Arm Mbed is known as a free, open source platform and operating system that makes it easier to design IoT products based on Cortex-M micro-controllers, but the company figured out it might be a good idea to make something similar for IoT devices based on Arm Cortex-A processor and that’s exactly what Mbed Linux OS is made for.
Embedded & IoT devices normally need to be supported for many years, often optimized for cost and battery life, and make sure security patchsets are applying to your products. Companies often managed to do all those themselves but it’s not the most cost-effective solution, so instead Arm decided to leverage Linux and offer Mbed Linux OS optimized for IoT devices yo their customers. The solution comes with built-in security, device management (e.g. OTA firmware upgrades) via the Pelion IoT Platform, common development tools for faster time to market, and so on.