Information Technology Reference
In-Depth Information
Chapter 8
Address Translation
Language forces us to perceive the world as man presents it to us.
{ Julia
Penelope
Words, like Nature, half reveal
And half conceal the Soul within. { Alfred, Lord Tennyson
Address translation has many benefits (it is not just about virtual memory).
Protection. Keep each process isolated
Sharing. Allow memory to be shared between processes (code segments,
but also shared regions of memory, copy on write). Memory sharing is
important not only because we might run out of memory, but more im-
portantly to make caches more ecient.
Virtualization. Provide OS services transparently to applications: the
illusion of infinite memory, but also virtual machines, process checkpoint-
ing and migration, information flow control, and other applications.
This chapter has three main ideas:
Address translation concept
How to make address translation flexible
How to make address translation ecient
8.1
Address translation concept
linking and base and bounds
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