Linux Configuration and Installation:Installing and Configuring XFree86






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Configuring the Monitor Section
The Monitor section describes your monitor to X. You can define a number of monitors in the XF86Config file, as each Monitor section is named. The Screen section (discussed later) then connects a monitor to a video card. For example, the following abbreviated entry defines our NEC MultiSync XE17 monitor:


Section "Monitor"
Identifier "NEC MultiSync XE17"
VendorName "NEC"
ModelName "MultiSync 4FGe"
HorizSync 31.5 - 64.3
VertRefresh 55-120
# Modes from the NEC MultiSync 4FGe monitor, a close monitor.
ModeLine "640x480" 31 640 680 704 832 480 489 492 520
ModeLine "800x600" 50 800 864 976 1040 600 637 643 666
ModeLine "1024x768" 81 1024 1068 1204 1324 768 776 782 807
EndSection


For each monitor, you need to define the items listed in Table 3.13.

Table 3.13 Monitor Data

Item
Usage



Identifier string
Used to identify the monitor later

VendorName string
Used for your reference

ModelName string
Used for your reference

Bandwidth bandwidth
The bandwidth for the monitor, in MHz

HorizSync range
Horizontal sync frequencies, in kHz

VertRefresh range
Vertical refresh range, in Hz

Gamma value
Gamma correction value for your monitor

Modeline values
A single resolution mode



The identifier is a string used to refer to the monitor later. You can define more than one monitor in the XF86Config file.
The HorizSync range describes the horizontal sync frequencies for your monitor. It can be a set of comma-separated values or a range separated by a dash, such as 42-65, for multisync monitors. You should get this value from your monitor documentation (where you’ll find most of the key information needed here).
The format for a Modeline is:


Modeline "name" horizontal-values vertical values


For example, the following sets up a standard VGA mode:



# 640x400 @ 70 Hz, 31.5 kHz hsync
Modeline "640x400" 25.175 640 664 760 800 400 409 411 450


There can be a whole set of modeline values. You can get this from the probeonly mode of X or from documentation that comes with XFree86. Some of the relevant documentation is listed in Table 3.14.
Table 3.14 Video-Mode Documentation with XFree86

File
Usage



VideoModes.doc
Explains—in excruciating detail—how to calculate modes

modeDB.txt
Database of modelines for monitors

Monitors
Database of modelines for monitors



All these files are located in /usr/X11R6/lib/X11/doc. An example entry from the Monitors file follows:


#Date: Sat, 17 Sep 1994 00:50:57 -0400
#From: Erik Nygren <[e-mail]>
Section "Monitor"
Identifier "NEC MultiSync 4FGe"
VendorName "NEC"
ModelName "MultiSync 4FGe"
BandWidth 80Mhz #\
HorizSync 27-62KHz #> from monitor documentation
VertRefresh 55-90Hz #/
ModeLine "640x480" 31 640 680 704 832 480 489 492 520
ModeLine "800x600" 50 800 864 976 1040 600 637 643 666
ModeLine "1024x768" 81 1024 1068 1204 1324 768 776 782 807
EndSection


One of the monitors we have, an NEC MultiSync XE17, was not in either the modeDB.txt or Monitors file. We found the closest monitor in the listing, an NEC MultiSync 4FGe, and experimented with those Modelines. Calculating the Modelines yourself is a real pain, so you want to find a monitor or a close facsimile in the Monitors or modeDB.txt files.

WARNING:  Having said that, be careful about using Modelines for other monitors. You can destroy your monitor if you’re not careful.

Configuring the Graphics Card Section
The Device section describes your graphics card to X. For example, a standard Super VGA device appears as the following:



# Standard VGA Device:
Device
Identifier "Generic VGA" VendorName "Unknown"
BoardName "Unknown"
Chipset "generic"
# VideoRam 256
# Clocks 25.2 28.3
EndSection


A more detailed device section, for an Actix S3 accelerated card, follows:



# Device configured by xf86config:
Section "Device"
Identifier "Actix GE32+ 2MB"
VendorName "Actix"
BoardName "GraphicsENGINE Ultra"
#VideoRam 1024
#Option "dac_8_bit"
Ramdac "att20c490"
Clocks 25 28 40 72 50 77 36 45 90 120 80 32 110 65 75 95
EndSection


Of these options, the clocks are the hardest to fill in. One option is to try X in probeonly mode to fill in the details. You can also look in a file called AccelCards in /usr/X11R6/lib/X11/doc for more information on accelerated chipsets and cards. An entry from the AccelCards file follows:


Card Vendor : Actix
Card Model : GraphicsEngine32 Plus
Card Bus (ISA/EISA/VLB) : ISA
Chipset : S3 86C801
Video Memory : 2048k
Memory Type (DRAM/VRAM) : DRAM
Memory Speed : 45ns
Clock Chip : Avasem AV9194-11
Programmable? (Y/N) : No
Number of clocks : 16
Clocks : 25.175 28.322 40.0 0.0 50.0 77.0 36.0 44.9
Clocks (cont) : 130.0 120.0 80.0 31.5 110.0 65.0 75.0 95.0
Option Flags :
RAMDAC : AT&T 20C490-11
Submitter : David E. Wexelblat <[e-mail]>
Last Edit Date : Sept 25, 1993


You can convert the Clocks lines into the proper syntax for the XF86Config file by placing the same values in order in a line (or lines) starting with Clocks in the Device section:


Clocks 25.175 28.322 40.0 0.0 50.0 77.0 36.0 44.9
Clocks 130.0 120.0 80.0 31.5 110.0 65.0 75.0 95.0


Be sure to put all the clock values in the original order.




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