Same here with an i915. Unity was completely unusable after upgrading 12.04 -> 14.04, the internal display which I never used was breaking 3d acceleration. I had the problem with both the Ubuntu default package and the Intel drivers from 01.org. The computer is a low-end PC used as a server, so unplugging the monitor on each reboot is quite inconvenient and using two displays could be useful. In my opinion, this is quite a serious bug.
The "video=LVDS-1:d" workaround fixed the issue, in order to have it permanently, I added the option in /etc/default/grub to the GRUB_CMDLINE_LINUX_DEFAULT variable and ran update-grub. -- You received this bug notification because you are a member of Desktop Packages, which is subscribed to unity-greeter in Ubuntu. https://bugs.launchpad.net/bugs/1292467 Title: Dual screen greeter can break 3D acceleration Status in Release Notes for Ubuntu: Fix Released Status in “unity-greeter” package in Ubuntu: Triaged Bug description: When booting with two screens (internal LVDS and VGA), lightdm comes up in a mode where it displays separate screen content on both displays (so no mirror mode). These screens seem to be arranged side- by-side regardless of the fact that (like in my case) the combined width can be greater than 2048 and that is not supported with 3D acceleration at least on that older i945GME graphics. This results in very poor graphics performance and compiz using a lot of cpu cycles (which are rather limited on this Atom N270 anyways). Even worse, this does not get resolved when changing the setup in system settings to either only having one screen active or arranging them on top of each other). WORKAROUND: * Plug in external monitor after login (1) * Boot with "video=LVDS-1:d" (2) (1) Booting with only the internal screen and then plugging in the external one after login seems to handle this better (although I probably need to remove any previous config to get into a kind of vanilla state again). Also it seems to be ok when I had the dual monitor boot and lightdm coming up side-by-side, when unplugging the external monitor before logging in. (2) This will completely disable the internal screen for that boot. It cannot be enabled through the settings dialogue. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu-release-notes/+bug/1292467/+subscriptions -- Mailing list: https://launchpad.net/~desktop-packages Post to : [email protected] Unsubscribe : https://launchpad.net/~desktop-packages More help : https://help.launchpad.net/ListHelp
