[arch-general] Xorg configuration on a dual graphic card system

[KangJing Huang]

Hi there,

I'm trying to setup my xorg configuration on my dual graphic card desktop
system. The system has two cards, one iGPU Intel HD Graphics 530, another
is a dGPU Nvidia GTX 1070 on PCIe. I plugged one monitor to the iGPU port
and another to the dGPU port and let the motherboard boot from iGPU.

Right now, the fbcon works well on the iGPU, and I installed Nvidia
non-free driver, and would like to run X on dGPU. I used the nvidia-xconfig
to generate a Xorg configuration, and after starting Xorg, I got display
from the monitor connected to dGPU, but it seems that the 3D rendering on
that screen is software-based, and `glxinfo | grep vendor` showed that
libglvnd on that X environment is selecting mesa as the GL library to use.
With mesa being called on a dGPU connected screen, apparently it could not
find a correct device to do dri, and fell back to software rendering.

Does anyone know the proper way of config X so that libglvnd could know
which GL library to use correctly in this case?

Thanks,
K.H.