Review: The Virtual Address Space
A typical process VAS space includes:
- user regions in the lower half
V->P mappings specific to each process
accessible to user or kernel code
- kernel regions in upper half
shared by all processes
accessible only to kernel code
- Nachos: process virtual address space includes only user portions.
mappings change on each process switch
A VAS for a private address space system (e.g., Unix) executing on a typical 32-bit architecture.