Summary

  This document has presented the architecture, design and initial implementation of the virtual memory system for the Nemesis operating system. The key concepts of isolation and accountability lead to an architecture in which most memory management operations are carried out by each domain for itself. There is no ``system pager'' or ``user-level pager'' as in typical monolithic or microkernel systems: instead domains are all self-paging .

The role of the system is merely to allocate resources and maintain potentially critical information within system-wide tables. Protection and translation are simply relations stored within these tables and generally are publicly readable. Distribution and persistence may be implemented at user-level if desired.

A prototype implementation has demonstrated the validity of the architecture, but is by no means yet complete. There is still a considerable amount of work to be done, in particular with regard to translation structures, supporting CISC architectures, and the difficult problem of resource revocation.