The LispOS Project: a position paper, part 2

Dwight Hughes
Tue, 3 Jun 1997 00:51:53 -0500

Some general comments:

The use of a Mach-type kernel would certainly be better for
our purposes than using a monolithic kernel based Un*x --
that much less to wade thru. What is the status of MkLinux?
Is it reasonably stable yet? How about on x86 hardware?

I would also agree that as a hardware platform for a LispOS,
the PowerPC would be much nicer to work with than the x86 
(I would like it better anyway) and it should produce
a superior system overall. The trouble is that I don't have a
PowerMac/clone and they are not something one just scrapes
together out of some spare parts like, say, a i486 system.
The $ entry point from that point of view is rather higher
for a PowerMac/clone, and I think will be for many on this

As for the goal of "Lisp down to the metal" -- that will be
thoroughly nontrivial, but I think there are also some
nontrivial advantages in it, even today and for a number
of years to come. Some advantages *I* am interested in: 
1) the tight integration of GC and virtual memory (both
hardware and software aspects), giving the ability to allow
each to control the other tightly and take maximum advantage
of resources (for example, being able to constrain GC to
only deal with in-memory pages whenever desired);
2) being able to dynamically create/destroy multiple 
scheduling policies definable by the applications
themselves, not predefined in the kernel. These are somewhat
outside the range of adaptability of any "standard" OSs,
probably for several more generations of these OSs. I
know you don't disagree with any of this -- you just see it
as a lower priority item than I do (or at least lower on your
list of interests).

My primary -reservations- about jumping on the Lisp-to-the-metal
wagon are 1) all the broken devices we will have to deal with
(I very much want to make maximum use of others' suffering
to create good device drivers, especially video drivers) and
2) having to develop a good GUI interface for LispOS, along with
everything else, and create programs using it. Sure, we could
create a pure server LispOS (and make Kelly very happy), but that
is definitely not on my interest list (I would want the LispOS
to have the capability, but not *just* that).

Your point that our time would be better spent *not* recreating
the Un*x software library is well taken.

About T and Orbit I know no more than what you and jrm have
said, but it seems like a possibility. I like having better
defined steps towards a more concrete goal.

-- Dwight