This joint talk by Silicon Labs and Antmicro will guide you through the process of enabling the EFR32 MCU family in the Zephyr Project, with all its ups and downs, presenting a timeline and lessons learned. The talk will detail adding Zephyr support for the Silicon Labs BG22 and XG24 platforms. A comprehensive overview of the entire process will be presented, starting from taking over a pre-existing codebase, getting it up to date with current Zephyr standards, resolving licensing issues, HAL co-dependencies, maintainership questions, prioritization in the face of customer demand, code freezes etc. etc. We will also provide an insight into the current status of the port and plans for the future, demonstrate examples (including BLE support) and explain how to use continuous integration driver testing in a simulated environment with Renode and how to plug in similar RTOS port development efforts into Zephyr’s testing infrastructure for a smoother experience in mainlining the work.