Ubuntu Lucid - dual monitor flickers on Lenovo T60 ATI card

I had some issues with Ubuntu 10 Lucid and my Lenovo T60 (ATI rage card). When I plugged in my secondary monitor (DELL 19'' LCD) the display started flickering. Turns out there seems to be an specific issue with the ATI video card. I found a forum post that solves the problem by editing /boot/grub/menu.lst and adding radeon.modeset=0 to the startup parameters.

The first problem I encountered was that the article said you should edit menu.lst but the Ubuntu Lucid setup installs grub 2 which has no menu.lst file.

I found this other article that explains how to edit the startup settings. I recommend booting up and editing the startup settings on the grub menu before changing the config files. This way if the parameters fail, you don't end up crashing your boot.

So in a nutshell, menu.lst has been replaced by /boot/grub/grub.cfg, so my file (first section, looks something like this:

… some other sections code here

### BEGIN /etc/grub.d/10_linux ###

menuentry 'Ubuntu, with Linux 2.6.32-22-generic' --class ubuntu --class gnu-linux --class gnu --class os {

recordfail

insmod ext2

set root='(hd1,1)'

search --no-floppy --fs-uuid --set f5046c00-0fb3-4b57-9968-cac7b8fc3fa9

linux /boot/vmlinuz-2.6.32-22-generic root=UUID=f5046c00-0fb3-4b57-9968-cac7b8fc3fa9 ro radeon.modeset=0 quiet splash

initrd /boot/initrd.img-2.6.32-22-generic

Editing this file and rebooting does the trick, although I'm not sure what this parameter does, I'll look it up later to see if there are other interesting settings.