Power consumption and thermal problems limit a further increase of speed in single-core processors. Processor architects are therefore moving toward multicore processors. However, a shift to multi-core processors is a big challenge for developers of embedded real-time systems, especially considering existing âlegacyâ systems which have been developed with single-core processor assumptions. These systems have been developed and maintained by many developers over many years, and cannot easily be replaced due to the huge development investments they represent. In this paper we investigate challenges of migrating complex legacy real-time systems to multi-core architectures. We propose a partitioning algorithm to prepare the migration. Partitioning groups task and maps them to the different cores on the multicore processor, increasing system performance while ensuring correctness. We have run experiments that compare outputs of the algorithm to the outputs of an exhaustive search. Based on a cost function, the algorithm produces systems very close to optimal partitioning with respect to the cost function.