Glossary · Automation software engineering and architecture
Hypervisor
Also known as: Virtual machine monitor (VMM)
German: Hypervisor
In computing, a hypervisor is software, firmware or hardware that creates and runs virtual machines by sharing and isolating the physical resources of a host, such as processor, memory and devices, among several guest operating systems. Real-time hypervisors allow a real-time control system and a general-purpose operating system to run on the same industrial PC.
- Software engineering
In one sentence
A hypervisor creates and runs virtual machines by sharing and isolating a host's hardware among several guest operating systems.
Example
An industrial PC runs a real-time hypervisor that hosts the soft PLC on two dedicated cores and a Windows HMI on the remaining cores.
How it applies
- Engineering: Virtualization consolidates functions that used to need separate hardware, such as control, HMI and data services. For control tasks, the hypervisor must guarantee timing, for example through dedicated cores and direct device access.
- Security: A hypervisor separates workloads with different trust levels, which can support network and Security zone concepts. The separation depends on correct configuration and on keeping the hypervisor itself patched.
- Documentation: Document the virtual machine layout, resource assignments, device pass-through, network configuration and update procedures. Service staff need to know which functions share hardware and what happens to each when the host restarts.
Hypervisor vs. container runtime
A hypervisor virtualizes hardware, and each virtual machine runs its own operating system kernel. A Container runtime isolates applications that share one kernel. Virtual machines offer stronger isolation and allow different operating systems; containers are lighter and faster to start.
Type 1 hypervisors run directly on hardware; type 2 hypervisors run on a host operating system.