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Hurd/L4 History

From: Neal H. Walfield
Subject: Hurd/L4 History
Date: Thu, 02 Aug 2007 14:12:31 +0200
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At Wed, 1 Aug 2007 18:30:20 +0200,
<olafBuddenhagen@gmx.net> wrote:
> On Wed, Jul 25, 2007 at 09:17:49PM -0400, Michael Casadevall wrote:
> > Hurdng - the project of porting hurd translators to another
> > microkernel beside mach such as L4.
> That is not fully correct. The original port to L4 was simply named
> Hurd/L4 -- which is exactly what it was: A port of the existing Hurd
> design to a different microkernel.

The idea of using L4 was proposed even earlier by Okuji.  He created
the l4-hurd mailing list in November 2000.  I don't think he got any
further than simply suggesting it as an alternative to Mach and doing
some reading.

I started the original Hurd/L4 port while I was at Karlsruhe in 2002.
My intention was to adapt the Hurd to exploit L4's concepts and
intended design patterns; it was not to simply provide a Mach
compatibility layer on top of L4.  When I left Karlsruhe, I no longer
had access to Pistachio as I was unwilling to sign an NDA.  Although
the specification was available, the Karlsruhe group only released
their code in May 2003 [1].  Around this time, Marcus began hacking on
Pistachio.  He created a relatively complete run-time.  I didn't
really become involved again until the second half of 2004, after I
complete by Bachelors degree.

> Later, when the original Hurd/L4 architects embraced Coyotos and
> suggested a total departure from the original Hurd design (and in fact,
> also from its goals...), still calling it "Hurd" no longer seemed
> appropriate -- so someone came up with ngHurd. (Oddly, most others
> picked that up as "Hurdng", which is ugly IMHO, and doesn't make any
> sense if you spell out the "Hurd" acronym...)

Before Marcus and I considered Coyotos, we had already rejected some
parts of the Hurd's design.  The resource management problems were
what prompted me to look at L4.  Also, some of the problems with
translators were already well-known to us.  (For a more detailed
description of the problems we have identified, see our paper in this
month's SIGOPS OSR [2].  We have also written a forward-looking
position paper [3].)

We visited Jonathan Shapiro at Hopkins in January 2006.  This resulted
in a number of discussions, some quite influential, and not always in
a way which aligned our position with that of Jonathan's.  This was
particularly true of a number of security issues.

Hurd-NG, as we originally called it, was an attempt to articulate the
system that we had come to envision in terms of interfaces and
description of the system's structure.  The new name was selected, if
I recall correctly, as it clearly wasn't the Hurd nor the Hurd based
on L4.


[1] https://lists.ira.uni-karlsruhe.de/pipermail/l4ka/2003-May/000345.html
[2] http://walfield.org/papers/200707-walfield-critique-of-the-GNU-Hurd.pdf

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