Programmers do not need to worry about physical memory
locations at all
Pieces of data (and instructions) are identified by virtual addresses
At different points in time, the same piece of data
(identified by its virtual address) may reside at
different locations in RAM (identified by different physical
addresses) or may not be present in RAM at all
OS keeps track of (virtual) address spaces:
What (virtual address) is located where (physical address)
Supported by hardware, memory management unit (MMU)
Translation of virtual into physical addresses (see next
slide)
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5. Conclusions
5.1. Summary
Virtual memory provides abstraction over RAM and secondary storage
Paging as fundamental mechanism
Isolation of processes
Stable virtual addresses, translated at runtime
Page tables managed by OS
Address translation at runtime
Hardware support via MMU with TLB
Page table sizes pose challenges (to be revisited)
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