Fiasco.OC is a 3rd-generation µ-kernel (microkernel).

The Fiasco.OC kernel can be used to construct flexible systems. Fiasco.OC is the base for our TUDO:OS system which supports running real-time, time-sharing and virtualization applications concurrently on one computer. However, Fiasco.OC is both suitable for big and complex systems, but also for small, embedded applications. We have developed the L4 Runtime Environment which provides the necessary infrastructure on top of Fiasco.OC for conveniently developing applications. Please refer to the Features page for more information on the capabilities of Fiasco.OC.

Fiasco is a preemptible real-time kernel supporting hard priorities. It uses non-blocking synchronization for its kernel objects. This guarantees priority inheritance and makes sure that runnable high-priority processes never block waiting for lower-priority processes.