Hardware Virtualization

Hardware Virtualization

1. Definition

   • It is the virtualization of computers as complete hardware platforms, certain logical abstractions of their componentry, or only the functionality required to run various operating systems.

2. Full Virtualization

   • the virtual machine simulates enough hardware to allow an unmodified "guest" OS designed for the same instruction set to be run in isolation.
   • In particular, sharing, aggregation, emulation, and isolation are the most relevant features.

3. Hardware Assisted Virtualization

   • the hardware provides architectural support that facilitates building a virtual machine monitor and allows guest OSs to be run in isolation.
   • Hardware-assisted virtualization reduces the maintenance overhead of paravirtualization as it reduces (ideally, eliminates) the changes needed in the guest operating system. It is also considerably easier to obtain better performance. A practical benefit of hardware-assisted virtualization has been cited by VMware engineers and Virtual Iron.

4. Paravirtualization

   • the virtual machine does not necessarily simulate hardware, but instead (or in addition) offers a special API that can only be used by modifying the "guest" OS.

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