Comment 8 for bug 1963701

In a hybrid (usually muxless) laptop the BIOS will flag the Intel GPU is the boot GPU, which means gnome-shell/mutter will flag that one as "primary" and will do ALL shell rendering on it.

In a hybrid desktop/workstation the BIOS will *usually* disable the integrated GPU leaving only the discrete GPU. But not always, and sometimes it's configurable like in my NUC Extreme. If the BIOS has left both GPUs enabled and booted with only the discrete GPU attached to a monitor then it is likely gnome-shell/mutter will flag that one as "primary" and will do the shell rendering on that "primary" discrete GPU.

"Secondary" GPUs in mutter still do a little work but only so much as copying the work of the primary GPU to external connectors owned by the secondary GPU.

So that explains the difference between a typical hybrid laptop and hybrid desktops.

I think we'll end up with multiple nvidia-wayland bugs in this area and as soon as I have time I will be focussing on bug 1959888 first because upstream (Jonas) seems confident that it's not implemented for hybrid laptops and shouldn't work in Wayland sessions.