Ar Maw, 2006-08-22 am 10:36 -0700, ysgrifennodd Zachary Amsden:

Write protection is great as a debug option to find accidental memory 
corruptions.  It is useless as a technique to prevent subversion.  Um 
hello, you're already at CPL-0.  Just rewrite the page tables already.

That depends upon how clever you are.  However if you want to load a
hypervisor under a running kernel and from it then you need an updatable
paravirt_ops.

Alan