[ubuntu-x] mulimonitor on intel using displayconfig-gtk (was Question on multi-head Dapper->Hardy upgrades)

[Bryce Harrington]

On Thu, Feb 14, 2008 at 10:45:16PM +0000, (``-_-????) -- Fernando wrote:
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> On Thursday 07 February 2008 19:11:26 Bryce Harrington wrote:
> > Alright, I think I can modify displayconfig-gtk when in BPX mode to not
> > offer to set up multi-head (which it would do incorrectly).  
> > 
> > Bryce
> 
> On Gutsy I could pretty use without any issues, two monitors (either cloning or extended desktop) by setting them up with displayconfig-gtk.
> But since I upgraded to Hardy, It wont even detect my Intel 855 (using the new generic Intel driver, but i810 also wont work).
> Any tips on how can I set multimonitor?
> grandr aint all that good, either (clicking on the monitor icons makes it crash).
> 

displayconfig-gtk relies on use of Xinerama for doing multi-monitor.
The -i810 driver uses Xinerama; -intel uses Xrandr.

displayconfig-gtk determines your driver by parsing it from xorg.conf;
recent upstream changes make dexconf no longer list the driver (although
I think Timo restored that for Ubuntu recently).  There is no mechanism
provided by Xorg to list the current driver, except booting X with no
config and scanning Xorg.0.log to see what it picked.  (Upstream prefers
going in a direction where less is included in xorg.conf anyway.)

Presently, the way to set up dual-monitor on Intel graphics hardware is
to use the xrandr command line tool.  For instance, this is the line I
put in my .xprofile:

  xrandr --output VGA-0 --auto --left-of DVI-0 --auto

See `man xrandr` for more info.

Alternately, you can configure your xrandr setup in your xorg.conf.  For
details on doing this, here is a pretty good resource:

   http://www.thinkwiki.org/wiki/Xorg_RandR_1.2

(It would be nice to have a doc like this but specific to Ubuntu
available from wiki.ubuntu.com).

Obviously, in either case the user is having to do some un-Ubuntu-ish
manual configuration work, which has been our intent to get away from.
In essense, what we need is a tool like displayconfig-gtk, but that uses
xrandr rather than Xinerama, and does its configuration "live" with
xrandr, instead of by modifying xorg.conf.  Ideally, like with
displayconfig-gtk, it would be helpful to implement in a split
frontend/backend fashion where the backend is window-system independent
and includes the bulk of the functionality, so it would be easy for
someone to make a Qt-ified version of the frontend for Kubuntu.
Further, it would be nice to implement this in a way that it would be
acceptable to upstreams, so we can share the maintenance load.

With the above goals in mind, I've taken a shot at implementing a tool
derived from libxrandr, xrandr, and gnome-control-center's display
capplet:  http://bryceharrington.org/drupal/display-config-0

I've only had 2 weeks so far working on it, but I hope to post a test
version by next week, once I have it functioning properly.  (Currently
it's applying the changes properly, but then the monitors lose sync.)

RedHat is also working on a gui xrandr config tool, but taking a
different approach; not sure what to make of it yet.

Bryce