CPSC 313 Lecture 14: [12/2] Virtual Memory cont.
5 Jun 2016
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Document Summary
Divide virtual and physical addresses into xed-sized chunks called pages. Programs can all share from the same page. Processes that don"t have access to a physical page do not have any virtual address mapped to it. Data that hasn"t been accessed in a while may be removed from memory. Virtual memory: protects code and data from illegal accesses helps os manage memory. Address space: collection of valid addresses it is linear if the addresses are consecutive ints from 0 to 2^n-1. Both addresses are divided into pages of 2^n addresses higher order n-p bits used as index to a page table. Sup bit: if set, only kernel can access. Read bit: if set, process can read page. Write bit: if set, process can write to page.
