Although the applicant/system integrator always has overall responsibility for all objectives, some objectives are extremely difficult to meet without strong support from the RTOS supplier and the RTOS itself. CAST-32A Objectives SummaryĬAST-32A lists ten objectives that augment guidance for multicore processors. Robust partitioning, therefore, is critical to meeting the goals of DO-297 Integrated Modular Avionics (IMA), particularly that applications are independently modifiable. ![]() It defines Robust Time Partitioning on a multicore processor as the “result of mitigating the time interference between partitions hosted on different cores no software partition consumes more than its allocation of execution time on the core(s) on which it executes, irrespective of whether partitions are executing on none of the other active cores or on all of the other active cores.” Robust partitioning enables “separate determination of the WCET of an application without any other applications executing.” Without robust partitioning, an application needs to be tested and verified together with all the other applications that will be running concurrently on other cores. The INTEGRITY-178 tuMP RTOS directly addresses the allocation and use of shared resources in a multicore system, and it is the first and only RTOS to be part of a multicore certification to DO-178C and CAST-32A.Ĭertification Authorities Software Team (CAST) Position Paper Multi-core Processors Robust PartitioningĬAST-32A pays special attention to “robust” partitioning. It is the operating system that can extend safety-critical determinism to cover the use and allocation of shared resources. Because multicore interference is inherently a hardware issue, the most effective and efficient solutions are possible in the software that interacts directly with the hardware, namely the operating system. CAST-32A does not proscribe methods for achieving those objectives but leaves those to the system integrator and their suppliers. ![]() The ten objectives in CAST-32A augment the DO-178C processes for multicore processors and span from planning through verification while focusing on shared resources and interference channels. That contention can also cause one application to impact the execution of another application, violating the requirement for isolation. The main concern is contention for shared resources, which can result in non-deterministic behavior. ![]() CAST-32A identifies issues that could impact the safety, performance, and integrity of software executing on a multicore processor, and it lists ten objectives to address those concerns. CAST-32A is a position paper published by the Certification Authority Software Team (CAST) in 2016 providing guidance on the use of multicore processors in software airborne systems.
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