The Linux Kernel: A Case Study for CVS

Robert Kiesling

Figure 1

The Linux kernel provided much of the inspiration for the Open Source model of software development, and the kernel, which is the core of all commercial and non-commercial Linux distributions, remains the most dramatic example of a successful Open Source development project. The source code of kernel version 2.2 comprises more than 1.5 million lines of C and assembly language code, and occupies more than 54 MB of disk space when uncompressed. The Linux developers consist of Linus Torvalds, who has the final say over what code becomes part of the "production" kernels, about a dozen core developers who maintain sections of the source tree, and anyone else who wishes to contribute. As tools often emerge to meet various needs, a new protocol that uses the Concurrent Version System (CVS) has begun to appear on the Internet to meet the needs of programmers who work on Open Source code projects. That protocol is anonymous CVS.

Managing the Source Code

The spiralling number of contributions by programmers has ensured that bugs get fixed rapidly and that new ideas and code get distributed, accepted, or rejected in hours and days instead of weeks and months. This makes kernel development a real-world case study for the Open Source model of software development.

Originally, kernel developers set up an anonymous CVS server at vger.rutgers.edu to provide access to all or part of the kernel source to anyone wishing to modify the source code. The server is not in operation, but the system is host to the Majordomo mailing list server, which handles the developers' messages.

To distribute the complete kernel source to Linux users, there is a system of anonymous ftp sites worldwide that archives the complete sources, as well as patches of intermediate versions. When a file is added to the main site at ftp.k