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Re: regarding "HURD"

From: B Douglas Hilton
Subject: Re: regarding "HURD"
Date: Mon, 13 Nov 2006 20:17:30 -0500
User-agent: Thunderbird (Windows/20060909)

address@hidden wrote:
One thing that the group *does* agree about -- and most notably, the
architects of the original Hurd system agree about this -- is that the
Mach kernel has failed us.
When and where did the architects of the original Hurd state that? I'm
not around very long yet, so maybe I just missed it; but I really never
heard of that so far...
The problem with the Mach kernel is manifold. Here are some of the basic

1. Clunky IPC and threading model which imposes heavy overhead on all
processes. It was designed
    with distributed computing in mind, but the heavy demands for
context changes and the limitations
    of the c-threads libs have severely crippled its ability,
especially in lieu of more modern solutions.

2. The code base has grown to where Mach is not really much of a
microkernel. Its more of a mega-
   microkernel. Actually, its a mess. The sad fact is that Mach is
pretty much incomprehensible and
   unmaintainable. Maybe Apple has the muscle to throw at it, but we
mere mortals are undone by its
   vast complexity and weird peculiarities. Like a rusted out old
classic car, it would be cool if we could
   restore it, but currently none of us has the time or means to
undertake such a vast project.

3. Impossible driver support. Mach has most of its drivers built into
the microkernel rather than loaded as
   modules. Because of this the hardware support is limited to ancient
hardware drivers that were created
   by the original team of university researchers and the later
corporate workers who were paid to develop
   them. The attempt to meld Mach with the OS-Kit failed when the Hurd
developers decided that it would
   be easier to start from scratch than keep patching an obsolescent

The L-4/Hurd effort is an attempt to rebuild the "Hurd of Unix Replacing
Daemons" to run on a sleek sexy new
microkernel without the associated baggage of previous implementations.
For the most part it is right now the
domain of Computer Science grad students and other extreme brainiacs.
That is not to say that we cannot follow
the developments with interest, as I do, but to do not presume to rush
the process because there is really nothing
to rush. This is a experimental project which may someday result in a
cool OS, but don't expect anything this year.

And finally, while RMS is probably interested in L4-Hurd, he has no say
in what happens here, the main leaders
are Mr. Brinkman and Dr. Shapiro, among a host of others. This project
has very little to do with the overall
GNU operating system other than to provide a kernel which GNU can be
compiled against. If you want to
experiment with the excellent GNU system them your best bet is to use
some sort of GNU/Linux system at the
moment which will surely satisfy your learning needs. There is little
difference between writing an application for
GNU/Linux or GNU/Hurd or GNU/L4-Hurd, etc.


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