[ Thanks to Jane Walker for this link.
]
“SearchOpenSource.com: You mentioned that User Mode
Linux differs from other virtualization technologies because it’s
more of a virtual operating system than a virtual machine. How does
a virtual operating system compare with a virtual
machine?“Jeff Dike: A virtual operating system has
greater contact with the host operating system. This allows
interactions between guest and host, which would be difficult or
impossible with a virtual machine. For example, UML has two file
systems [with somewhat different properties], which allow a host
directory to be mounted as a UML file system…”