L4Linux is a port of the Linux kernel to the L4 microkernel. Ports for Linux versions 2.6, 2.4 and 2.2 are available.
L4Linux is for the L4 developer community, and operating systems researchers and developers at large. L4Linux offers a great environment in which to develop and research with L4 microkernels. It offers the support infrastructure of Linux, yet the advantages of the L4 microkernel.
Like the Linux kernel, the L4Linux kernel is available under the GPL version 2 license.
The paper presented at the 16th ACM SOSP in 1997 entitled The Performance of µ-Kernel-Based Systems (pdf, ps) describes one of the first adaptations of Linux to L4. The paper demonstrates that it is possible to implement a high-performance conventional operating system on a microkernel, and that a high-performance microkernel is crucial to achieve this. Authors: H. Härtig, M. Hohmuth, J. Liedtke, S. Schönberg, and J. Wolter. The Linux version was 2.0.21, and the L4 microkernel was Jochen Liedtke's x86 assembler kernel (which implemented the L4 V2 API).
The L4Linux ports:
is an alternative port of Linux to L4, aimed at embedded systems and platform independence.