I've managed to install amdgpu-pro and that has brought me a b=
it closer to
narrowing this down. Just for reference, the software versions are amdgpu-p=
ro
17.10.401251-2 and related packages
(https=
://aur.archlinux.org/packages/?O=3D0&K=3Damdgpu), mesa-noglvnd 17.1=
.4,
xorg-server 1.18.4-1.

With amdgpu-pro I could narrow the freeze down to a specific option in the
game: nvidia hairworks. With that option disabled I do not get the freeze. =
As
soon as it is enabled and a game loaded the machine freezes.

I've used this to get a apitrace quickly and I have one with just 1.1 GB.
However, replaying it does not produce the freeze. Maybe the actual freeze
trigger didn't make it into the file. I'll provide you the file if you tell=
 me
how.
I do have a lot of warnings and errors on console when I replay that file (=
see
console_out).

Nvidia hairworks does not trigger the freeze with amdgpu, but it does so
immediately with amdgpu-pro. amdgpu triggers the freeze seemingly randomly,=
 at
least in Velen, not in White Orchard. amdgpu-pro does not trigger the freez=
e in
Velen (unless hairworks is enabled of course).

Since both amdgpu and amdgpu-pro use mesa and the non-mesa proprietary nvid=
ia
driver does not trigger this bug it is likely something in mesa. I hope the
above helps to track it down.