The M5 Simulator System

M5 is a modular platform for computer system architecture research, encompassing system-level architecture as well as processor microarchitecture.

New: There will be a tutorial on M5 on Sunday, June 5, in conjunction with ISCA 2005. We will be releasing an updated version of M5 prior to the tutorial.

Key features

Pervasive object orientation. Major simulation structures (CPUs, busses, caches, etc.) are represented as objects, both externally and internally. M5's configuration language allows flexible composition of these objects to describe complex simulation targets, e.g., multi-system networks where each system comprises multiple CPUs and a hierarchy of caches. M5's internal object orientation (using C++) provides in addition to the usual software engineering advantages.
Multiple interchangeable CPU models. M5 currently provides three interchangeable CPU objects: a simple, functional, one-CPI CPU; a detailed model of an out-of-order SMT-capable CPU; and a random memory-system tester. The first two models are use a common high-level ISA description (though only the Alpha ISA is supported at this time).
Event-driven memory system. M5 features a detailed, event-driven memory system including non-blocking caches and split-transaction busses. These components can be arranged flexibly, e.g., to model complex multi-level cache hierarchies. The caches support a separable coherence policy module; M5 currently includes a simple snooping cache coherence protocol.
Full-system capability. M5 models a DEC Tsunami system in sufficient detail to boot unmodified Linux 2.4/2.6 or L4Ka::Pistachio. We have also booted HP/Compaq's Tru64 5.1 operating system in the past, though we no longer actively maintain that capability.
Multiprocessor / multi-system capability. Thanks to M5's object orientation, instantiation of multiple CPU objects within a system is trivial. Combined with the snooping bus-based coherence protocol supported by the caches, M5 can model symmetric multiprocessor systems. Because a complete system is just a collection of objects (CPUs, caches, memory, etc.), multiple systems can be instantiated within a single simulation process. In conjunction with full-system modeling, this feature allows simulation of entire client-server networks.

For a more detailed (though dated) discussion of M5's features, see our paper "Network-Oriented Full-System Simulation using M5" from the 2003 CAECW Workshop.

Additional details

Application-only support. In application-only (non-full-system) mode, M5 can execute Alpha Tru64 binaries with OS emulation or SimpleScalar EIO trace files. Support for Alpha Linux binaries (allowing the use of binaries generated by an x86-hosted cross-platform gcc) is in progress.
Platforms. M5 runs on Intel x86-compatible systems running Linux or OpenBSD, and should be readily portable to other little-endian hosts and other Unix-like operating systems.
Provenance. Portions of M5 (EIO trace support and parts of the detailed CPU model) were derived from SimpleScalar. These portions are being released under the SimpleScalar license. We are in the process of developing a new detailed CPU model that will eliminate this dependency. We are also grateful to the SimOS and SimOS/Alpha developers, as SimOS/Alpha was an invaluable reference platform during our development of full-system mode.
Licensing. M5 is being released under a Berkeley-style open source license. Roughly speaking, you are free to use our code however you wish, as long as you leave our copyright on it. For more details, see the LICENSE file included in the source download. Note that the portions of M5 derived from other sources are also subject to the licensing restrictions of the original sources (notably SimpleScalar).

Download

The current public release of M5 is available at SourceForge. (This release is quite dated; a new release with significant updates will be made available prior to the ISCA 2005 tutorial.) Please use the SourceForge tools to file bug reports, support/feature requests, and patches. We also ask that you use the m5sim-users mailing list hosted at SourceForge to ask questions regarding M5. You may also want to subscribe to the SourceForge m5sim-announcement list.

Documentation

M5 uses doxygen for code documentation (though we still have a long way to go in documenting all the code). You can browse the documentation here. Included in the doxygen output are a number of overview and how-to type pages. There is also an overview of the stats package that we haven't moved in to doxygen yet.

Acknowledgments

The M5 simulator is being developed with generous support from several sources, including the National Science Foundation, Hewlett-Packard, Intel, and IBM. Individuals working on M5 have also been supported by an Intel Fellowship (Nate Binkert), a Lucent Fellowship (Lisa Hsu), and a Sloan Research Fellowship (Steve Reinhardt).

This material is based upon work supported by the National Science Foundation under Grant Nos. CCR-0105503 and CCR-0219640. Any opinions, findings and conclusions or recomendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation (NSF).

Why is it called M5?

The M5 Development Team

Last modified: Wed Feb 2 20:49:23 EST 2005