Porting a Real-Time Operating System – A Student Endeavour

The paper describes the integration of the Realtime Onboard Dependable Operating System (RODOS) into a CubeSat satellite developed by SeeSat e.V. in partnership with DHBW Ravensburg. It is achieved by porting RODOS onto an ARM Cortex-R family microcontroller, particularly the ARM Cortex-R5F. This enables the use of the operating system with various off-the-shelf RFSoCs to interface with radio links and attitude and control systems that require hard real-time constraints. Validation and Verification checks are first developed for an runtime environment utilizing the ARM Cortex-M4 architecture, which is already supported by RODOS. Afterwards they are transferred to the new ARM Cortex-R5 platform. The V andV campaign aims to prove the correct functioning of the ported operating system by executing the same test suite on the M4 as well as the R5 architecture. In addition to the porting activities, considerations are made regarding the general portability of RODOS to new platforms under various aspects. As a result of this project, a working RODOS port for ARM Cortex-R5 is made available, along with the V and V campaign that includes a test suite to ease future porting efforts of this real-time operating system. Additionally, various lessons learned about the general porting approach and the portability of RODOS are shared in the paper.