Xv6


xv6 is a modern reimplementation of Sixth Edition Unix in ANSI C for multiprocessor x86 and RISC-V systems. It was created for educational purposes in MIT's Operating System Engineering course in 2006.
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Purpose

MIT's Operating System Engineering course formerly used the original V6 source code. xv6 was created as a modern replacement, because PDP-11 machines are not widely available and the original operating system was written in archaic pre-ANSI C. Unlike Linux or BSD, xv6 is simple enough to cover in a semester, yet still contains the important concepts and organization of Unix.

Self-documentation

One feature of the Makefile for xv6 is the option to produce a PDF of the entire source code listing in a readable format. The entire printout is only 99 pages, including cross references. This is reminiscent of the original V6 source code, which was published in a similar form in ''Lions' Commentary on UNIX 6th Edition, with Source Code.''

xv6 book

xv6 source code is paired with a commentary book that explains key concepts of operating systems using xv6 as an example. It also mentions which parts of the OS can be improved further, and how. For example, version 5 of RISC-V xv6 book, among others, introduces the following topics:

Compared to other teaching operating systems

xv6 differs from other operating systems being very small to be covered in a semester, by kernel type, and by having more of modern techniques.

Educational use

xv6 has been used in operating systems courses at many universities, including: