Eu tenho três monitores conectados via DVI em duas placas ATI diferentes no Arch Linux usando o driver xf86-video-ati .
Todos os três estão servindo a saída, mas um dos meus displays (o do segundo cartão) volta para uma tela cinza e um cursor preto "x" depois de fazer o login no GDM.
É interessante notar que a exibição funciona na tela de login do GDM, exibindo o plano de fundo da tela de login (mas não a caixa de login, como fazem os outros dois monitores).
Como conseguir um desktop de trabalho com todos os três displays?
Estou usando o GDM e o Gnome3, com o seguinte xorg.conf:
Section "ServerLayout"
Identifier "X.org Configured"
Screen 0 "Screen0" 0 0
Screen 1 "Screen1" RightOf "Screen0"
Screen 2 "Screen2" RightOf "Screen1"
Screen 3 "Screen3" RightOf "Screen2"
InputDevice "Mouse0" "CorePointer"
InputDevice "Keyboard0" "CoreKeyboard"
EndSection
Section "Files"
ModulePath "/usr/lib/xorg/modules"
FontPath "/usr/share/fonts/misc/"
FontPath "/usr/share/fonts/TTF/"
FontPath "/usr/share/fonts/OTF/"
FontPath "/usr/share/fonts/Type1/"
FontPath "/usr/share/fonts/100dpi/"
FontPath "/usr/share/fonts/75dpi/"
EndSection
Section "Module"
Load "glx"
EndSection
Section "InputDevice"
Identifier "Keyboard0"
Driver "kbd"
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"
EndSection
Section "Monitor"
Identifier "Monitor1"
VendorName "Monitor Vendor"
ModelName "Monitor Model"
EndSection
Section "Monitor"
Identifier "Monitor2"
VendorName "Monitor Vendor"
ModelName "Monitor Model"
EndSection
Section "Monitor"
Identifier "Monitor3"
VendorName "Monitor Vendor"
ModelName "Monitor Model"
EndSection
Section "Device"
### Available Driver options are:-
### Values: <i>: integer, <f>: float, <bool>: "True"/"False",
### <string>: "String", <freq>: "<f> Hz/kHz/MHz",
### <percent>: "<f>%"
### [arg]: arg optional
#Option "NoAccel" # [<bool>]
#Option "SWcursor" # [<bool>]
#Option "EnablePageFlip" # [<bool>]
#Option "ColorTiling" # [<bool>]
#Option "ColorTiling2D" # [<bool>]
#Option "RenderAccel" # [<bool>]
#Option "SubPixelOrder" # [<str>]
#Option "AccelMethod" # <str>
#Option "EXAVSync" # [<bool>]
#Option "EXAPixmaps" # [<bool>]
#Option "ZaphodHeads" # <str>
#Option "EnablePageFlip" # [<bool>]
#Option "SwapbuffersWait" # [<bool>]
Identifier "Card0"
Driver "radeon"
BusID "PCI:3:0:0"
EndSection
Section "Device"
### Available Driver options are:-
### Values: <i>: integer, <f>: float, <bool>: "True"/"False",
### <string>: "String", <freq>: "<f> Hz/kHz/MHz",
### <percent>: "<f>%"
### [arg]: arg optional
#Option "NoAccel" # [<bool>]
#Option "SWcursor" # [<bool>]
#Option "EnablePageFlip" # [<bool>]
#Option "ColorTiling" # [<bool>]
#Option "ColorTiling2D" # [<bool>]
#Option "RenderAccel" # [<bool>]
#Option "SubPixelOrder" # [<str>]
#Option "AccelMethod" # <str>
#Option "EXAVSync" # [<bool>]
#Option "EXAPixmaps" # [<bool>]
#Option "ZaphodHeads" # <str>
#Option "EnablePageFlip" # [<bool>]
#Option "SwapbuffersWait" # [<bool>]
Identifier "Card1"
Driver "radeon"
BusID "PCI:4:0:0"
EndSection
Section "Device"
### Available Driver options are:-
### Values: <i>: integer, <f>: float, <bool>: "True"/"False",
### <string>: "String", <freq>: "<f> Hz/kHz/MHz",
### <percent>: "<f>%"
### [arg]: arg optional
#Option "ShadowFB" # [<bool>]
#Option "DefaultRefresh" # [<bool>]
#Option "ModeSetClearScreen" # [<bool>]
Identifier "Card2"
Driver "vesa"
BusID "PCI:3:0:0"
EndSection
Section "Device"
### Available Driver options are:-
### Values: <i>: integer, <f>: float, <bool>: "True"/"False",
### <string>: "String", <freq>: "<f> Hz/kHz/MHz",
### <percent>: "<f>%"
### [arg]: arg optional
#Option "ShadowFB" # [<bool>]
#Option "DefaultRefresh" # [<bool>]
#Option "ModeSetClearScreen" # [<bool>]
Identifier "Card3"
Driver "vesa"
BusID "PCI:4:0:0"
EndSection
Section "Screen"
Identifier "Screen0"
Device "Card0"
Monitor "Monitor0"
SubSection "Display"
Viewport 0 0
Depth 1
EndSubSection
SubSection "Display"
Viewport 0 0
Depth 4
EndSubSection
SubSection "Display"
Viewport 0 0
Depth 8
EndSubSection
SubSection "Display"
Viewport 0 0
Depth 15
EndSubSection
SubSection "Display"
Viewport 0 0
Depth 16
EndSubSection
SubSection "Display"
Viewport 0 0
Depth 24
EndSubSection
EndSection
Section "Screen"
Identifier "Screen1"
Device "Card1"
Monitor "Monitor1"
SubSection "Display"
Viewport 0 0
Depth 1
EndSubSection
SubSection "Display"
Viewport 0 0
Depth 4
EndSubSection
SubSection "Display"
Viewport 0 0
Depth 8
EndSubSection
SubSection "Display"
Viewport 0 0
Depth 15
EndSubSection
SubSection "Display"
Viewport 0 0
Depth 16
EndSubSection
SubSection "Display"
Viewport 0 0
Depth 24
EndSubSection
EndSection
Section "Screen"
Identifier "Screen2"
Device "Card2"
Monitor "Monitor2"
SubSection "Display"
Viewport 0 0
Depth 1
EndSubSection
SubSection "Display"
Viewport 0 0
Depth 4
EndSubSection
SubSection "Display"
Viewport 0 0
Depth 8
EndSubSection
SubSection "Display"
Viewport 0 0
Depth 15
EndSubSection
SubSection "Display"
Viewport 0 0
Depth 16
EndSubSection
SubSection "Display"
Viewport 0 0
Depth 24
EndSubSection
EndSection
Section "Screen"
Identifier "Screen3"
Device "Card3"
Monitor "Monitor3"
SubSection "Display"
Viewport 0 0
Depth 1
EndSubSection
SubSection "Display"
Viewport 0 0
Depth 4
EndSubSection
SubSection "Display"
Viewport 0 0
Depth 8
EndSubSection
SubSection "Display"
Viewport 0 0
Depth 15
EndSubSection
SubSection "Display"
Viewport 0 0
Depth 16
EndSubSection
SubSection "Display"
Viewport 0 0
Depth 24
EndSubSection
EndSection