Xorg/Guide/en

Xorg is the X Window server which allows users to have a graphical environment at their fingertips. This guide explains what Xorg is, how to install it, and the various configuration options.

Graphical vs command-line
The average user may be frightened at the thought of having to type in commands. Why wouldn't he be able to point and click his way through the freedom provided by Gentoo (and Linux in general)? Well, of course you are able to do this! Linux offers a wide variety of flashy user interfaces and environments which you can install on top of your existing installation.

This is one of the biggest surprises new users come across: a graphical user interface is nothing more than an application which runs on your system. It is not part of the Linux kernel or any other internals of the system. It is a powerful tool that fully enables the graphical abilities of your workstation.

As standards are important, a standard for drawing and moving windows on a screen, interacting with the user through mouse, keyboard and other basic, yet important aspects has been created and named the X Window System, commonly abbreviated as X11 or just X. It is used on Unix, Linux and Unix-like operating systems throughout the world.

The application that provides Linux users with the ability to run graphical user interfaces and that uses the X11 standard is Xorg-X11, a fork of the XFree86 project. XFree86 has decided to use a license that might not be compatible with the GPL license; the use of Xorg is therefore recommended. The official Portage tree does not provide an XFree86 package anymore.

The X.org project
The X.org project created and maintains a freely redistributable, open-source implementation of the X11 system. It is an open source X11-based desktop infrastructure.

Xorg provides an interface between your hardware and the graphical software you want to run. Besides that, Xorg is also fully network-aware, meaning you are able to run an application on one system while viewing it on a different one.

Installation
Before you can install Xorg, you need to prepare your system for it. First, we'll set up the kernel to support input devices and video cards. Then we'll prepare so that the right drivers and Xorg packages are built and installed.

Input driver support
By default, Xorg uses, a generic input driver. You'll need to activate support for  by making a change to your kernel configuration. Read the Kernel Configuration Guide if you don't know how to setup your kernel.

Kernel modesetting
Modern open source video drivers rely on kernel mode setting (KMS). KMS provides an improved graphical boot with less flickering, faster user switching, a built-in framebuffer console, seamless switching from the console to Xorg, and other features.

First prepare the kernel for KMS. This step regardless of which Xorg video driver will be used:

Next configure the kernel to use the proper KMS driver for the video card. Intel, nVidia, and AMD/ATI are the most common cards, so follow code listing for each card below.

For Intel cards see the kernel section of the Intel article.

For nVidia cards:

For newer AMD/ATI cards (RadeonHD 2000 and up), emerge or. Once one of these packages has been installed, configure the kernel as detailed in the firmware section of Radeon article:

Exit the kernel configuration, rebuild the kernel, and reboot.

Now that KMS has been set up, continue preparing in the next section.

make.conf configuration
Now that the kernel is prepared, two important variables in the file must be configured before installing Xorg.

The first variable is VIDEO_CARDS. This is used to set the video drivers that you intend to use and is usually based on the kind of video card you have. The most common settings are  for nVidia cards or   for ATI cards. Both have actively developed, well-supported open-source drivers.

The  driver may be used for desktops or laptops with common Intel integrated graphics chipsets.

The second variable is INPUT_DEVICES and is used to determine which drivers are to be built for input devices. In most cases setting it to  should work just fine. If you use alternative input devices, such as a Synaptics touchpad for a laptop, be sure to add it to INPUT_DEVICES.

Decide which drivers will be used and add necessary settings to the file:

If the suggested settings does not work emerge the package(see the step below). Check all the options available and choose those which apply to the system. This example is for a system with a keyboard, mouse, Synaptics touchpad, and a Radeon video card.

After setting all the necessary variables Xorg can be installed:

When the installation is finished, some environment variables will need to re-initialized before continuing. Source the profile with this command:

NVidia users
For NVidia users it might be beneficial to run in order to generate a working  file for the selected graphics card. Without this step the file will need to be created manually as described below. Missing the will sometimes generate a "No screens found" error to the terminal when attempting to.

Also the NVidia driver will only work after a reboot, so be sure to restart the system after running.

It is both possible and recommended to set the OpenGL renderer to the hardware renderer instead of a software renderer:

Configuration
The X server is designed to work out-of-the-box, with no need to manually edit Xorg's configuration files. It should detect and configure devices such as displays, keyboards, and mice.

Try using startx without editing any configuration files. If Xorg will not start, or there is some other problem, then manual configuration of Xorg will be needed. This is explained in the following section.

The directory
Most of the configuration files for Xorg are stored in. Each file is given a unique name and ends in. The file names in Xorg's configuration directory will be read in alpha numeric order. For example, will be read before ;  will be read before, and so on. The files in this directory are not required to be numbered, but doing so will help to keep them organized. Organization is helpful when debugging faulty configuration files.

Using startx
Try to start up the X server. is a script (it's installed by ) that executes an X session; that is, it starts the X server and some graphical applications on top of it. It decides which applications to run using the following logic:


 * If a file named exists in the home directory, it will execute the commands listed there.


 * Otherwise, it will read the value of the XSESSION variable from the file and execute the relevant session accordingly. Values for XSESSION are available in . To set a system wide default session run:




 * This will create the file and set the default X session to Xfce. Remember to run  after making changes to.

If no window manager has been installed a solid black screen will appear. Since this can also be a sign that something is wrong, the and  packages can be installed only to test X.

Once the programs are installed, run again. A few windows should appear, making it easy to verify the X server is working correctly. Once satisfied with the results, unmerge and  if installed in the step above to remove the testing packages. They will not be needed to setup a proper desktop environment.

The session (program to start) could also be given as an argument to :

You can also pass X11 server options, by preceding them with a double dash:

Setting the screen resolution
If the screen resolution looks to be wrong, you will need to check two sections in your configuration. First of all, you have the Screen section which lists the resolutions that your X server will run at. This section might not list any resolutions at all. If this is the case, Xorg will estimate the resolutions based on the information in the second section, Monitor.

Now let us change the resolution. In the next example from we add the   line so that our X server starts at 1440x900 by default. The  in the   section must match the name of your monitor, which can be obtained by running. Install  just long enough to get this information. The argument after the monitor name (in the  section) must match the   in the   section.

Run X to discover it uses the desired resolution.

Multiple monitors
More than one monitor in can be established in. Give each monitor a unique identifier, then list its physical position, such as "RightOf" or "Above" another monitor. The following example shows how to configure a DVI and a VGA monitor, with the VGA monitor as the right-hand screen:

Configuring the keyboard
To setup X to use an international keyboard create the appropriate config file in. This example features a Czech keyboard layout:

For methods of switching the keyboard layout see the Keyboard layout switching article.

The "terminate" command lets users kill the X session by using the ++ key combination. This will, however, make X exit disgracefully -- something that users might want to avoid. It can be useful when programs have frozen the display entirely, or when configuring and tweaking the Xorg environment. Be careful when killing the desktop with this key combination - most programs really do not like it when they are ended this way. Some, if not all, of the information that has not been written to the disk (information stored in "open documents") will be lost.

Finishing up
Run and be happy about the result. Congratulations, you now (hopefully) have a working Xorg! The next step is to install a useful window manager or desktop environment such as KDE, GNOME, or Xfce. Information on installing these desktop environments can be found here on the wiki.

Creating and editing config files
First of all, and  provide quick yet complete references about the syntax used by these configuration files. Be sure to have them open on a terminal when editing Xorg configuration files!

There are also many online resources on editing config files in. Only a few are listed here; use a favorite search engine to find more.

Other resources
More information about installing and configuring various graphical desktop environments and applications can be found in the section of our documentation.

When upgrading to xorg-server 1.9 or higher, be sure to read the migration guide.

X.org provides many FAQs on their website, in addition to their other documentation.