Review: User-Mode Linux

Other than the fun factor of running Linux under Linux, there are some very serious uses for UML. UML lets you tweak and torture a virtual system without having to risk your own stable system or maintain an extra system for testing. Instead, you can work with one or more UML virtual machines and do all the damage you want without worrying about trashing your system while testing device drivers and so on. If your job requires testing the latest and greatest development kernels, for example, UML is a great way to do that without having to use an unstable kernel for your workstation. There are a number of other testing scenarios where it's very helpful to be able to set up a slew of virtual machines instead of using multiple physical machines.