Are virtual-machine monitors microkernels done right?

Abstract

A paper by Hand et al. at the recent HotOS workshop re-examined microkernels and contrasted them to virtual-machine monitors (VMMs). It found that the two kinds of systems share architectural commonalities but also have a number of technical differences which the paper examined. It concluded that VMMs are a special case of microkernels, "microkernels done right". A closer examination of that paper shows that it contains a number of statements which are poorly justified or even refuted by the literature. While we believe that it is indeed timely to reexamine the merits and issues of microkernels, such an examination needs to be based on facts.