"Switchable Graphics" Support in Red Hat Enterprise Linux

Modern laptops frequently come equipped with multiple graphics adapters -- the lower power integrated Intel Graphics, and a higher performance discrete GPU from AMD or NVIDIA.

Additionally there are several different ways OEMs implement this configuration. On high end systems it is common to include a hardware mux on the system board and have a BIOS option to switch between "Discrete Graphics" and "Switchable Graphics". On lower end systems in order to keep prices low OEMs will not include a hardware mux and instead rely on only "Switchable Graphics".

"Discrete Graphics"

In this mode the integrated graphics is disabled completely. Only the discrete GPU drives the display. The system will not load the Intel video module.

"Switchable Graphics"

The Intel graphics drives the video. The discrete graphics can be used for computation or it can be used with "DRI_PRIME=1" to render 3D graphics and then copy the VRAM to the Intel GPU for display. (e.g. DRI_PRIME=1 glxgears will execute the OpenGL application glxgears using the dGPU for rendering, but copy the video memory to the Intel iGPU for display)

(As mentioned in the Hardware Certification Policy Guide , Red Hat does not require 3D graphics or GPGPU functionality or performance to be tested for system certification.)

In "Switchable Graphics" mode if you wish to disable the discrete GPU altogether (to save more power, for compatibility, or other reasons) you can pass kernel or module parameter to do so.

e.g. the kernel command line option "module_blacklist=amdgpu" would prevent the amdgpu driver from being loaded. Some modules have the ability to load, but be disabled e.g. Passing "nouveau.modeset=0" on the kernel command line or adding "options nouveau modeset=0" to /etc/modprobe.d/nouveau.conf