Master Thesis - Past Projects - Abstract

Implementing Memory Protection in a Minimal OS

ID: LIU-IDA/LITH-EX-A--09/006--SE

The car industry has created a series of standards called AutoSAR as a response to the increasing number of processors in modern vehicles. Among these specifications is one for real-time operating systems (RTOS). This RTOS standard includes requirements for memory protection. This thesis outlines the work involved in introducing the memory protection outlined in this specification in the OSEck operating system. The work consisted of updating the operating system, implementing the AutoSAR OS API, and updating the suite of tools used to build the finished system. The AutoSAR specifications were found to be very thorough and well thought out. The OS API was successfully implemented, and the data-structures needed to permit its functionality. The existing software tools were updated to conform with the new requirements from AutoSAR, and additional software was created to ease the configuration process. Memory protection was successfully implemented in the OSEck operating system, including two implementations of the trap interface. The memory protection functionality adds yet another layer of user-configuration to the operating system. Also, additional overhead for system calls, context switches and message passing is expected. A general evaluation of how OSEck application performance is aff ected is beyond the scope of this thesis, but preliminary studies of additional instruction counts on certain system calls have been performed.

Keywords: MMU, Autosar, OSEK, Memory Protection, Embedded Systems

Author(s): Per Fagrell and Richard Eklycke

Contact: Simin Nadjm-Tehrani