1. CS533 Concepts of Operating Systems Class 12
Micro-kernels (or Extensibility via Hardware-Based Protection)

2. CS533 - Concepts of Operating Systems
Questions
What is the motivation for modular operating systems?
Does this imply modules with hardware protection?
.. and what do I mean by hardware protection for modules?
What is the motivation for using hardware protection at module boundaries?
Does this imply message passing across module boundaries?
… what other alternatives do you have?
What is the motivation for using message-passing for inter-module communication?
CS533 - Concepts of Operating Systems

3. CS533 - Concepts of Operating Systems
Questions
What is the structure of a pure emulation library-based OS above a micro-kernel?
How are system calls handled?
What is the structure of a single-server based OS above a micro-kernel?
What is the structure of a multi-server based OS above a micro-kernel?
CS533 - Concepts of Operating Systems

4. CS533 - Concepts of Operating Systems
Questions
What are the main sources of overhead in micro-kernel based OSs compared to monolithic OSs?
How does L4 address these overheads?
Do these optimizations completely solve the problem?
What is the difference between L4 IPC and a protected control transfer (PCT)?
Would you expect a lot of difference in performance following extreme optimization of both?
What minimal abstractions should a kernel provide?
CS533 - Concepts of Operating Systems

5. CS533 - Concepts of Operating Systems
Questions
What is extensibility and how does micro-kernel-based OS structure help?
What other approaches are there?
CS533 - Concepts of Operating Systems

6. CS533 - Concepts of Operating Systems
Reminder
Take a look at the Liedtke paper from SOSP’93
Presenters, start working your talk early!
Don’t leave it to the last minute! You can’t expect to do an adequate job if you do it the night before.
Send me a draft of your slides early enough that I have some time to work with you
CS533 - Concepts of Operating Systems