1. CS533 Concepts of Operating Systems Class 6
Micro-kernels
Extensibility via Hardware and Software Based Protection

2. CS533 - Concepts of Operating Systems
Questions
What are the main sources of overhead in micro-kernel based OSs compared to monolithic OSs?
How do L3 and L4 address these overheads?
Do these optimizations completely solve the problem?
What minimal abstractions should a kernel provide?
Should they be hardware independent (portable)?
CS533 - Concepts of Operating Systems

3. 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

4. CS533 - Concepts of Operating Systems
Questions
Why does Sandboxing slow down normal execution?
Why does it speed up inter-module communication compared to Mach?
What is a jump-table and why is it needed?
On balance is Sandboxing a win or loss?
compared to Mach?
compared to L3/L4?
CS533 - Concepts of Operating Systems

5. CS533 - Concepts of Operating Systems
Questions
What exactly is a protection domain in SPIN?
How are module boundaries implemented in SPIN?
What implications does this have for kernel extensions?
How does extension code invoke SPIN’s core services, or code in other modules?
How do SPIN’s core services compare to those of micro-kernels?
CS533 - Concepts of Operating Systems

6. CS533 - Concepts of Operating Systems
Questions
Does the SPIN approach slow down normal execution?
How does it speed up inter-module communication?
On balance is it a win or loss?
compared to Mach?
compared to L3/L4?
compared to Sandboxing?
CS533 - Concepts of Operating Systems