If you have the same problem as the title of this post, Ubuntu unknown monitor or Monitor not detected in Ubuntu 11.10, hope this tweaks help you. Previously, I upgraded my 11.04 Ubuntu to 11.10. No problems appear except can be solved as I post in GNU/Linux label in this blog. Yesterday, I got the problem after running some tweaks and computer janitor (maybe that caused the problem). My screen or display resolution is changed to lower resolution, i.e 1024×768.
Then, I try to change manually trough display configuration. What I get is my monitor not detected by Ubuntu. It said unknown monitor. I run xrandr in terminal, and got the following output
$ xrandrxrandr: Failed to get size of gamma for output default…
After a day find solution, below is work for me. Find the similar code in your /etc/boot/grub.cfg. For example, type in terminal: sudo gedit /etc/boot/grub.cfg
linux /boot/vmlinuz-2.6.32-26-generic root=UUID=c3732ca6-61fa-48c6-b115-6ed668cdeedd ro …
Add the “i915.modeset=1 gfxpayload=1366×768”. So, it becomes
linux /boot/vmlinuz-2.6.32-26-generic root=UUID=c3732ca6-61fa-48c6-b115-6ed668cdeedd ro i915.modeset=1 gfxpayload=1366×768 quiet splash
And reboot. It works for me, and I hope also for you. Don’t forget to change screen resolution according to your display size. The figure below show the difference when I got the problem and after solving it.
|My laptop display when got unknown monitor problem.
The screen resolution is low i.e 1024×768
|My screen after solving the problem with 915 driver. I looks clear|
Note that the problem above is caused by VGA driver which disappear unfortunately. So, I add 915 driver on boot based on reference from internet source.