Question about dual monitors

[Dana J. Laude]

On Friday 21 April 2006 18:24, Daniel Carrera wrote:
> Antony Gelberg wrote:
> >> You see that those are actually the same device? Okay,
> >> you've chosen different identifiers. But the identifier is
> >> just a user-chosen string. There is nothing to tell X that
> >> "ATI_1" means "VGA out". These two devices are the same.
> >
> > The Devices are not the same.  They are different due to the
> > differing Screen parameter.
>
> Okay, so this shifts the question to the Screen parameter. How
> does X or Xinerama know that Screen 0 is supposed to be the
> LCD and Screen 1 is supposed to be the CRT?

Here's a snip of my xorg.conf file.  I'm using a Matrox G400 
card. If you take notice the Identifier strings in sections 
Device, Monitor and Screen. Then the naming in the ServerLayout 
section, specifically the Screen naming.  Notice how everything 
match's the identifier strings for the others?
<snip>
ection "Device"
        Identifier      "Matrox Graphics, Inc. MGA G400 AGP"
        Driver          "mga"
        BusID           "PCI:2:0:0"
        Screen 0
        Option          "AGPMode" "4"
EndSection

Section "Device"
        Identifier      "Matrox Graphics, Inc. MGA G400 AGP_2"
        Driver          "mga"
        BusID           "PCI:2:0:0"
        Screen 1
        Option          "AGPMode" "4"
EndSection

Section "Monitor"
        Identifier      "Sylvania"
        HorizSync       30-69
        VertRefresh     50-90
        Option          "DPMS"
EndSection

Section "Monitor"
        Identifier      "ViewSonic"
        HorizSync       30-70
        VertRefresh     50-120
        Option          "DPMS"
EndSection

Section "Screen"
        Identifier      "Sylvania"
        Device          "Matrox Graphics, Inc. MGA G400 AGP"
        Monitor         "Sylvania"
        DefaultDepth    24
        SubSection "Display"
                Depth           16
                Modes           "1280x1024" "1024x768" "800x600"
        EndSubSection
        SubSection "Display"
                Depth           24
                Modes           "1280x1024" "1024x768" "800x600" 
"640x480"
        EndSubSection
EndSection

Section "Screen"
        Identifier      "ViewSonic"
        Device          "Matrox Graphics, Inc. MGA G400 AGP_2"
        Monitor         "ViewSonic"
        DefaultDepth    24
        SubSection "Display"
                Depth           16
                Modes           "1280x1024" "1024x768" "800x600" 
"640x480"
        EndSubSection
        SubSection "Display"
                Depth           24
                Modes           "1280x1024" "1024x768" "800x600" 
"640x480"
        EndSubSection
EndSection

Section "ServerLayout"
        Identifier      "Default Layout"
        InputDevice     "Generic Keyboard"
        InputDevice     "Configured Mouse"
        Option          "Xinerama" "on"
        Screen          "Sylvania" 0 0
        Screen          "ViewSonic" RightOf "Sylvania"
EndSection

Section "DRI"
        Mode    0666
EndSection
</snip>

Also, the Section "module" should have Load "dri" if needed.

Regards,

Dana