Colla Rsch:CRD: Community Resource Development: An Open Source Project Proposed: This collaborative project, developing an extensible open source Virtual Machine Monitor (VMM) for modern architectures (those that support the Intel VT or AMD Pacifica virtualization extensions), aims to maintain a small codebase size while supporting extensive extensibility. The approach combines compile-time composition of major modules to configure the VMM with run-time extensibility akin to a microkernel. The project is expected to produce a fundamental tool for research in systems and architecture, an open source extensible virtual machine monitor. Expecting to meet the needs within the high-end computing community identified by the FAST-OS effort, the VMM will be used as a shared community resource. Broader Impacts: The infrastructure will be useful in research and education and production context. It will be free and available to all in source code form. Underrepresented groups are impacted through Northwestern's AGEP program and through U NM, a minority serving university.