Alberto, this is probably not an upstream bug. the prime support is ubuntu specific.
I am not sure if this is fatal, but there is an error setting up prime offload, seems like the helper scripts are not getting called as root anymore. Kov 19 22:59:55 username-Lenovo-Z70-80 /usr/lib/gdm3/gdm-x-session[912]: /usr/bin/prime-supported: 35: /usr/bin/prime-supported: cannot create /var/log/prime-supported.log: Permission denied Kov 19 22:59:55 username-Lenovo-Z70-80 /usr/lib/gdm3/gdm-x-session[912]: warning: output not found; ignoring Kov 19 22:59:55 username-Lenovo-Z70-80 /usr/lib/gdm3/gdm-x-session[912]: warning: output not found; ignoring ** Changed in: gdm3 (Ubuntu) Status: Incomplete => Triaged ** Also affects: linux (Ubuntu Xenial) Importance: Critical Status: Invalid ** Also affects: gdm3 (Ubuntu Xenial) Importance: Critical Status: Triaged -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1559576 Title: Ubuntu Gnome boots to black screen when using proprietary Nvidia drivers on a laptop with Optimus Status in gdm: New Status in gdm3 package in Ubuntu: Triaged Status in linux package in Ubuntu: Invalid Status in gdm3 source package in Xenial: Triaged Status in linux source package in Xenial: Invalid Bug description: Using latest Ubuntu Gnome x64 daily build with all updates installed. Lenovo Z70-80 laptop with Nvidia 840M, BIOS updated to latest version, secure boot and other potentially problematic BIOS settings disabled. Can only see a black screen instead of a log-in screen after boot completes when proprietary Nvidia drivers are installed. Regular Ubuntu works absolutely fine on the same machine with the same driver version. Attempting to use older drivers on Ubuntu Gnome made no difference. Bug is affecting more than just me. We were talking about workarounds in ubuntuforums. User fthx claims that switching to lightdm fixes the issue http://ubuntuforums.org/showthread.php?t=2317628&p=13457703#post13457703 ProblemType: Bug DistroRelease: Ubuntu 16.04 Package: linux-image-4.4.0-14-generic 4.4.0-14.30 ProcVersionSignature: Ubuntu 4.4.0-14.30-generic 4.4.5 Uname: Linux 4.4.0-14-generic x86_64 NonfreeKernelModules: nvidia_uvm nvidia_modeset nvidia ApportVersion: 2.20-0ubuntu3 Architecture: amd64 Date: Sat Mar 19 23:19:21 2016 HibernationDevice: RESUME=UUID=4f8fb76c-f99d-4c54-8a67-eed0653d8eb6 InstallationDate: Installed on 2016-03-19 (0 days ago) InstallationMedia: Ubuntu-GNOME 16.04 LTS "Xenial Xerus" - Alpha amd64 (20160318) MachineType: LENOVO 80FG ProcFB: 0 inteldrmfb ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.4.0-14-generic.efi.signed root=UUID=572a19f6-7324-4269-ad36-7ffc9919f7a2 ro noprompt persistent quiet splash vt.handoff=7 RelatedPackageVersions: linux-restricted-modules-4.4.0-14-generic N/A linux-backports-modules-4.4.0-14-generic N/A linux-firmware 1.156 SourcePackage: linux UpgradeStatus: No upgrade log present (probably fresh install) dmi.bios.date: 09/22/2015 dmi.bios.vendor: LENOVO dmi.bios.version: ABCN96WW dmi.board.asset.tag: NO Asset Tag dmi.board.name: Lenovo Z70-80 dmi.board.vendor: LENOVO dmi.board.version: NO DPK dmi.chassis.asset.tag: NO Asset Tag dmi.chassis.type: 10 dmi.chassis.vendor: LENOVO dmi.chassis.version: Lenovo Z70-80 dmi.modalias: dmi:bvnLENOVO:bvrABCN96WW:bd09/22/2015:svnLENOVO:pn80FG:pvrLenovoZ70-80:rvnLENOVO:rnLenovoZ70-80:rvrNODPK:cvnLENOVO:ct10:cvrLenovoZ70-80: dmi.product.name: 80FG dmi.product.version: Lenovo Z70-80 dmi.sys.vendor: LENOVO To manage notifications about this bug go to: https://bugs.launchpad.net/gdm/+bug/1559576/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp