> >
> > There are plenty of address lines from the chip (I forget exactly how many, 40?).
> > To access it from software you need to change the memory mappings since
> > you can only see 4G at a time.
>
> It's called PAE (Physical Address Extensions), allowing for 36-bit
> physical addresses. It's all hidden in the page table, which has
> entried widened to 64 bits, so that the 36 bits of physical address
> fit in there. Virtual address space is still 32 bits wide.

so there is some bit in CPU control register turning on use of double-wide
pagetables?