13.1. Configuring the X11 Server
The initial configuration for the graphical interface can be awkward at times; very recent video cards often don't work perfectly with the X.org version shipped in the Debian stable version.
A brief reminder: X.org is the software component that allows graphical applications to display windows on screen. It includes a driver that makes efficient use of the video card. The features offered to the graphical applications are exported through a standard interface, X11 (Jessie contains its X11R7.7 version).
Current versions of X.org are able to autodetect the available hardware: this applies to the video card and the monitor, as well as keyboards and mice; in fact, it is so convenient that the package no longer even creates a /etc/X11/xorg.conf configuration file. This is all made possible by features provided by the Linux kernel (in particular for keyboards and mice), by having each driver list the video cards it supports, and by using the DDC protocol to fetch monitor characteristics.
The keyboard configuration is currently set up in
/etc/default/keyboard. This file is used both to configure the text console and the graphical interface, and it is handled by the
keyboard-configuration package. Details on configuring the keyboard layout are available in
Section 8.1.2, “Configuring the Keyboard”.
The xserver-xorg-core package provides a generic X server, as used by the 7.x versions of X.org. This server is modular and uses a set of independent drivers to handle the many different kinds of video cards. Installing xserver-xorg ensures that both the server and at least one video driver are installed.
Note that if the detected video card is not handled by any of the available drivers, X.org tries using the VESA and fbdev drivers. The former is a generic driver that should work everywhere, but with limited capabilities (fewer available resolutions, no hardware acceleration for games and visual effects for the desktop, and so on) while the latter works on top of the kernel's framebuffer device. The X server writes its messages to the /var/log/Xorg.0.log log file, which is where one would look to know what driver is currently in use. For example, the following snippet matches what the intel driver outputs when it is loaded:
(==) Matched intel as autoconfigured driver 0
(==) Matched modesetting as autoconfigured driver 1
(==) Matched vesa as autoconfigured driver 2
(==) Matched fbdev as autoconfigured driver 3
(==) Assigned the driver to the xf86ConfigLayout
(II) LoadModule: "intel"
(II) Loading /usr/lib/xorg/modules/drivers/intel_drv.so
