Editing User-mode Linux (section)

== Comparison with other technologies ==
User-mode Linux is generally considered{{by whom|date=November 2018}} to have lower performance than some competing technologies, such as [[Xen]] and [[OpenVZ]].{{Citation needed|date=September 2011}} Future work in adding support for [[x86 virtualization]] to UML may reduce this disadvantage.

Often cited as a strength of [[Xen]] (a competing technology) is support for [[thread-local storage]] (TLS). This is now also supported in the latest UML kernels. Xen concentrates on virtualizing the whole machine, and thus all systems running on a Xen machine are really virtual machines. In UML, the host machine is not virtualized in any way, and only guest systems are true virtual machines. This allows UML guest direct access to host filesystems and hardware, where it is common to map a host directory (e.g., {{mono|/uml/root}} → {{mono|/}}).