What This Document Is
This document is a mini lab exercise designed for students enrolled in an Operating Systems Principles course (COMSCI 111) at the University of California, Los Angeles. It focuses on the fundamental interaction between software and hardware within an operating system environment, specifically exploring the implementation of interrupt handling. The lab utilizes a provided Ubuntu image (CS111-35-ubuntu) as its operating environment. It’s a practical exercise intended to solidify theoretical understanding through hands-on implementation.
Why This Document Matters
This mini lab is crucial for students aiming to grasp the core mechanisms of how user-level applications request services from the operating system kernel. It’s particularly beneficial for those who are learning about system calls, interrupt handling, and the transition between user and kernel modes. Students preparing for more advanced operating systems concepts, or those interested in systems programming, will find this lab a valuable stepping stone. It’s best utilized *during* the practical component of the course, alongside lectures on system calls and interrupts.
Topics Covered
* System Calls and Interrupts: The relationship and implementation details.
* Interrupt Handling: Understanding the role of the Programmable Interrupt Controller (PIC).
* User Mode vs. Kernel Mode: The transition and privileges associated with each.
* Software Interrupt Generation: Utilizing assembly language instructions for system requests.
* Process Creation: Exploring the concepts behind forking a new process.
* Stack Management: Understanding how process stacks are handled during forking.
* Assembly Language Integration: Using inline assembly within C code.
What This Document Provides
* Definitions of key system calls, including examples of how they are assigned numerical codes.
* A detailed outline of the structure of an interrupt handler function.
* Code snippets illustrating the use of assembly language for generating interrupts.
* A framework for implementing a `fork` system call.
* Guidance on managing process states and utilizing process arrays within the kernel.
* An explanation of how to locate and utilize available process slots for new process creation.
