Comment 2 for bug 1769857

nastys (alisfquarto) wrote :

nvidia-drm.modeset=1 is used for PRIME Sync. In a gist, it copies the framebuffer from the dGPU to the iGPU without tearing. Without this, VSync is not effective no matter what.

I have switched back to gdm3. In Xorg, OpenGL works as expected, with the NVIDIA GPU (according to glxinfo), but Vulkan still doesn't work. In Wayland, OpenGL is rendered by the Intel GPU and when I try to run vulkan-smokeinfo I get:

Xlib: extension "NV-GLX" missing on display ":0".
terminate called after throwing an instance of 'std::runtime_error'
  what(): VkResult -3 returned

I remember Ubuntu 17.10 wouldn't let me log in at all if nvidia-drm.modeset=1 was enabled, but lightdm worked without issues (and it still does). Also SSDM is not affected either. Somehow gdm3 doesn't like this option...