Setting up Dual Monitors with a single graphics card ...

ozzydaws · 08-29-2009, 12:27 PM

Hi everyone,

I'm new to these forums so hopefully someone can point me in the right direction.

First things first, I know that there have been many posts on this subject before, and to my knowledge I have done everything instructed in them but to no avail.

I have two monitors running off one dual headed Nvidia graphics card, and I want to use xinerama to create one large desktop area spanning the two screens. So far, I have managed to use X -configure to make a new xorg.conf file which does indeed use both monitors, but clones them. I.e. both show exactly the same thing.

I know that I need to edit my xorg.conf file to show relationships. Here is my current one:

Code:

Section "ServerLayout"
	Identifier     "X.org Configured"
	Screen      0  "Screen0" 0 0
        Screen         "Screen1" Rightof "Screen0"
	InputDevice    "Mouse0" "CorePointer"
	InputDevice    "Keyboard0" "CoreKeyboard"
        Option "Xinerama" "on"         - Using /etc/X11/Xorg.conf
        Option "Clone"    "off"
EndSection

Section "Files"
	RgbPath      "/usr/share/X11/rgb"
	ModulePath   "/usr/lib/xorg/modules"
	FontPath     "/usr/share/fonts/TTF"
	FontPath     "/usr/share/fonts/OTF"
	FontPath     "/usr/share/fonts/Type1"
	FontPath     "/usr/share/fonts/misc"
	FontPath     "/usr/share/fonts/75dpi/:unscaled"
EndSection

Section "Module"
	Load  "record"
	Load  "glx"
	Load  "extmod"
	Load  "xtrap"
	Load  "dri"
	Load  "dbe"
	Load  "freetype"
	Load  "type1"
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   "main"
	VendorName   "Monitor Vendor"
	ModelName    "Monitor Model"

Section "Monitor"
	Identifier   "secondary"
	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"
        ### [arg]: arg optional
        #Option     "SWcursor"           	# [<bool>]
        #Option     "HWcursor"           	# [<bool>]
        #Option     "NoAccel"            	# [<bool>]
        #Option     "ShadowFB"           	# [<bool>]
        #Option     "UseFBDev"           	# [<bool>]
        #Option     "Rotate"             	# [<str>]
        #Option     "VideoKey"           	# <i>
        #Option     "FlatPanel"          	# [<bool>]
        #Option     "FPDither"           	# [<bool>]
        #Option     "CrtcNumber"         	# <i>
        #Option     "FPScale"            	# [<bool>]
        #Option     "FPTweak"            	# <i>
        Option     "DualHead"           	"True"
	Identifier  "Card0"
	Driver      "nv"
	VendorName  "nVidia Corporation"
	BoardName   "G80 [GeForce 8800 GTS]"
	BusID       "PCI:1:0:0"
EndSection

Section "Screen"
	Identifier "Screen0"
	Device     "Card0"
	Monitor    "main"
	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

Section "Screen"
	Identifier "Screen1"
	Device     "Card0"
	Monitor    "secondary"
	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

Can anyone see a problem with this? When I quit out of X and run "startx -- +xinerama" it tells me it could not connect to the X server.

Any ideas? Thanks all ...

jschiwal · 08-31-2009, 06:45 AM

Which distro do you use? You may have a graphics configuration wizard that can help you set it up. For nvidia, read their documentation and look for "TwinView". Also, the propriety nvidia driver includes documentation, and some utility programs. One of them is nvidia-settings which would be the easiest way of doing it. Also look in the the xorg.conf man page under the Server and Screen sections. You also need to configure your desktop environment.

johnsfine · 08-31-2009, 07:21 AM

Are you using the open source nVidia driver on purpose and/or for a good reason?

The non open source version generally works better. I think that also gives you the choice to extend the desktop over both monitors without xinerama, which is simpler to set up. Jschiwal's answer seems to assume the non open source driver.

Also, many problems in starting X become a lot easier to understand when you look at the details logged in /var/log/Xorg.0.log

i92guboj · 08-31-2009, 08:50 AM

Newer versions of X are migrating to randr for this thing, xinerama is about to be deprecated and I think that randr is now the default. Not sure though, it all depends on the driver really, and I never used 'nv'.

If you have no philosophical issue with the closed driver, I suggest using it instead, and twinview instead of xinerama. If not, you might need to disable xrandr explicitly before your dual head setup can be used. However, as said, the key might lie in your log file.

ozzydaws · 09-01-2009, 08:33 AM

thanks very much for the replys guys.

I did in fact look into using twinview just after I submitted the thread. The nvidia manager wouldn't let me do anything, however, because I was not using an nvidia based xorg.conf file. Which I was.

To solve this I backed up my file and deleted the original. I run nvidia-xconfig and forced it to make a whole new one based on my specs. After restarting X I just set up twinview through the nvidia GUI. it turns out I could easily have done it manually, but hey.

Thanks again for the tips, and I'm using slackware.