I am running Arch Linux with the latest 4.6 stable kernel and xorg-server 1.18.3. My laptop has two graphics cards: an integrated intel GPU and a dedicated GeForce GTX 970M Nvidia GPU. If the xorg server is started while the Nvidia card is switched off with bbswitch, then the complete system freezes. There are no log messages available and a hard reset is required. However if I switch on the dedicated Nvidia card before starting the xorg server everything works well. I am also able to successfully switch off the dedicated card after starting the xorg server. Under Wayland this problem does not exists. I also tried to ignore the dedicated card with: Section "Device" Identifier "Nvidia" VendorName "NVIDIA Corporation" Option "Ignore" "true" EndSection Output of 'lspci | grep -E "VGA|3D"': 00:02.0 VGA compatible controller: Intel Corporation Skylake Integrated Graphics (rev 06) 01:00.0 3D controller: NVIDIA Corporation GM204M [GeForce GTX 970M] (rev a1) Hope we can get this fixed!
I noticed following warning message: xf86EnableIOPorts: failed to set IOPL for I/O (Operation not permitted) This warning is not displayed if the dedicated GPU is on and Xorg freezes the system...
After hours of debugging I made following experience: Xorg and Wayland both have problems when the dedicated GPU is switched off and no kernel module is loaded. However if the nouveau module with the proprietary firmware is loaded, then the problem seams to be fixed. The latest nouveau module handles powersaving and switches the GPU automatically off. This is a good workaround, but prevents from using the proprietary nvidia modules for bumblebee...
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