Date: Tue, 07 Dec 1999 01:01:26 -0700 From: Wes Peters <wes@softweyr.com> To: Andrew Reilly <a.reilly@lake.com.au> Cc: Matthew Dillon <dillon@apollo.backplane.com>, Kris Kennaway <kris@hub.freebsd.org>, freebsd-hackers@FreeBSD.ORG Subject: Re: PCI DMA lockups in 3.2 (3.3 maybe?) Message-ID: <384CBED6.FECBC219@softweyr.com> References: <Pine.BSF.4.21.9912041823460.94804-100000@hub.freebsd.org> <199912050514.VAA58998@apollo.backplane.com> <3849FD95.F0434263@softweyr.com> <199912050646.WAA59445@apollo.backplane.com> <384B228D.FFE9728@softweyr.com> <19991207123419.A76129@gurney.reilly.home>
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Andrew Reilly wrote:
>
> On Sun, Dec 05, 1999 at 07:42:21PM -0700, Wes Peters wrote:
> > Software
> > is created by humans, and humans are fallible, therefore the software
> > is also fallible.
>
> No, that doesn't logically follow. Just because it's possible
> for humans to make mistakes doesn't mean that it's impossible to
> do or make something (eventually) without mistakes.
And in theory, theory is better than practice. In practice, it rarely is.
I've worked on formal proofs for software, and in the most rigorous software
evaluations ever performed - the Nuclear Safety Cross Check Analysis for
intercontinental ballistic missiles. With the exception of TeX, *no*
software is bug-free. In my extensive experience, no software with the
exception of TeX is free of serious bugs. This includes the ICBM control
system. Your belief or lack thereof doesn't change the existence of the
bugs, it just leads YOU to be surprised when they crop up in the oddest
ways, while I am not.
BTW, if you know anyone at Boeing, ask them if they ever *really* got the
"uncommanded flap excursion" bug fixed, or if this is what killed EgyptAir
800. Watch them go into fits. If you can't PROVE it's correct, how much
empirical testing are you going to accept?
--
"Where am I, and what am I doing in this handbasket?"
Wes Peters Softweyr LLC
wes@softweyr.com http://softweyr.com/
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