What is the implementation of hardware abstraction level virtualization
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Fancy Wang 1121 2022
Hardware abstraction level virtualization
Hardware abstraction level virtualization refers to mapping different processors, memory, network, I/O, disk and other resources in the underlying hardware of the host machine to resources that the client system can recognize through the virtual machine monitor, so as to run on the host machine.
The client on the server provides a unified and abstract resource access interface, so that the underlying hardware is relatively transparent to the guest operating system and the host operating system, and the underlying hardware resources that the client can see is converted through the virtual machine monitor. Resources make no difference.
Using hardware abstraction level virtualization technology, an actual physical host machine can be virtualized into one or more clients, and each client has allocated virtual hardware resources.
Because the virtualization operation is performed directly on the hardware level, each client has its own separate kernel, and different clients do not share the system kernel of the host, which can ensure the independence of the execution environments between the clients.
In the process of virtualization, it is necessary to isolate and virtualize the hardware resources of the computer, and this part of the work is realized by the virtual machine monitor.
A virtual machine monitor is a system software that is installed on the host, manages the real physical resources of the host, treats CPU, memory, disk, network, etc. as a resource pool, and can reasonably isolate these resources according to the client and allocation, to provide hardware resource interface for virtual machine.
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A is classified according to the implementation
In hardware abstraction level virtualization, it can be further classified according to different implementation methods and different implementation structures of virtual machine monitors. According to its different implementation methods, it can be divided into full virtualization technology and paravirtualization technology. The full-virtualization technology can be further divided into software-implemented full-virtualization technology and hardware-assisted full-virtualization technology.
Full virtualization means that virtualization can be implemented on the host through a virtual machine monitor without any modification to the target guest operating system. The virtual machine monitor will initialize all the physical resources and devices of the host, and provide a unified abstract interface for the client system to use.
For the guest operating system, it is completely unaware that it is running on the virtual machine monitor. Think of yourself as running on a real physical machine and have direct control over the underlying physical resources.
b: Paravirtualization
Paravirtualization requires the assistance of the guest operating system. The guest system running on the virtual machine monitor is not an ordinary operating system, but a specific operating system with targeted modifications to the kernel.
Para-virtualization and full-virtualization both solve the problem of how to normally execute sensitive instructions or privileged instructions in the client system, but they provide two different solutions. Unlike full virtualization, which solves this problem at the binary code level at the hypervisor or hardware level, paravirtualization solves this problem at the source code level on the guest operating system.
Paravirtualization only needs to modify the code of designing privileged instructions in the client system, so that the guest operating system can actively adapt to the virtual monitor and the host operating system can determine the privileged instructions of the client without scanning and capturing.