Various L4-related questions...

Espen Skoglund esk at
Mon Nov 17 14:47:43 CET 2003

[Michael Engel]
> Hi,
> The currently maintained L4-compatible microkernels seem to be
> Fiasco (Dresden) and L4KA::Hazelnut/Pistachio (Karlsruhe). Is there
> a document describing the differences/compatibility between the
> various versions, probably comparing these implementations to the
> original L4 kernel?

Back in March I posted a short summary of the differences between the
various L4 APIs.

A short summary of the summary:

  o L4Ka::Pistachio implements the most recent API and supports more
    architectures than any other implementation.  L4Ka::Pistachio is
    the main kernel research and development platform for the
    Karlsruhe and Sydeny L4 groups.

  o L4Ka::Hazelnut implements an experimental API, and was only meant
    as a platform to try out new ideas.  Development on L4Ka::Hazelnut
    has been discontinued.

  o Fiasco implements the original API (and also the experimental API
    supported by L4Ka::Hazelnut).  Fiasco is being developed by the
    Dresden L4 group.

> The platform for my project will probably be a AMD "Hammer"-based
> system (e.g. Athlon 64 or Opteron). Is there already work underway
> to run Fiasco or L4KA in 64-bit mode on the x86-64 CPUs? If not, I'm
> thinking about starting an effort to port one of the kernels (based
> on the x86-32 version). Which do you think would be most
> appropriate?

L4Ka::Pistachio (an AMD64 port already exists, but has never been
tested on real hardware).

> Btw., the squirrel on the L4KA web pages is quite cute ;-) - is
> there a high-res bitmap or vector graphics version of the logo
> available?

No vector version is available.  Should probably put out a more high
resolution version one of these days.

> My last question concerns L4Linux. The most recent version seems to
> be based on kernel 2.2.25. Are there any plans to adapt a more
> recent Linux kernel version, like 2.4 or the upcoming 2.6, as a L4
> personality? (I'm aware that this might involve a lot of work...)

The L4 people have internally been using a 2.4 version for quite some
time already.  There has been talk about cleaning up and releasing
L4Linux 2.4 for months now, but I have no idea when this will actually


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