为了增强不同安全等级的复杂嵌入式安全关键系统的高可信能力,Hades架构以“时空隔离”思想和分区机制为基础,各分区分时共享系统物理资源.针对Hades中分区的实时调度问题,提出一种固定延迟分区调度模型,并采用优先级位图算法设计了分区级和任务级两级调度机制;为了保障分区中所有实时任务的可调度性,对分区中任务组采用单调速率调度和最早截止时间优先2种调度策略,并分别给出任务可调度条件.最后,通过仿真实验进一步验证了该调度模型的有效性.
To enhance the dependability and security of complex embedded security/safety-critical systems with multi-levels security (MLS), a trusted architecture, called Hades, is presented. Hades is based on "the concept of temporal and spatial isolation and the partition mechanism. Each partition shares the physical resource and uses only a fraction of the time, and so it is free from the interference of one another. This paper also proposes a scheduling model of the bounded-delay partition to solve the scheduling problem of partitions, and designs a two-level scheduling mechanism with priority bitmap algorithm using two scheduling policies, Rate Monotonic (RM) and Earliest Deadline First (EDF). The schedulable conditions for preemptive fixed priority and dynamic priority scheduling policies are provided separately. Simulation results demonstrated the effectiveness of the proposed model.