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Date:      Sat, 10 Jan 98 07:12:31 -0500
From:      Garance A Drosehn <gad@mlor.its.rpi.edu>
To:        hackers@FreeBSD.ORG
Subject:   Re: FreeBSD Netcards
Message-ID:  <9801101212.AA28463@mlor.its.rpi.edu>
References:  <Pine.SV4.3.95.980110180117.17965B-100000@parkplace.cet.co.jp>

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Michael Hancock <michaelh@cet.co.jp> wrote:
> I'm firmly in the camp that correctness is a higher priority than
> robustness.
> 
> A user process should be terminated quickly when it does something
> wrong.  This ends up giving us far higher quality code than having
> the kernel sweeping possibly insidious bugs under the carpet.
> These include NULL value errors and double FREEs.

I am too.  We used a similar strategy of generating a page-fault
on MTS (what we used for a mainframe operating system) for page-zero
references.  We also did other things which would cause aborts or
clearly-incorrect-results for stupid programming errors.  We often
got complaints from people bringing programs from other operating
systems.  I've seen many a program which "worked" on some other
operating system, but only if you will accept that "quietly producing
absolutely incorrect results" is "working".

In some cases, those absolutely incorrect results on other operating
systems had already been used in real-world situations (such as,
say, building a bridge over a river(*)), and believe you me I'd
very much rather the program had aborted immediately and shot the
programmer instead of "working" by the above definition.

Of course, it's also fine if it aborts immediately and doesn't
shoot the programmer.  I just don't want to have to worry every
time I drive over a bridge.

(* - this really happened.  somewhere in connecticut there is a
bridge which was built based on unquestionably incorrect results
from one such program.  Now, maybe that bridge is fine and dandy,
and maybe it will even last longer than the pyramids in Egypt, but
for my money I would much rather that correct results had been
available for the decisions made when building that bridge.  This
probably about twenty years ago now, so it's also possible the
bridge has already fallen down...)

---
Garance Alistair Drosehn     =     gad@eclipse.its.rpi.edu
Senior Systems Programmer        (MIME & NeXTmail capable)
Rensselaer Polytechnic Institute;           Troy NY    USA



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