[Wlug] Xinerama issues with Fedora Core 8...

[Chuck Anderson]

On Mon, Nov 19, 2007 at 01:07:54PM -0500, Tim Keller wrote:
> As far as I can tell... Xinerama support is totally borked in Fedora Core
> 8.  Has anybody come across any solutions?

Xinerama is no longer supported in Xorg.  But not to fear!  It has 
been replaced by a new, dynamic method of doing dual-head with the 
XRandR extension.  Unfortunately, neither the Release Notes nor the 
system-config-display tool have taken these changes into account.  
Also, this won't work with multiple separate video cards, only single 
video cards with multiple output on them.  The fact that the X server 
segfaults when configured with Xinerama is a bug.

You can turn on/off and configure multiple displays all dynamically 
using the xrandr command.  Try this to display the available outputs 
while the X server is running:

xrandr

To configure a specific output, try these commands:

xrandr --output DVI-1 --auto

Or:

xrandr --output DVI-1 --mode 1024x768

To configure dual-head (NOTE: You have to pre-configure the maximum 
combined virtual resolution you want to use in xorg.conf first, as 
specified below):

xrandr --output DVI-1 --right-of DVI-0

This is nice because it means you can dynamically set up dual-head for 
an external VGA port on a laptop going to an LCD projector, for 
example.  The internal LCD and external VGA could run at different 
resolutions too.

For more fun, you can play with rotating screen images.

You can also configure this in xorg.conf.  The key differences from 
traditional multi-head and Xinerama are that you only use a single 
Screen in your ServerLayout section:

Section "ServerLayout"
        Identifier     "new dual-head configuration"
        Screen      0  "Screen0" 0 0
        InputDevice    "Keyboard0" "CoreKeyboard"
EndSection

Then refer to multiple monitors in the Device section.  Here the 
format is Option "Monitor-<actual-monitor-id-from-xrandr>" "<monitor-identifier>"

Section "Device"
        Identifier  "Videocard0"
        Driver      "radeon"
        Option      "Monitor-DVI-0" "first"
        Option      "Monitor-DVI-1" "second"
EndSection

Then specify the multiple Monitor sections themselves, using the 
monitor-identifiers specified above, with the placement options 
RightOf or LeftOf:

Section "Monitor"
        Identifier  "first"
EndSection

Section "Monitor"
        Identifier  "second"
        Option      "RightOf" "first"
EndSection

And then of course the single screen section.  Note that you MUST 
specify the Virtual resolution as the sum of the resolutions of the 
multiple monitors you want to use (either horizontally or vertically, 
depending on your preferred monitor orientation).  So below I have 
specified Virtual 3200 1200 so that I can place two 1600x1200 monitors 
side-by-side.  The Monitor "first" is there just to satisfy the 
requirement for a Monitor to be specified--you don't put both monitors 
here.
        
Section "Screen"
        Identifier "Screen0"
        Device     "Videocard0"
        Monitor    "first"
        DefaultDepth     24
        SubSection "Display"
                Viewport   0 0
                Virtual 3200 1200
                Depth     24
                Modes    "1600x1200" "1600x1024" "1440x900" "1400x1050" "1360x768" "1280x1024" "1280x960" "1280x800" "1280x720" "1152x864" "1024x768" "800x600" "640x480"
        EndSubSection
EndSection