Re: [SystemSafety] Stupid Software Errors [was: Overflow......]

From: David MENTRÉ < >
Date: Tue, 05 May 2015 06:21:14 +0200


Le 2015-05-05 00:47, Heath Raftery a écrit :
> Is the implicit assumption that zero run-time errors is better, actually
> sound? Here's a "run time error":

[ ... nice example... ]
> Tada! No run-time errors! Of course, it stops working after a minute.

No, of course. As you perfectly illustrated it, a programmer can "hide" a run-time error behind an unwanted behavior. As others said, one must take the whole socio-technical context into account and no proponents of formal tools said "we have a silver bullet". One should use a formal tool AND proper use of the tool, programming language, etc.

> Yes, the tools are great, and not using them would take extraordinary
> justification. But to cry that "integer overflow was fixed 30 years
> ago!" may be missing the point.

I know that Airbus is using such sound static analysis tool on its safety critical code. It is part of their process.

That's why I was asking for more information: was the issue identified by Boeing (using formal tool or another method) and classified as "won't happen" (and probably not documented as such), or was it a real bug discovery?

For the latter case, we are several on this list to claim that proper tool exists, are perfectly usable on regular desktop machine and should be part of the development process.

In the former case, I find it as interesting. How to be sure that such a "small" issue, probably identified by some developer in a cubicle, can transform into a system requirement "reboot your plane every 120 days"? I'm pretty sure several readers of this list would say "it's part of the process". But to have such a process really applied in software development, not only for avionics safety-critical software, is still an open issue for me.

Best regards,
D. Mentré

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systemsafety_at_xxxxxx Received on Tue May 05 2015 - 06:21:22 CEST

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