13.1. Configuration du serveur X11
La phase de configuration initiale de l'interface graphique est toujours un peu délicate ; il arrive fréquemment qu'une carte vidéo très récente ne fonctionne pas parfaitement avec la version de X.org livrée dans la version stable de Debian.
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 (Stretch contains version X11R7.7).
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.
En ce qui concerne la configuration du clavier, elle est désormais indiquée dans
/etc/default/keyboard. Ce fichier contrôle la configuration de la console ainsi que celle de l'interface graphique et il est géré par le paquet
keyboard-configuration. La configuration de la disposition du clavier est détaillée dans la
Section 8.1.2, « Configurer le clavier ».
Le paquet xserver-xorg fournit le serveur X générique exploité par les versions 7.x de X.org. Ce serveur modulaire dispose d'une collection de pilotes pour gérer les différents modèles de carte vidéo. L'installation de xserver-xorg assure que le serveur et au moins un pilote graphique sont installés.
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. VESA 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 fbdev works on top of the kernel's framebuffer device. Nowadays the X server runs without any administrative privileges (this used to be required to be able to configure the screen) and thus its log file is now stored in the user's home directory in ~/.local/share/xorg/Xorg.0.log (whereas it used to be in /var/log/Xorg.0.log for versions older than Stretch). That log file 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
