4. Conclusion and outlook

Virtualization is mainly used to mask hardware and system heterogeneity. An operating system virtualizes peripherals, while a virtual machine virtualizes the processor. Concrete virtual machines virtualize existing processors, while abstract virtual machines define new abstract processors. Virtualization has been an essential and much-studied topic in recent years, partly because of the emergence of the Internet and the need to standardize applications, and partly because of the power of recent processors, which enable several systems to be housed on the same machine.

Finally, the proliferation of embedded hardware (smart cards, telephones, PDAs) is leading to specialization. Indeed, we have implicitly considered standard computers (a sufficiently powerful processor, enough memory for the virtual machine and its applications, and access to an efficient network),...