Building Fundamentally Extensible Application-Specific OperatingSystems in SPACE

We refine and extend previous work towards a new approach to implementingoperating systems. This approach, called SPACE, uses processors, addressspaces, and a generalized exception mechanism as the basic abstractions ratherthan processes, virtual memory, and interprocess communication. The result isthat the facilities provided by the hardware architecture are exposed, and canbe directly used by applications to achieve higher performance and more diversefunctionality than is possible with conventional operating systemabstractions. In SPACE the conventional abstractions can coexist with newapplication-specific abstractions, due to the fundamental extensibility of theSPACE primitives. Applications can implement their own versions of systemservices to satisfy critical functional and performance requirements whilestill benefiting from standard system services. In this paper we present ageneralization of our earlier framework which allows the SPACE primitivesthemselves to be extended, and illustrate SPACE by describing an implementationon the SPARC architecture. We then give examples of implementing mechanisms inSPACE.