The Denali operating system

Operating system

An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...

 is "an IA-32

IA-32

IA-32 , also known as x86-32, i386 or x86, is the CISC instruction-set architecture of Intel's most commercially successful microprocessors, and was first implemented in the Intel 80386 as a 32-bit extension of x86 architecture...

 virtual machine monitor, that allows for untrusted services to be run in isolated (protected) domains."

Denali makes use of paravirtualization

Paravirtualization

In computing, paravirtualization is a virtualization technique that presents a software interface to virtual machines that is similar but not identical to that of the underlying hardware....

 to support high performance virtual machines, even on the notoriously uncooperative x86 architecture (see x86 virtualization

X86 virtualization

In computing, x86 virtualization is the facility that allows multiple operating systems to simultaneously share x86 processor resources in a safe and efficient manner, a facility generically known as hardware virtualization...

). The envisioned usage model for the original Denali was to support virtual machines running lightweight single application operating systems for internet services. A later revision of Denali (uDenali) includes support for running full-featured operating systems.