problem with radeon dual head xinerama mode

Peter Boy pboy at
Thu Jul 31 11:44:10 UTC 2008


I used my radeon dual DVI card up to F7 without any problems in MergedFB
mode as one big screen (xinerama). In Fedora 9 MergedFB mode is gone and
replaced by randr compatible configuration. I figured out how to modify

My current state is:

- as soon as graphical boot screen comes up I can move the
  mouse from one screen to the other and back, it is, it feels
  like xinerama, but only one screen is used for messages  - OK

- when gdm starts I have one big screen as expected  -  OK

- after login the display switches to cloned configuration - Problem

- I can manually switch to one big screen (xinerama-like) using
  xrandr --output DVI-0 --right-of DVI-1

Obviously I have missed something in my configuration file. Please,
could someone have a look on it?

Section "ServerLayout"
	Identifier     "ATI dual head configuration"
	Screen      0  "Default Screen" 0 0
	InputDevice    "Mouse0" "CorePointer"
	InputDevice    "Keyboard0" "CoreKeyboard"

.... (keyboard / mouse left off)

Section "Device"

	Identifier	"ATI Radeon"
	Driver		"radeon"
	VendorName	"ATI corp."
	BoardName	"ATI Technologies Inc RV350 AP [Radeon 9600]"
	BusID		"PCI:1:0:0"
	# Option	"AccelMethod"  "EXA"
	Option		"Monitor-DVI-0" "Panel-0"
	Option		"Monitor-DVI-1" "Panel-1"

Section "Monitor"

	Identifier   "Panel-1"
	ModelName    "NEC MultiSync LCD1700NX (Digital)"
	Option	"dpms"


Section "Monitor"

	Identifier   "Panel-0"
	ModelName    "NEC MultiSync LCD1700NX (Digital)"
	Option	    "dpms"
	Option	"RightOf" "Panel-1"


Section "Screen"
	Identifier "Default Screen"
	Device     "ATI Radeon"
#	Monitor    "Panel-1"
	DefaultDepth     24

	SubSection "Display"
		Viewport   0 0
		Depth     24
		# big virtual screen to place the monitors
		Virtual   2560 1024


There is no error message in Xorg.log but an information:

Any help greatly appreciated.
(==) No monitor specified for screen "Default Screen".
        Using a default monitor configuration.

If I add a monitor option it makes no difference.


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