CAST-32A

CAST-32A, Multi-core Processors is a position paper,[1] by the Certification Authorities Software Team (CAST). It is not official guidance, but is considered informational by certification authorities such as the FAA and EASA. A key point is that multi-core "interference can affect execution timing behavior, including worst case execution time (WCET)."[2]

The original document was published in 2014 by an "international group of certification and regulatory authority representatives."[3] The current revision A was released in 2016. "The Federal Aviation Administration (FAA) and European Aviation Safety Agency (EASA) worked with industry to quantify a set of requirements and guidance that should be met to certify and use multi-core processors in civil aviation, described e.g. in the FAA CAST-32A Position Paper and the EASA Use of MULticore proCessORs in airborne Systems (MULCORS) research report."[4] An Advisory Circular (AC) that formalizes guidance for multicore systems and harmonizes guidance between FAA and EASA is expected to replace this position paper in late 2020.[5][6]

One of the first mixed-criticality multicore avionics systems is expected to be certified sometime in 2020.[7] The objectives of the standard are applicable to software on multicore processors, including the operating system.[8][9] However, the nature of the underlying processor hardware must examined in detail to identify potential interference channels due to inter-core contention for shared resources.[10] Verification that multicore interference channels have been mitigated can be accomplished through the use of interference generators, i.e., software tuned to create a heavy usage pattern on a shared resource.[11] By creating stress on the shared resource, the impact of contention between cores can be measured and quantified.