setting up xrandr with two graphics cards

martin f krafft madduck at
Mon Nov 19 04:41:30 PST 2007


I had a triple-head setup, using two Radeon 92x0 cards. This worked
fine with Xinerama for years, until this morning when it would no
longer start up.

Instead of trying to find the problem, I chose to migrate to RANDR
1.2, which I already use on other machines. However, this machine
has two graphics cards and three monitors connected, and I cannot
get it to work.

Here are details:

  Card 0: PCI:0:12:0: Radeon 9250:
    Port1: TMDS / DVI-I           Monitor 0 (Acer AL922)
    Port2: VGA                    unused

  Card 1: PCI:1:0:0: Radeon 9200:
    Port1: TMDS / DVI-I           Monitor 1 (Acer AL922)
    Port2: CRT / VGA              Monitor 2 (MRM B18XA)

My desired setup has monitor 0 left of monitor 1 left of monitor
2 and a 3840x1024 workspace across them.

I tried to change my configuration according to the instructions at, but I could not
get the workspace to split across several monitors. The result is
the same as what I got when I tried Xorg auto-detection.

I went ahead and removed the configuration file. The X server comes
up, but only uses card 1, sets up monitor 1 with 1280x1024 and
monitor 2 to mirror monitor 1, but only with 640x480, so that the
1280x1024 are virtual on the second monitor.

The log file is attached.

xrandr prints:
  Screen 0: minimum 640 x 480, current 1280 x 1024, maximum 1280 x 1024
  default connected 1280x1024+0+0 0mm x 0mm
    1280x1024     303.0* 
    1024x768      303.0  
    832x624       303.0  
    800x600       303.0  
    640x480       303.0    306.0  

and no matter what I try, I cannot seem to get the second screen to
be right-of the first one, or to make it display 1280x1024, which it
can. Calls like

  xrandr --auto
  xrandr --output CRT --right-of TMDS
  xrandr --output VGA --right-of DVI-I

all just don't seem to do anything, and even with --verbose just
return immediately without any information.

Furthermore, I cannot figure out how to let X know about the second
card. It autodetects it, but does not autoconfigure/use it. See the
attached log file.

I have tried to use Xorg -configure to create a configuration file,
but that generates a Xinerama setup and thus didn't really help.

I have also tried to hand-craft a configuration file with a Device
stanza for each card, the three monitors, and a single screen with
a large enough virtual space, but the result is the same, except
that the virtual screen is now 3840x1024 on both monitors, while
their physical resolution is still 1280 and 640, as before.

The configuration file is also attached.

I would appreciate if someone could help me with this. Ideally I'd
want auto-detection of the two cards and the three monitors, and
then be able to call xrandr from my Xsession to set up the screen
estate before handing over to the window manager.


martin;              (greetings from the heart of the sun.)
  \____ echo mailto: !#^."<*>"|tr "<*> mailto:" net at madduck
"no, 'eureka' is greek for 'this bath is too hot.'"
                                                            -- dr. who
spamtraps: madduck.bogus at
-------------- next part --------------
# /etc/X11/xorg.conf (xorg X Window System server configuration file)

Section "ServerLayout"
	Identifier	"Standard"
	Screen		"Base screen"
	InputDevice	"Generic Keyboard"
	InputDevice	"Configured Mouse"

Section "ServerFlags"
	Option		"DontZap" "yes"
	Option		"AllowDeactivateGrabs" "yes"
	Option		"AllowClosedownGrabs" "yes"

Section "InputDevice"
	Identifier	"Generic Keyboard"
	Driver		"kbd"
	Option		"CoreKeyboard"
	Option		"XkbRules"		"xorg"
	Option		"XkbModel"		"pc104"
	Option		"XkbLayout"		"us"
	Option		"XkbOptions"		"ctrl:nocaps"

Section "InputDevice"
	Identifier	"Configured Mouse"
	Driver		"mouse"
	Option		"CorePointer"
	Option		"Device"		"/dev/input/mice"
	Option		"Protocol"		"ImPS/2"
	Option		"Emulate3Buttons"	"true"
	Option		"ZAxisMapping"		"4 5"

Section "Device"
	Identifier	"Radeon 9250 [left]"
	Driver		"radeon"
	BusID		"PCI:0:12:0"

Section "Device"
	Identifier	"Radeon 9200 [right]"
	Driver		"radeon"
	BusID		"PCI:1:0:0"

Section "Monitor"
	Identifier	"Acer AL922 [left]"
#	HorizSync	24-80
#	VertRefresh	56-75
	Option		"DPMS"

Section "Monitor"
	Identifier	"Acer AL922 [middle]"
#	HorizSync	24-80
#	VertRefresh	56-75
	Option		"DPMS"

Section "Monitor"
	Identifier	"MRM B18XA [right]"
#	HorizSync	24-80
#	VertRefresh	30-60
	Option		"DPMS"

Section "Screen"
	Identifier	"Base screen"
	Device		"Radeon 9200 [right]"
	Monitor		"Acer AL922 [middle]"
	DefaultDepth	24
	SubSection "Display"
		Depth	24
		Virtual	3840 1024
-------------- next part --------------
A non-text attachment was scrubbed...
Name: Xorg.0.log.gz
Type: application/octet-stream
Size: 10919 bytes
Desc: not available
URL: <>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: digital_signature_gpg.asc
Type: application/pgp-signature
Size: 189 bytes
Desc: Digital signature (see
URL: <>

More information about the xorg mailing list