Note: install with: yum install xorg-x11-Xdmx
Created Thursday 26/7/2007
This document attempts to describe some pitfalls with configuring X11 under linux. Mostly, distributions like FC provide a fairly straight forward no knowledge required configuration, but occasionally updates and hardware installations may lead to problems. There is a wiki at wiki.X.Org
X11 now uses the xorg.conf file, located in /etc/X11/xorg.conf. The file format is much the same as the old XFree86.conf and XFree86-4.conf files in that there are several sections corresponding to what modules should be loaded (e.g., freetype, dri, etc) to what display resolution should be used.
Font configuration in X is typically done using xfs, which is indicated by the "FontPath" entry
"FontPath "unix/:7100""
See also:
Xdmx is proxy X server that provides multi-head support for multiple displays attached to different machines (each of which is running a typical X server). When Xinerama is used with Xdmx, the multiple displays on multiple machines are presented to the user as a single unified screen. A simple application for Xdmx would be to provide multi-head support using two desktop machines, each of which has a single display device attached to it. A complex application for Xdmx would be to unify a 4 by 4 grid of 1280x1024 displays (each attached to one of 16 computers) into a unified 5120x4096 display.
Note: install with: yum install xorg-x11-Xdmx
Some video cards provide multiple video outputs on a single card (e.g., the nVidia GeForce 7600 GT). See also:
Specify a "device" section for video card. Each device section must specify the slot where the card is located (e.g., PCI:1:0:0) and etc. After defining the devices, specify multiple "screen" sections. Each screen will refer to particular "device".
The placement (or location) of the screens is defined in the "serverlayout" section of xorg.conf. Each screen location is specified as being relative to another, e.g., "RIGHT OF", "LEFT OF" other screens. For example, 2 screens in the "serverlayout" section might be placed as:
Section "ServerLayout"
Identifier "Multihead layout"
Screen 0 "PhilipsScreen" LeftOf "ViewSonicScreen"
Screen 1 "ViewSonicScreen" 0 0
Option "Xinerama" "on"
InputDevice "Keyboard0" "CoreKeyboard"
EndSection
Xorg 7.1 ships with AIGLX and therefore supports 3-D compositing and rendering. To use these features requires that the Xorg configuration load modules that enable 3-D support. This is done by adding a module section to /etc/X11/xorg.conf (see 4.A).
Before specifying the modules to load, it may be necessary to tell Xorg where any additional video card or 3rd party specific modules can be found. Typically, 3rd party drivers like the nVidia and ATI drivers are installed to an extensions directory, such as /usr/lib64/xorg/modules/extensions/nvidia. Xorg can be told where additional modules are by specifying a "Files" section, similar to:
Section "Files"
ModulePath "/usr/lib64/xorg/modules/extensions/nvidia"
ModulePath "/usr/lib64/xorg/modules"
EndSection
Clearly, the module paths must reflect the correct pathnames for the system in which they are installed.
After telling Xorg where to find any additional modules, it is necessary to ensure that certain 3-D support modules are loaded in addition to the default. This is done by modifying the "module" section. It may be the case that the xorg configuration /etc/X11/xorg.conf does not have a "module" section and if this is true then one should be added. In either case, the "module" section should load (at least) the following modules:
Section "Module"
Load "dbe" # Double buffer extension
Load "fbdevhw" # Frame buffer hardward
Load "freetype" # Freetype font module
Load "type1" # Type1 font module
Load "glx" # OpenGL 3-D module
Load "extmod" # The miscellaneous extensions module
Load "dri" # The DRI module
EndSection
Stuart Moorfoot © 26 July 2007 foo@bund.com.au