L4based

L4based is a term used to describe software platforms, operating systems, and research projects built on the L4 family of microkernels. Originating from work in the 1990s by Jochen Liedtke, the L4 microkernel family emphasizes a minimal kernel that provides core hardware abstraction, interprocess communication, and basic scheduling, while most OS services run in user space. L4based systems aim for strong isolation, modularity, and portability across architectures such as x86 and ARM, making them suitable for embedded, real-time, and safety-critical contexts.

In L4based designs, kernel size remains small and services such as file systems, drivers, and networking run as separate user-mode servers. Communication occurs via efficient IPC, enabling fault containment and easier updates, since a crash or compromise in one service does not necessarily affect others.

Notable L4based platforms include seL4, a formally verified microkernel; L4Re (L4 Runtime Environment), which provides a framework for running systems on L4; and various research OSes that explore real-time scheduling, security, and componentized architectures.

The term L4based also guides discussions about formal verification, performance trade-offs, software portability, and the balance between kernel simplicity and rich user-space services. It serves as a broad descriptor for a family of systems that use the L4 microkernel as their foundation.