Virtualization

Virtualization:

It refers to the concept of creating something that does not exist in real. In virtualization an imaginary version of something is created rather than creating that in real.

The concept of virtualization is not limited to software only. Hardware resources are also associated with this concept now.

Definition:

          “It is a technique for hiding the physical characteristics of computing resources from the way in which other systems, applications, or end users interact with those resources”

History:

It was started in the 60’s by IBM M44/44X

It was abandoned in the 80’s and 90’s because the cheaper  x86 machines were more famous.

But VMware started virtualization in 99.

CPU Virtualization Architecture:

Full Virtualization:

Virtualization layer uses binary translation to replace with privileged instruction with instructions that have the same affect on the Virtual Machine.

Para Virtualization:

Guest operating systems is modified to call functions instead of issuing privileged instructions.

Hardware assist:

CPU support of virtualization is present that eliminates the needs for binary translation.

 Memory Virtualization Architecture:

Hardware supports virtual to physical translation of messages. Another layer from guest physical to host physical is needed for virtualization. This is done with shadow page tables that hold guest virtual to host virtual translation that are loaded to the hardware for direct translation.