MISRA C is a set of software development guidelines for the C programming language developed by the Motor Industry Software Reliability Association (MISRA).
embOS is MISRA-C:2012 compliant.
What needs to be done in order to be MISRA-C:2012 compliant?
The official MISRA-C:2012 document, Guidelines for the use of the C language in critical systems, explains what needs to be done in order to achieve MISRA-C:2012 compliance.
MISRA-C:2012 defines a set of guidelines that must to be followed by the C program author. These guidelines are split into two categories, Directives and Rules. Furthermore, all guidelines are deemed to either be mandatory, required or advisory. Guidelines that are deemed mandatory must never be violated. Required and advisory guidelines, on the other hand, may be violated, but every violation of a required guideline must be documented and justified in a dedicated MISRA document.
Most of the guidelines can be tested with a static analysis tool. Other guidelines can be checked using a C compiler or manual code review only. Therefore, C source code may not actually be MISRA-C:2012 compliant just because a static analysis tool does not report any issue. Instead, a dedicated MISRA document is mandatory. The official MISRA-C:2012 document explains the structure of such a MISRA document.
What part of an actual embOS port is MISRA compliant?
Generally, embOS consists of three parts:
- generic sources, which are the same for all embOS ports,
- core/compiler specific sources, and
- board support package files.
The embOS MISRA compliance covers the embOS generic sources only.
In case MISRA compliance for core/compiler specific sources is required, this needs to be requested at SEGGER.
The board support package files typically are not checked to be MISRA compliant.
What static analysis tool is used?
We use PC-lint v9 by Gimpel Software. The embOS source code contains respective Lint suppression comments for some MISRA guidelines. These help in analyzing which MISRA-C:2012 guidelines were violated in the embOS source code and thus need to be justified in our MISRA document. Advisory guidelines are treated the same as required guidelines: we document and justify both violations of the required guidelines and violations of the advisory guidelines.
I use another static analysis tool and it reports violations. How can I deal with that?
If your static analysis tool reports MISRA-C:2012 violations, this doesn't indicate embOS was not MISRA-C:2012 compliant. embOS merely does not contain suppression comments for your chosen static analysis tool. With many different tools available, we cannot include according comments for all of these in the embOS source code.
The easiest way to deal with this is to disable the chosen MISRA checker for all embOS files in your project. It is not necessary to check the embOS files for compliance, since that was already done by SEGGER.
How can I get the embOS MISRA-C:2012 document?
If embOS is part of your application and you need to prove your application is MISRA-C:2012 compliant, the embOS MISRA-C:2012 document is available for purchase from SEGGER.