Last-modified: 2 Jul 95
-----BEGIN PGP SIGNED MESSAGE-----
*** The Linux XFree86 HOWTO is posted automatically by the Linux
*** HOWTO coordinator, Greg Hankins <gr...@sunsite.unc.edu>. Please
*** direct any comments or questions about this HOWTO to the author,
*** Matt Welsh <m...@sunsite.unc.edu>.
- --- BEGIN Linux XFree86 HOWTO part 1/1 ---
The Linux XFree86 HOWTO
by Matt Welsh, m...@sunsite.unc.edu
v3.0, 15 March 1995
This document describes how to obtain, install, and configure version
3.1.1 of the XFree86 version of the X Window System (X11R6) for Linux
systems. It is a step-by-step guide to configuring XFree86 on your
The X Window System is a large and powerful (and somewhat complex)
graphics environment for UNIX systems. The original X Window System
code was developed at MIT; commercial vendors have since made X the
industry standard for UNIX platforms. Virtually every UNIX workstation
in the world runs some variant of the X Window system.
A free port of the MIT X Window System version 11, release 6 (X11R6)
for 80386/80486/Pentium UNIX systems has been developed by a team of
programmers originally headed by David Wexelblat (d...@XFree86.org).
The release, known as XFree86, is available for System V/386, 386BSD,
and other x86 UNIX implementations, including Linux. It includes all
of the required binaries, support files, libraries, and tools.
In this document, we'll give a step-by-step description of how to
install and configure XFree86 for Linux, but you will have to fill in
some of the details yourself by reading the documentation released
with XFree86 itself. (This documentation is discussed below.)
However, using and customizing the X Window System is far beyond the
scope of this document---for this purpose you should obtain one of the
many good books on using the X Window System.
2. Hardware requirements
As of XFree86 version 3.1.1, released in February 1995, the following
video chipsets are supported. The documentation included with your
video adaptor should specify the chipset used. If you are in the
market for a new video card, or are buying a new machine that comes
with a video card, have the vendor find out exactly what the make,
model, and chipset of the video card is. This may require the vendor
to call technical support on your behalf; in general vendors will be
happy to do this. Many PC hardware vendors will state that the video
card is a ``standard SVGA card'' which ``should work'' on your system.
Explain that your software (mention Linux and XFree86!) does not
support all video chipsets and that you must have detailed
You can also determine your videocard chipset by running the
SuperProbe program included with the XFree86 distribution. This is
covered in more detail below.
The following standard SVGA chipsets are supported:
o Tseng ET3000, ET4000AX, ET4000/W32
o Western Digital/Paradise PVGA1
o Western Digital WD90C00, WD90C10, WD90C11, WD90C24, WD90C30,
o Genoa GVGA
o Trident TVGA8800CS, TVGA8900B, TVGA8900C, TVGA8900CL, TVGA9000,
TVGA9000i, TVGA9100B, TVGA9200CX, TVGA9320, TVGA9400CX, TVGA9420
o ATI 18800, 18800-1, 28800-2, 28800-4, 28800-5, 28800-6, 68800-3,
68800-6, 68800AX, 68800LX, 88800
o NCR 77C22, 77C22E, 77C22E+
o Cirrus Logic CLGD5420, CLGD5422, CLGD5424, CLGD5426, CLGD5428,
CLGD5429, CLGD5430, CLGD5434, CLGD6205, CLGD6215, CLGD6225,
o Compaq AVGA
o OAK OTI067, OTI077
o Avance Logic AL2101
o MX MX68000, MX680010
o Video 7/Headland Technologies HT216-32
The following SVGA chipsets with accelerated features are also
o 8514/A (and true clones)
o ATI Mach8, Mach32
o Cirrus CLGD5420, CLGD5422, CLGD5424, CLGD5426, CLGD5428, CLGD5429,
CLGD5430, CLGD5434, CLGD6205, CLGD6215, CLGD6225, CLGD6235
o S3 86C911, 86C924, 86C801, 86C805, 86C805i, 86C928, 86C864, 86C964
o Western Digital WD90C31, WD90C33
o Weitek P9000
o IIT AGX-014, AGX-015, AGX-016
o Tseng ET4000/W32, ET4000/W32i, ET4000/W32p
Video cards using these chipsets are supported on all bus types,
including VLB and PCI.
All of the above are supported in both 256 color and monochrome modes,
with the exception of the Avance Logic, MX and Video 7 chipsets, which
are only supported in 256 color mode. If your video card has enough
DRAM installed, many of the above chipsets are supported in 16 and 32
bits-per-pixel mode (specifically, some Mach32, P9000, S3 and Cirrus
boards). The usual configuration is 8 bits per pixel (that is, 256
The monochrome server also supports generic VGA cards, the Hercules
monochrome card, the Hyundai HGC1280, Sigma LaserView, and Apollo
monochrome cards. On the Compaq AVGA, only 64k of video memory is
supported for the monochrome server, and the GVGA has not been tested
with more than 64k.
This list will undoubtedly expand as time passes. The release notes
for the current version of XFree86 should contain the complete list of
supported video chipsets.
One problem faced by the XFree86 developers is that some video card
manufacturers use non-standard mechanisms for determining clock
frequencies used to drive the card. Some of these manufacturers either
don't release specifications describing how to program the card, or
they require developers to sign a non-disclosure statement to obtain
the information. This would obviously restrict the free distribution
of the XFree86 software, something that the XFree86 development team
is not willing to do. For a long time, this has been a problem with
certain video cards manufactured by Diamond, but as of release 3.1 of
XFree86, Diamond has started to work with the development team to
release free drivers for these cards.
The suggested setup for XFree86 under Linux is a 486 machine with at
least 8 megabytes of RAM, and a video card with a chipset listed
above. For optimal performance, we suggest using an accelerated card,
such as an S3-chipset card. You should check the documentation for
XFree86 and verify that your particular card is supported before
taking the plunge and purchasing expensive hardware. Benchmark ratings
comparisons for various video cards under XFree86 are posted routinely
to the USENET newsgroups comp.windows.x.i386unix and comp.os.linux.x.
As a side note, my personal Linux system is a 486DX2-66, 20 megabytes
of RAM, and is equipped with a VLB S3-864 chipset card with 2
megabytes of DRAM. I have run X benchmarks on this machine as well as
on Sun Sparc IPX workstations. The Linux system is roughly 7 times
faster than the Sparc IPX (for the curious, XFree86-3.1 under Linux,
with this video card, runs at around 171,000 xstones; the Sparc IPX at
around 24,000). In general, XFree86 on a Linux system with an
accelerated SVGA card will give you much greater performance than that
found on commercial UNIX workstations (which usually employ simple
framebuffers for graphics).
Your machine will need at least 4 megabytes of physical RAM, and 16
megabytes of virtual RAM (for example, 8 megs physical and 8 megs
swap). Remember that the more physical RAM that you have, the less
that the system will swap to and from disk when memory is low. Because
swapping is inherently slow (disks are very slow compared to memory),
having 8 megabytes of RAM or more is necessary to run XFree86
comfortably. A system with 4 megabytes of physical RAM could run much
(up to 10 times) more slowly than one with 8 megs or more.
3. Installing XFree86
The Linux binary distribution of XFree86 can be found on a number of
FTP sites. On sunsite.unc.edu, it is found in the directory
/pub/Linux/X11. (As of the time of this writing, the current version
is 3.1.1; newer versions are released periodically).
It's quite likely that you obtained XFree86 as part of a Linux
distribution, in which case downloading the software separately is not
If you are downloading XFree86 directly, This table lists the files in
the XFree86-3.1 distribution.
One of the following servers is required:
Server for 8514-based boards.
Server for AGX-based boards.
Server for Mach32-based boards.
Server for Mach8-based boards.
Server for monochrome video modes.
Server for P9000-based boards.
Server for S3-based boards.
Server for Super VGA-based boards.
Server for VGA/EGA-based boards.
Server for ET4000/W32-based boards.
All of the following files are required:
The rest of the X11R6 binaries.
Config files for xdm, xinit and fs.
Documentation and manpages.
Shared X libraries and support files.
The following files are optional:
Selected contrib programs.
Extra XFree86 servers and binaries.
Server linkkit for customization.
75-dpi screen fonts.
100-dpi screen fonts.
Large Kanji and other fonts.
Scaled fonts (Speedo, Type1).
PEX binaries, includes and libraries.
Static X libraries and support files.
Daemons which reside in /usr/bin.
Shadow password version of xdm.
The XFree86 directory should contain README files and installation
notes for the current version.
All that is required to install XFree86 is to obtain the above files,
create the directory /usr/X11R6 (as root), and unpack the files from
/usr/X11R6 with a command such as:
gzip -dc XF86-3.1.1-bin.tar.gz | tar xfB -
Remember that these tar files are packed relative to /usr/X11R6. so
it's important to unpack the files there.
After unpacking the files, you first need to link the file
/usr/X11R6/bin/X to the server that you're using. For example, if you
wish to use the SVGA color server, /usr/bin/X11/X should be linked to
/usr/X11R6/bin/XF86_SVGA. If you wish to use the monochrome server
instead, relink this file to XF86_MONO with the command
ln -sf /usr/X11R6/bin/XF86_MONO /usr/X11R6/bin/X
The same holds true if you are using one of the other servers.
If you aren't sure which server to use, or don't know your video card
chipset, you can run the SuperProbe program found in /usr/X11R6/bin
(included in the XF86-3.1-bin listed above). This program will
attempt to determine your video chipset type and other information;
write down its output for later reference.
You need to make sure that /usr/X11R6/bin is on your path. This can
be done by editing your system default /etc/profile or /etc/csh.login
(based on the shell that you, or other users on your system, use). Or
you can simply add the directory to your personal path by modifying
/etc/.bashrc or /etc/.cshrc, based on your shell.
You also need to make sure that /usr/X11R6/lib can be located by
ld.so, the runtime linker. To do this, add the line
to the file /etc/ld.so.conf, and run /sbin/ldconfig, as root.
4. Configuring XFree86
Setting up XFree86 is not difficult in most cases. However, if you
happen to be using hardware for which drivers ar under development, or
wish to obtain the best performance or resolution from an accelerated
graphics card, configuring XFree86 can be somewhat time-consuming.
In this section we will describe how to create and edit the XF86Config
file, which configures the XFree86 server. In many cases it is best to
start out with a ``basic'' XFree86 configuration, one which uses a low
resolution, such as 640x480, which should be supported on all video
cards and monitor types. Once you have XFree86 working at a lower,
standard resolution, you can tweak the configuration to exploit the
capabilities of your video hardware. The idea is that you want to know
that XFree86 works at all on your system, and that something isn't
wrong with your installation, before attempting the sometimes
difficult task of setting up XFree86 for real use.
In addition to the information listed here, you should read the
o The XFree86 documentation in /usr/X11R6/lib/X11/doc (contained
within the XFree86-3.1-doc package). You should especially see the
file README.Config, which is an XFree86 configuration tutorial.
o Several video chipsets have separate README files in the above
directory (such as README.Cirrus and README.S3). Read one of these
o The man page for XFree86.
o The man page for XF86Config.
o The man page for the particular server that you are using (such as
XF86_SVGA or XF86_S3).
The main XFree86 configuration file is /usr/X11R6/lib/X11/XF86Config.
This file contains information on your mouse, video card parameters,
and so on. The file XF86Config.eg is provided with the XFree86
distribution as an example. Copy this file to XF86Config and edit it
as a starting point.
The XF86Config man page explains the format of this file in detail.
Read this man page now, if you have not done so already.
We are going to present a sample XF86Config file, piece by piece.
This file may not look exactly like the sample file included in the
XFree86 distribution, but the structure is the same.
Note that the XF86Config file format may change with each version of
XFree86; this information is only valid for XFree86 version 3.1.
Also, you should not simply copy the configuration file listed here to
your own system and attempt to use it. Attempting to use a
configuration file which doesn't correspond to your hardware could
drive the monitor at a frequency which is too high for it; there have
been reports of monitors (especially fixed-frequency monitors) being
damaged or destroyed by using an incorrectly configured XF86Config
file. The bottom line is this: Make absolutely sure that your
XF86Config file corresponds to your hardware before you attempt to use
Each section of the XF86Config file is surrounded by the pair of lines
The first part of the XF86Config file is Files, which looks like this:
The RgbPath line sets the path to the X11R6 RGB color database, and
each FontPath line sets the path to a directory containing X11 fonts.
In general you shouldn't have to modify these lines; just be sure that
there is a FontPath entry for each font type that you have installed
(that is, for each directory in /usr/X11R6/lib/X11/fonts).
The next section is ServerFlags, which specifies several global flags
for the server. In general this section is empty.
# Uncomment this to cause a core dump at the spot where a signal is
# received. This may leave the console in an unusable state, but may
# provide a better stack trace in the core dump to aid in debugging
# Uncomment this to disable the <Crtl><Alt><BS> server abort sequence
Here, we have all lines within the section commented out.
The next section is Keyboard. This should be fairly intuitive.
AutoRepeat 500 5
Other options are available as well---see the XF86Config file if you
wish to modify the keyboard configuration. The above should work for
The next section is Pointer which specifies parameters for the mouse
# Baudrate and SampleRate are only for some Logitech mice
# BaudRate 9600
# SampleRate 150
# Emulate3Buttons is an option for 2-button Microsoft mice
# ChordMiddle is an option for some 3-button Logitech mice
The only options that you should concern yourself with now are Proto-
col and Device. Protocol specifies the mouse protocol that your mouse
uses (not the make or brand of mouse). Valid types for Protocol (under
Linux---there are other options available for other operating systems)
BusMouse should be used for the Logitech busmouse. Note that older
Logitech mice should use Logitech, but newer Logitech mice use
either Microsoft or Mouseman protocols. This is a case in which
the protocol doesn't necessarily have anything to do with the make
of the mouse.
Device specifies the device file where the mouse can be accessed. On
most Linux systems, this is /dev/mouse. /dev/mouse is usually a link
to the appropriate serial port (such as /dev/cua0) for serial mice, or
to the appropriate busmouse device for busmice. At any rate, be sure
that the device file listed in Device exists.
The next section is Monitor, which specifies the characteristics of
your monitor. As with other sections in the XF86Config file, there may
be more than one Monitor section. This is useful if you have multiple
monitors connected to a system, or use the same XF86Config file under
multiple hardware configurations. In general, though, you will need a
single Monitor section.
Identifier "CTX 5468 NI"
# These values are for a CTX 5468NI only! Don't attempt to use
# them with your monitor (unless you have this model)
# Modes: Name dotclock horiz vert
ModeLine "640x480" 25 640 664 760 800 480 491 493 525
ModeLine "800x600" 36 800 824 896 1024 600 601 603 625
ModeLine "1024x768" 65 1024 1088 1200 1328 768 783 789 818
The Identifier line is used to give an arbitrary name to the Monitor
entry. This can be any string; you will use it to refer to the Monitor
entry later in the XF86Config file.
they are listed below.
HorizSync specifies the valid horizontal sync frequencies for your
monitor, in kHz. If you have a multisync monitor, this can be a range
of values (or several comma-separated ranges), as seen above. If you
have a fixed-frequency monitor, this will be a list of discrete
values, such as:
HorizSync 31.5, 35.2, 37.9, 35.5, 48.95
Your monitor manual should list these values in the technical specifi-
cations section. If you do not have this information available, you
should either contact the manufacturer or vendor of your monitor to
obtain it. There are other sources of information, as well;
VertRefresh specifies the valid vertical refresh rates (or vertical
synchronization frequencies) for your monitor, in Hz. Like HorizSync
this can be a range or a list of discrete values; your monitor manual
should list them.
HorizSync and VertRefresh are used only to double-check that the
monitor resolutions that you specify are in valid ranges. This is to
reduce the chance that you will damage your monitor by attempting to
drive it at a frequency for which it was not designed.
The ModeLine directive is used to specify a single resolution mode for
your monitor. The format of ModeLine is
ModeLine name clock horiz-values vert-values
name is an arbitrary string, which you will use to refer to the reso-
lution mode later in the file. dot-clock is the driving clock
frequency, or ``dot clock'' associated with the resolution mode. A
dot clock is usually specified in MHz, and is the rate at which the
video card must send pixels to the monitor at this resolution. horiz-
values and vert-values are four numbers each which specify when the
electron gun of the monitor should fire, and when the horizontal and
vertical sync pulses fire during a sweep.
How can you determine the ModeLine values for your monitor? The file
VideoModes.doc, included with the XFree86 distribution, describes in
detail how to determine these values for each resolution mode that
your monitor supports. First of all, clock must correspond to one of
the dot clock values that your video card can produce. Later in the
XF86Config file you will specify these clocks; you can only use video
modes which have a clock value supported by your video card.
There are two files included in the XFree86 distribution which may
include ModeLine data for your monitor. These files are modeDB.txt and
Monitors, both of which are found in /usr/X11R6/lib/X11/doc.
You should start with ModeLine values for the VESA standard monitor
timings, which most monitors support. modeDB.txt includes timing
values for VESA standard resolutions. In that file, you will see
entries such as
# 640x480@60Hz Non-Interlaced mode
# Horizontal Sync = 31.5kHz
# Timing: H=(0.95us, 3.81us, 1.59us), V=(0.35ms, 0.064ms, 1.02ms)
# name clock horizontal timing vertical timing flags
"640x480" 25.175 640 664 760 800 480 491 493 525
This is a VESA standard timing for a 640x480 video mode. It uses a dot
clock of 25.175, which your video card must support to use this mode
(more on this later). To include this entry in the XF86Config file,
you'd use the line
ModeLine "640x480" 25.175 640 664 760 800 480 491 493 525
Note that the name argument to ModeLine (in this case "640x480") is an
arbitrary string---the convention is to name the mode after the reso-
lution, but name can technically be anything descriptive which
describes the mode to you.
For each ModeLine used the server will check that the specifications
for the mode fall within the range of values specified with Bandwidth,
HorizSync and VertRefresh. If they do not, the server will complain
when you attempt to start up X (more on this later). For one thing,
the dot clock used by the mode should not be greater than the value
used for Bandwidth. (However, in many cases it is safe to use modes
with a slightly higher bandwidth than your monitor can support.)
If the VESA standard timings do not work for you (you'll know after
trying to use them later) then the files modeDB.txt and Monitors
include specific mode values for many monitor types. You can create
ModeLine entries from the values found in those two files as well. Be
sure to only use values for the specific model of monitor that you
have. Note that many 14 and 15-inch monitors cannot support higher
resolution modes, and often resolutions of 1024x768 at low dot clocks.
This means that if you can't find high resolution modes for your
monitor in these files, then your monitor probably does not support
those resolution modes.
If you are completely at a loss, and can't find working ModeLine
values for your monitor, you can follow the instructions in the
VideoModes.doc file included in the XFree86 distribution to generate
ModeLine values from the specifications listed in your monitor's
manual. While your mileage will certainly vary when attempting to
generate ModeLine values by hand, this is a good place to look if you
can't find the values that you need. VideoModes.doc also describes the
format of the ModeLine directive and other aspects of the XFree86
server in gory detail.
Lastly, if you do obtain ModeLine values which are almost, but not
quite, right, then it may be possible to simply modify the values
slightly to obtain the desired result. For example, if while running
XFree86 the image on the monitor is shifted slightly, or seems to
``roll'', you can follow the instructions in the VideoModes.doc file
to try to fix these values. Also, be sure to check the knobs and
controls on the monitor itself! In many cases it is necessary to
change the horizontal or vertical size of the display after starting
up XFree86 in order for the image to be centered and be of the
appropriate size. Having these controls on the front of the monitor
can certainly make life easier.
You shouldn't use monitor timing values or ModeLine values for
monitors other than the model that you own. If you attempt to drive
the monitor at a frequency for which it was not designed, you can
damage or even destroy it.
The next section of the XF86Config file is Device, which specifies
parameters for your video card. Here is an example.
Identifier "#9 GXE 64"
# Nothing yet; we fill in these values later.
This section defines properties for a particular video card.
Identifier is an arbitrary string describing the card; you will use
this string to refer to the card later.
Initially, you don't need to include anything in the Device section,
except for Identifier. This is because we will be using the X server
itself to probe for the properties of the video card, and entering
them into the Device section later. The XFree86 server is capable of
probing for the video chipset, clocks, RAMDAC, and amount of video RAM
on the board.
Before we do this, however, we need to finish writing the XF86Config
file. The next section is Screen, which specifies the monitor/video
card combination to use for a particular server.
Device "#9 GXE 64"
Monitor "CTX 5468 NI"
Modes "1024x768" "800x600" "640x480"
ViewPort 0 0
Virtual 1024 768
The Driver line specifies the X server that you will be using. The
value values for Driver are:
o Accel: For the XF86_S3, XF86_Mach32, XF86_Mach8, XF86_8514,
XF86_P9000, XF86_AGX, and XF86_W32 servers;
o SVGA: For the XF86_SVGA server;
o VGA16: For the XF86_VGA16 server;
o VGA2: For the XF86_Mono server;
o Mono: For the non-VGA monochrome drivers in the XF86_Mono and
You should be sure that /usr/X11R6/bin/X is a symbolic link to the
server that you are using.
The Device line specifies the Identifier of the Device section
corresponding to the video card to use for this server. Above, we
created a Device section with the line
Identifier "#9 GXE 64"
Therefore, we use "#9 GXE 64" on the Device line here.
Similarly, the Monitor line specifies the name of the Monitor section
to be used with this server. Here, "CTX 5468 NI" is the Identifier
used in the Monitor section described above.
Subsection "Display" defines several properties of the XFree86 server
corresponding to your monitor/video card combination. The XF86Config
file describes all of these options in detail; most of them are icing
on the cake and not necessary to get the system working.
The options that you should know about are:
o Depth. Defines the number of color planes---the number of bits per
pixel. Usually, Depth is set to 8. For the VGA16 server, you would
use a depth of 4, and for the monochrome server a depth of 1. If
you are using an accelerated video card with enough memory to
support more bits per pixel, you can set Depth to 16, 24, or 32.
If you have problems with depths higher than 8, set it back to 8
and attempt to debug the problem later.
o Modes. This is the list of video mode names which have been defined
using the ModeLine directive in the Monitor section. In the above
section, we used ModeLines named "1024x768", "800x600", and
"640x480". Therefore, we use a Modes line of
Modes "1024x768" "800x600" "640x480"
The first mode listed on this line will be the default when XFree86
starts up. After XFree86 is running, you can switch between the modes
listed here using the keys ctrl-alt-numeric + and ctrl-alt-numeric -.
It might be best, when initially configuring XFree86, to use lower
resolution video modes, such as 640x480, which tend to work on most
systems. Once you have the basic configuration working you can modify
XF86Config to support higher resolutions.
o Virtual. Sets the virtual desktop size. XFree86 has the ability to
use any additional memory on your video card to extend the size of
your desktop. When you move the mouse pointer to the edge of the
display, the desktop will scroll, bringing the additional space
into view. Therefore, even if you are running at a lower video
resolution such as 800x600, you can set Virtual to the total
resolution which your video card can support (a 1-megabyte video
card can support 1024x768 at a depth of 8 bits per pixel; a
2-megabyte card 1280x1024 at depth 8, or 1024x768 at depth 16). Of
course, the entire area will not be visible at once, but it can
still be used.
The Virtual feature is a nice way to utilize the memory of your
video card, but it is rather limited. If you want to use a true
virtual desktop, we suggest using fvwm, or a similar window
manager, instead. fvwm allows you to have rather large virtual
desktops (implemented by hiding windows, and so forth, instead of
actually storing the entire desktop in video memory at once). See
the man pages for fvwm for more details about this; most Linux
systems use fvwm by default.
o ViewPort. If you are using the Virtual option described above,
ViewPort sets the coordinates of the upper-left-hand corner of the
virtual desktop when XFree86 starts up. Virtual 0 0 is often used;
if this is unspecified then the desktop is centered on the virtual
desktop display (which may be undesirable to you).
Many other options for this section exist; see the XF86Config man page
for a complete description. In practice these other options are not
necessary to get XFree86 initially working.
5. Filling in video card information
Your XF86Config file is now ready to go, with the exception of
complete information on the video card. What we're going to do is use
the X server to probe for the rest of this information, and fill it
Instead of probing for this information with the X server, the
XF86Config values for many cards are listed in the files modeDB.txt,
AccelCards, and Devices. These files are all found in
/usr/X11R6/lib/X11/doc. In addition, there are various README files
for certain chipsets. You should look in these files for information
on your video card, and use that information (the clock values,
chipset type, and any options) in the XF86Config file. If any
information is missing, you can probe for it as described here.
In these examples we will demonstrate configuration for a #9 GXE 64
video card, which uses the XF86_S3 chipset. This card happens to be
the one which the author uses, but the discussion here applies to any
The first thing to do is to determine the video chipset used on the
card. Running SuperProbe (found in /usr/X11R6/bin) will tell you this
information, but you need to know the chipset name as it is known to
the X server.
To do this, run the command
This will give the chipset names known to your X server. (The man
pages for each X server list these as well.) For example, with the
accelerated XF86_S3 server, we obtain:
XFree86 Version 3.1 / X Window System
(protocol Version 11, revision 0, vendor release 6000)
Operating System: Linux
S3: accelerated server for S3 graphics adaptors (Patchlevel 0)
The valid chipset names for this server are mmio_928 and s3_generic.
The XF86_S3 man page describes these chipsets and which videocards use
them. In the case of the #9 GXE 64 video card, mmio_928 is
If you don't know which chipset to use, the X server can probe it for
you. To do this, run the command
X -probeonly > /tmp/x.out 2>&1
if you use bash as your shell. If you use csh, try:
X -probeonly &> /tmp/x.out
You should run this command while the system is unloaded, that is,
while no other activity is occurring on the system. This command will
also probe for your video card dot clocks (as seen below), and system
load can throw off this calculation.
The output from the above (in /tmp/x.out should contain lines such as
XFree86 Version 3.1 / X Window System
(protocol Version 11, revision 0, vendor release 6000)
Operating System: Linux
S3: accelerated server for S3 graphics adaptors (Patchlevel 0)
(--) S3: card type: 386/486 localbus
(--) S3: chipset: 864 rev. 0
(--) S3: chipset driver: mmio_928
Here, we see that the two valid chipsets for this server (in this
case, XF86_S3) are mmio_928 and s3_generic. The server probed for and
found a video card using the mmio_928 chipset.
In the Device section of the XF86Config file, add a Chipset line,
containing the name of the chipset as determined above. For example,
# We already had Identifier here...
Identifier "#9 GXE 64"
# Add this line:
Now we need to determine the driving clock frequencies used by the
video card. A driving clock frequency, or dot clock, is simply a rate
at which the video card can send pixels to the monitor. As we have
seen, each monitor resolution has a dot clock associated with it. Now
we need to determine which dot clocks are made available by the video
First you should look into the files (modeDB.txt, and so forth)
mentioned above and see if your card's clocks are listed there. The
dot clocks will usually be a list of 8 or 16 values, all of which are
in MHz. For example, when looking at modeDB.txt we see an entry for
the Cardinal ET4000 video board, which looks like this:
# chip ram virtual clocks default-mode flags
ET4000 1024 1024 768 25 28 38 36 40 45 32 0 "1024x768"
As we can see, the dot clocks for this card are 25, 28, 38, 36, 40,
45, 32, and 0 MHz.
In the Devices section of the XF86Config file, you should add a Clocks
line containing the list of dot clocks for your card. For example,
for the clocks above, we would add the line
Clocks 25 28 38 36 40 45 32 0
to the Devices section of the file, after Chipset. Note that the
order of the clocks is important! Don't resort the list of clocks or
If you cannot find the dot clocks associated with your card, the X
server can probe for these as well. Using the X -probeonly command
described above, the output should contain lines which look like the
(--) S3: clocks: 25.18 28.32 38.02 36.15 40.33 45.32 32.00 00.00
We could then add a Clocks line containing all of these values, as
printed. You can use more than one Clocks line in XF86Config should
all of the values (sometimes there are more than 8 clock values
printed) not fit onto one line. Again, be sure to keep the list of
clocks in order as they are printed.
Be sure that there is no Clocks line (or that it is commented out) in
the Devices section of the file when using X -probeonly to probe for
the clocks. If there is a Clocks line present, the server will not
probe for the clocks---it will use the values given in XF86Config.
Note that some accelerated video boards use a programmable clock chip.
(See the XF86_Accel man page for details; this generally applies to
S3, AGX, and XGA-2 boards.) This chip essentially allows the X server
to tell the card which dot clocks to use. If this is the case, then
you may not find a list of dot clocks for the card in any of the above
files. Or, the list of dot clocks printed when using X -probeonly will
only contain one or two discrete clock values, with the rest being
duplicates or zero.
For boards which use a programmable clock chip, you would use a
ClockChip line, instead of a Clocks line, in your XF86Config file.
ClockChip gives the name of the clock chip as used by the video card;
the man pages for each server describe what these are. For example, in
the file README.S3, we see that several S3-864 video cards use an
``ICD2061A'' clock chip, and that we should use the line
instead of Clocks in the XF86Config file. As with Clocks, this line
should go in the Devices section, after Chipset.
Similarly, some accelerated cards require you to specify the RAMDAC
chip type in the XF86Config file, using a Ramdac line. The XF86_Accel
man page describes this option. Usually, the X server will correctly
probe for the RAMDAC.
Some video card types require you to specify several options in the
Devices section of XF86Config. These options will be described in the
man page for your server, as well as in the various files (such as
README.cirrus or README.S3. These options are enabled using the Option
line. For example, the #9 GXE 64 card requires two options:
Usually, the X server will work without these options, but they are
necessary to obtain the best performance. There are too many such
options to list here, and they each depend on the particular video
card being used. If you must use one of these options, fear not---the
X server man pages and various files in /usr/X11R6/lib/X11/doc will
tell you what they are.
So, when you're finished, you should end up with a Devices section
which looks something like this:
# Device section for the #9 GXE 64 only!
Identifier "#9 GXE 64"
Most video cards will require a Clocks line, instead of ClockChip, as
described above. The above Device entry is only valid for a particular
video card, the #9 GXE 64. It is given here only as an example.
There are other options that you can include in the Devices entry.
Check the X server man pages for the gritty details, but the above
should suffice for most systems.
6. Running XFree86
With your XF86Config file configured, you're ready to fire up the X
server and give it a spin. First, be sure that /usr/X11R6/bin is on
The command to start up XFree86 is
This is a front-end to xinit (in case you're used to using xinit on
other UNIX systems).
This command will start the X server and run the commands found in the
file .xinitrc in your home directory. .xinitrc is just a shell script
containing X clients to run. If this file does not exist, the system
default /usr/X11R6/lib/X11/xinit/xinitrc will be used.
A standard .xinitrc file looks like this:
xterm -fn 7x13bold -geometry 80x32+10+50 &
xterm -fn 9x15bold -geometry 80x34+30-10 &
oclock -geometry 70x70-7+7 &
xsetroot -solid midnightblue &
This script will start up two xterm clients, an oclock, and set the
root window (background) color to midnightblue. It will then start up
twm, the window manager. Note that twm is executed with the shell's
exec statement; this causes the xinit process to be replaced with twm.
Once the twm process exits, the X server will shut down. You can cause
twm to exit by using the root menus: depress mouse button 1 on the
desktop background---this will display a pop up menu which will allow
you to Exit Twm.
Be sure that the last command in .xinitrc is started with exec, and
that it is not placed into the background (no ampersand on the end of
the line). Otherwise the X server will shut down as soon as it has
started the clients in the .xinitrc file.
Alternately, you can exit X by pressing ctrl-alt-backspace in
combination. This will kill the X server directly, exiting the window
The above is a very, very simple desktop configuration. Many wonderful
programs and configurations are available with a bit of work on your
.xinitrc file. For example, the fvwm window manager will provide a
virtual desktop, and you can customize colors, fonts, window sizes and
positions, and so forth to your heart's content. Although the X
Window System might appear to be simplistic at first, it is extremely
powerful once you customize it for yourself.
If you are new to the X Window System environment, we strongly suggest
picking up a book such as The X Window System: A User's Guide. Using
and configuring X is far too in-depth to cover here. See the man pages
for xterm, oclock, and twm for clues on getting started.
7. Running Into Trouble
Often, something will not be quite right when you initially fire up
the X server. This is almost always caused by a problem in your
XF86Config file. Usually, the monitor timing values are off, or the
video card dot clocks set incorrectly. If your display seems to roll,
or the edges are fuzzy, this is a clear indication that the monitor
timing values or dot clocks are wrong. Also be sure that you are
correctly specifying your video card chipset, as well as other options
for the Device section of XF86Config. Be absolutely certain that you
are using the right X server and that /usr/X11R6/bin/X is a symbolic
link to this server.
If all else fails, try to start X ``bare''; that is, use a command
X > /tmp/x.out 2>&1
You can then kill the X server (using the ctrl-alt-backspace key com-
bination) and examine the contents of /tmp/x.out. The X server will
report any warnings or errors---for example, if your video card
doesn't have a dot clock corresponding to a mode supported by your
The file VideoModes.doc included in the XFree86 distribution contains
many hints for tweaking the values in your XF86Config file.
Remember that you can use ctrl-alt-numeric + and ctrl-alt-numeric - to
switch between the video modes listed on the Modes line of the Screen
section of XF86Config. If the highest resolution mode doesn't look
right, try switching to lower resolutions. This will let you know, at
least, that those parts of your X configuration are working correctly.
Also, check the vertical and horizontal size/hold knobs on your
monitor. In many cases it is necessary to adjust these when starting
up X. For example, if the display seems to be shifted slightly to one
side, you can usually correct this using the monitor controls.
The USENET newsgroup comp.windows.x.i386unix is devoted to discussions
about XFree86, as is comp.os.linux.x. It might be a good idea to
watch that newsgroup for postings relating to your video
configuration---you might run across someone with the same problems as
This document is Copyright (c)1995 by Matt Welsh. This work may be
reproduced and distributed in whole or in part, in either printed or
electronic form, subject to the following conditions:
1. The copyright notice and this license notice must be preserved
complete on all complete or partial copies.
2. Any translation or derivative work must be approved by the author
in writing before distribution.
3. If you distribute the Work in part, instructions for obtaining a
complete version (in printed or electonic form) must be included,
and a means for obtaining a complete version provided.
4. Small portions may be reproduced as illustrations for reviews or
quotes in other works without this permission notice if proper
citation is given.
Exceptions to these rules may be granted for academic purposes, write
to the author of the Work, and ask. These restrictions are here to
protect the authors, not to restrict you as educators and learners.
- --- END Linux XFree86 HOWTO part 1/1 ---
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