User Mode Linux
User Mode Linux (hereinafter UML called, not to be confused with the Unified Modeling Language, which is also abbreviated as UML) is a variant of the Linux kernel, which makes it possible to perform a complete Linux kernel and application processes within of Operating Linux systems, without their configuration and thus to influence stability.
The possibilities are endless. Network services in a UML environment completely isolated from the main drain system. Often UML is also used to install a so-called " honeypot ", with the security of a computer or network can be tested. Another field of application is testing and bug fixes ( " debugging " ) of software, for example, a version of the Linux kernel. The advantage is that the host system is not affected.
Another conceivable area for the use of user-mode Linux is the driver development for Linux, since the error cleanup of a user-mode process is easier than with a full-fledged kernel. In addition, a " kernel panic " (stop the system due to a kernel error) in a virtual kernel for the actual system without consequences, because it can be a new virtual kernel can be started. Finally, the simultaneous launch of multiple virtual kernel is interesting (for example, provider of dedicated web servers, which thereby can offer to the customer on the same system, the Linux distribution of their choice ).
Originally UML " Linux on Linux" (Linux to Linux ) should be called. The idea was rejected to avoid confusion with the acronym LOL.
Since kernel version 2.6.0 UML is included in the official Linux kernel sources so that you can let this kernel operate as UML processes under a host Linux. In addition, when a ŠKAS patch is played on the host Linux, the host kernel helps the UML kernel with certain administrative tasks, which increases security and performance.
UML is still actively developed, this concerns mainly the ŠKAS extensions.