Re: [ACPI] Weirdness in arch/i386/kernel/acpi_wakeup.S

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

Hi!

> > > (The problem I'm having is that the console VGA is not re-initialized upon 
> > > coming back from an S3 suspend and I am trying to debug that)
> > 
> > Have you tried acpi_sleep=s3_bios and acpi_sleep=s3_mode (not yet in
> > 2.5.59, but already in 2.5.59-acpi?)
> 
> (tried with 2.5.60 now including the 4096 byte wakeup .org fix, and btw this 
> is on an Acer Travelmate 634LC laptop).
> 
> Without s3_bios and s3_mode, and without any drivers compiled into the 
> kernel, the kernel wakes up after the suspend, and you can execute stuff 
> using the keyboard but the VGA never resumes. Close call!

Good.

> With s3_bios, the display lights up and the cursor starts blinking in the 
> upper left corner, but it hangs there (no keyboard input possible). I guess 
> the BIOS call succeeded in reinitializing the display but something after 
> that hung.
> 
> With s3_mode, the display neither lights up nor allows keyboard
> input :)

Do you use vgacon or vesafb or ...?

> Anyway, may I ask what debugging methods are best for tracking down problems 
> like this on an i386. I'm used to doing kernel debugging on embedded systems 
> but then you have access to logic analysers, LED-lighting etc.. what would 
> be an appropriate way to debug such low level code on a PC - I noticed these 
> references in acpi_wakeup.S like "movw	$0x0e00 + 'L', %fs:(0x10)" that seem 
> to be some kind of debug messages - what do they really do - write to the 
> VGA character memory ?

Yes, exactly. I'd suggest 8 leds on printer port as a debugging
trick... [VGA is easier -- when it works. Try moving 'L' just after
"call bios" to see if it ever returns etc.]

								Pavel
-- 
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cryptography in U.S.A. and free speech in Czech Republic.