Re: The Hurd: what is it?

[Marcus Brinkmann]

At Wed, 9 Nov 2005 17:02:45 +0100,
Bas Wijnen <shevek@fmf.nl> wrote:
> > Marcus made a promise to Jeff Bailey that the Hurd on L4 would be runnable
> > last year.
> 
> Marcus told you this day that he doesn't like it if you are claiming that he
> said things, because you seem to have a habit of misunderstanding him.  Since
> this promise was appearantly not made by you, and not to you, I'm not going to
> take your word on it.  And since it doesn't have much to do with the
> discussion, I don't think Marcus needs to react to it either.

In this case, Alfred is right.  I did promise this, in a mood of
positive spirit.

And I _had_ banner running eventually!  We have the screenshots to prove it.

We could have continued in this fashion.  Adding a simple filesystem
and shell (which is what I promised) is easy enough.  One thing that
was missing which was more critical was the capability copy
functionality.

You all know what happened next: I got serious doubts about the design
at that point.  The doubts started when I looked at the implications
of the cap copy protocol for "transparent" interposition of proxy
servers.  Because of the global IDs in Pistachio, this turned out to
be particularly ugly.  It took some time to thoroughly understand the
issue, and to decide that the solution would be to have a central
capability server, which fixed a couple of other warts as well.

From there, things escalated.  I made a design for a capability
server, and this exposed a series of mini-problems in the L4 design,
which even existed in the upcoming designs L4ng (by Espen Skoglund in
Karlsruhe) and L4.sec (by the L4 group in Dresden).  By now, these
designs have been enhanced to potentially address _some_ of the
issues, but it is too early to say that for sure.  It is also not at
all clear that the enhancements are satisfying to anybody (those
needing them and those not needing them).

Also at that point we got a lot of interesting input from Jonathan
Shapiro about some other issues.  This has now resulted in a major
interruption and reevaluation.

Thanks,
Marcus