By introducing an operating system to an embedded device, we can expand its functionality and thereby speed-up the development of the end-product. We describe porting of a Linux operating system to a custom developed board based on ARM architecture. First part of the thesis starts with a short introduction into the history and design philosophy of the ARM architecture and operation of ARM processors. We use this information as a theoretical background for the project. Then we continue with the description of the LUX9 family of custom modules and boards based on ARM processors. Module LUX-SF9G with microprocessor Atmel AT91SAM9G is then described more into detail. The main part of the thesis describes porting of Linux operating system on the module and defines four most important elements of porting Linux to new devices. Following chapters describe porting of bootloaders, first stage AT91Bootstrap bootloader and second stage U-Boot bootloader, and customization and adaptation of the Linux kernel. We finish this section with the description of the root filesystem and building of Ångström distribution. Results and challenges we were facing during the project are presented at the end.