Re: A simple question

[Bas Wijnen]

On Thu, Apr 13, 2006 at 02:39:08AM +0200, address@hidden wrote:
> Hi,
> 
> On Tue, Apr 11, 2006 at 07:42:43PM +0200, Bas Wijnen wrote:
> 
> > No, it has to do with us, I suppose.
> 
> It's important to point out that "us" here doesn't mean the Hurd
> community as a whole, but only part of it.

Yes, sorry if that wasn't clear.

> > Pistachio was considered, because it could solve Mach's (performance)
> > problems.  However, it doesn't actually do (much) more than that: the
> > result will be similar to Hurd on Mach, but faster.  It is a lot of
> > work to write it, though.  Speaking for myself, I can say that I
> > wasn't really motivated to put in that much work, just for some
> > performance gain.
> 
> That's not quite true. Hurd/L4 was stopped because it turned out not to
> be possible/feasible to implement a system like Hurd on Pistachio.

Before it was stopped, I did work on it, but not very much.  If we'd all have
continued with such small effort as I did at the time, Hurd/L4 would never
have been finished.  That's what I was talking about.

The reason is was stopped wasn't that the Hurd as it is now could not be
implemented AFAIK.  It's that we wanted new features, which weren't possible.

> The desire to create a completely different system only came with Shapiro's
> influence, way after microkernel reevaluation was already under way.

That's not how I remember it.  Shapiro's influence was mostly in showing us
interesting features which we may want to have, and explain what EROS can and
can't do.  And of course sketch what he expected Coyotos to become.

> In fact, AFAIK the microkernel choice is mostly independant from the
> redesign.

Well, if you change microkernel, you need a redesign.  After speaking with
Shapiro, it seemed clear (at least to me) that pistachio couldn't do all the
nice things that we now knew about and wanted.  So we would use some other
microkernel, be it Coyotos or an other L4 variant.  In both cases we would
need a redesign.

> > Also, Linux has changed to allow several things which only Hurd could
> > do before (user space file systems, for example), which makes it even
> > less attractive to work on it.
> > 
> > Coyotos is different.  It would give us a new system with new exciting
> > features.  Features which aren't going to be present in Linux, because
> > a complete rewrite would be required for them.
> 
> You do not seem to have much understanding of what the (existing) Hurd
> has to offer, if you believe a kernel like Linux could do the same or
> even come close *without* a complete rewrite.

Seen from a user perspective, it already comes close.  The cool features of
the Hurd are not so spectacular that they'll be impossible on Linux.  Right,
you need root access to do things with Linux, and you don't need it on Hurd.
We consider that a very good thing.  But do you really think the user cares
about it?  Only when things go wrong, and his whole computer is taken over
because he did things as root, then he cares.  But if that was a real concern,
how many people would still use Windows?

> Sure, Linux *does* slowly move in that direction, bit by bit (if
> something is The Right Thing To Do (TM), you can expect some
> convergence...) -- but holding the current pace, it will require some 40
> years or so (and probably a couple of maintainer changes) until it can
> compete.

It does already compete, and it's winning big time because most people think
performance is more important than "a cool environment for developers".

> > If you're interested, search the list archive for "capability",
> > "security" and "persistence".
> 
> Sorry if this sounds harsh, but from last fall's discussions you should
> have learned that "capability" and "persistance" are not features but
> mechanisms,

I didn't mean to suggest that these were the cool features I was talking about
(although persistence, as a feature (meaning a power outage doesn't make you
lose much of your work), is one of them).  However, the discussions about the
features should be found when searching for these terms, I think.  That's what
I said, too. ;-)  But actually, I expect most of the readers to have followed
it at the time, so they all know what it's about anyway.

> and that "security" means nothing without explaining what you are talking
> about.

This is not the place to explain these things.  The explanations can be found
when searching the archive for "security".  I didn't say "these are the
features", I said "Here's how you can find them".  That's what I meant, too.

> So please don't spread confusion.

Sorry about that.  I hope things are cleared up now.

Thanks,
Bas

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