A Study on the Portability of IoT Operating Systems Renata Gomes and Marcel Baunach The IoT is set to permeate our lives as a new and global super infrastructure, where billions of devices with an unprecedented variety of hardware architectures will interact. To enable IoT applications and services to run everywhere without major adaptation, operating systems (OS) provide standardized interfaces to the heterogeneous hardware. As a consequence, an operating system for IoT devices must be available for a huge number of target platforms, from low-end to high-end devices, and it must guarantee different levels of dependability (e.g., safety, security, real-time, maintainability) that each application will require. Some of these hardware architectures do already exist, others will emerge over time and introduce new or improved features that must be supported or exploited by the OS. In order to succeed, an OS must thus be portable, not only concerning its functionality, but also its verified dependability. This paper tries to answer the question of how portable existing IoT OSs are, analyzing five popular OSs on their design, development, and testing processes, as well as the quality of available ports. We close with a suggestion on how to improve portability for future OS designs.