Changes

As outlined in the above diagram, the guest operating systems operate in virtual machines within the virtualization application which , in turn , runs on top of the host operating system in the same way as any other application. Clearly, the multiple layers of abstraction between the guest operating systems and the underlying host hardware are not conducive to high levels of virtual machine performance. This technique does, however, have the advantages advantage that no changes are necessary to either host or guest operating systems and no special CPU hardware virtualization support is required.