The Differences Between x86 Virtualisation Techniques

Virtualisation is not a new technology and has existed since the 1960s when IBM pioneered the first ‘full virtualisation’ CP/CMS operating system, providing virtual System/360 computer instances.

However, arguably it wasn’t until the advent of x86 virtualisation in the late 1990s that the technology achieved critical mass in terms of exposure and implementation potential.

Initially only one form of x86 virtualisation technique was mastered, which has now become almost ubiquitous for enterprise deployments. However, as Atiek Arian, senior consultant at GlassHosue Technologies outlines, today there are three forms of x86 virtualisation that operate in a different ways.

In order to understand the differences between the three, it’s first important to identify the primary barrier towards virtualising x86 platforms.

This is the issue of privilege isolation between the hardware, operating system and applications. x86 operating systems expect ownership of the hardware upon which they are running. They traditionally run at the lowest privilege sphere, just above the hardware, with the applications running in a sphere above that.

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The main achievement of x86 virtualisation was inserting hypervisor and ‘virtual machine monitor’ (VMM) layers between the hardware and the operating system, whilst still allowing the latter to operate in a more privileged sphere than the applications.

The VMMs abstract the hardware from each guest operating system and provide the interface via which the necessary translation is performed between them and the hypervisor.