Sucess with dual monitors

Marius Gedminas marius at
Tue Jun 27 10:41:58 UTC 2006

On Sat, Jun 24, 2006 at 10:22:12PM +0100, phenix777 wrote:
> Regardin xorg.conf:
> I have 2 Devices set
> I have 2 Monitors set
> I have 2 Screens set
> These all work fine.  X froze on me a few times but now it's running
> fine.  However, what I have is two mirrored monitors.
> If it helps, here is the relevant portion of xorg.conf:
> =====
> Section "Device"
> 	Identifier	"ATI Technologies, Inc. RV350 AP [Radeon 9600]"
> 	Driver		"ati"
> 	BusID		"PCI:01:00:0"
> 	Screen 0
> 	Option		"UseFBDev"	"true"
> EndSection
> Section "Device"
> 	Identifier	"ATI Technologies, Inc. RV350 AP [Radeon 9600] Secondary"
> 	Driver		"ati"
> 	BusID		"PCI:01:00:1"
> 	Screen 1
> 	Option		"UseFBDev"	"true"
> EndSection

I heard that you have to specify the *same* BusID for both heads if you
have a Radeon card and want Xinerama.  The second PCI ID is just a fake
to enable Windows to recognize that this card is able to do dual-head.

So, try BusID "PCI:01:00:0" in both Device sections.  It worked for me
with my Radeon 7500.

Alternatively, you may want to try MergedFB mode.  It has certain
advantages: you can switch between dual-head and clone mode without
restarting X (and killing all open programs).  There was a time when
Xinerama was incompatible with DRI (3D acceleration), and the only way
to get both DRI and dual-head was to use MergedFB.

Marius Gedminas
Never, ever expect hackers to be able to read closed proprietary document
formats like Microsoft Word. Most hackers react to these about as well as you
would to having a pile of steaming pig manure dumped on your doorstep.
	-- ESR (
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 189 bytes
Desc: Digital signature
URL: <>

More information about the ubuntu-users mailing list