6 Enabling Safe Symmetric Multi-Processing (SMP)

Regular homogenous multicore CPUs are also treated as multicore by the RTOS (scheduling), for example, running multiple tasks at the same time on different cores. When looking at freedom of interference between critical and non-critical software partitions a new dimension has to be considered: the cores. Cores share resources such as crossbars, cache and memory, and therefore can interfere with each other. The certified INTEGRITY RTOS package (separation kernel, safety layer) provides interference freedom of the cores and yet detects soft errors with high diagnostic coverage utilizing software lock-step. For the software lock-step, safety-critical tasks, performing identical calculations with differing algorithms, are scheduled in parallel on different cores by the OS. Then, the safety layer provides the possibility to define synchronization points to check for consistency of the (intermediate) results to detect safety-relevant faults.