Section 12.10
Review Questions
Protection in Virtual Memory systems
  1. Do virtual memory systems need extra protection mechanisms?
answer...
no
  1. How is a program's memory protected from other errant or malicious programs in a virtual memory system?
answer...
a program cannot create a physical address unless the physical address of the start of the frame is in its page table. If programs do not have the same page numbers in their page tables, they are safe.
  1. What happens if a job needs only as much memory as 25.5 frames would provide?
answer...
it would get 26 pages
  1. Can jobs share frames of memory? Why not?
answer...
yes they can and do, by simply including the frame numbers of the shared pages in both their page tables. They must be careful to use it correctly, though.