Although this interface is intended to be useful in a wide range of
situations, it is currently used specifically by several Xen
subsystems, for example: to ensure that pagetables have been allocated
for a virtual address range, and to construct batched special
pagetable update requests to map I/O memory (in ioremap()).
This interface is great, and highly useful. But it doesn't seem to be able to work on native hardware, as it doesn't support large pages.