OS design...

Kragen kragen@pobox.com
Tue, 20 Oct 1998 08:04:23 -0400 (EDT)

On Tue, 20 Oct 1998, Francois-Rene Rideau wrote:
> Using again the LCD approach is just reinventing Unix, poorly.

He might be reinventing Unix well, actually --- he might do a better
job than Thompson did in 1970-72, with the stuff we know now.  If he's
really brilliant, he might come up with something like EROS.

> > I think it is a mistake to make one
> > compiler more priveleged than another,
> Reread the GNU Jargon File, Appendix A, AI Koans, Sussman&Minsky Koan.

I'm not clear on the relevance of this koan.  Is this the one about the
randomly-wired neural net?

> As for "certifications" of code, they are due when changing the environment,
> anyway. Just don't play with implicit hypotheses, like Ariane V did.

(For those readers who don't read RISKS, Ariane 5 crashed because an
exceptional condition arose in its Ada control program.  Ariane 4 had
used the same software, but that condition could never arise, which is
why the control software had not handled that exception.)

> > 	2) Compiled code produced by [Other] compilers
> Different conventions, GC, etc, means (logically) separated address spaces.
> This means that non-native low-level conventions will be disadvantaged
> by requiring a protection barrier, just like under Unix. So what?

So you lose the context-switch speed you gained by having memory
protection done in software, and you suddenly gain back all the
potential disadvantages from having everything written in C.

Why don't you just hack a Lisp interpreter into the Linux kernel?

> protection; but then you're not actually *using* LispOS, just running
> in a virtual hardware emulator on top of it (see DOSEMU, Wine, etc).

Dosemu emulates hardware; Wine doesn't, AFAIK.


<kragen@pobox.com>       Kragen Sitaker     <http://www.pobox.com/~kragen/>
A well designed system must take people into account.  . . .  It's hard to
build a system that provides strong authentication on top of systems that
can be penetrated by knowing someone's mother's maiden name.  -- Schneier