paravirtualization

Para-virtualization uses a special kernel, sometimes referred to as the xen kernel or kernel-xen to virtualized another environment while using the hosts libraries and devices. A para-virtualized installation will have complete access to all devices on the system. Para-virtualization is significantly faster than full virtualization can can be effectively used for load balancing, provisioning, security and consolidation advantages. As of Fedora 9 a special kernel will no longer be needed. Once this patch is accepted into the main Linux tree all linux kernels after that version will have para-virtualization enabled or available.

Para-virtualization is a technology initiated by the Open Source community and described as "Enlightenment" by Microsoft. A guest operating system is modified so that it executes the corresponding instructions of the hypervisor directly within a virtual machine so that no performance loss arises from the emulation of the complete hardware. The approach was originally developed at the University of Cambridge under the name Xen. Many Linux distributions have been adapted to Xen; XenSource, on the other hand, works on the para-virtualization of the Windows server of Microsoft. XenSource, Inc. was acquired by Citrix in August 2007. Xen Open Source project continues to be freely available at http://xen.org.

supporting multiple, possibly heterogeneous operating systems on the same hardware platform by modifying the operating systems to make them "virtualization aware." This reduces hypervisor overhead and increases performance by eliminating the need for full hardware virtualization but often prevents virtual to physical migrations. Compare to full virtualization.

An enhancement of virtualization technology, where guest OSes need to be adapted (recompiled) before being ready for installation inside virtual machines. It reduces virtualization overhead and improves performances. It's an alternative approach to Binary Translation (BT).

An approach to virtualisation which requires modifications to the operating system in order to run in a virtual machine. Xen uses paravirtualisation but preserves binary compatibility for user space applications.