Virtual machines (VMs) recently regained attention as a solution to problems not only in high-performance computing, servers, and desktops, but in embedded systems as well. For example, network-enabled embedded systems use virtual machines to provide hardened subsystems for banking, encryption, and digital rights management.

Virtual machine systems and microkernels share a common set of goals such as reliability, security, isolation and, flexibility, so that integrating VMs and microkernels is a promising approach. In fact, modern microkernels already provide the abstractions and mechanisms necessary to cater for virtual machines.

In this paper we show how virtual machine concepts map to the concepts of a microkernel, the L4 microkernel. We identify shortcomings of the current kernel API with respect to virtual machine support and propose a minimalistic set of extensions.