Memory Management Units (MMUs) are traditionally used by operating systems to implement disk-paged virtual memory. Some operating systems allow user programs to specify the protection level (inaccessbile, read-only, read-write) of pages, and allow user programs to handle protection violations, but these machanisms are not always robust, efficient, or well-matched to the needs of applications. We survey several user-level algorithms that make use of page-protection techniques, and analyze their common characteristics, in an attempt to answer the question, "What virtual-memory primitives should the operating system provide to user processes, and how do today's operating systems provide them?

This technical report has been published as

Virtual memory primitives for user programs. Andrew W. Appel and Kai Li, Proc. Fourth Int'l Conference on Architectural Support for Prog. Languages and Operating Systems, (ACM SIGPLAN Notices 25(4)) pp.96-107, April 1991.