  Using the Xinerama Extensions to MultiHead X V. 4.0
  Dennis Baker drbaker@softhome.net
  v1.0, May 2, 2000

  This document describes how to configure XFree86 Version 4.0 with Mul­
  tiple monitors and the Xinerama extentions.
  ______________________________________________________________________

  Table of Contents


  1. Introduction

  2. Planning

  3. Video Card set up.

  4. Scan the PCI Bus

  5. Editing your XConfig File

     5.1 Adding all of your video cards
     5.2 Identifying Your Video Cards
     5.3 Configuring the ServerLayout Section

  6. Testing Your Configuration

  7. Editing your startup files

  8. Sample XF86Config Files



  ______________________________________________________________________

  1.  Introduction

  This is not meant to be a guide on how to set up your specific
  monitor,  or videocard.  In fact,  I assume that you already have X
  windows running for your setup.  Please refer to the XF86
  Documentation for more information.

  As far as I know,  there are no limits to which video cards you can
  configure this way,  nor does it seem to matter if you mix different
  types of video cards in a setup,  The sample configuration I use in
  this documentation uses two different video cards,  a AGP Fire GL 1000
  and a PCI Matrox Millenium II.  What effect this has on 3d
  Accelleration I don't know as I don't currently accellerate either of
  my video cards.


  This Howto assumes that you know how to edit text files,  do basic
  video card configuration for X Windows, add and remove hardware from
  your system, start and stop system services, and follow simple
  instructions.  If feel you will have trouble with any of these things,
  please seek help.  I am not responsible if you damage any of your
  stuff.


  2.  Planning

  Planning a Xinerama setup is pretty straight forward.  There as
  essentially three things you need to take into account,  screen
  resolution, color depth, and screen layout.


  It is possible to have each physical screen in your Xinerama setup to
  have a different resolution. There are some advantages to this,  I was
  able to use an old monitor which only operates at 640x480,  and a
  bigger 17" at 1280x1024 in my setup.  I have also heard of web
  developers and graphics designed who use one big "preview" screen and
  flank it with one or two smaller screens.  I think this is one of the
  great things about the Xinerama extensions.


  There is one significant problem with using multiple screen
  reolutions.  Current generation window managers assume the screen is
  rectangular and will assume this rectangle is equal in size to the
  heighth and width of your total desktop.  If you have one monitor at
  1600x1200 and another at 800x600,  your window manager will assume
  your desktop is 2400x1200.  This leaves a big area below the smaller
  screen which the window manager interprets as "Empty", many window
  managers will try to utilize this space for new windows.  There are
  ways to configure your window manager to minimize this problem but is
  a nuisance. As window managers become Xinerama aware and this problem
  will go away quickly.



  Unlike with screen resolotion, Xinerama limits your entire virtual
  screen to one color depth.  If you were planning on pulling out a
  cheap video card for your second display you need to keep this in
  mind.  If your old video card only supports 8 bit color you might get
  a bigger display but most newer programs look lousy in 256 colors.


  Layout decisions are fairly simple,  you just need to decide how you
  want to lay out your monitors.  Most people will simply place their
  monitors in a row and view their desktop as one giant monitor.  It is
  also possible to overlap displays, or place them in more complex
  layouts.  Keep in mind though what I said above about window managers
  expecting rectangular displays.


  3.  Video Card set up.

  This is a good time to back up your existing config file: I did it
  like this:


       root# > cp /etc/X11/XF86Config /etc/X11/XFree86Config.working



  Before we start the multihead portion of this process you need to have
  ALL of your existing cards working properly with the display they will
  have in the final configuration.  If you haven't already,  configure
  and install each different video card/ monitor combination you are
  going to have in your final setup.  If you have several identical
  video cards you can get away with configuring one and copying the
  configuration for the other cards.


  After you have each card set up, back up or print it's config file as
  you will need it later.  Here's how I did it:


       root# > cp /etc/X11/XF86Config /etc/X11/XFree86Config.Matrox



  If your video cards are identical you can probably get away with just
  one copy.  However don't skip this step,  If all else fails this will
  be you backup config file incase my instructions lead you astray.


  Once you have all of your displays configured you are almost there...


  4.  Scan the PCI Bus

  This is a good time to put all of your video cards into your system
  and set up your monitors.  Set everything up the way you want it when
  you are done,  as you will have to repeat steps later if you change
  things.

  This next step needs to be done from the console with-out X running.
  If you are in X, exit now.  If your system uses a display manager such
  as xdm or gdm exit you need to stop that service.  If you need to stop
  a display manager from RedHat the easiest way is like this:


       root# > telinit 3


  for Debian,  Storm or Corel :


       root# > /etc/init.d/xdm stop


  If neither of these methods work you, reboot your computer and start
  up in single user mode.


  In a multi-head setup you need to explicitly identify each video card
  in your config file.  To do this you need to use the PCI Bus
  Identifier your system assigns the card.  At this time, all video
  cards need to be in your system.

  To find out what your PCI bus IDs are:


       root# > XFree86 -scanpci


  X will then output a code for each device on your PCI bus.


       ______________________________________________________________________
       (0:0:0) Intel 82443BX Host
       (0:1:0) Intel 82443BX AGP
       (0:7:0) Intel 82371AB PIIX4 ISA
       (0:7:1) Intel 82371AB PIIX4 IDE
       (0:7:2) Intel 82371AB PIIX4 USB
       (0:7:3) Intel 82371AB PIIX4 ACPI
       (0:9:0) Adaptec 2940U/UW
       (0:11:0) 3COM 3C900 10b Combo
       (0:12:0) Matrox unknown card (0x2007) using a Matrox MGA 2164W
       (1:0:0) unknown card (0x1092/0x0152) using a Texas Instruments Permedia 2
       ______________________________________________________________________



  PCI cards and devices are identified with a leading 0, AGP cards with
  a 1.  In my case I have a Matrox Millenium II (0:12:0) and a Diamond
  FireGL(1:0:0).  Find your video cards and write down the numbers
  associated with them.  It is important that you know which number goes
  with which card.


  5.  Editing your XConfig File

  If I haven't lost you so far,  we are in the home stretch now.  This
  section is pretty confusion so I suggest you also read the manpage for
  XF86Config,  or at least skim it.  Do it now... I'll wait.



        root# > man XF86Config



  5.1.  Adding all of your video cards

  Open your current XF86Config file and scroll down to the Monitor
  Section.  You want to copy the following sections from the XF86Config
  backup files you created above : Monitor, Device, Screen.  These
  sections should go in your XF86Config file after the coresponding
  section in the file you have open.  As you copy each section make
  certain that the Identifier is unique for each section,  you will
  reference these identifies later.


  Clear as Mud Right?  You should now have a Monitor Section, a Device
  Section,  and a Screen Section for EACH video card/monitor
  combination, each Section should have a unique Identifier.  If you are
  still confused reread the prior paragraph.  If that doesn't help, look
  at the sample ``'' I have included at the end.  You did read the
  manpage right?


  5.2.  Identifying Your Video Cards

  Now you need to add the coresponding PCI BusID as an option at the end
  of each Device Section.  The entry should look like this: BusID
  "PCI:0:12:0",  substituting the three numbers with the PCI bus ID
  which identifies YOUR video card you should have this ID from the
  ``''.  Here is a sample Device Section for one of my video cards.



       ______________________________________________________________________
       Section "Device"
           Identifier  "FireGL"
           Driver      "glint"
           BusID      "PCI:1:0:0"
       EndSection
       ______________________________________________________________________



  Please note,  even AGP cards use this layout.


  5.3.  Configuring the ServerLayout Section

  Now you need to edit the ServerLayout Section at the end of the
  XF86Config File.  The ServerLayour Section is exactally that,  it
  tells you what Screens to use, how to lay them out logically, and what
  input devices to assign to them.  Your current layout is for one
  screen, keyboard, and mouse.  For each Screen section you have created
  about you need reference in this section for them to appear in your
  display.


  Using the existing screen reference as a starting point,  create
  additional references for your other Screen Sections.  The reference
  looks like this:


       Screen "Screen 2" Relationship "Screen 1"


  This defines the relationship between the "Screen 2" and "Screen 1".
  Valid Relationships include: RightOf, Below, Above, LeftOf, Absolute X
  Y, Relative.  Use of the first four relationships is pretty obvious as
  illustrated in my sample:


       ______________________________________________________________________
       Section "ServerLayout"
           Identifier  "Simple Layout"
           Screen "Screen 2"
           Screen "Screen 1" RightOf "Screen 2"
           InputDevice "Mouse1" "CorePointer"
           InputDevice "Keyboard1" "CoreKeyboard"
       EndSection
       ______________________________________________________________________



  I have other examples in the ``'' section.

  6.  Testing Your Configuration

  Once you have completed changing your XF86Config file, save it and
  your can now test your configuration :



        root# > startx -- +xinerama


  Hopefully you can now enjoy X with multiple partners... er that is,
  Monitors.


  7.  Editing your startup files

  If this worked you will probably want to change your X configuration
  to start X this way automatically.  There are lots of ways to do this
  and there are probably better ways than what I've shown below.  Here
  are the methods I used for changing startx and gdm.


  If you run X from the command prompt add the +xinerama option to the
  startx script.



        root# > vi /usr/X11R6/bin/startx


  At the very end of the file the script starts X with the command
  xinit.  Add the +xinerama option to the very end of that line.


  To Configure gdm to start with the xinerama extentions look for
  [servers] section at the bottom of /etc/X11/gdm/gdm.conf.  Add the
  +xinerama extension to the end of the line that starts with 0=.  It
  should look like this :



        0=/usr/bin/X11/X +xinerama


  I am certain configuring KDE, and xdm to start xinerama are equally
  easy,  if you figure it out please drop me a note and I will add it to
  this Howto.


  8.  Sample XF86Config Files

  My current XF86Config File :



  ______________________________________________________________________

  Section "Module"
      Load        "dbe"       # Double buffer extension
      SubSection  "extmod"
        Option    "omit xfree86-dga"   # don't initialise the DGA extension
      EndSubSection
      Load        "type1"
      Load        "freetype"
  # This loads the GLX module
  #    Load       "glx"
  EndSection

  Section "Files"
      RgbPath     "/usr/X11R6/lib/X11/rgb"
      FontPath   "/usr/X11R6/lib/X11/fonts/local/"
      FontPath   "/usr/X11R6/lib/X11/fonts/misc/"
      FontPath   "/usr/X11R6/lib/X11/fonts/75dpi/:unscaled"
      FontPath   "/usr/X11R6/lib/X11/fonts/100dpi/:unscaled"
      FontPath   "/usr/X11R6/lib/X11/fonts/Type1/"
      FontPath   "/usr/X11R6/lib/X11/fonts/Speedo/"
      FontPath   "/usr/X11R6/lib/X11/fonts/75dpi/"
      FontPath   "/usr/X11R6/lib/X11/fonts/100dpi/"
  # The module search path.  The default path is shown here.
  #    ModulePath "/usr/X11R6/lib/modules"
  EndSection

  Section "ServerFlags"

  EndSection

  Section "InputDevice"
      Identifier  "Keyboard1"
      Driver      "Keyboard"
      Option "AutoRepeat" "500 30"
      Option "XkbRules"       "xfree86"
      Option "XkbModel"       "pc101"
      Option "XkbLayout"      "us"
  EndSection

  Section "InputDevice"
      Identifier  "Mouse1"
      Driver      "mouse"
      Option "Protocol"    "PS/2"
      Option "Device"      "/dev/psaux"
  EndSection

  Section "Monitor"
      Identifier  "Mini"
      HorizSync   31.5
      VertRefresh 50-90
  EndSection

  Section "Monitor"
      Identifier  "Impression"
      HorizSync   31.5 - 82.0
      VertRefresh 50-100
  EndSection

  # Video Card #1, Matrox Millenium II PCI Video Card
  Section "Device"
      Identifier  "Matrox"
      Driver      "mga"
      VideoRam 8192
      BusID      "PCI:0:12:0"
  EndSection
  # Video Card # 2, Fire GL 1000 AGP video card.
  Section "Device"
      Identifier  "FireGL"
      Driver      "glint"
      #VideoRam    8192
      BusID      "PCI:1:0:0"

  EndSection

  Section "Screen"
      Identifier  "Screen 2"
      Device      "FireGL"
      Monitor     "Impression"
      DefaultDepth 16

      Subsection "Display"
          Depth       16
          Modes       "1280x1024" "640x480"
          ViewPort    0 0
      EndSubsection
  EndSection

  # My Miniature monitor,  notice that I used the virtual option so it is
  #   the same heighth as the larger monitor,  this is not necessary.
  Section "Screen"
      Identifier  "Screen 1"
      Device      "Matrox"
      Monitor     "Mini"
      DefaultDepth 16

      Subsection "Display"
          Depth       16
          Modes       "640x480"
          ViewPort    0 0
          Virtual     640 1024
      EndSubsection
  EndSection

  Section "ServerLayout"
      Identifier  "Simple Layout"
      Screen "Screen 2"
      Screen "Screen 1" Rightof "Screen 2"
      InputDevice "Mouse1" "CorePointer"
      InputDevice "Keyboard1" "CoreKeyboard"
  EndSection
  ______________________________________________________________________



  An alternate ServerLayout Section with one Monitor above the other.

  ______________________________________________________________________
  Section "ServerLayout"
      Identifier  "Simple Layout"
      Screen "Screen 2"
      Screen "Screen 1" Below "Screen 2"
      InputDevice "Mouse1" "CorePointer"
      InputDevice "Keyboard1" "CoreKeyboard"
  EndSection
  ______________________________________________________________________



  Screens can overlap too.  In this configuration I make the two
  monitors overlap by 80 pixels..

  ______________________________________________________________________
  Section "ServerLayout"
      Identifier  "Simple Layout"
      Screen "Screen 2"
      Screen "Screen 1" Relative "Screen 2" 1200 0
      InputDevice "Mouse1" "CorePointer"
      InputDevice "Keyboard1" "CoreKeyboard"
  EndSection
  ______________________________________________________________________



