Comment # 9 on bug 105251 from dxxf@volny.cz

So one more update:
My boot issue went away after updating:
- kernel-firmware to 20180525 (as there were some amdgpu firmware updates in
20180518).
- libLLVM6 from 6.0.0rc1 to 6.0.0 (and I strongly suspect this was the cause as
I had VM pagefault issues before with libLLVM5 - but only in some OpenGL
applications, not at boot).