The Linux Gamers' HOWTO
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# 9. Miscellaneous Problems

## 9.1. Hardware Acceleration Problems

XFree86 4.x provides a more centralized and self-contained approach to video. Much of the funkyness like kernel modules for non-root access of video boards is, thankfully, gone.

### 9.1.1. Hardware acceleration isn't working at all

If you're getting like 1 fps, then your system isn't using hardware 3D acceleration. There's one of two things that can be going on.

1. Your 3D system is misconfigured (more likely)

2. Game X is misconfigured (less likely)

The first step is to figure out which one is happening.

1. If you have X 4.0 (X 3.* users procede to step 2), look at the output of `X -probeonly`. You'll see:

       (II) XXXXXX: direct rendering enabled

   or

       (II) XXXXXX: direct rendering disabled

   where XXXXXXX depends on which video card you have. If direct rendering is disabled, then your X configuration is definitely faulty. Your game is not at fault. You need to figure out why DRI is disabled. The most important tool for you to use at this point is the `DRI Users Guide'. It is an excellently written document that gives you step by step information on how to get DRI set up correctly on your machine. A copy is kept at http://www.xfree86.org/4.0/DRI.html.

   Note that if you pass this test, your system is CAPABLE of direct rendering. Your libraries can still be wrong. So procede to step 2.

2. There is a program called glxgears which comes with the "mesademos" package. You can get mesademos with Debian ( apt-get install mesademos) or you can hunt for the rpm on http://www.rpmfind.net. You can also download and compile the source yourself from the mesa homepage.

   Running glxgears will show some gears turning. The xterm from which you run glxgears will display "X frames in Y seconds = X/Y FPS". You can compare your system to the list of benchmarks below.

           CPU TYPE     VIDEO CARD     X VERSION    AVERAGE FPS

   Compiling Mesa and DRI modules yourself can increase your FPS by 15 FPS; quite a performance boost! So if your number is, say, about 20 FPS slower than a comparable machine, chances are that glxgears is falling back on software rendering. In other words, your graphics card isn't 3D accelerating graphics.

   More important than FPS is having a constant FPS for small and large windows. If hardware acceleration is working, the FPS for glxgears should be nearly independent of window size. If it's not, then you're not getting hardware acceleration.

## 9.2. Hardware acceleration works only for the root user

### 9.2.1. XFree86 4.x

If the following lines aren't present in your XF86Config-4 file, put them in:

        Section "DRI"
            Mode 0666
        EndSection

This allows all non-root users to use DRI. For the paranoid, it's possible to restrict DRI to only a few non-root users. See the DRI User Guide.

### 9.2.2. XFree86 3.x

#### 9.2.2.1. Voodoo cards

Voodoo card hardware acceleration only takes place ONLY at 16bpp color and fails silently when starting X in another color depth.

Also, Voodoo cards need the `3dfx.o` kernel module and a `/dev/3dfx` device file (major 107, minor 0) for non-root hardware acceleration. Neither the module nor the device file are used under XFree86 4.x.

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