Dual Head without Xinerama

[Alex Deucher]

On Mon, Oct 18, 2010 at 6:49 AM, Ulf Markwardt
<ulf.markwardt at tu-dresden.de> wrote:
> Hello there,
>
> is there a way to use the ati/radeon driver for a dual head setup
> without Xinerama. I.e. I would like to have separate displays.
> I had this possibility with fglrx but see no way to do it with the
> OpenSource driver. The ServerFlag Xinerama=off results in a cloned
> output.
> I have seen the MergedFB option (e.g.
> http://ubuntuforums.org/showthread.php?t=221174) but got the impression
> that this option is deprecated and replaced by xrandr.
>

Yes.  there are two options for handling multi-head, zaphod
(optionally with xinerama) and xrandr.  xrandr allow you to
dynamically adjust the display configuration of your GPU, however, in
multi-head setups, you will end up with a single logical screen that
you can move windows between.  With zaphod mode, you can create
separate protocol screens (e.g., :0.0 and :0.1) that you can not move
windows between.  If you want to move windows between protocol screens
(on the same of different GPUs), you need to enable xinerama.  For
zaphod, you need a configuration like the following sample xorg.conf.
Adjust the BusID options to match your system (look up the bus id in
lspci), and adjust the output assigned to each instance of the driver
with the ZaphodHeads option.  Finally uncomment the xinerama option if
you want to enable it.

Section "ServerLayout"
	Screen	0	"Screen0" 0 0
	Screen		"Screen1" LeftOf "Screen0"
	#Option "xinerama" "true"
EndSection


Section "Device"
	Identifier  "Card0"
	Option "ZaphodHeads" "DVI-0"
	BusID        "PCI:1:5:0"
	Screen 0
EndSection

Section "Device"
	Identifier  "Card1"
	Option "ZaphodHeads" "DVI-1"
	BusID        "PCI:1:5:0"
	Screen 1
EndSection

Section "Screen"
	Identifier "Screen0"
	Device "Card0"
EndSection

Section "Screen"
	Identifier "Screen1"
	Device "Card1"
EndSection

> Or is this a question for the xrandr or the gnome mailinglists?
>
>
> Thank you
> Ulf
>
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