Work-In-Progress: Real-Time RPC for Hybrid Dual-OS System

For the power and space sensitive systems such as automotive/avionic computers, an important trend is isolating and integrating multiple Operating Systems (OSs) in one physical platform, which is named as hybrid multi-OS system. Generally, in a commonly used hybrid dual-OS system, a RTOS (realtime operating system) and a GPOS (general-purpose operating system) are integrated. Cooperation (among the OSs) is a vital feature of a hybrid system to obtain the necessary capabilities, and inter-OS communication is the key. However, it is difficult to satisfy the real-time metrics of inter-OS communication required by the RTOS, due to the uncertainty in communication maintenance and the time-sharing policy of the GPOS. This paper aims to build a time predictable and secure RPC mechanism (i.e., the primary and critical communication unit in a hybrid multiOS system). Afterwards, a real-time RPC scheme (termed RTRG-RPC) is proposed, which is applied to a ready-built TrustZonebased hybrid dual-OS system (i.e., TZDKS). RTRG-RPC achieves accurate time control through three mechanisms: SGI message transforming, interrupt handler RPC servicing, and priority-swapping. Evaluations show that RTRG-RPC can achieve realtime predictability and can also reduce priority inversion.