1. Virtualization context

With the birth of computing came the need to factor out functions common to different applications, and the need to unify access to hardware. The aim of this factorization is twofold. On the one hand, to reduce the work involved in developing an application by reusing code developed by other players in the market; on the other, to develop an application once for different hardware. This factorization of functionalities has given rise to a software layer that sits between the hardware and the application: the operating system. An operating system virtualizes hardware resources for the application and provides a uniform programming interface for applications, independent of the hardware present in the computer.

Numerous industrial and academic players have tackled the construction of operating systems: MSDos, Windows, OS/2, MacOS, Linux, FreeBSD, OpenBSD, Unix, Minix,...