[cip-dev] [SystemSafety] Critical systems Linux

Paul Sherwood
2018-11-20T18:58:05Z

Now to attempt to answer the question...

On 2018-11-20 18:45, Paul Sherwood wrote:
>> The question is:-
>>
>> As Linux is monolithic, already written (with minimal
>> requirements/design
>> docs) and not to any coding standard
>> How would the world go about making a Certifiable Linux?

>> Is it possible?
>>

Some initiatives have already started down this road, for example
SIL2LINUXMP (in cc)

But my personal perspective is

1) it may be the the certifications themselves are inappropriate. It's
far from clear to me that the current standards are fit for purpose.

2) there are many cases of folks retrofitting documentation to support
compliance with standards, so perhaps that would be a feasible thing to
attempt (although there is far too much code in the Linux kernel and
associated FOSS tooling and userland components to make this something
which could be achieved in a short time)

3) if we could establish justifiable concrete improvements to make in
Linux (and the tools, and the userland), we could hope to persuade the
upstreams to make them, or accept our patches.

4) we could construct new software to meet the ABI commitments of Linux
(and other components) while adhering to some specific standards and/or
processes, but I'm unconvinced this could be achieved in a
time/cost-effective way.

>> And the question I asked: why do it at all when there are plenty of
>> other
>> POSIX Compliant RTOS and OS out there that have full Safety
>> Certification to
>> 61508 SIL3 and Do178 etc.?

My understanding is that existing certified RTOS/OS tend to be
microkernels with limited functionality, limited hardware support, and
performance limitations for some usecases. I'd be happy to be wrong, and
no-doubt advocates of some of those technologies can explain the reality
by return.

br
Paul