Re: GGI, EGCS/PGCC, Kernel source (amusing thread :)

Geert Uytterhoeven (
Tue, 3 Mar 1998 03:51:47 +0100 (CET)

On Mon, 2 Mar 1998, teunis wrote:
> On 2 Mar 1998, Jes Degn Soerensen wrote:
> > >>>>> "Teunis" == teunis <> writes:
> > Teunis> Neither card is safe from userspace FWIW, and S3-ViRGE/GX has
> > Teunis> a nasty tendency to crash under XFree86 for me...
> >
> > Doesn't the ViRGE allow you to access everything from the mmio area?
> Noone ever claimed it was safe or stable (it's not either - but it's far
> more stable than the Trio64V+).
> Please remember that the current linux assumes videomemory is located in a
> conventional location (absolute A0000 or B8000).

Oh, you're talking about Linux/ia32? :-)

> Once you enter MMIO neither of these addresses are valid. And the text is
> now 8 bytes per character rather than 2. (had to learn that through trial
> and error - it's not documented). Also font programming is completely
> different.

Yeah, I saw that too on my S3 968 in my PPC. I've got a text mode, correct
colors, but the character-to-font mapping seems to be weird. Then I bought the
ATI and left the 968 alone. Very recently I've got the 968 databook, so I can
start writing a frame buffer device for it.

> Oh - and one last note. To program MMIO mode, you have to reprogram the
> cards' PCI registers. Is there a safe way to do this under linux without
> doing it in a kernel driver? Just curious....

Yes, I assume the frame buffer device will setup the PCI config registers for
me, since it has to program the video mode anyway.



Geert Uytterhoeven           
Wavelets, Linux/{m68k~Amiga,PPC~CHRP}
Department of Computer Science -- Katholieke Universiteit Leuven -- Belgium

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