L4, a family of *(OS)es originally by
<A HREF="http://l4ka.org/team/liedtke.jpg"
  >Jochen Liedtke</A>
(R.I.P., was chair of the <A HREF="http://i30www.ira.uka.de/index.php"
  >System Architecture Group</A> at the University of Karlsruhe)
are _(microkernel)s to demonstrate how optimizing performance requires
_(OS) _(kernel)s to be completely hardware-dependent, and even _(CPU)-version
dependent in a same family of _(CPU)s.

<A HREF="http://l4ka.org/"
  >L4/Ka - The L4 microkernel family and friends</A>
at <A HREF="http://i30www.ira.uka.de/"
  >System Architecture Group</A>, University of Karlsruhe

<A HREF="http://os.inf.tu-dresden.de/L4/"
  >The L4 -Kernel Family</A>
at <A HREF="http://os.inf.tu-dresden.de/"
  >Operating Systems Group</A>, TU Dresden.
