What makes virtualization work? The kernel execution and programming context

In order to understand what makes virtualization work, it's important to first understand what virtualization is. Virtualization is the process of creating a virtual version of something, such as an operating system, a server, or a network. In the context of computer science, virtualization refers to the creation of a virtual machine (VM) that runs on a physical host machine. The virtual machine appears to the user and the applications running on it as if it were a physical machine, but in reality it is a software-based emulation of a machine's hardware.

One of the key components that makes virtualization work is the kernel execution and programming context. The kernel is the core of an operating system that manages system resources and provides low-level services to applications. In a virtualized environment, the kernel of the host machine is responsible for managing the resources of the physical hardware, while the kernel of the guest machine is responsible for managing the resources of the virtual hardware.

The programming context is also important in virtualization. Each virtual machine has its own programming context, which includes the operating system, applications, and data. The programming context is isolated from other virtual machines and from the host machine, which allows for greater security and reliability.

Another important component of virtualization is the hypervisor. The hypervisor is a layer of software that sits between the physical hardware and the virtual machines. It is responsible for managing the virtual machines and their resources, and for enforcing the separation between the host machine and the guest machines. There are two main types of hypervisors: Type 1 hypervisors run directly on the hardware, while Type 2 hypervisors run on top of a host operating system.

Memory management is also crucial to virtualization. Each virtual machine has its own memory space that is isolated from other virtual machines and from the host machine. The hypervisor is responsible for managing memory resources and ensuring that each virtual machine has enough memory to operate efficiently.

Finally, virtualization relies on hardware support. Modern processors have built-in support for virtualization, which allows for better performance and greater security. For example, Intel processors have the Intel Virtualization Technology (VT-x) feature, while AMD processors have the AMD Virtualization (AMD-V) feature.

In summary, virtualization works by creating a software-based emulation of a machine's hardware, using the kernel execution and programming context, the hypervisor, memory management, and hardware support. These components work together to create a virtualized environment that is isolated from other virtual machines and from the host machine, which allows for greater security, reliability, and flexibility.