Video BIOS reset?

Video BIOS reset?

[Nate Lawson]

I am looking into a common problem on FreeBSD.  Whenever I resume, the
console is messed up.  X works fine.  When data is printed to the console,
it scrolls diagonally and skips lines.  My first thought was that the VESA
display was not in linear mode.

I looked at the Linux code and noted two parts that seem to be intended to
address this:

1. lcall 0xc0000,$3
2. int 0x10, func 0x4f02

The first one appears to only be a read of the current VESA mode register.
The second is Set Mode.  I tried adding this manually to our resume code
but there is no change.  I also looked at vgacon.c to see if our console
resume code wasn't complete but nothing jumped out at me.  Any ideas what
we might be missing?

Src:
linux/arch/i386/kernel/acpi/wakeup.S
linux/drivers/video/console/vgacon.c

Thanks,
Nate


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Re: Video BIOS reset?

[Pavel Machek]

Hi!

[Greetings to root.org. There's root.cz in our country, and I have
some friends there].

> I am looking into a common problem on FreeBSD.  Whenever I resume, the
> console is messed up.  X works fine.  When data is printed to the console,
> it scrolls diagonally and skips lines.  My first thought was that the VESA
> display was not in linear mode.
> 
> I looked at the Linux code and noted two parts that seem to be intended to
> address this:
> 
> 1. lcall 0xc0000,$3
> 2. int 0x10, func 0x4f02

> The first one appears to only be a read of the current VESA mode
> register.

The first one is "init VGA rom". 

> The second is Set Mode.  I tried adding this manually to our resume code
> but there is no change.  I also looked at vgacon.c to see if our console
> resume code wasn't complete but nothing jumped out at me.  Any ideas what
> we might be missing?

Notice that both lcall and int 0x10 are extremely ugly hacks, that are
not guaranteed to work, and have to be enabled manually by
commmand-line option. It does not work on all machines, either (there
are machines where neither 1. nor 2. works). Its a mess. Unfortunately
anything better needs video driver that knows how to bring up video
card from resume :-(.

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


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