Strong partitioning protocol for a multiprocessor VME system

The trend in implementing today´s embedded applications is toward the use of commercial-off-the-shelf open architecture. Reducing costs and facilitating systems integration are among the motives for that trend. The use of the VME bus becomes very common in many industrial applications. The VME bus attracts developers with its rigorous specifications, multiprocessing support and boards availability through multiple vendors. However, VME bus standard supports multiprocessing through shared memory, which does not impose strong function partitioning and allows fault propagation from one board to another. Such weakness limits the use of the VME bus in highly critical applications such as avionics. This paper presents techniques for strong partitioning of multiprocessor applications that maintains fault containment on the VME bus. The suggested techniques do not require any modification in the standard and the existing boards, and consequently maintains the plug-and-play advantage of the VME bus hardware products. The techniques are equally applicable to other tightly coupled multiprocessor systems. In addition, the paper describes the implementation of these techniques and reports performance results. Finally, the benefits of this technology for a space vehicle and commercial avionics are discussed.