lsg05.htm

linux-unix130.linux.and.unix.ebooks130 linux and unix ebookslinuxLearning Linux - Collection of 12 E

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<FONT SIZE=5 COLOR="#FF0000"><B>Configuring XFree86</B></FONT></CENTER></H3>



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<P>Before you can run XFree86, you should specify some configuration information. This part tends to frustrate newcomers to XFree86 because getting your configuration files exactly right so that XFree86 runs properly can be a convoluted process. The step-by-step instructions in this section should streamline the process.



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<P>A utility called either ConfigFX86 or fx86config that is provided with many distributions of Linux and XFree86 simplifies the entire XFree86 installation process, but only if you have one of the supported graphics cards. A list of cards supported by ConfigFX86 and fx86config is usually included in the Hardware HOWTO file provided with the Linux distribution software. If you can't find the HOWTO file, you can obtain it from most FTP and BBS locations (see <A HREF="lsg02.htm">Chapter 2</A>, &quot;Linux Hardware and Software&quot;). Make sure the version of the file corresponds to the Linux version you are running. The section &quot;Using ConfigFX86 and fx86config&quot; provides more details about ConfigFX86 and fx86config. (You can, in some cases, provide enough information for ConfigFX86 and fx86config to use your unlisted video card for the installation. This procedure is discussed in the &quot;Using ConfigFX86 and fx86config&quot; section.) If you don't have the Hardware HOWTO file or your video card is not listed and you don't want to use a generic driver, you must manually configure XFree86. Even if you use the ConfigXF86 or fx86config script to install XFree86, you may still have to make manual modifications to your installation.



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<P>Most of the configuration details for XFree86 version 2.x are contained in a file called Xconfig; XFree86 version 3.x uses a file called XF86Config or Xconfig, depending on the version. The bare-bones instructions for setting up an Xconfig or XF86Config file are spread out over several text files included with the XFree86 distribution set. Check the README, VideoModes.doc, README.Config, and README.Linux files. Also, read the man pages for Xconfig, XF86Config, XFree86, and Xfree86kbd. Finally, check the man pages for the server version you are running, if some are provided. It's a good idea to print out the man pages for easier reference.



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<P>You need a few items of information to properly complete the Xconfig or FX86Config file. Before you start configuring XFree86, take a moment to note the following details:



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<LI>XFree86 server to be used



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<LI>Type of mouse on your system and the port to which it is connected



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<LI>Your video card's brand name and chipset. If you're not sure of the chipset, either consult your documentation or use a utility program like SuperProbe (Linux) or MSD (DOS).



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<LI>Your video monitor brand name and model number, as well as the size of the monitor. It also helps to know the maximum horizontal and vertical scan frequencies; this information is usually available from the monitor's documentation.



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<LI>Type of keyboard you will be using if not the U.S. generic type. Most users have the U.S. type, although some countries have customized keyboards that require different key mappings.



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<P>If you don't know some of the information and don't have an easy way (such as a utility program) to find out, check the documentation that comes with XFree86. Many distributions contain a directory such as /usr/X11/lib/X11/doc (usually linked to /usr/X386/lib/X11/doc or /usr/X11R6/lib/X11/doc) that contains a number of files describing many cards and monitors supported by XFree86 and the essential configuration information (such as monitor scan rates, which are always difficult to determine because you invariably don't remember where you placed the manual). Figure 5.1 shows an extract from the /usr/X11R6/lib/X11/doc/Monitors file. This entry shows the parameters that a Gateway 2000 system with a CrystalScan monitor requires. The Monitors file has entries for most popular monitor models. Another file included with most CD-ROM distributions is AccelCards, which lists popular video cards and their parameters. Figure 5.2 shows an extract from this file, which shows the S3 card series. Use these files, and any others in the doc directory, to identify the hardware you will be using.



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<P><B> <A HREF="05LSG01.gif">Figure 5.1</B>



<BR><B>The Monitors file in the X11/doc directory offers configuration </B><B>information for many popular monitor models.</A></B>



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<P><B> <A HREF="05LSG02.gif">Figure 5.2.</B>



<BR><B>The AccelCards file lists many popular video cards and the configuration </B><B>information they require.</A></B>



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<P>When you've noted all this configuration information, you are ready to start. Configuring XFree86 begins with the Xconfig or XF86Config file.



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<FONT SIZE=4 COLOR="#FF0000"><B>Deciding Where to Put Xconfig or XF86Config</B></FONT></CENTER></H4>



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<P>You can put the Xconfig or XF86Config file in several places on the Linux filesystem. Usually, it resides in the /usr/X386/lib/X11 directory, which is also where a sample Xconfig or XF86Config file is often found. If you have easy access to the /usr/X386/lib/X11 directory, it's the best place for the Xconfig or XF86Config file. (Formally, the file is referenced in /usr/X11R6/lib/X11 or /etc, but because /usr/X386 is linked to /usr/X11R6, the two directories point to the same place. The documentation may reference the X11R6 directory, but you can use either /usr/X386 or /usr/X11R6 as long as the link to the X386 directory is in place.) 



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<NOTE>Unless you are manually installing configuration information, don't worry about whether you should use Xconfig or XF86Config. Automated installation scripts will use the proper file. If you are performing a manual configuration, use Xconfig for XFree86 version 2.X and XF86Config for XFree86 version 3.x.</NOTE>



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<P>If you can't use the /usr/X386/lib/X11 directory (maybe it's read-only or on a remote server) or don't want to because you need a customized version of the Xconfig file, you can also place the file in the /etc directory or in your home directory. If the Xconfig file is in your home directory, it applies to your sessions only; any configuration information will not be valid for other users. The /etc directory location for the XFree86 Xconfig file means the configuration information is applicable to all users.



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<P>You can also put the Xconfig file in the directory /usr/X386/lib/X11 specific to a particular host machine. To do this, append the name of the host machine to Xconfig filename. For example, the file Xconfig.merlin applies the configuration information only to users logging in from the machine called merlin.



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<P>The Linux convention for the Xconfig file is to place it in the /etc directory. Because this location is not the usual one for XFree86 installations, you must create a link to the /etc/Xconfig file to /usr/X386/lib/X11 or your home directory. This link enables XFree86 to find the Xconfig file. To create the link just mentioned, issue the following command:



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<FONT COLOR="#000080">ln -s /usr/X386/lib/X11 /etc/Xconfig</FONT></PRE>



<P>The -s option creates a symbolic link (compared to a hard link), which is explained in <A HREF="lsg18.htm">Chapter 18</A>, &quot;Filesystems and Disks.&quot;



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<FONT SIZE=4 COLOR="#FF0000"><B>Using SuperProbe</B></FONT></CENTER></H4>



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<P>SuperProbe is a utility that attempts to determine the type of video card (and the amount of video RAM installed on that card) in a PC system. It works on ISA, EISA, and VLB (local bus) architectures, but not on MCA or PCI architectures (although SuperProbe versions for these systems may be available by the time you read this book). If you already know which video card you have, SuperProbe is of little use to you.



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<P>SuperProbe attempts to identify video cards by probing for certain known unique registers on each video card it knows about. This process has one drawback&#151;some instructions executed by SuperProbe can cause your machine to lock up. Although it is unlikely damage will occur because of SuperProbe, the filesystem will have to be cleaned if the machine must be reset. For this reason, make sure you are the only user on the machine. Making a backup of your system is also advisable.



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<NOTE>Running SuperProbe by itself is almost guaranteed to lock up any machine. Use it with care and follow the instructions in this section for giving SuperProbe a basic idea of the testing it should do.</NOTE>



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<P>SuperProbe is usually included as part of the XFree86 distribution set on CD-ROMs; you also can get it from FTP and BBS sites that offer Linux software. SuperProbe is not exclusive to Linux; it can run under several other PC UNIX systems as well. A man page is available for SuperProbe.



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<P>SuperProbe uses a number of command-line options to specify its behavior. Although the exact options change with each new release of the software, the basic options of interest to you are limited to a few:



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-bios



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Specifies the video card BIOS' address, normally set to C0000. If you had to set your BIOS address to some other value, it should be specified with this option.</FONT>



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-info



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Displays a list of all video cards SuperProbe knows about and the card's names as recognized by SuperProbe.</FONT>



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-no_16



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Disables 16-bit testing. This option is used only for old, 8-bit video cards.</FONT>



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-no_bios



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Disables testing of the video card BIOS and assumes the card is an EGA, VGA, SVGA, or later type. If your video card is new, this option is useful for preventing many BIOS-caused system freezes.</FONT>



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-no_dac



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Disables testing for a RAMDAC type. You can use this option with VGA and SVGA cards to prevent potential freezes.</FONT>



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-no_mem



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Skips the testing for the amount of video RAM installed on the video card.</FONT>



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-order



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Specifies the order in which chipsets should be tested. This option is useful if you think you know the types of chipsets, but want confirmation. Alternatively, if you suspect the video card has one of a few chipsets, you can list just those.</FONT>



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-verbose



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Displays information on-screen as to SuperProbe's actions and results. You should use this option in all cases to show progress and potential problems.</FONT>



</TABLE><P>One of the first steps to take is to display a list of all the video cards SuperProbe knows about. Issue the command



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<FONT COLOR="#000080">SuperProbe -info</FONT></PRE>



<P>and you will see a list that shows the cards, chipsets, and RAMDACs that SuperProbe can recognize. Note that the utility name SuperProbe is mixed case, with uppercase S and P. This format is unusual for a Linux system and may take experienced UNIX and Linux users a moment to get used to.



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<P>If you have an older 8-bit card, you can determine the chipset with the command



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