A new protection model for component-based operating systems

This paper describes a new model of program protection particularly suited to component-based operating systems. Instead of the traditional separate user and kernel processor modes and paging, segmentation is combined with a simple software technique to avoid the use of separate processor modes while maintaining full protection. This new model offers dramatically improved performance, simplified and improved architectures and increased flexibility. A component-based OS (called Go!) has been implemented using such techniques and early experiences with it are described in this paper. In this paper we show that Go! offers fully protected round-trip RPC in just 85 cycles on the Pentium, and the single processor mode allows the Object Request Broker (Go's analogue of a kernel) to be responsible only for component management. We show that such a system allows multithreading, device management, and even interrupt handling to be provided by separate 'application level' components without compromising protection.