Now I tried extracting the firmware myself, but the dump doesn't contain the
register addresses that the firmware page states it should. But I think I
followed all the steps correctly (start mmiotrace, cat into dump file, modprobe
nvidia, Xorg, DISPLAY=":0" xterm, kill everything and stop mmiotrace), so this
is rather puzzling. The dump itself is 23 MB in size, and through that xterm I
also checked glxinfo to confirm that the NVIDIA drivers were running (they
were, including direct rendering).