# Mesa fbdev/DRI Drivers

# 1. Introduction

The fbdev/DRI environment supports hardware-accelerated 3D rendering without the X window system. This is typically used for embedded applications.

Contributors to this project include Jon Smirl, Keith Whitwell and Dave Airlie.

Applications in the fbdev/DRI environment use the MiniGLX interface to choose pixel formats, create rendering contexts, etc. It's a subset of the GLX and Xlib interfaces allowing some degree of application portability between the X and X-less environments.

Note that this environment is not well-supported and these instructions may not be completely up to date.

# 2. Compilation

## 2.1 glxproto

Get glxproto.h. Copy it to the /mesa/include/GL/ directory.

## 2.2 libpciaccess

Check if you have libpciaccess installed:

    pkg-config --modversion pciaccess

If not you can download the latest code from:

       git clone git://anongit.freedesktop.org/git/xorg/lib/libpciaccess

Run autogen.sh to generate a configure file. autogen.sh uses autoconf utility. This utility may not be installed with your linux distro, check if it is available. if not you can use your package manager or type:

    sudo apt-get install autoconf

The next step is to install the libpciaccess library.

    make
    make install

Now your libpciaccess.a file is saved into /usr/local/lib directory. If you have a libpciaccess.a in /usr/lib you may simply copy and overwrite these files. Don't forget to copy libpciaccess.pc file to /usr/lib/pkgconfig, which is also located in /usr/local/lib/pkgconfig/. Or you may use the following system variables:

    export LD_LIBRARY_PATH=/usr/local/lib
    export PKG_CONFIG_PATH=/usr/local/lib/pkgconfig

## 2.3 drm

The next step is to compile the drm. DRM consists of two seperate parts, the DRM client library(lindrm.so) and kernel device module(such as radeon.ko). We need to make a small change in kernel device module. So you need to download the kernel source. You may choose the nearest mirror from www.kernel.org, or you are using Fedora Core 5, for example, you may need to install RPMs such as: kernel-smp-devel-2.16.15-1.2054_FC5.i686.rpm kernel-devel-2.6.15-1.2054_FC5.i686.rpm etc. You can find a detailed information here.

You will find drm_drv.c at /usr/src/LINUX-VERSION/drivers/char/drm/. Edit this code and comment out the following part:

       /* ||
       ((ioctl->flags & DRM_MASTER) && !priv->master)*/

Now you are ready to compile your kernel. If your kernel version is identical to the version you have compiled, you can simply over write your new "ko" files over older ones. If you have compiled a different kernel, you must configure your grub or lilo to be able to boot your new kernel.

You'll need fbdev header files. Check with:

       ls -l /usr/include/linux/fb.

This file may be missing if you have not installed linux header files.

## 2.4 Mesa

Get latest development Mesa sources from git repository (currently 7.1-prerelease)

       git clone git://anongit.freedesktop.org/git/mesa/mesa

You will need the makedepend utility which is a part of mesa project to build your linux-solo. You probably wont have this utility. You can download its source from following git repulsitory:

       git clone git://anongit.freedesktop.org/git/xorg/util/makedepend

Get the latest stable mesa version from SourceForge (currently 7.0.3) http://sourceforge.net/project/showfiles.php?group_id=3

Copy the miniglx folder from 7.1-prerelease to 7.0.3. You may also extract GLUT to 7.0.3 version at this step.

Edit linux-solo.conf at /conf directory, just only compile the graphics driver you need, delete the unwanted drivers names from the list(some drivers are causing problems...)

       while(build==0)
       {
         make linux-solo

         There will be some missing header files, copy them from 7.1-prerelease
       }

When complete you should have the following:

- lib/libGL.so - the GL library which applications link with
- lib/*_dri_so - DRI drivers
- lib/miniglx.conf - sample MiniGLX config file
- progs/miniglx/* - several MiniGLX sample programs

To install these files into appropriate locations in system:

       make install

Now your openGL libraries are copied to /usr/local/lib and miniglx.conf is copied to /etc. You may copy them to /usr/lib and overwrite your old GL libraries. Or you may export following variable:

       export LIBGL_DRIVERS_PATH=/usr/local/lib

# 3. Using fbdev/DRI

If an X server currently running, exit/stop it so you're working from the console. Following command shuts down the x window and also the multi user support.

       init 1

Also you may define the runlevel as 1 in "/etc/inittab". Your system will always start in single user mode and without x-window with this option set.

## 3.1 Load Kernel Modules

You'll need to load the kernel modules specific to your graphics hardware. Typically, this consists of the agpgart module, an fbdev driver module and the DRM kernel module.

As root, the kernel modules can be loaded as follows:

If you have Intel i915/i945 hardware:

       modprobe agpgart            # the AGP GART module
       modprobe intelfb            # the Intel fbdev driver
       modprobe i915               # the i915/945 DRI kernel module

If you have ATI Radeon/R200 hardware:

       modprobe agpgart            # the AGP GART module
       modprobe radeonfb           # the Radeon fbdev driver
       modprobe radeon             # the Radeon DRI kernel module

If you have ATI Rage 128 hardware:

       modprobe agpgart            # the AGP GART module
       modprobe aty128fb           # the Rage 128 fbdev driver
       modprobe r128               # the Rage 128 DRI kernel module

If you have Matrox G200/G400 hardware:

       modprobe agpgart            # the AGP GART module
       modprobe mgafb              # the Matrox fbdev driver
       modprobe mga                # the Matrox DRI kernel module

To verify that the agpgart, fbdev and drm modules are loaded:

       ls -l /dev/agpgart /dev/fb* /dev/dri

Alternately, use lsmod to inspect the currently installed modules. If you have problems, look at the output of dmesg.

## 3.2 Configuration File

review/edit /etc/miniglx.conf. Alternately, the MINIGLX_CONF environment variable can be used to indicate the location of miniglx.conf

To determine the pciBusID value, run lspci and examine the output. For example:

       /sbin/lspci:
       00:02.0 VGA compatible controller: Intel Corporation 82915G/GV/910GL Express Chipset Family Graphics Controller (rev 04)

00:02.0 indicates that pciBusID should be PCI:0:2:0

## 3.3 Running fbdev/DRI Programs

Make sure your LD_LIBRARY_PATH environment variable is set to the location of the libGL.so library. You may need to append other paths to LD_LIBRARY_PATH if libpciaccess.so is in a non-standard location, for example.

Change to the `Mesa/progs/miniglx/` directory and start the sample_server program in the background:

       ./sample_server &

Then try running the `miniglxtest` program:

       ./miniglxtest

You should see a rotating quadrilateral which changes color as it rotates. It will exit automatically after a bit.

If you run other tests in the miniglx/ directory, you may want to run them from a remote shell so that you can stop them with ctrl-C.

# 4.0 Troubleshooting

1. If you try to run miniglxtest and get the following:

          [miniglx] failed to probe chipset
          connect: Connection refused
          server connection lost

   It means that the sample_server process is not running.

# 5.0 Programming Information

OpenGL/Mesa is interfaced to fbdev via the MiniGLX interface. MiniGLX is a subset of Xlib and GLX API functions which provides just enough functionality to setup OpenGL rendering and respond to simple input events.

Since MiniGLX is a subset of the usual Xlib and GLX APIs, programs written to the MiniGLX API can also be run on full Xlib/GLX implementations. This allows some degree of flexibility for software development and testing.

However, the MiniGLX API is not binary-compatible with full Xlib/GLX. Some of the structures are different and some macros/functions work differently. See the `GL/miniglx.h` header file for details.