http://www.spinellis.gr/pubs/conf/2008-ICSE-4kernel/html/Spi08b.html This is an HTML rendering of a working paper draft that led to a publication. The publication should always be cited in preference to this draft using the following reference: Diomidis Spinellis. A tale of four kernels. In Wilhelm Schäfer, Matthew B. Dwyer, and Volker Gruhn, editors, ICSE '08: Proceedings of the 30th Internationa