Simple Memory Protection for Embedded Operating System Kernels

This paper describes the design and implementation of memory protection in the Roadrunner/pk operating system. The design is portable between various CPUs that provide page-level protection using Memory-Management Unit (MMU) hardware. The approach maps logical addresses one-to-one to physical addresses and uses the MMU to overlay protection domains over regions of memory that are in use by application threads and the kernel. An analysis of code size shows that this design and implementation can be executed with an order of magnitude less code than similar function in the Linux 2.2.14 kernel while providing comparable performance for basic memory protection operations.