[Gllug] Multiple Monitors with RedHat 8.0

[Steve Nicholson]

On Thu, Mar 06, 2003 at 02:35:21PM -0000, Simon Morris wrote:
> Has anyone has any experience with Multiple Monitors and Linux.

These are the secrets I found important a while ago when I did this
(using two cards, using dualhead now though). You need a separate
"device" section for each graphics card. For each one you need to
specify the "BusID" e.g.

Section "Device"
	identifier 	"card0"
	BusID	  	"PCI:0:8:0
EndSection

Section "Device"
        identifier      "card1"
        BusID           "PCI:0:9:0
EndSection

obviously you need more in there than that (Screen, Driver etc,) but the
BusID is very important, the ones above are made up, you need to find
out what they are for your set up.  I thought scanpci gave you this but
you have to know how to interpret it.  Easier way is to look in your
/var/log/XFree86.0.log after starting X with the two cards in.  Look for
the section starting with: 

(II) PCI: PCI scan 
     ---->> after this will be a list of PCI busID's used <<------

further down it should list your cards against the busID e.g.
(--) PCI:*(1:0:0) Matrox MGA G400 AGP


Other area I had problems was knowing that you need Xinerama on to
enable your desktop to stretch across two screens. So put it in your
serverFlags in the XF86Config-4 (Note: I think using mulitple cards only
works in xfree > V4)

Section "ServerFlags"
        Option          "Xinerama" "on"
EndSection

read through the /var/log/XFree86.0.log after starting X if you are
having problems, this will give you an idea where the problems are.
You should be able to use more than two cards, I tried my old PCI
Matrox with my AGP G400 card to use 3 monitors but it's didn't work for
some reason and haven't had time to find out why.

HTH good luck.

Steve.

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