A software approach for managing shared resources in multicore IMA systems

Multicore processors are now considered as relevant candidates for the next generation of Integrated Modular Avionics (IMA) systems. One expected benefit of multicore introduction inside IMA platforms is an increase of the number of avionic applications hosted on a single platform. This can be achieved by deploying several ARINC 653 partitions simultaneously on different cores. However to be certifiable, such an architecture must fulfill many dependability requirements. In this paper we focus on the problem of Worst Case Execution Time (WCET) computation of embedded partitions under the Robust Partitioning constraint. Today´s multicore processors internal features make those requirements fulfillment difficult to ensure on the platform for any set of hosted partitions. That comes from the difficulty to characterize with a satisfying confidence the processor behavior when several unknown applications use simultaneously shared hardware resources, such as the main memory. We present in this paper a generic software solution that constrains the use of shared resources to remain inside predefined usage domains for which the processor has a deterministic behavior. We illustrate this approach with a case study based on a COTS processor from the Freescale QorIQ series.