Fun with Xorg

by Dru Lavigne
12/07/2006

Chapter 5 of the FreeBSD Handbook provides an excellent overview for understanding and configuring the X Window system. Today's article goes beyond the Handbook to demonstrate some of the cool things you can do with your FreeBSD system and other systems running X.

Getting the Most out of your Video Card

While Xorg -configure does a good job of configuring video cards, the X drivers don't provide automatic support for DRI (Direct Rendering Interface), DRM (Direct Rendering Manager), or OpenGL (OPEN Graphics Library)--meaning you're probably not getting the most out of your video hardware.

The dri and linux_dri packages provide these missing features by installing FreeBSD kernel loadable modules for several cards:

Card/Chipset	Module Name
Intel i810	i810
Intel i830	i830 (not available in linux_dri)
Intel i915	i915
ATI Mach64	mach64
Matrox Gxxx	mga
ATI Rage128	r128
ATI Rage200	r200
ATI Rage300	r300
ATI Radeon	radeon
S3 Savage	savage
SiS 3xx	sis
Voodoo 3dfx	tdfx

Note: if you have a NVidia card and want to use the binary-only driver, instead make install the nvidia-driver port as it needs to compile against your kernel.

Depending upon the software you have installed, these DRI modules may already be on your system. Check with the command:

# pkg_info | grep dri

If you receive your prompt back with no output, or the output mentions only linux_dri, install the dri package:

# pkg_add -r dri

Once you have it installed, add a few lines to the end of /etc/X11/xorg.conf:

Section "DRI"
    Mode 0666
EndSection

Note: if that file doesn't exist, then:

# cp /root/xorg.conf.new /etc/X11/xorg.conf

Finally, double-check that Xorg will load dri and glx; if these lines don't exist, add them to the Section "Module" portion of /etc/X11/xorg.conf:

# grep dri /etc/X11/xorg.conf
    Load  "dri"

# grep glx /etc/X11/xorg.conf
    Load  "glx"

Loading and Testing the Kernel Module

Now you're ready to determine which kernel module to load. First, figure out which video card Xorg wants to use:

# grep Name /etc/X11/xorg.conf
    VendorName   "IBM"
    ModelName    "IBM G72"
    VendorName  "ATI Technologies Inc"
    BoardName   "Rage 128 Pro Ultra TF"

Compare that output to the earlier table. This system needs to use the r128 module. If I issue this command at Alt-F1 (the console), a successful driver load will display as bright white text:

# kldload r128
drm0: <ATI Rage 128 Pro Ultra TF (AGP)> port 0xd000-0xd0ff mem 0xf4000000-0xf7ff
ffff,0xfbefffff irq 10 at device 0.0 on pci1
info: [drm] AGP at 0xf0000000 64MB
info: [drm] Initialized r128 2.5.0 20030725

Once your driver successfully loads, start an X session as a regular user and check the OpenGL rendering capabilities from within the GUI:

% glxinfo | grep rendering
direct rendering: Yes

Once you have rendering enabled, add a line to /boot/loader.conf as the superuser so the driver automatically loads when the system boots. My line looks like:

r128_load="YES"

Replace r128 with the module name for your video card and double-check the file for typos.

3d-Desktop is an xgl-ish desktop switcher and a cool way to test your DRI:

# pkg_add -r 3ddesktop

Once installed, run it from the GUI as a regular user:

% 3ddesk

Use your arrow keys to rotate the cube of desktops and Enter or Space to bring a desktop into the foreground.

Nesting Xservers

When you install X, you get a whole suite of interesting utilities, many of which you may not be aware of. One of these is Xnest, which allows you to run multiple window managers simultaneously. Confirm that you have Xnest installed with:

# pkg_info|grep nest
xorg-nestserver-6.9.0_1 Nesting X server from Xorg

If you just get your prompt back, install the program with the command:

# pkg_add -r xorg-nestserver

Here is an example of how to use Xnest. On a system already configured for KDE, I installed three additional window managers:

# pkg_add -r windowmaker
# pkg_add -r xfce
# pkg_add -r fluxbox

Note: Window Managers for X provides screenshots of hundreds of window managers. On FreeBSD, you can see which window managers are available at the Freshports X11 window managers listing.

Once installed, start the GUI as a regular user. In my case, I see the KDE desktop. I can use Xnest to start windowmaker, which will appear as just another window with "Windowmaker" in the title bar:

% Xnest :1 -ac -name Windowmaker & wmaker -display :1

Note: X assigns the first window manager you start (in my case, KDE) a display number of :0. In this example, windowmaker gets the second display, :1, which Xnest nests within the original display.

To start two more window managers, bump up the display number and specify the name of the window manager:

% Xnest :2 -ac -name XFCE & xfce -display :2
% Xnest :3 -ac -name Fluxbox & fluxbox -display :3

Figure 1 shows all four window managers running simultaneously.

Figure 1. Four window managers running simultaneously through Xnest (click for full-size image)

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