Re: Via KT400 and AGP 8x Support

From: I Am Falling I Am Fading (skuld@anime.net)
Date: Wed Jun 11 2003 - 20:34:03 EST


On Wed, 11 Jun 2003, Dave Jones wrote:

> On Wed, Jun 11, 2003 at 02:28:24AM -0600, I Am Falling I Am Fading wrote:
>
> > I've had this problem as well.
> >
> > What I've been able to do is to use a backport for one of the 2.4.21-pre*
> > series, and move the code forward to the current 2.4.21-rc's .
>
> That's not a proper fix. The agp code in 2.4.21pre supports the KT400
> only in AGP2.0 mode. When you put an AGP3.0 (x8) card in the slot,
> the chipset configures itself into AGP3 mode, and registers change
> meaning.
>
> > Here's info on the relevant patch:
> > http://lists.insecure.org/lists/linux-kernel/2003/Mar/3999.html
>
> Very, very dated now. Many fixes have gone into the agp code since
> 2.5.64, on which that backport is based.

I'm aware that it doesn't work right, unfortunately getting AGP3.0 working
at all under the 2.4 kernel doesn't have any real solution, with the
exception of nVidia's binary-only drivers for the nForce2.

This solution at least initializes some stuff and allows me to use the ATI
drivers for 2D acceleration on my KT400-based board, whcih didn't work
before I applied that patch. Consequently, it's the best solution I have
now for people who want to use their R3xx-series ATI cards on AGP3.0
systems.

The only other solution is to kick your card down into AGP 2.0 mode, which
most BIOSes do not allow you to do in software. Instead what you have to
do is cut/unsolder traces on your video card for the pins used for AGP 3.0
detection. This is a near-permanent and horrible solution but it does get
everything working. :-/

Dave, if you have a better solution for the 2.4 kernel I'd be very, very
happy to see it. :-( Unfortunately I'm not a good enough coder to write
proper AGP3.0 support for the 2.4 kernel myself, and can only shuffle
other people's code around.

Someday 2.6 is going to fix all this but it's just not ready yet, and
while it's fun to run a 2.5 kernel it's not something I would recommend to
someone else (aside from this, it wouldn't fix his situation since the ATI
binary-only drivers puke on 2.5).

I despair at the DRI project ever getting back in gear -- it's in horrible
disarray and the development list is now 75% spam. Some good improvements
came thanks to a donation from the Weather Channel, but it's not enough to
provide comprehensive support. :-( Maybe there needs to be a "save DRI"
fund. :-/

-----
James Sellman -- ISU CoE-CS/ISLUG Linux Lab Admin |"Lum, did you just see
----------------------------------------------------| a hentai rabbit flying
skuld@inconnu.isu.edu | // A4000/604e/60 128M| through the air?"
skuld@anime.net | \X/ A500/20 3M | - Miyake Shinobu

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