CS533 Concepts of Operating Systems

Class 16

Exokernel

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Questions

What is the difference between virtualization and secure multiplexing?

o What do Exokernel and Disco have in common?o What do Exokernel and Xen have in common?o Do Xen or Disco do secure multiplexing?o Does Exokernel create virtual machines?

Is Exokernel a micro-kernel?o What abstractions does it support?

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Questions

What is a "process" in the Exokernel? Does the Exokernel "paravirtualize" privileged

instructions? How are address translations and physical

memory managed in the Exokernel? How does Exokernel’s visible revocation relate to

scheduler activations?o How does it differ from Xen and Disco in this respect?

How does PCT relate to LRPC?o What is the difference between synchronous and

asynchronous PCT?

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Questions

How does Exokernel use hardware support to improve performance?

How are "software caches" used to improve performance?

How is "downloaded code" used to improve performance?

o How does this relate to Sandboxing?o How does this relate to SPIN?o How does this relate to Specialization?

What do hardware support, software caches and downloaded code have in common?

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Reminder

Send me a draft of your slides early