The kernel from kernel-ppa/mainline (linux-image-3.7.0-7-generic) gives this error too, so it is not just my own kernel.
Jan 4 11:49:02 koli kernel: [ 1956.519825] nouveau E[ DRM] fail ttm_validate Jan 4 11:49:02 koli kernel: [ 1956.519831] nouveau E[ DRM] validate vram_list Jan 4 11:49:02 koli kernel: [ 1956.520511] nouveau E[ DRM] validate: -12 -- You received this bug notification because you are a member of Ubuntu-X, which is subscribed to xserver-xorg-video-nouveau in Ubuntu. https://bugs.launchpad.net/bugs/1072403 Title: Unity and GnomeShell hang or crash with nouveau kernel error messages "fail ttm_validate", "validate vram_list" and "validate: -12" To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xserver-xorg-video-nouveau/+bug/1072403/+subscriptions _______________________________________________ Mailing list: https://launchpad.net/~ubuntu-x-swat Post to : ubuntu-x-swat@lists.launchpad.net Unsubscribe : https://launchpad.net/~ubuntu-x-swat More help : https://help.launchpad.net/ListHelp