In general nvidia-drm.modeset=1 is required to have Nvidia PRIME enabled, which reduces (or even removes) tearing of moving images on Optimus setups.
KMS - kernel mode settings, allows kernel to control video card and in Optimus setups, among other features, this allows to synchronize graphics buffers by both graphics cards - so there are no artifacts/tearing/etc, because before displaying anything on monitor buffers are fully copied from one card to another. When modeset is disabled for Nvidia driver - buffers of both graphics cards cannot be synchronized properly so sometimes images that are displayed are only partially updated and this is visible as taring or other similar artifacts (part of the screen is filled with current frame and part of the screen is filled with previous frame). The problem is that for some reason when KMS is enabled for Nvidia driver - vulkan requires root privileges to be initialized properly. After initialization for the first time (as root), it can be used with normal user privileges. The bug is still there on Ubuntu 18.04 with newer drivers and kernel: nvidia-driver-418 linux-image-4.18.0-16-generic -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to nvidia-graphics-drivers-390 in Ubuntu. https://bugs.launchpad.net/bugs/1800465 Title: Vulkan error when using NVIDIA-Prime Status in NVIDIA Drivers Ubuntu: New Status in nvidia-graphics-drivers-390 package in Ubuntu: Confirmed Status in nvidia-prime package in Ubuntu: Confirmed Bug description: After installing Ubuntu 18.10 and the Nvidia driver + Vulkan-Utils, switching to NVIDIA and then running vulkaninfo or vulkan-cube works perfectly. But when you reboot and update, then switch to Intel, then back to Nvidia, all Vulkan programs give an "Assertion `!err' failed." Vulkaninfo: ======= Presentable Surfaces: ===================== GPU id : 0 (GeForce GTX 960M) Surface type : VK_KHR_xcb_surface vulkaninfo: /build/vulkan-tools-ZnxIl9/vulkan-tools-1.1.82.0+dfsg1/vulkaninfo/vulkaninfo.c:1253: AppDumpSurfaceFormats: Assertion `!err' failed. Annullato (core dump creato) Vulkancube: vulkan-cube: /build/vulkan-tools-ZnxIl9/vulkan-tools-1.1.82.0+dfsg1/cube/cube.c:3416: demo_init_vk_swapchain: Assertion `!err' failed. Annullato (core dump creato) I still have not found a workaround for that, the only way to get it working again is to reinstall everything. - Install Ubuntu 18.10 - Install proprietary 390 NVIDIA drivers - Switch NVIDIA-Prime to NVIDIA - Testing the vulkan capabilities works - Updating the system then switching to intel - Reboot - Switch to nvida - Now all Vulkan programs when using NVIDIA give that error To manage notifications about this bug go to: https://bugs.launchpad.net/nvidia-drivers-ubuntu/+bug/1800465/+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
