Microkernen

Microkernen, or microkernels, are a class of kernel architecture in computer operating systems characterized by a minimal kernel that provides only a small set of fundamental services. The rest of the operating system, including device drivers, file systems, and network protocols, runs in user space as separate processes or servers. This separation aims to improve modularity, fault isolation, and security by limiting the code that operates at the most privileged level.

Key design principles include a small trusted computing base, explicit inter-process communication, and a clean separation between kernel space and user space. In a typical microkernel design, core responsibilities such as scheduling, basic memory management, and IPC (inter-process communication) are handled by the kernel, while higher-level services are implemented as user-space servers. This architecture enables easier maintenance and the possibility of replacing or updating individual components without affecting the entire system.

The microkernel concept originated in academic research in the 1980s and was popularized by researchers such as Jochen Liedtke. It has influenced several operating systems, including MINIX 3, the L4 family, and seL4, as well as commercial systems like QNX. Microkernels are particularly common in embedded, real-time, and safety-critical environments where reliability and fault containment are crucial.

Advantages of microkernels include improved modularity, easier fault isolation, and a smaller attack surface. Challenges include potential performance overhead from context switches and IPC, increased system complexity in designing robust user-space servers, and the difficulty of achieving broad compatibility with legacy software. Today, microkernel designs remain influential in niche and safety-critical domains, while many general-purpose systems use monolithic or hybrid architectures.