8. FAQ: Glide and XFree86?

8.1 Does it run with XFree86?

Basically, the Voodoo Graphics (tm) hardware does not care about X. The X server will not even notice that the video signal generated by the VGA hardware does not reach the display in single screen configurations. If your application is not written X aware, Glide switching to full screen mode might cause problems (see troubleshooting section). If you do not want the overhead of writing an X11-aware application, you might want to use SVGA console mode instead.

So yes, it does run with XFree86, but no, it is not cooperating if you don't write your application accordingly. You can use the Mesa "window hack", which will be significantly slower than fullscreen, but still a lot faster than software rendering (see section below).

8.2 Does it only run full screen?

See above. The Voodoo Graphics (tm) hardware is not window environment aware, neither is Linux Glide. Again, the experimental Mesa "window hack" covered below will allow for pasting the Voodoo Graphics (tm) board framebuffer's content into an X11 window.

8.3 What is the problem with AT3D/Voodoo Rush (tm) boards?

There is an inherent problem when using Voodoo Rush (tm) boards with Linux: Basically, these boards are meant to be VGA 2D/3D accelerator boards, either as a single board solution, or with a Voodoo Rush (tm) based daughterboard used transparently. The VGA component tied to the Voodoo Rush (tm) is a Alliance Semiconductor's ProMotion-AT3D multimedia accelerator. To use this e.g. with XFree86 at all, you need a driver for the AT3D chipset.

There is a mailing list on this, and a web site with FAQ at www.frozenwave.com/linux-stingray128. Look there for most current info. There is a SuSE maintained driver at ftp.suse.com/suse_update/special/xat3d.tgz. Reportedly, the XFree86 SVGA server also works, supporting 8, 16 and 32 bpp. Official support will probably be in XFree86 4.0. XFree86 decided to prepare an intermediate XFree86 3.3.2 release as well, which might already address the issues.

The following XF86Config settings reportedly work.

# device section settings
Chipset "AT24"
Videoram 4032

# videomodes tested by Oliver Schaertel
#  25.18  28.32  for 640 x 480   (70hz)
#  61.60         for 1024 x 786  (60hz) 
#  120           for 1280 x 1024 (66hz)  

If you want a more technical explanation: Voodoo Rush (tm) support requires X server changes to support grabbing a buffer area in the video memory on the AT3D board, as the Voodoo Rush (tm) based boards need to store their back buffer and z buffer there. This memory allocation and locking requirement is not a 3Dfx specific problem, it is also needed e.g. for support of TV capture cards, and is thus under active development for XFree86. This means changes at the device dependend X level (thus XAA), which are currently implemented as an extension to XFree86 DGA (Direct Graphics Access, an X11 extension proposal implemented in different ways by Sun and XFree86, that is not part of the final X11R6.1 standard and thus not portable). It might be part of an XFree86 GLX implementation later on. The currently distributed X servers assume they have full control of the framebuffer, and use anything that is not used by the visual region of the framebuffer as pixmap cache, e.g. for caching fonts.

8.4 What about GLX for XFree86?

There are a couple of problems.

The currently supported Voodoo Graphics (tm) hardware and the available revision of Linux Glide are full screen only, and not set up to share a framebuffer with a window environment. Thus GLX or other integration with X11 is not yet possible.

The Voodoo Rush (tm) might be capable of cooperating with XFree86 (that is, an SVGA compliant board will work with the XFree86 SVGA server), but it is not yet supported by Linux Glide, nor do S3 or other XFree86 servers support these boards yet.

In addition, GLX is tied to OpenGL or, in the Linux case, to Mesa. The XFree86 team is currently working on integrating Mesa with their X Server. GLX is in beta, XFree86 3.3 has the hooks for GLX. See Steve Parker's GLX pages at www.cs.utah.edu/~sparker/xfree86-3d/ for the most recent information. Moreover, there is a joint effort by XFree86 and SuSe, which includes a GLX, see www.suse.de/~sim/. Currently, Mesa still uses its GLX emulation with Linux.

8.5 Glide and commerical X Servers?

I have not received any mail regarding use of Glide and/or Mesa with commercial X Servers. I would be interested to get confirmation on this, especially on Mesa and Glide with a commercial X Server that has GLX support.

8.6 Glide and SVGA?

You should have no problems running Glide based applications either single or dual screen using VGA modes. It might be a good idea to set up the 640x480 resolution in the SVGA modes, too, if you are using a single screen setup.

8.7 Glide and GGI?

A GGI driver for Glide is under development by Jon M. Taylor, but has not officially been released and was put on hold till completion of GGI 0.0.9. For information about GGI see synergy.caltech.edu/~ggi/. If you are adventurous, you might find the combination of XGGI (a GGI based X Server for XFree86) and GGI for Glide an interesting prospect. There is also a GGI driver interfacing the OpenGL API; tested with unaccelerated Mesa. Essentially, this means X11R6 running on a Voodoo Graphics (tm), using either Mesa or Glide directly.