Back to main page
The Fiasco µ-Kernel
Site Navigation:

Quick links:

Status information


The current release of Fiasco is version 1.2, released 26 Sep 2005.

Newer versions are available via read-only SVN. Fiasco is very stable, and it is feature complete.

We will be releasing new snapshots from time to time, especially when new features or other major enhancements have been implemented.


The following table summarizes what's implemented and what's not (in the current SVN version, not necessarily in the current snapshot release): (status as of March 2007)

Implemented Missing
  • creating and deleting threads and tasks
  • short IPC
  • page-fault and memory-flexpage IPC
  • long-message IPC, including aborts
  • page-fault timeouts for long IPC
  • attaching to hardware interrupts, and IRQ-to-IPC translation
  • user-level IDT emulation
  • int3 debug messages
  • Sigma0
  • source-level debugging via remote GDB
  • built-in low-level debugger
  • profiling
  • FPU-register saving
  • I/O flexpages
  • L4/V2 and L4/X.0 interfaces
  • tagged-TLB emulation (``small address spaces'') optimization
  • exception IPC
  • segment register support
  • L4/X.2 interface
  • IPC doesn't check thread version numbers
  • IPC redirection via chiefs
  • preempters (not implemented by any version of L4)
We are currently designing and implementing experimental replacements for clans & chiefs and preempters.

Although some really small points are still missing Fiasco implements enough L4 functionality to be able to run L4Linux. It can be used as a drop-in replacement for L4/x86.


Current work on Fiasco concentrates on performance improvements as well abstraction and portability issues. There haven't been many performance optimizations yet -- except that the most commonly used short IPC now uses a short-circuited code path.

Fiasco is pretty good in the real-time predictability arena as Frank Mehnert demonstrated with his measurements using L4RTL, an implementation of the RT-Linux API on L4.


What's up next (in order of priority):
  • profiling and performance optimization
  • deal with out-of-kernel-memory situations, and other production-stability and robustness issues

See also the wish list.

Last modified: Thu Mar 29 2007, 10.46:41 CEST

Team Fiasco