Automotive ADAS systems generally require ASIL-D certification, which is much easier with an RTOS than Linux. I don't have much experience with real-time embedded Linux, but my understanding is that it is very difficult or impossible to certify to ASIL-D. Can someone correct me?
A RTOS helps because the vendor will usually provide the RTOS already certified for ASIL-D application. The rest of the software components will also need to reach ASIL-D, but getting the RTOS to ASIL-D makes things a little bit easier.
Usually this boils down to the ASIL-D RTOS systems are much smaller, e.g. much simpler to verify, leaving the developers of the systems above with much more job to verify there parts.
Also in my experience it might have been easier to reach the ASIL-D requirements, using a smarter combination of a Limiter on RTOS and using more generic code on something like linux for more of the code. This probably also would end up in more used and tested applications reaching more stability. (That's is partly outside ASIL-D).
Functional safety and ISO-26262 is much misunderstood in automotive development and architecture.
Also imho the certifications, well with out the safety case are kind of useless. You still have to make the assessment how you will find the problems with it in your use case. That might ever so slightly differ from what they certified. The automotive industry thou loves to have someone else to blame, e.g. the supplier of the RTOS, Compiler etc. Using Linux makes the blame game hard.
