Linux kernel variant

Software to run both Windows and Linux

MkLinux (Microkernel Linux) is a discontinued open-source experimental operating system for PowerPC Macintosh computers. It was launched in 1995 as a collaboration between the Open Software Foundation (OSF) and Apple Computer, as a critical pivot in Apple's technical and social history. MkLinux became Apple's first official free and open-source software community project, and the debut of Linux on the first Power Macintosh.

Linux feature to run a kernel virtualized as a user-space process

RTLinux is a hard real-time operating system (RTOS) microkernel that runs the entire Linux operating system as a fully preemptive process. The hard real-time property makes it possible to control robots, data acquisition systems, manufacturing plants, and other time-sensitive instruments and machines from RTLinux applications. The design was patented. Despite the similar name, it is not related to the Real-Time Linux project of the Linux Foundation.

L4Linux is a variant of the Linux kernel for operating systems, that is altered to the extent that it can run paravirtualized on an L4 microkernel, where the L4Linux kernel runs a service. L4Linux is not a fork but a variant and is binary compatible with the Linux x86 kernel, thus it can replace the Linux kernel of any Linux distribution.