Embedded hypervisor

An embedded hypervisor is a hypervisor that supports the requirements of embedded systems.

The requirements for an embedded hypervisor are distinct from hypervisors targeting server and desktop applications. An embedded hypervisor is designed into the embedded device from the outset, rather than loaded subsequent to device deployment. While desktop and enterprise environments use hypervisors to consolidate hardware and isolate computing environments from one another, in an embedded system, the various components typically function collectively to provide the device's functionality. Mobile virtualization overlaps with embedded system virtualization, and shares some use cases.

Typical attributes of embedded virtualization include efficiency, security, communication, isolation and real-time capabilities.

Software virtualization has been a major topic in the enterprise space since the late 1960s, but only since the early 2000s has its use appeared in embedded systems. The use of virtualization and its implementation in the form of a hypervisor in embedded systems are very different from enterprise applications. An effective implementation of an embedded hypervisor must deal with a number of issues specific to such applications. These issues include the highly integrated nature of embedded systems, the requirement for isolated functional blocks within the system to communicate rapidly, the need for real-time/deterministic performance, the resource-constrained target environment and the wide range of security and reliability requirements.

A hypervisor provides one or more software virtualization environments in which other software, including operating systems, can run with the appearance of full access to the underlying system hardware, where in fact such access is under the complete control of the hypervisor. These virtual environments are called virtual machines (VM)s, and a hypervisor will typically support multiple VMs managed simultaneously.

Hypervisors are generally classed as either type 1 or type 2, depending on whether the hypervisor runs exclusively in supervisor mode or privileged mode (type 1) or is itself hosted by an operating system as a regular application (type 2).

Type 1 hypervisors manage key system resources required to maintain control over the virtual machines, and facilitate a minimal trusted computing base (TCB). Type 2 hypervisors typically run as an application within a more general purpose operating system, relying on services of the OS to manage system resources. Nowadays kernel extensions are often loaded to take advantage of hardware with virtualization support.

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