Xorg-7.6-2 Testing and Configuration

Checking the Direct Rendering Infrastructure (DRI) Installation

DRI is a framework for allowing software to access graphics hardware in a safe and efficient manner. It is installed in X by default (using MesaLib) if you have a supported video card.

To check if DRI is installed properly, check the log file /var/log/Xorg.0.log for statements like:

(II) R128(0): Direct rendering enabled

Note

DRI configuration may differ if you are using alternate drivers, such as those from NVIDIA or ATI.

Although all users can use software acceleration, any hardware acceleration (DRI2) is only available to root and members of the video group.

To see if hardware acceleration is available for your driver, look in /var/log/Xorg.0.log for statements like:

 (II) intel(0): direct rendering: DRI2 Enabled

If your driver is supported, add any users that might use X to that group:

usermod -a -G video <username>

If you elected to install the Mesa-Demos package when installing MesaLib-8.0.2, from an xterm, run glxinfo and first look for the phrase:

direct rendering: Yes

If direct rendering is enabled, you can add verbosity by running LIBGL_DEBUG=verbose glxinfo. This will show the drivers, device nodes and files used by the DRI system.

If DRI is enabled, to confirm that DRI2 hardware acceleration is working you can (still in the xterm) run the command glxinfo | grep "OpenGL renderer string" - if that reports something other than Software Rasterizer then you have working acceleration for the user who ran the command.

Again, if you have added the Mesa-Demos package, you can also run the test program glxgears. This program brings up a window with three gears turning. The xterm will display how many frames were drawn every five seconds, so this is a reasonable benchmark. The window is scalable, and the frames drawn per second is highly dependent on the size of the window.

Creating an X11R6 Compatibility Symlink

Until recently (relatively speaking) almost every X Window installation you performed or came across was installed in the /usr/X11R6 directory. That was the standard for years. Developers picked up on this and wrote their package installation scripts looking for X in the standard location. Things have changed and the trend is to now install X in /usr. Some people want to install it in a custom location.

Many package developers have not caught up to the change and their packages are still trying to find X in /usr/X11R6 and subsequently fail when you try to build the package. Though for most packages it is not difficult to 'hack' the installation script to fix the problem, that is not the long term solution to the problem. Upstream developers need to modernize their installation scripts and eliminate the problem altogether.

Until then, you can create a symbolic link to satisfy the /usr/X11R6 requirement so that you won't be inconvenienced with a package build failure due to this known issue. If you wish to create the symlink, issue the following command as the root:

ln -vsf $XORG_PREFIX /usr/X11R6

Xft Font Protocol

Xft provides antialiased font rendering through Freetype, and fonts are controlled from the client side using Fontconfig. The default search path is /usr/share/fonts and ~/.fonts. Fontconfig searches directories in its path recursively and maintains a cache of the font characteristics in fonts.cache-1 files in each directory. If the cache appears to be out of date, it is ignored, and information is (slowly) fetched from the fonts themselves. This cache can be regenerated using the fc-cache command at any time. You can see the list of fonts known by Fontconfig by running the command fc-list.

If you've installed Xorg in any prefix other than /usr, the X fonts were not installed in a location known to Fontconfig. This prevents Fontconfig from using the poorly rendered Type 1 fonts or the non-scalable bitmapped fonts. Symlinks were created from the OTF and TTF X font directories to /usr/share/fonts/X11-{OTF,TTF}. This allows Fontconfig to use the OpenType and TrueType fonts provided by X (which are scalable and of higher quality).

Fontconfig uses names such as "Monospace 12" to define fonts. Applications generally use generic font names such as "Monospace", "Sans" and "Serif". Fontconfig resolves these names to a font that has all characters that cover the orthography of the language indicated by the locale settings. Knowledge of these font names is included in /etc/fonts/fonts.conf. Fonts that are not listed in this file are still usable by Fontconfig, but they will not be accessible by the generic family names.

Standard scalable fonts that come with X provide very poor Unicode coverage. You may notice in applications that use Xft that some characters appear as a box with four binary digits inside. In this case, a font set with the available glyphs has not been found. Other times, applications that don't use other font families by default and don't accept substitutions from Fontconfig will display blank lines when the default font doesn't cover the orthography of the user's language. This happens, e.g., with Fluxbox in the ru_RU.KOI8-R locale.

In order to provide greater Unicode coverage, it is recommended that you install these fonts:

The list above will not provide complete Unicode coverage. For more information, please visit the Unicode Font Guide.

As an example, consider the installation of the DejaVu fonts. From the unpacked source directory, run the following commands as the root user:

install -v -d -m755 /usr/share/fonts/dejavu &&
install -v -m644 *.ttf /usr/share/fonts/dejavu &&
fc-cache -v /usr/share/fonts/dejavu

Setting up Xorg Devices

For most hardware configurations, modern Xorg will automatically get the server configuration correct without any user intervention. There are, however, some cases where auto-configuration will be incorrect. Following are some example manual configuration items that may be of use in these instances.

cat > /etc/X11/xorg.conf.d/xkb-defaults.conf << "EOF"
Section "InputClass"
    Identifier "XKB Defaults"
    MatchIsKeyboard "yes"
    Option "XkbOptions" "terminate:ctrl_alt_bksp"
EOF

cat > /etc/X11/xorg.conf.d/videocard-0.conf << "EOF"
Section "Device"
    Identifier  "Videocard0"
    Driver      "radeon"
    VendorName  "Videocard vendor"
    BoardName   "ATI Radeon 7500"
    Option      "NoAccel" "true"
EndSection
EOF

cat > /etc/X11/xorg.conf.d/server-layout.conf << "EOF"
Section "ServerLayout"
    Identifier     "DefaultLayout"
    Screen      0  "Screen0" 0 0
    Screen      1  "Screen1" LeftOf "Screen0"
    Option         "Xinerama"
EndSection
EOF