Comment # 50 on bug 108521 from Dimitar Atanasov

There is two windows on this system. Small one below 4GB which is 2.5GB and
bigger one over 4GB which is 64GB. Address space for thunderbolt is only 200
MB. As I know AMDGPU needs 250 MB in low 4GB and rest is in big space.
Interesting enough, is that I have XPS 9570 which is 8750h and there is BIOS
option how to assign MMIO space, there is no such option here.