Virtual machine (VM) technology has been around for 40 years and has been experiencing a resurgence with commodity machines. VMs have been shown to improve system and network flexibility, availability, and security in a variety of novel ways. This paper introduces Xen, an efficient secure open source VM monitor, to the Linux community. Key features of Xen are:
We discuss the interface that Xen/x86 exports to guest operating systems, and the kernel changes that were required to Linux to port it to Xen. We compare Xen/Linux to User Mode Linux as well as existing commercial VM products.