Why Hurd? (was: Re: A proposed Roadmap)

[olafBuddenhagen]

Hi,

On Fri, Sep 14, 2007 at 07:54:17PM +0200, Alfred M. Szmidt wrote:

> If the goal is just to be different for the sake of being different,
> then we should use the Hurd.  But how exactly will GNU be different
> >from GNU/Linux?  Or, how different enough will it be to warrent a
> different kernel, and why could not Linux (or ...) be modified to do
> these different things?

You are talking like Linus Torvads now -- I seriously wonder why you got
interested in the Hurd in the first place.

Of course any specific feature can, in theory, be added to existing
systems. That's Linus approach: Only adapt the system if there is a
specific problem at hand that requires it.

The difference is in the cost. With Linux (or other monolithic kernels),
any change at system level requires kernel hacking, which is very
involved. Moreover, for the changes to be realistically useful, they
need to go upstream, which requires even more involvement, costing a lot
of time and energy, and there is no guarantee that they it will even
succeed in the end.

The result is that much more often people settle for solutions based on
existing kernel features, which tend to be much more complicated,
fragile, limited, hard to setup and manage, and inefficient.

With the Hurd, it's not only much easier to change functionality at
system level; but also the change can be immediately used, on any
machine running the Hurd -- without requiring consent from upstream or
from the admin. Even normal application programs can come with modified
Hurd servers, providing mechanisms better suited for the applicaton.

If the changes prove generally useful, they will go upstream sonner or
later -- but they don't need to.

That's the real power of the Hurd design: Lowering barriers to
system-level hacking, it allows for more individual setups, more
innovation, and more elegant and powerful applications. This is
something that can not be achieved by adding a few features to Linux or
some other mainstream kernel. It requires a system designed for that
from ground up.

I'm not saying the current Hurd implementation is already perfect in
this. Some things are still too hard to do, and I hope we can further
optimize the design over time. But even as it is, the Hurd is much more
powerful in this regard than any other system I know of, UNIX-compatible
or not.

-antrik-