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Improving Virtualization on L4

Improving Virtualization on L4
Type:Diploma Thesis

Prof. Dr. Frank Bellosa, Joshua LeVasseur

Graduand:Thomas Blattmann


A variety of classes of hypervisors run virtual machines. One approach is to use specialized, thin kernels as a base for virtual machine construction. A second approach is to build virtual machines on the higher-level abstractions offered by platform-independent operating system APIs. Virtual machines have also been successfully set up on top of µ-kernels. A µ-kernel is a thin hypervisor with a minimally trusted computing base. Unlike pure hypervisors, however, it is not specialized to one specific purpose. Instead, common µ-kernels are designed to perform well as generic platforms upon which many and various systems can be built. This generality, on the downside, allows pure hypervisors to outperform µ-kernels in their virtualization specific application area.

This work investigates L4, a second generation µ-kernel, with respect to virtual machine construction. It identifies several L4 characteristics that complicate virtual machine construction and cause a performance overhead, respectively. Also, it proposes µ-kernel extensions that are well suited to the usage patterns of a virtual machine but still conform to L4's design philosophy. Finally, the thesis provides a reference implementation that demonstrates the new L4 interface extensions. It reveals that many challenges can be overcome.


  author = {Thomas Blattmann},
  title = {Improving Virtualization on L4},
  type = {Diploma Thesis},
  address = {System Architecture Group, University of Karlsruhe, Germany},
  month = feb # "~14",
  year = 2007,
  url = {http://i30www.ira.uka.de/teaching/theses/pasttheses/}