The Exception Handling Effectiveness of POSIX Operating Systems
IEEE Transactions on Software Engineering
A provably correct operating system: &dgr;-core
ACM SIGOPS Operating Systems Review
Safety critical systems: challenges and directions
Proceedings of the 24th International Conference on Software Engineering
Distance-Constrained Scheduling and Its Applications to Real-Time Systems
IEEE Transactions on Computers
EMERALDS: a microkernel for embedded real-time systems
RTAS '96 Proceedings of the 2nd IEEE Real-Time Technology and Applications Symposium (RTAS '96)
On memory protection in real-time OS for small embedded systems
RTCSA '97 Proceedings of the 4th International Workshop on Real-Time Computing Systems and Applications
Partition Scheduling in APEX Runtime Environment for Embedded Avionics Software
RTCSA '98 Proceedings of the 5th International Conference on Real-Time Computing Systems and Applications
Scheduling real-time applications in an open environment
RTSS '97 Proceedings of the 18th IEEE Real-Time Systems Symposium
Matching micro-kernels to modern applications using fine-grained memory protection
SPDP '95 Proceedings of the 7th IEEE Symposium on Parallel and Distributeed Processing
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In this paper, to research and design ultra-dependable embedded real time operating system supporting security and safety, spatial and temporal isolation safeguard is proposed and used. Temporal isolation mechanism guarantees a subsystem can exclusively use a pre-allocated processing time without any intervention from other subsystem. On the other hand, spatial isolation implies that a subsystem cannot inadvertently access other subsystem's space resources, like memory, buffers, I/O ports, and registers. Thus, a subsystem is the owner of its resources, such as memory, I/O ports, and processor time units. From this, the real time tasks running in different subsystems never interfere with each other. To support the temporal isolation among subsystems, a two-level scheduling model is designed, which consists of a low-level cyclic schedule at the operating system level and high-level fixed priority schedule at subsystem level. Thus, a real time task in a subsystem can only be scheduled and executed during the static time window allocated to the subsystem, and any task overrun cannot cross the time window boundaries of subsystem. It is very easy to restrain a task time-failure within the subsystem with temporal isolation mechanism. In reference to spatial isolation safeguard, a based on hard currency and error holding mechanism is presented, it apply to most embedded modern processors with memory protection unit, such as i386sx, PowerPC. As a result, an ultra-dependable embedded RTOS supporting temporal and spatial isolation safeguard is implemented and verified. It is called ERTOS designed by Software Engineering Institute of East China Normal University.