[SystemSafety] Collected stopgap measures

[Peter Bernard Ladkin]

On 2018-11-04 12:41 , Martyn Thomas wrote:
> 
> You are right of course that Linux is used in critical systems but it is
> an open question whether that is adequately safe, secure or (in some
> countries) legal, because of the problem of establishing its effect on
> the dependability of the system. (There's been a lot of debate here
> about the "proven in use" approach to assurance. Summarising that
> deserves a separate thread but, in essence, there's insufficient
> scientific basis for almost all such claims).

In the second sentence of the current Part 7 Annex D on statistical evaluation of "proven in use"
for SW, it is mentioned, misleadingly, that the techniques described therein could be used for
evaluating operating systems. They can't.

Indeed, one German MT member has argued for eliminating Annex D. He has faced calls from clients for
qualifying versions of Linux for use in SFs according to Annex D - after all, it says you can!

The answer to that issue seems to me to be to get rid of the sentence (there is certainly consensus
on that!). Maybe even to add a warning ("at present, it is not considered feasible to evaluate SW
with complex functionality, such as an operating system, statistically to establish its
compatibility with a SIL requirement").

PBL

Prof. Peter Bernard Ladkin, Bielefeld, Germany
MoreInCommon
Je suis Charlie
Tel+msg +49 (0)521 880 7319  www.rvs-bi.de





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