[LinuxBIOS] LinuxTag Berlin 29/5-2/6

Luc Verhaegen libv at skynet.be
Sun May 27 00:50:43 CEST 2007


On Sat, May 26, 2007 at 05:29:28PM +0200, Stefan Reinauer wrote:
> > 
> > No, this is purely to get 640x480 textmode to work on the CRT 
> > connection. This is the safe option that will work for 98% of the EPIA-M 
> > users out there. The other 2% are those who are fully dependant on the 
> > DVI or LVDS/RGB display modules.
>  
> Or they will just use the VGA BIOS which can do all, I think.

Well, VIAs VGA BIOS is table based and not always the right solution.
 
> > I can of course insert a full modesetting system, but that will mean 
> > doing things like EDID parsing and cvt modeline generation in linuxbios. 
> > And this will all be getting rather big rather quickly.
> 
> Does VIA's graphics bios do all that? Can it be done in a non-VIA-only
> way?

It only does some rudimentary EDID parsing and some very basic output 
handling, including both CRTCs with scaling and simultaneous (needed to 
get 640x400 on a CLE266 with a panel or DVI). It's fully table based 
though, so you only get those resolutions and modes that were 
programmed. So you can forget about 1360x768, 1440x900 or 1680x1050.

Actually, i have quite a ball on VIAs forums, pointing windows users to 
linux. It seems their drivers depend on what is programmed in the BIOS, 
and VIa seems utterly unable to fix it without creating new BIOS images 
:)

Try finding a manufacturer willing to create a bios with 1680x1050 for a 
board for which production stopped in 2005. Then hope that this is the 
manufacturer for your exact board :)

> > 640x480 at 60Hz is somewhat safe, as most devices on the CRT connection 
> > will be able to handle this, as this is the default BIOS textmode.
> 
> default text mode sucks ;) but ignore me, i'm the bootsplash guy

Well, this textmode is a life-saver. It's perfectly ok to live with only 
a mode from X... this right until the time an fsck requires user 
intervention, and serial isn't responding (which i had a month or so 
ago). You're very glad to see a textmode then.

I'm not sure how you get to busybox in linuxbios when something goes 
wrong, but my guess is that anyone will be over the moon when able to 
use this directly, even if it's just 640x480.

Nobody will ever be as glad to see a boot splash. It will never save 
somebody any time or effort. Besides, i think you need a vga textmode 
if you want the kernel to properly log its output without an FB driver.

Not that i'm totally against a bootsplash or a full modeset in BIOS, but 
imho other things are way more important.

I will have to do a bit more work than what i'm currently doing though, 
i will need to make it possible to use textmode on DVI or a panel on the 
CLE266. That way all basic needs are taken care of.

Luc Verhaegen.




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