A multi-core version of FreeRTOS verified for datarace and deadlock freedom

Abstract

We present the design of a multicore version of FreeRTOS, a popular open source real-time operating system for embedded applications. We generalize the scheduling policy of FreeRTOS to schedule the n highest-priority longest-waiting tasks, for an n-core processsor. We use a locking mechanism that provides maximum decoupling between tasks, while ensuring mutually exclusive access to kernel data-structures. We provide an implementation of the portable part of FreeRTOS (written in C) and provide the device specific implementation of the locking mechanism for Intel and ARM Cortex multicore processors. We model the locking mechanism and the locking protocol used by the API's in the Spin model-checking tool and verify that the design is free from dataraces and deadlocks. Finally, we extend the existing FreeRTOS Windows simulator to simulate our multicore version of FreeRTOS, and evaluate its performance on some demo applications.

Formal Analysis of FreeRTOS Scheduler on ARM Cortex-M4 Cores

“…They propose a process to check the software in development [11] with Bounded Model Checking [14]. Chandrasekaran et al [8] modeled a custom implementation of multi-core FreeRTOS in PROMELA. They used SPIN to verify their model against data-race and deadlock.…”