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CS533 Concepts of Operating Systems Class 9. Virtualization and Exo-Kernels. Virtualization and Fault Isolation. Do VMMs support fault isolation? If so, how? Is the fault isolation problem they solve the same as the one tackled by micro-kernel architectures?. Multi-tasking.
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CS533 Concepts of Operating SystemsClass 9 Virtualization and Exo-Kernels
Virtualization and Fault Isolation • Do VMMs support fault isolation? • If so, how? • Is the fault isolation problem they solve the same as the one tackled by micro-kernel architectures? CS533 - Concepts of Operating Systems
Multi-tasking • At what granularity do VM monitors support multitasking? • How does it differ from conventional multitasking? • How do virtualized CPUs differ from threads/processes? CS533 - Concepts of Operating Systems
Virtualization and Hardware • Why is it difficult to virtualize the x86 CPU? • What hardware support would be useful for virtualization? • Does virtualization hide any characteristics of the real hardware? CS533 - Concepts of Operating Systems
True vs Para Virtualization • Why would you want true virtualization? • Why would you want para-virtualization? • Why is it harder to virtualize CPUs with hardware specified page tables than software managed TLBs? • Xen is not transparent to a guest OS. In what ways can the OS distinguish execution on Xen from execution on bare hardware? CS533 - Concepts of Operating Systems
VMMs vs Micro-Kernels • Is Disco a micro-kernel? • Is Xen a micro-kernel? • Do micro-kernels do virtualization? CS533 - Concepts of Operating Systems
Exo-kernel • What is the difference between virtualization and secure multiplexing? • Do Xen or Disco do secure multiplexing? • Does Exokernel create virtual machines? • How do the approaches differ? • Is Exo-kernel a micro-kernel? • What abstractions does it support? CS533 - Concepts of Operating Systems
Exo-kernel • Does Exokernel support the process abstraction? • Does the Exokernel "paravirtualize" privileged instructions? • How does Exokernel’s visible revocation relate to scheduler activations? • How does it differ from Xen and Disco in this respect? • How does PCT relate to LRPC? • What is the difference between synchronous and asynchronous PCT? CS533 - Concepts of Operating Systems
Exo-kernel • How does Exo-kernel use hardware support to improve performance? • How are "software caches" used to improve performance? • How is "downloaded code" used to improve performance? • How does this relate to Sandboxing? • How does this relate to SPIN? CS533 - Concepts of Operating Systems