It really seems to be related to drm for i915 driver when switching to nvidia via prime-select and login via lightdm. The Xorg.0.log shows an error like:
[ 25.199] (EE) intel(G1): [drm] failed to set drm interface version: Permission denied [13]. [ 25.199] (II) intel(G1): [drm] Contents of '/sys/kernel/debug/dri/0/clients': [ 25.199] (II) intel(G1): [drm] command pid dev master a uid magic [ 25.199] (II) intel(G1): [drm] Xorg 2173 0 y y 0 0 [ 25.199] (II) intel(G1): [drm] Xorg 2173 0 n y 0 0 [ 25.199] (EE) intel(G1): Failed to claim DRM device. I found a thread with an alternative workaround: http://vxlabs.com/2015/02/05/solving-the-ubuntu-14-04-nvidia-346-nvidia-prime-black-screen-issue/ by switching the intel driver to modesetting in xorg.conf and preventing the gpu-manager from reverting. But I'm not really interested in doing a manual hack every time I want to switch. I hope this will be fixed soon, at the latest when switching to "wily". -- You received this bug notification because you are a member of Ubuntu-X, which is subscribed to xserver-xorg-video-intel in Ubuntu. https://bugs.launchpad.net/bugs/1449560 Title: Cannot login with Nvidia Optimus hardware installed(Ubuntu 15.04) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xserver-xorg-video-intel/+bug/1449560/+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
