The following schedule is tentative and subject to change without notice.

Credit: Most of slides for this lecture are based on materials provided by the authors of the textbook and references.

For project submission and automatic grading, we are running a dedicated server at https://sys.snu.ac.kr. If you want to access the sys server outside of the SNU campus, please send a request via a Google Form whose URL is posted in the eTL.

Project #4: Holy COW!

COW (Copy-on-Write) is a virtual memory technique that lets multiple address spaces share the same physical memory until one of them tries to modify it. Instead of eagerly copying all user memory during fork(), the kernel marks shared pages read-only and creates a private copy only on a write fault. In this project, you will implement COW in xv6 in two stages: first for user pages, and then for leaf page-table pages as well. The goal of this project is to understand the xv6 virtual memory subsystem.

• Project specification available here
• Due date: 11:59 PM, May 31 (Sunday).

Project #3: CPU Hotplugging

CPU hotplugging is the ability of an operating system to dynamically bring a CPU core online or take it offline while the system is running. This mechanism is useful for power management, fault isolation, and adapting the number of active CPUs to the current workload. In this project, you will extend xv6 so that individual harts can be turned on and off at runtime in a controlled and safe manner. The goal is to understand the low-level interaction between the scheduler, interrupts, and multiprocessor hardware while implementing a practical OS mechanism for dynamic CPU management.

• Project specification available here
• Due date: 11:59 PM, May 3 (Sunday).

Project #2: System Calls

System calls are interfaces that allow user applications to request various services from the operating system kernel. This project aims to explore and understand how system calls are implemented in the xv6 operating system.

• Project specification available here
• Due date: 11:59 PM, April 5 (Sunday).

Project #1: Hello world, xv6

xv6 is an instructional operating system developed by MIT based on Ken Thompson and Dennis Ritchie’s Unix version 6 (v6). In this course, we will use xv6-riscv, a version recently ported to a multi-core RISC-V machine. The goal of this project is to set up your development environment on Linux or macOS and familiarize yourself with our project submission server.

• Project specification available here
• Due date: 11:59 PM, March 17 (Tuesday).

xv6 Resources

• xv6 source code: https://github.com/snu-csl/xv6-riscv-snu (our customized version)
• xv6: a simple, Unix-like teaching operating system (Rev. 5)
• The RISC-V Reader: An Open Architecture Atlas
• RISC-V Instruction Set Manual Volume I: Unprivileged Architecture, Version 20250508
• RISC-V Instruction Set Manual Volume II: Privileged Architecture, Version 20250508