The X Server Configuration HOWTO1. What is the X Window Server? 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 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. 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 /etc/make.conf so that the right drivers and Xorg packages are built and installed. By default, Xorg uses evdev, a generic input driver. You'll need to activate support for evdev by making a change to your kernel configuration. Read the Kernel Configuration Guide if you don't know how to setup your kernel.
Modern open-source video drivers rely on kernel modesetting (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. KMS conflicts with legacy framebuffer drivers, which must remain disabled in your kernel configuration. First, prepare your kernel for KMS. You need to do this step regardless of which Xorg video driver you're using.
Next, configure your kernel to use the proper KMS driver for your video card. Intel, nVidia, and ATI are the most common cards, so follow code listing for your card below. For Intel cards:
For nVidia cards:
For newer ATI cards (RadeonHD 2000 and up), you will need to emerge radeon-ucode. Once you have installed radeon-ucode, configure your kernel as shown:
Now that you're done setting up KMS, continue with preparing /etc/make.conf in the next section. Now that your kernel is prepared, you have to configure two important variables in the /etc/make.conf file before you can install 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 nouveau for nVidia cards or radeon for ATI cards. Both have actively developed, well-supported open-source drivers.
The intel 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 evdev 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. Now you should decide which drivers you will use and add necessary settings to the /etc/make.conf file:
If the suggested settings don't work for you, you should run emerge -pv xorg-drivers, check all the options available and choose those which apply to your system. This example is for a system with a keyboard, mouse, Synaptics touchpad, and a Radeon video card.
After setting all the necessary variables you can install the Xorg package.
When the installation is finished, you will need to re-initialise some environment variables before you continue. Just run env-update followed by source /etc/profile and you're all set.
Now it's time to start the Hardware Abstraction Layer (HAL) daemon and set it to automatically start each time you boot. This is necessary to get a working X environment, otherwise your input devices won't be detected and you'll probably just get a blank screen. We'll cover HAL more in the next section.
The X server is designed to work out-of-the-box, with no need to manually edit Xorg's configuration files. You should first try starting X without creating /etc/X11/xorg.conf. If Xorg won't start (if there's something wrong with the screen, or with your keyboard/mouse), then you can try fixing problems by using the right configuration files. By default, Xorg uses HAL (Hardware Abstraction Layer) to detect and configure devices such as keyboards and mice. HAL comes with many premade device rules, also called policies. These policy files are available in /usr/share/hal/fdi/policy/. Just find a few that suit your needs most closely and copy them to /etc/hal/fdi/policy/.
For example, to get a basic working keyboard/mouse combination, you could copy the following files to /etc/hal/fdi/policy/:
There are several other HAL policies in /usr/share/hal/fdi/ that may interest you, such as laptop configurations, storage device handling, power management, and more. Just copy any of the policies to /etc/hal/fdi/policy/.
You can edit the policy files in /etc/hal/fdi/policy to your liking. You may want to make a few tweaks or to expose additional functionality. Let's go through an example of tweaking a HAL policy. One very convenient trick is to kill the X server entirely by pressing Ctrl-Alt-Backspace. This is useful when your X server is malfunctioning, frozen, etc. It's not as extreme as rebooting the whole machine with Ctrl-Alt-Del. Recent X server versions disabled this key combination by default. However, you can reenable it by copying 10-x11-input.fdi to /etc/hal/fdi/policy and editing it. You'll need to add just one line to the appropriate section, as shown below:
Once you're done, run /etc/init.d/hald restart so that HAL picks up your changes. There, now you have a handy way of killing an unresponsive X server. This is useful when programs have frozen your display entirely, or when configuring and tweaking your Xorg environment. Be careful when killing your desktop with this key combination -- most programs really don't like it when you end them this way, and you may lose some (or all) of what you were working on. Hopefully just working with the HAL policy files results in a working X desktop. If Xorg still won't start, or there's some other problem, then you'll need to manually configure xorg.conf as shown in the next section.
The configuration file of Xorg is called xorg.conf and it resides in /etc/X11. Xorg provides an example configuration as /etc/X11/xorg.conf.example which you can use to create your own configuration. It is heavily commented, but if you are in need of more documentation regarding the syntax, don't hesitate to read the man page:
Automatic Generation of xorg.conf Xorg itself is able to guess most parameters for you. In most cases, you will only have to change some lines to get the resolution you want up and running. If you are interested in more in-depth tweaking, be sure to check the resources at the end of this chapter. But first, let us generate a (hopefully working) Xorg configuration file.
Be sure to read the last lines printed on your screen when Xorg has finished probing your hardware. If it tells you it failed at some point, you're forced to manually write an xorg.conf file. Assuming that it didn't fail, it will have told you that it has written /root/xorg.conf.new ready for you to test. So let's test. :)
If all goes well, you should see a simple black and white pattern. Verify if your mouse works correctly and if the resolution is good. You might not be able to deduce the exact resolution, but you should be able to see if it's too low. You can exit any time by pressing Ctrl-Alt-Backspace. Let us copy over the xorg.conf.new to /etc/X11/xorg.conf now, so we won't have to continuously run X -config -- typing just startx is easier. :)
Now try startx to start up your X server. startx is a script 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:
You can kill the X session by using the Ctrl-Alt-Backspace key combination. This will, however, make X exit disgracefully -- something that you might not always want. If you haven't yet installed a window manager, all you'll see is a black screen. Since this can also be a sign that something's wrong, you may want to emerge twm and xterm only to test X. Once those two programs are installed, run startx again. A few xterm windows should appear, making it easier to verify that X is working correctly. Once you're satisfied with the results, run emerge --unmerge twm xterm as root to get rid of the testing packages. You won't need them once you've setup a proper desktop environment. If you feel that the screen resolution is wrong, you will need to check two sections in your xorg.conf configuration. First of all, you have the Screen section which lists the resolutions, if any that your X server will run at. By default, 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. What happens is that Xorg checks the settings of HorizSync and VertRefresh in the Monitor section to compute valid resolutions. For now, leave these settings as-is. Only when the changes to the Screen section (which we will describe in a minute) don't work, then you will need to look up the specs for your monitor and fill in the correct values.
Now let us change the resolution. In the next example from /etc/X11/xorg.conf we add the PreferredMode line so that our X server starts at 1440x900 by default. Don't mind the given strings -- they are examples and will most likely differ from the settings on your system. However, the Option in the Device section must match the name of your monitor (DVI-0), which can be obtained by running xrandr. You'll need to emerge xrandr just long enough to get this information. The argument after the monitor name (in the Device section) must match the Identifier in the Monitor section.
Run X (startx) to discover it uses the resolution you want. You can configure more than one monitor in /etc/X11/xorg.conf. All you have to do is give each monitor an identifer, 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:
To setup X to use an international keyboard, you can copy the content of /usr/share/doc/hal-*/*/use-estonian-layout.fdi.bz2 to /etc/hal/fdi/policy/10-xinput-configuration.fdi:
Now you can just edit 10-xinput-configuration.fdi and change the Estonian keyboard layout (ee) to your own, such as Great Britain (gb) or Polish (pl). When you're finished, run /etc/init.d/hald restart as root to make sure that HAL picks up your configuration file changes. Run startx and be happy about the result. Congratulations, you now (hopefully) have a working Xorg on your system. The next step is to install a useful window manager or desktop environment such as KDE, GNOME, or Xfce, but that's not part of this guide. Creating and Tweaking xorg.conf First of all, man xorg.conf and man evdev provide quick yet complete references about the syntax used by these configuration files. Be sure to have them open on a terminal near you when you edit your configuration files! Also, be sure to look at /etc/X11/xorg.conf.example; you may wish to copy this and use it as a foundation for writing your own xorg.conf. You may find the X.org FAQ provided on their website, in addition to their other documentation. There are also many online resources on editing xorg.conf. We only list few of them here, be sure to Google for more. More information about installing and configuring various graphical desktop environments and applications can be found in the Gentoo Desktop Documentation Resources section of our documentation. If you're upgrading to xorg-server 1.8 from an earlier version, then be sure to read the migration guide. The contents of this document are licensed under the Creative Commons - Attribution / Share Alike license. |
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