CMSC 421 Spring 2015

Final Study Guide

Real-Time Operating Systems:

What is the difference between soft and hard real-time systems?
What is the difference between interrupt and dispatch latency?
What are the advantages and disadvantages of the various schedulers that are designed for real-time operating systems?

Memory Systems

When would an operating system have swap memory, and when would it not?
What are some uses for memory maps?
Given the page table on slide 12 of lecture 13, what is the physical address given the virtual address 0xF?
Within a page table, what do the protection and valid bits mean?
What is the benefit of a hierarchical paging system?
What happens when a page fault occurs?
What are the advantages and disadvantages of the various page replacement algorithms?

Device Drivers

What is the difference between character, block, and network devices? Give an example of each.
How does a kernel know which device driver to use given a particular piece of hardware?
What is involved when loading a program? When loading a kernel?
What are the steps involved in handling a hardware interrupt?

Linux Kernel Modules

What is the difference between a driver's init, probe, remove, and exit functions?
What is the relationship between a function's return value and the errno variable?
What is the difference between user and interrupt context? Give an example of each.
How does a driver allocate memory?
How is the container_of() macro used when implementing linked lists?
What is the difference between a mutex and a spinlock? When would a driver use one or the other?

Mass Storage

What schedulers exist for a hard disk drives? What are the advantages and disadvantages of each?
What is the difference between sequential and random access? Between blocking and non-blocking I/O?
How do directories store files and the files' metadata?
How do filesystems allocate space for files?
What optimizations exist for various filesystems?
How do filesystems handle error conditions?
On a typical Linux system, what filesystems are available? Why are there multiple filesystems employed at the same time?

Kernel Security

In Linux, give an example of a coarse-grained and a fine-grained security model.
Name three ways how an access matrix could be implemented.
What is the difference between an access capability versus a Linux capability? How are they implemented differently?

Networking