'X64' mode doesn't seem to be running in Long Mode

[vsrinivas]

When CPUID claims 64-bit support, memtest86+ prints that it is going to Long mode and changes the '32b' printout to 'X64'.

rowhammer/src/main.c:test_start() seems to try to go to long mode by just setting the 'Long Mode Enable' bit of EFER. To go to long mode, paging must be enabled; long mode state will be reflected in the EFER.LMA bit. I don't see CR0[PG] or EFER[LMA] set while running the rowhammer test, however...

map_page() should call paging_on(), so perhaps I'm missing something here...