Eu executei uma configuração de três monitores usando xinerama e duas placas gfx da Nvidia. Isso funciona com o X.org 1.9.4. Dê uma olhada no meu xorg.conf:
Section "ServerLayout"
Identifier "X.org Configured"
Option "Clone" "off"
Option "Xinerama" "on"
Screen 0 "Screen0"
Screen 1 "Screen1" RightOf "Screen0"
Screen 2 "Screen2" LeftOf "Screen0"
InputDevice "Mouse0" "CorePointer"
InputDevice "Keyboard0" "CoreKeyboard"
EndSection
Section "ServerFlags"
Option "DontZap" "false"
EndSection
Section "Files"
ModulePath "/usr/lib/xorg/modules"
FontPath "/usr/share/fonts/misc"
FontPath "/usr/share/fonts/100dpi:unscaled"
FontPath "/usr/share/fonts/75dpi:unscaled"
FontPath "/usr/share/fonts/TTF"
FontPath "/usr/share/fonts/Type1"
FontPath "/usr/share/fonts/local"
EndSection
Section "Module"
Load "record"
Load "extmod"
Load "dbe"
Load "dri2"
Load "dri"
Load "glx"
EndSection
Section "InputDevice"
Identifier "Keyboard0"
Driver "kbd"
Option "XkbLayout" "gb"
Option "XkbOptions" "terminate:ctrl_alt_bksp"
EndSection
Section "InputDevice"
Identifier "Mouse0"
Driver "mouse"
Option "Protocol" "auto"
Option "Device" "/dev/input/mice"
Option "ZAxisMapping" "4 5 6 7"
EndSection
Section "Monitor"
Identifier "Monitor0"
VendorName "Monitor Vendor"
ModelName "Monitor Model"
Option "DPMS"
EndSection
Section "Monitor"
Identifier "Monitor1"
VendorName "Monitor Vendor"
ModelName "Monitor Model"
Option "DPMS"
EndSection
Section "Monitor"
Identifier "Monitor2"
VendorName "Monitor Vendor"
ModelName "Monitor Model"
Option "DPMS"
EndSection
Section "Device"
Identifier "Card0"
Driver "nvidia"
VendorName "nVidia Corporation"
BoardName "G80 [GeForce 8800 GTS]"
BusID "PCI:1:0:0"
Option "NoLogo" "1"
Option "RenderAccel" "True"
Screen 0
EndSection
Section "Device"
Identifier "Card1"
Driver "nvidia"
VendorName "nVidia Corporation"
BoardName "G80 [GeForce 8800 GTS]"
BusID "PCI:1:0:0"
Option "NoLogo" "1"
Option "RenderAccel" "True"
Screen 1
EndSection
Section "Device"
Identifier "Card2"
Driver "nvidia"
VendorName "nVidia Corporation"
BoardName "G92 [GeForce 8800 GTS 512]"
BusID "PCI:4:0:0"
Option "NoLogo" "1"
Option "RenderAccel" "True"
Screen 0
EndSection
Section "Screen"
Identifier "Screen0"
Device "Card0"
Monitor "Monitor0"
Option "Metamodes" "1680x1050"
SubSection "Display"
Depth 24
Modes "1680x1050"
EndSubSection
EndSection
Section "Screen"
Identifier "Screen1"
Device "Card1"
Monitor "Monitor1"
Option "Metamodes" "1680x1050"
SubSection "Display"
Depth 24
Modes "1680x1050"
EndSubSection
EndSection
Section "Screen"
Identifier "Screen2"
Device "Card2"
Monitor "Monitor2"
Option "Metamodes" "1680x1050"
SubSection "Display"
Depth 24
Modes "1680x1050"
EndSubSection
EndSection
Section "DRI"
Mode 0666
EndSection
Sim, eu sei que o Xinerama é velho e todos os garotos legais devem usar o xrandr. Bem, se alguém puder me mostrar uma configuração do Xrandr que funcione, eu mudaria em um piscar de olhos.
Outra solução seria usar um dispositivo de hardware que multiplexa seus monitores. Caro, mas permitiria executar o SLI / xrandr / etc em vez do Xinerama. Gizmos aqui