Editing Hypervisor (section)

==Embedded systems==
[[Embedded hypervisor]]s, targeting [[embedded system]]s and certain [[real-time operating system]] (RTOS) environments, are designed with different requirements when compared to desktop and enterprise systems, including robustness, security and [[real-time computing|real-time]] capabilities. The resource-constrained nature of multiple embedded systems, especially battery-powered mobile systems, imposes a further requirement for small memory-size and low overhead. Finally, in contrast to the ubiquity of the x86 architecture in the PC world, the embedded world uses a wider variety of architectures and less standardized environments. Support for virtualization requires [[memory protection]] (in the form of a [[memory management unit]] or at least a memory protection unit) and a distinction between [[user mode]] and [[privileged mode]], which rules out most [[microcontroller]]s. This still leaves [[x86]], [[MIPS architecture|MIPS]], [[ARM architecture|ARM]] and [[PowerPC]] as widely deployed architectures on medium- to high-end embedded systems.<ref>
{{cite book
| last = Strobl
| first = Marius
| title = Virtualization for Reliable Embedded Systems
| url = http://www.grin.com/e-book/233001/
| year = 2013
| publisher = GRIN Publishing GmbH
| location = Munich
| isbn = 978-3-656-49071-5
| pages = 5–6
| access-date = 2015-03-07}}
</ref>

As manufacturers of embedded systems usually have the source code to their operating systems, they have less need for full virtualization in this space. Instead, the performance advantages of [[paravirtualization]] make this usually the virtualization technology of choice. Nevertheless, ARM and MIPS have recently added full virtualization support as an IP option and has included it in their latest high-end processors and architecture versions, such as [[ARM Cortex-A15 MPCore]] and ARMv8 EL2.

Other differences between virtualization in server/desktop and embedded environments include requirements for efficient sharing of resources across virtual machines, high-bandwidth, low-latency inter-VM communication, a global view of scheduling and power management, and fine-grained control of information flows.<ref name=Hei08>{{cite conference | author=Gernot Heiser | author-link=Gernot Heiser | title=The role of virtualization in embedded systems | book-title=Proc. 1st Workshop on Isolation and Integration in Embedded Systems (IIES'08) | pages=11–16 | date=April 2008 | url=http://ertos.nicta.com.au/publications/papers/Heiser_08.abstract | access-date=April 8, 2009 | archive-url=https://web.archive.org/web/20120321212358/https://ertos.nicta.com.au/publications/papers/Heiser_08.abstract | archive-date=March 21, 2012 | url-status=dead }}</ref>