Seeing O S Processes To Improve Dependability And Safety

This document proposes and evaluates a sealed process architecture as an alternative to the traditional open process architecture used in most modern operating systems. The key aspects of a sealed process architecture are: 1. Code within a process cannot change once execution begins (fixed code invariant). 2. A process's state cannot be directly accessed by other processes (state isolation invariant). 3. All communication between processes is explicit, with sender and receiver control (explicit communication invariant). 4. The kernel API respects the above invariants and does not allow them to be subverted (closed API invariant). The document describes an implementation of sealed processes in the Singularity operating system and presents preliminary benchmarks showing competitive performance compared to open