The GUI interface for your desktop display is implemented by the X Window System. The version used on Ubuntu is X.org (x.org). X.org provides its own drivers for various graphics cards and monitors. You can find out more about X.org at www.x.org.
X.org will automatically detect most hardware. The /etc/X11/xorg.conf file is no longer used for the open source drivers (nv and ati). It is still used to a limited extent by proprietary drivers, though mouse and keyboard entries are ignored. Information such as the monitor used is determined automatically. Should you want to change the screen resolution, use the Display tool accessible from System | Preferences | Monitors. If you have an older monitor that is not correctly detected, you may have to specify monitor information by editing the /etc/X11/xorg.conf file.
Resolution Preferences: RandR
The X display drivers for Linux used on Ubuntu now support user level resolution and orientation changes. Any user can specify their own resolution or orientation without affecting the settings of other users. Display Preferences provides a simple interface for setting rotation, resolution, and selecting added monitors, allowing for cloned or extended displays across several connected monitors. Open the Monitors window by selecting Administration | Preferences | Monitors. From the drop-down menus, you can set the resolution, refresh rate, and rotation. After you select a resolution, click Apply. The new resolution is displayed with a dialog with buttons that asks you whether to keep the new resolution or return to the previous one. You can use the Detect Monitors button to detect any other monitors connected to your system. The “Show monitors in panel” checkbox will display a button for each display in the top panel, letting you switch between them easily.
Vendor drivers: restricted hardware
Your display will be detected automatically, configuring both your graphics card and monitor. Normally you should not need to perform any configuration yourself. However, if you have a graphics card that uses Graphics processors from a major Graphics vendor like ATI (AMD) or Nvidia, you have the option of using their driver, instead of the open source X drivers installed with Ubuntu. Some cards may work better with the vendor driver, and provide access to more of the card’s features like 3D support. The open source ATI driver is xserver-xorg-video-ati, and the open source Nvidia driver is xserver-xorg-video-nv for older cards and xserver-xorg-video-nouveau for newer cards.
After you install Ubuntu and login, your graphic card will be detected and you will be notified that you can use a vendor driver instead for better performance. A restricted hardware notification icon is displayed on the top panel. Click on it or select System | Administration | Hardware Drivers to open the Hardware Drivers window. This invokes the jockey application, which will detect and mange the installation of needed hardware drivers.
Select the driver entry and then click on the Activate button to use download and install the driver. Once installed the Activate button will change to a Deactivate button. You are notified to Restart your system. Close the Hardware Drivers window and then restart your system. On restart, your system will then be using the vendor drivers such as ATI or Nvidia. The drives are part of the restricted repository, supported by the vendor but not by Ubuntu. They are not open source, but proprietary. This situation is beginning to change, with AMD (ATI) and Nvidia releasing much of its driver source code as open source.
Once installed, an examination of the Hardware Drivers window will show the selected driver in use. Should you want to remove the driver for any reason, click the Remove button. The driver will be removed and you will have to restart your system. Upon restart, the open source Xorg driver will be automatically selected and used. For Nvidia cards, the Nouveau open source drivers are used, which provides some acceleration support.
When new version of the proprietary drivers becomes available, you will be notified and prompted to select the new version. A note will tell you that a different version is currently in use, and the Activate button will be displayed. Clicking it will download and install the new version.
The graphic vendors also have their own Linux-based configuration tools, which are installed with the driver. The Nvidia configuration tool is in the nvidia-settings package. Once installed, you will see the Nvidia X Server Settings entry in the Administration menu (System | Administration | Nvidia X Server Settings). This interface provides Nvidia vendor access to many of the features of Nvidia graphics cards like color corrections, video brightness and contrast, and thermal monitoring. You can also set the screen resolution and color depth.
ATI/AMD provides a Linux version of its Catalyst configuration tool for use on Linux, the fglrx-amdcccle package. Much of the ATI video drivers have now become open source, making the ATI video driver much more Linux compatible.
If you have problems with the vendor driver, you can always uninstall it. Your original Xorg open source driver will be used instead. The changeover will be automatic. To uninstall the vendor driver, use the Hardware Drivers window and un-check the vendor driver entry. After the uninstall process, you will be prompted to reboot.
If the problem is more severe, with the display not working, you can use the GRUB menu on start up to select the recovery kernel. Your system will be started without the vendor graphics driver. You can use the “drop to shell” to enter the command line mode. From there you can use apt-get command-line APT tool to remove the graphics driver. The ATI drivers normally would have the prefix fglrx and Nvidia have nvidia. In the following example, the asterisk will match on all the fglrx packages (ATI).
sudo apt-get remove nvidia*
Note: All hardware display drivers will generate an X Window System configuration file called /etc/X11/xorg.conf. The xorg.conf file performs minimal configuration such as selecting the driver to use and any specialized modules for acceleration. Most settings are now detected and configured automatically.