changes the specified pages to have protection
Not all implementations will guarantee protection on a page basis;
the granularity of protection changes may be as large as an entire region.
A region is the virtual address space defined by the start
and end addresses of a
Currently these protection bits are known,
which can be combined, OR'd together:
No permissions at all.
The pages can be read.
The pages can be written.
The pages can be executed.