Overview

What is Fiasco?

Fiasco is a new µ-kernel (microkernel) running on x86 PCs intended to be compatible with the L4 µ-kernel for x86. It implements the L4 ABI as defined in the L4/x86 Reference Manual.

The Fiasco kernel can be used to construct flexible systems. We at TU Dresden use it as a base for our DROPS system which supports running real-time and time-sharing applications concurrently on one computer. However, Fiasco is not only suitable for big and complex systems, but also for small, embedded applications.

What are Fiasco's distinctive features (i.e., buzzwords)?

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.

When using L⁴Linux on top of Fiasco, hard-real-time applications can share one machine with time-sharing (Linux) applications.

Fiasco is a real, second-generation µ-kernel protecting applications in address spaces. Thanks to its efficient task and context switching mechanism and its performace-oriented design, the performance penalties induced by address-space security are neglible - much smaller than in older, first-generation µ-kernels like Mach.

Motivation

The original L4 µ-kernel for x86 has some shortcomings which we intend to fix with this new implementation. The Fiasco kernel:

• can be studied and maintained better because it has been written in a high-level language (C++)
• has better real-time properties than L4/x86 because it can be preempted at almost any time
• is freely redistributable under the GPL

Please see also the section, ``Why another kernel?,'' in the Fiasco FAQ.

Current release

The current release is version 1.2. It is release-quality software.

This release is capable of running L⁴Linux, DROPS, and many other L4 applications. For details on Fiasco's L4 compatibility, please see the status page.

Availability

Fiasco is freely available under the GNU General Public License from the download page.

For questions about other licensing variants, please contact us.

Developers welcome!

Fiasco is Open-Source^TM software; you are welcome to use it or join developing it.

Please consider subscribing to our developer's mailing list l4-hackers. The discussion language for this mailing list is English.

Before posting to the mailing list, you may want to check out the mailing list archive and the FAQ.

Reporting bugs

To report a bug in the Fiasco µ-kernel, please use the l4-hackers mailing list. See the previous point for more information on this list.