A hypervisor allows a single server to run multiple
virtual machines, each with their own operation system, independently from each other.
A virtual machine submits requests for resources to the hypervisor, and the hypervisor coordinates the access to the physical providers of these resources.
Level 1 and level 2 hypervisors
A level 1 hypervisor is loaded before any of the virtual machines and thus act as intermediary between the hardware and VMs.
A level 2 hypervisor is an application that runs inside an existing OS.
Thus, a virtual machine can profit from the OS's drivers and services.
Examples of level 1 hypervisors include
- KVM
- Hyper-V
- VMware ESXi
- Citrix Hypervisor (formlerly: XenServer)
Examples of level 2 hypervisors include
Because Hyper-V is a level 1 hypervisor, it means that
Windows 10, once Hyper-V is enabled, itself
becomes a virtual machine.