I have a StarTech.com StarView SV221DVIDD 2 Port Dual Display KVM switch that sits between 2 PC's (running openSUSE 10.3 and openSUSE 11.0) and 2 identical DELL 1504FP LCD screens. This message is linked to the operation of the KVM switch with the openSUSE 10.3 PC which has an nvidia GeForce 6600 graphics board (I haven't tried the other PC-KVM link as I believe the fault is probably common to both PC systems). Xorg.conf has been set up with the latest nvidia driver and both monitors work OK with Xinerama and Compiz effects when monitors are coupled directly to the PC.
My original problem with the KVM installed was that both monitors became blank when starting X windows (monitors showed the normal text startup script until StartX). An email reply from StarTech.com indicated that this was probably an EDID fault where the details regarding the monitors were not being passed through the KVM and had to be specifically included in xorg.conf . So I used nvidia-settings to save the EDID settings for each monitor in edid1.bin and edid2.bin and put these files into a CustomEDID option in separate Device sections in xorg.conf as Option "CustomEDID" "DFP-0:/etc/X11/edid1.bin" (and similar for the DFP-1 monitor)
This nearly worked - I now have one of the monitors working under X windows but the other remains blank.
The funny thing is that if I start X windows with the monitors directly linked to the PC and then couple up the KVM switch between the PC and the monitors - then the KVM switch happily shows both monitors in correct fashion and even allows me to switch back and forth without losing a monitor.
So my impression is that the "fault" is still something to do with the EDID configuration - but this is in binary so it's not easy to know where to look. As the monitors are identical, I have tried using edid1.bin in both CustomEDID options and the same for edid2.bin - but still same result - 1 monitor works and the other doesn't.
I have copied the relevant parts of Xorg.conf below - any thoughts would be appreciated. I have commented out options in the Device sections of the working Xorg.conf as these appear to my mind to cause some logical confusion and their exclusion does not cause any on-screen errors - the monitor relationships (LeftOf and RightOf) are then contained in the ServerLayout section.


Section "Monitor"
Option "CalcAlgorithm" "XServerPool"
DisplaySize 304 228
HorizSync 29-60
Identifier "Monitor[0]"
ModelName "1504FP (DIGITAL)"
Option "DPMS"
VendorName "DELL"
VertRefresh 56-75
# UseModes "Modes[0]"
EndSection

Section "Monitor"
Option "CalcAlgorithm" "XServerPool"
DisplaySize 304 228
HorizSync 29-60
Identifier "Monitor[1]"
ModelName "1504FP (DIGITAL)"
Option "DPMS"
VendorName "DELL"
VertRefresh 56-75
# UseModes "Modes[1]"
EndSection

Section "Modes"
Identifier "Modes[0]"
EndSection

Section "Modes"
Identifier "Modes[1]"
EndSection

Section "Screen"
DefaultDepth 24
SubSection "Display"
Depth 15
Modes "1024x768" "1024x600" "800x600" "768x576" "640x480"
EndSubSection
SubSection "Display"
Depth 16
Modes "1024x768" "1024x600" "800x600" "768x576" "640x480"
EndSubSection
SubSection "Display"
Depth 24
Modes "1024x768" "1024x600" "800x600" "768x576" "640x480"
EndSubSection
SubSection "Display"
Depth 8
Modes "1024x768" "1024x600" "800x600" "768x576" "640x480"
EndSubSection
Device "Device[0]"
Identifier "Screen[1]"
Monitor "Monitor[1]"
EndSection

Section "Screen"
DefaultDepth 24
SubSection "Display"
Depth 15
Modes "1024x768" "1024x600" "800x600" "768x576" "640x480"
EndSubSection
SubSection "Display"
Depth 16
Modes "1024x768" "1024x600" "800x600" "768x576" "640x480"
EndSubSection
SubSection "Display"
Depth 24
Modes "1024x768" "1024x600" "800x600" "768x576" "640x480"
EndSubSection
SubSection "Display"
Depth 8
Modes "1024x768" "1024x600" "800x600" "768x576" "640x480"
EndSubSection
Device "Device[0]"
Identifier "Screen[0]"
Monitor "Monitor[0]"
EndSection

Section "Device"
BoardName "GeForce 6600/GeForce 6600 GT"
Driver "nvidia"
Identifier "Device[0]"
Option "CustomEDID" "DFP-0:/etc/X11/edid_DFP-0.bin"
Option "SaXDualHead"
Option "TwinView"
Option "SaXDualMonitorVendor" "DELL"
# Option "SaXDualOrientation" "RightOf"
Option "MetaModes" "1024x768,1024x768;1024x600,1024x600;800x600,800x600;768x576,768x576;640x480,640x480"
Option "SaXDualResolution" "1024x768"
# Option "TwinViewOrientation" "RightOf"
Option "SaXDualMode" "Xinerama"
# Option "SecondMonitorVertRefresh" "56-75"
Option "SaXDualHSync" "30-60"
Option "SaXDualMonitorModel" "1504FP (DIGITAL)"
Option "SaXDualVSync" "56-75"
Screen 0
VendorName "NVIDIA"
EndSection

Section "Device"
BoardName "GeForce 6600/GeForce 6600 GT"
Driver "nvidia"
Identifier "Device[0]"
Option "CustomEDID" "DFP-1:/etc/X11/edid_DFP-1.bin"
Option "SaXDualHead"
Option "TwinView"
Option "SaXDualMonitorVendor" "DELL"
# Option "SaXDualOrientation" "RightOf"
Option "MetaModes" "1024x768,1024x768;1024x600,1024x600;800x600,800x600;768x576,768x576;640x480,640x480"
Option "SaXDualResolution" "1024x768"
# Option "TwinViewOrientation" "RightOf"
Option "SaXDualMode" "Xinerama"
# Option "SecondMonitorVertRefresh" "56-75"
Option "SaXDualHSync" "30-60"
Option "SaXDualMonitorModel" "1504FP (DIGITAL)"
Option "SaXDualVSync" "56-75"
Screen 1
VendorName "NVIDIA"
EndSection

Section "ServerLayout"
Identifier "Layout[all]"
InputDevice "Keyboard[0]" "CoreKeyboard"
InputDevice "Mouse[1]" "CorePointer"
Option "Clone" "off"
Option "Xinerama" "off"
Screen "Screen[0]" LeftOf "Screen[1]"
Screen "Screen[1]" RightOf "Screen[0]"
EndSection

Section "DRI"
Group "video"
Mode 0660
EndSection

Section "Extensions"
Option "Composite" "Enable"
EndSection