Fedora™ Unleashed, 2008 edition

Section 'InputDevice'
 Identifier 'Mouse0'
 Driver 'mouse'
 Option 'Device' '/dev/input/mice'
 Option 'Protocol' 'IMPS/2'
 Option 'Emulate3Buttons' 'off'
 Option 'ZAxisMapping' '4 5'
EndSection

NOTE

If you change your computer's pointing device, you should then run Fedora's system-config-mouse client, which automatically updates your system's xorg.conf file.

CAUTION

From Fedora Core 3 onward, the location for the mouse device changed from /dev/mouse to /dev/input/mice. Unfortunately, when system-config-display writes the xorg.conf file, it sometimes gets a little confused and still maps the mouse to /dev/mouse rather than /dev/input/mice. This is where a little knowledge of vi comes in handy!

The Monitor Section

The Monitor section configures the designated display device as declared in the ServerLayout section, as shown in this example:

Section 'Monitor'
 Identifier 'Monitor0'
 VendorName 'Monitor Vendor'
 ModelName 'Monitor Model'
 DisplaySize 300 220
 HorizSync 31.5-48.5
 VertRefresh 50-70
 Option 'dpms'
EndSection

Note that the X server automatically determines the best video timings according to the horizontal and vertical sync and refresh values in this section. If required, old-style mode- line entries (used by distributions and servers prior to XFree86 4.0) might still be used. If the monitor is automatically detected when you configure X (see the 'Configuring X' section later in this chapter), its definition and capabilities are inserted in your xorg.conf file from the MonitorsDB database. This database contains more than 600 monitors and is located in the /usr/share/hwdata directory.

The Device Section

The Device section provides details about the video graphics chipset used by the computer, as in this example:

Section 'Device'
 Identifier 'Videocard0'
 Driver     'radeon'
 VendorName 'Videocard vendor'
 BoardName  'ATI Radeon Mobility M6'
EndSection

This example identifies an installed video card as using an ATI Mobility M6 graphics chipset. The Driver entry tells the Xorg server to load the radeon_drv.o module from the /usr/lib/modules/drivers directory. Different chipsets have different options. For example, here's the entry for a NeoMagic video chipset:

Section 'Device'
 Identifier 'NeoMagic (laptop/notebook)'
 Driver 'neomagic'
 VendorName 'NeoMagic (laptop/notebook)'
 BoardName 'NeoMagic (laptop/notebook)'
 Option 'externDisp'
 Option 'internDisp'
EndSection

In this example, the Device section specifies the driver for the graphics card (neomagic_drv.o) and enables two chipset options (externDisp and internDisp) to allow display on the laptop's LCD screen and an attached monitor.

The Xorg server supports hundreds of different video chipsets. If you configure X11 but subsequently change the installed video card, you need to edit the existing Device section or generate a new xorg.conf file, using one of the X configuration tools discussed in this chapter, to reflect the new card's capabilities. You can find details about options for some chipsets in a companion man page. You should look at these sources for hints about optimizations and troubleshooting.

The Screen Section

The Screen section ties together the information from the previous sections (using the Screen0, Device, and Monitor Identifier entries). It can also specify one or more color depths and resolutions for the session. Here's an example:

Section 'Screen'
 Identifier 'Screen0'
 Device 'Videocard0'
 Monitor 'Monitor0' DefaultDepth 24
 SubSection 'Display'
  Viewport 0 0 Depth 16
  Modes '1024x768' '800x600' '640x480'
 EndSubSection
EndSection

In this example, a color depth of thousands of colors and a resolution of 1024?768 is the default, with optional resolutions of 800?600 and 640?480. Multiple Display subsection entries with different color depths and resolutions (with settings such as Depth 24 for millions of colors) can be used if supported by the graphics card and monitor combination. You can also use a DefaultDepth entry (which is 24, or thousands of colors, in the example), along with a specific color depth to standardize display depths in installations

You can also specify a desktop resolution larger than that supported by the hardware in your monitor or notebook display. This setting is known as a virtual resolution in the Display subsection. This allows, for example, an 800?600 display to pan (that is, slide around inside) a virtual window of 1024?768.

NOTE

If your monitor and graphics card support multiple resolutions and the settings are properly configured, you can use the key combination of Ctrl+Alt+Keypad+ or Ctrl+Alt+Keypad to change resolutions on-the-fly during your X session.