CS 4973:  For the optional extra credit, youi should choose just
          one of Exercise 2, 3, or 4 below.  - Prof. Cooperman
===

From Prof. Cheng Tan,
I am writing about my course, CS6640: Operating Systems Implementation (OSI).

Concepts such as exceptions, system calls, and privilege levels are central, yet tightly coupled; without hands-on implementation, they tend to remain abstract. To address this, I designed a sequence of exercises that guide students through these mechanisms in a concrete setting.

The lab materials are available here:
https://naizhengtan.github.io/26spring/labtutorials/lab4/ 

Upstream repository:
https://github.com/NEU-CS6640-labs/egos-upstream 

Please checkout to lab4 for the following exercises:
$ git checkout lab4

The exercises could be organized as follows:

Exercise 2: implementing system calls
https://naizhengtan.github.io/26spring/labtutorials/lab4/#implementing-synchronous-syscalls 
Exercise 3: handling exceptions
https://naizhengtan.github.io/26spring/labtutorials/lab4/#handling-exceptions 
Exercise 4: implementing privilege levels (running user applications in U-mode)
https://naizhengtan.github.io/26spring/labtutorials/lab4/#run-user-apps-in-u-mode