Composable and Predictable Dynamic Loading for Time-Critical Partitioned Systems

In time-critical systems such as in avionics, for safety and timing guarantees, applications are isolated from each other. Resources are partitioned in time and space creating a partition per application. Such isolation allows fault containment and independent development, testing and verification of applications. Current partitioned systems do not allow dynamically adding applications. Applications are statically loaded in their respective partitions. However dynamic loading can be useful or even necessary for scenarios such as on-board software updates, dynamic reconfiguration or re-loading applications in case of a fault. In this paper we propose a software architecture to dynamically create and manage partitions and a method for compostable dynamic loading which ensures that loading applications do not affect the running applications and vice versa. Furthermore the loading time is also predictable i.e. the loading time can be bounded a priori. We achieve this by splitting the loading process into parts, wherein only a small part which reserves minimum required resources is executed in the system partition and the other parts are executed in the allocated application partition which ensures isolation from other applications. We implement the software architecture for a SoC prototype on an FPGA board and demonstrate its composability and predictability properties.