Possible bug: nasty interaction between framebuffer and DRI/DRM

Possible bug: nasty interaction between framebuffer and DRI/DRM

[Chris Howells]

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Hi,

I seem to have discovered a nasty interaction between framebuffer and DRI/DRM 
in OpenGL applications. I can reproduce this problem in at least Return to 
Castle Wolfenstein (version 1.1b) and Tux Racer.

I am using a 32 MB ATI Rage Pro 128 on Debian woody (XFree86 4.1). If I run 
Tuxracer or RTCW, and wait for the game to load, everything is alright. 
However if I switch to a spare virtual terminal, and switch back to X, the 
fonts become illegible -- they just appear as coloured boxes with no 
outlines, making things unplayable.

The problem does not occur when using software based OpenGL rendering which is 
why I believe DRI/DRM is involved. This problem only occurs when framebuffer 
is enabled in the kernel, if framebuffer is disabled the problem disappears, 
so I believe framebuffer is also at fault.

Greatful for any help...

Chris Howells
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Re: Possible bug: nasty interaction between framebuffer and DRI/DRM

[Chris Howells]

Hi,

On Friday 31 May 2002 12:54 pm, Chris Howells wrote:

> I seem to have discovered a nasty interaction between framebuffer and
> DRI/DRM in OpenGL applications. I can reproduce this problem in at least
> Return to Castle Wolfenstein (version 1.1b) and Tux Racer.


Meant to say this before...

I can reproduce this under both kernel 2.4.17 and 2.4.18.


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Re: Possible bug: nasty interaction between framebuffer and DRI/DRM

[Geert Uytterhoeven]

On Fri, 31 May 2002, Chris Howells wrote:
> I seem to have discovered a nasty interaction between framebuffer and DRI/DRM 
> in OpenGL applications. I can reproduce this problem in at least Return to 
> Castle Wolfenstein (version 1.1b) and Tux Racer.
> 
> I am using a 32 MB ATI Rage Pro 128 on Debian woody (XFree86 4.1). If I run 
> Tuxracer or RTCW, and wait for the game to load, everything is alright. 
> However if I switch to a spare virtual terminal, and switch back to X, the 
> fonts become illegible -- they just appear as coloured boxes with no 
> outlines, making things unplayable.
> 
> The problem does not occur when using software based OpenGL rendering which is 
> why I believe DRI/DRM is involved. This problem only occurs when framebuffer 
> is enabled in the kernel, if framebuffer is disabled the problem disappears, 
> so I believe framebuffer is also at fault.

Do you use `option UseFBDev' in your XF86Config?

Gr{oetje,eeting}s,

						Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
							    -- Linus Torvalds


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Re: Possible bug: nasty interaction between framebuffer and DRI/DRM

[Chris Howells]

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Hi,

On Friday 31 May 2002 1:08 pm, Geert Uytterhoeven wrote:

> Do you use `option UseFBDev' in your XF86Config?

No I'm not. Should I be?

Cheers

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Re: Possible bug: nasty interaction between framebuffer and DRI/DRM

[Geert Uytterhoeven]

On Fri, 31 May 2002, Chris Howells wrote:
> On Friday 31 May 2002 1:08 pm, Geert Uytterhoeven wrote:
> 
> > Do you use `option UseFBDev' in your XF86Config?
> 
> No I'm not. Should I be?

Yes. Without that option, the X server will change the graphics chip's
registers behind the back of aty128fb.

Gr{oetje,eeting}s,

						Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
							    -- Linus Torvalds


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Re: [Dri-devel] Possible bug: nasty interaction between framebuffer and DRI/DRM

[Keith Whitwell]

Chris Howells wrote:
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> Hash: SHA1
> 
> Hi,
> 
> I seem to have discovered a nasty interaction between framebuffer and DRI/DRM 
> in OpenGL applications. I can reproduce this problem in at least Return to 
> Castle Wolfenstein (version 1.1b) and Tux Racer.
> 
> I am using a 32 MB ATI Rage Pro 128 on Debian woody (XFree86 4.1). If I run 
> Tuxracer or RTCW, and wait for the game to load, everything is alright. 
> However if I switch to a spare virtual terminal, and switch back to X, the 
> fonts become illegible -- they just appear as coloured boxes with no 
> outlines, making things unplayable.

It sounds like the texture cache is getting wiped out, but the DRI drivers 
aren't realizing that it's happened.  This shouldn't be too hard to fix if 
someone has time.

Keith



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