X Server Configuration

Initial X Configuration

The version of Xorg-X11 that comes with cAos-2 has the capabilities to run without a configuration file. It will probe to try and find the best configuration. If this does not work, the problem is usually associated with not being able to probe the monitor or the video card is not supported. If the problem is with the monitor configuration (resolution and/or refresh rates) or you wish to change some of the default configurations, you can create your own config file. This may be done in following manner:

– Install the xorg-x11-config package by the command: yum install xorg-x11-config

– Menu based X configuration is started up by the command: xorgconfig

– Graphically X configuration is started up by the command: xorgcfg

This will create an xorg.config or xorg.conf file in your home directory (eg. /root/xorg.config.example). You will need to copy or move that to /etc/X11/xorg.config to activate it.

To activate some signs of a non-US keybord as well as the mouse’s scroll function should the xorg.config file be edited in following way (use your favorite editor):

Core keyboard’s InputDevice section

    Option "XkbRules"   "xorg"
    Option "XkbModel"   "pc105"
    Option "XkbLayout"  "se"                (in this example a Swedish keyboard)
    Option "XkbVariant" "nodeadkeys"  (this script activates the signs)

    Identifier  "Mouse1"
    Driver      "mouse"
    Option "Protocol" "IMPS/2"       (this script activates the scroll)
    Option "Device"      "/dev/mice"
    Option "ZAxisMapping" "4 5"    (this script activates the scroll)^

Getting the Right Mode for an LCD monitor

You may have a monitor designed for a specific mode that isn’t available to X under normal conditions. A widescreen LCD like the Envision H193wk is a specific example. This monitor has a native resolution of 1440×900 at 60Hz. The LCD emulates other resolutions, but these other resolutions are often unsquare, "fuzzy," or go offscreen as the monitor attempts to "fit" the image to the display area. The 1440×900@60Hz mode isn’t part of the standard set of VESA modes, and may not be included in the "legal" modes returned by the video driver for your graphics card.

To add the mode to the "known" set of modes, it is necessary to define the mode for X. This is accomplished by adding a Modeline statement to the "Monitor" section of your xorg.conf file. The Modeline contains a number of specifications beyond just resolution and vertical refresh rate. An easy way of generating a full Modeline statement is to use the gtf command.

Using the gtf Command

The gtf command outputs a ready-to-use Modeline statement for your monitor given the input of resolution and vertical refresh rate of your monitor. To create the correct information for the Modeline statement, look at your monitor’s manual and determine its exact native resolution and precise vertical refresh rate for that resolution. For the Envision H193wk, it is listed as 1440 by 900 at 60Hz.

Plug these values into the gtf invocation:

[root@compy ~]# gtf 1440 900 60

yielding:

# 1440x900 @ 60.00 Hz (GTF) hsync: 55.92 kHz; pclk: 106.47 MHz
Modeline "1440x900_60.00"  106.47  1440 1520 1672 1904  900 901 904 932 -HSync +Vsync

The first line is a comment and need not be transferred. Paste or transcribe the Modeline anywhere inside the "Monitor" section that is referred to by the "Screen" section. Then make sure the "Screen" section includes the mode defined by your Modeline statement:

Section "Monitor"
    Identifier    "h193wk"
    Modeline      "1440x900_60.00"  106.47  1440 1520 1672 1904  900 901 904 932 -HSync +Vsync
EndSection
(...)
Section "Screen"
    Identifier    "Screen1"
    Device        "nvidia0"
    Monitor       "h193wk"
    Subsection "Display"
        Depth     24
        Modes     "1440x900_60.00"
        ViewPort  0 0
    EndSubsection
EndSection

Running startX should yield an X session matching your monitor’s resolution.

Before inserting the Modeline statement into your xorg.conf file, create a copy of xorg.conf so you can revert to the machine generated file if necessary.

If you have a problem after starting X, you may kill the X session by pressing <ctrl-alt-Backspace>.