> >> +	movw	video_flags - wakeup_code + 2, %ax
> >> lcall   $0xc000,$3
> 
> Pavel> Are you sure you wanted to touch this code? Zeroing %ax on entry to
> Pavel> BIOS might be good idea, but...
> 
> It is absolutely necessary, see below for how I've reused the
> real->pmode switch. The VGA BIOS expect the PCI bus/slot/function from
> %ax and C passes us that information in the upper 16 bits of
> acpi_video_flags.

Hmm, that's perhaps why so little BIOSen work with this hack.. Is
there chance that passing this value when acpi_sleep=s3_bios is going
to help?

> Pavel> Ouch, so you call wakeup_start once again?
> 
> Yes, I didn't want to implement yet another real->pmode switch, it
> would have been a blue-print copy of wakeup_start and
> acpi_copy_wakeup_routine anyway.

Aha, its actually okay.

> Pavel> How do you manage to return from this routine?
> 
> Precisely like do_suspend_lowlevel_s4bios: calling save_registers and
> effectively reusing the tail-end of do_suspend_lowlevel.

Hmm, okay, nice hack but you want it documented at some point. Perhaps
comment just after jump to acpi_wakeup is good idea? 

									Pavel
-- 
Horseback riding is like software...
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