Troubleshooting Your Desktop
Troubleshooting Your Desktop
If your desktop is not functioning properly (or at all) it may be that your video card was not configured properly. This section helps you get your video card configured properly and your desktop up and running smoothly.
GUI doesn't work at start-up
If Red Hat Linux has been successfully installed (along with the desired desktop environment) but the GUI wasn't set to start at boot time, you may only see a simple text-based login prompt when you start Red Hat Linux. This login prompt may look something like this:
Fedora Core release 1 Kernel 2.4.22 on an i686 YourComputer login:
Log in as the root user. As noted earlier, you can check if you have a GUI that is at least working well enough for you to correct it. Type the following command:
# startx
If the desktop works fine when you type startx, you might want to change to a graphical login, so the GUI starts automatically every time. See the "What Happens During Desktop Startup" sidebar for information on booting to a GUI.
If your GUI is so distorted you can't even see to correct it, switch to a virtual terminal to correct the problem. For example, hold the Ctrl and Alt keys, and press F2. You will see a plain text login prompt. Log in as root user and type init 3 to make the garbled GUI login screen go away. Then you can try tuning your video card as described in the following section.
| Tip? |
Switching virtual terminals is a great way to get out of a GUI that is broken or stuck and run the commands you need to fix a problem. You can use any function key from F1 through F8 with Ctrl+Alt to switch terminals. The GUI itself is probably on the F7 virtual terminal. Linux experts use virtual terminals during Red Hat installation to debug a problem or during startup to view text startup messages. |
 |
The X server and graphical login screen is started by the prefdm script. By default, the login screen is displayed by the GNOME display manager (gdm command), which handles both logging in and starting the desktop environment for your console monitor, as well as graphical logins from other computers and X terminals. (If you don't like the way the login screen appears, run gdmsetup as root user. It will let you change the login greeter screen or even allow no-password logins.)
The prefdm script is launched only if the run level in the /etc/inittab file is set to 5, as follows:
id:5:initdefault:
If the initdefault state is 3, the system boots to a text-based login prompt. See Chapter 12 for information on Linux run states and start-up processes.
If you are unable to get the video card and monitor configured properly, or if you don't need a GUI, you can configure the computer to start up in text mode. To do this using any shell text editor (such as the vi command described in Chapter 3), change the initdefault line in the /etc/inittab file from id:5:initdefault: to id:3:initdefault.
If you prefer to have Red Hat Linux boot to a GUI, change the 3 to a 5 instead.
|
Tuning your video card and monitor
If your GUI is starting up but needs some tuning (to get better resolution, more colors, or to fix flickering), you can use the Display Settings window to fix your desktop. For the current Red Hat Linux, the Display Settings window was enhanced so that you can use it from a command with no GUI running. The next sections describe how to run the Display Settings window, then how to review the resulting XF86Config file to understand your settings.
Running the Display Settings window
Red Hat recently replaced the Xconfigurator tool with a new Display Settings window (redhat-config-xfree86 command). This window lets you set the most basic functions relating to your display, monitor, and video card. The Display Settings window is easy-to-use and no longer requires a running X desktop to use it.
To open the Display Settings window from the Red Hat menu, click System Settings ? Display. To open that window from a text prompt (even with no GUI running), type redhat-config-xfree86 (as root). The Display Settings window appears, as shown in Figure 3-20.
Figure 3-20: Use the Display Settings window to configure basic desktop, video card, and monitor settings.
From the Display tab, you can try different resolutions (screen width and height in pixels) and color depth (from 256 colors to millions of color). Click the Advanced tab to try to configure your monitor and video card. Click OK to save your changes.
Here are a few tips for using the Display Settings window:
-
If you know your monitor type, but it is not being detected, click the Advanced tab and then click Configure. You can select the monitor from a list of monitors (by manufacturer) or, if it's not on the list, enter information about the monitor's horizontal and vertical sync rates from the manufacturer's instructions.
-
If the video card supports 3D hardware acceleration, but is not turned on, you might be able to enable that feature from the Advanced tab under the Video Card section. Just click the Enable Hardware 3D Acceleration check box.
Changes made in the Display Settings window result in the creation of a new /etc/X11/XF86Config file. The next section describes what the XF86Config file contains.
| Tip? |
If the Display Settings window fails to create a working XF86Config file, you can try another approach. With no GUI on as root user, type the following commands from a shell: # XFree86 -configure # XFree86 -xf86config /root/XF86Config.new The first line creates XF86Config.new in the /root directory. The second tries to start your GUI with that new config file. If the GUI works, copy XF86Config.new to /etc/X11/XF86Config. You may need to run redhat-config-mouse to get the mouse working properly after this. |
Understanding the XF86Config file
The XF86Config file (located in the /etc/X11 directory) contains definitions used by the X server to use your video card, keyboard, mouse, and monitor. In general, novice users should not edit this file directly. For some video cards, however, manual configuration may be required to get the card working properly.
The following is a description of the basic information contained in the XF86Config file:
-
ServerLayout section — Binds input and output devices for your X session. Lets you set server definitions for different X servers (if necessary).
-
Module section — Describes which X server modules should be loaded.
-
Files section — Sets the locations of the RGB (color) and fonts databases.
-
InputDevice sections — Separate sections identify keyboard and mouse input devices.
-
Monitor section — Sets the type of monitor, along with its horizontal sync rate, vertical refresh rate, and settings needed to operate at different resolutions.
-
Device section — Identifies your video card and, optionally, video RAM and clock information for the chipset.
-
Screen section — Binds the graphics board and monitor information to be referenced later by the ServerLayout section.
-
Keyboard section — Sets keyboard settings, including the layout of the keyboard and the way certain key sequences are mapped to the keyboard.
-
Pointer section — Selects the pointer you are using (typically a mouse linked to /dev/mouse). Also sets speed and button emulation, when appropriate.
-
DRI — Provides information for Direct Rendering Infrastructure (used for accelerated 3D graphics).
Configuring video cards for gaming
Some games and video players require special features to work properly (or at all, in some cases). For games that require 3D hardware acceleration, including some that run under TransGaming's WineX, TransGaming recommends using nVIDIA GeForce Graphics cards.
Because only basic nVIDIA video card drivers are included in Red Hat Linux (nVIDIA's own drivers are not open source), you need to get nVIDIA drivers yourself to use those cards for gaming. You can download nVIDIA drivers for Linux from:
www.nvidia.com/object/linux_display_archive.html
Select the latest drivers from the list (look for version 1.0-4496 or later). Download and install the drivers as described.
Games that don't require 3D hardware acceleration should work fine with most video cards that are supported by XFree86 4.0 and higher drivers.
| Tip? |
To use hardware DRI acceleration on Voodoo 3 cards, you must have your display set to use 16bpp resolution. On Voodoo 5 cards, only 16bpp and 24bpp resolutions are supported. |
Getting more information
If you tried configuring X and you still have a server that crashes or has a garbled display, your video card may either be unsupported or may require special configuration. Here are several locations you can check for further information:
-
XFree86.org (www.xfree86.org) — The latest information about the X servers that come with Red Hat Linux is available from the XFree86.org Web site. XFree86 is the freeware version of X used with all major Linux distributions.
-
Red Hat Support (www.redhat.com/support) — Search the Red Hat support database for the model of your card. There may already be reports of problems (and hopefully fixes) related to your card.
-
X documentation — README files that are specific to different types of video cards are delivered with XFree86. Visit the XFree86 doc directory (/usr/X11R6/lib/X11/doc) for a README file specific to the type of video card (or more specifically, the video chipset) you are using. A lot of good information can also be found on the XF86Config man page (type man XF86Config).
