Comment 7 for bug 429369

On a Karmic installation, you can add the option to GRUB_CMDLINE_LINUX_DEFAULT in /etc/default/grub (after quiet and splash). If your system is upgraded from Jaunty, it still uses an older Grub version and you need to edit /boot/grub/menu.lst.

Note that this is a workaround and not a fix, and that the UMS option is likely to be removed in the future (hopefully only when bugs like this have been fixed). It would be nice if you could add the ModeDebug option described above and attach the resulting Xorg.0.log here, since that will tell us how the monitor detection works with UMS. The problem seems to be that with KMS the driver thinks that no monitors are attached. It would be nice if you could also attach the output of dmesg for when you boot with KMS (i.e. without the i915.modeset=0 option).