Introduce functions to control logging of memory regions.
We select regions based on its start address, a
guest_physical_addr (target_phys_addr_t, in qemu nomenclature).

The main user of this interface right now is VGA optimization
(a way of reducing the number of mmio exits).
Signed-off-by: NGlauber Costa <glommer@redhat.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>



git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5792 c046a42c-6fe2-441c-8c8c-71466251a162