Dual monitor with desktop effects in 8.10

Mark, 8th Nov 2008

Just a quicky for those experiencing problems getting desktop effects to work in Ubuntu Intrepid Ibex 8.10, after enabling dual monitor or dual head support. In my case, the problem is the Intel driver not supporting a high enough texture size. This is not yet fixed in 8.10, but should be at some point. Here is the link:

https://bugs.launchpad.net/ubuntu/+source/mesa/+bug/146859

The problem is that compiz is checking GL_MAX_TEXTURE_SIZE and failing if the value is not as high as the Virtual Screen size that's set in xorg.conf. You can check the value by running:

glxinfo -l | grep GL_MAX_TEXTURE_SIZE

If this is lower than the value in your /etc/X11/xorg.conf file, compiz won't start! You'll see the error if you try run compiz from the command line.

In the meantime, you can work around this by stacking your monitors on top of each other instead of side by side, thus reducing the virtual resolution to within the required bounds. This works for me as my secondary screen is my TV, so it doesn't really matter what the virtual positioning is!

Thanks!

starwed (not verified), 30th Jun 2009

Thanks, I just spent forever searching for information on this problem. While I saw some posts mentioning the solution, this is the only place I found an actual explanation as to what's going wrong... :)

Dual Monitor With Compiz

roystreet (not verified), 24th Aug 2009

Hi - Just to clarify for my little brain: Are you referring to in the settings state that one monitor is on top of the other & thus will fix the problem? I guess I don't totally understand what you mean by one on top of the other?

I am finding that on my laptop screen that compiz works beautifully. Once I plug in my external monitor compiz no longer works. I have not tried closing the lid on my laptop & seeing if compiz would now work on the external monitor as it is only using one monitor. It's worth a test I guess.

I use ubuntu 9.04 now.

Thanks,
~roystreet