Introducing FeS2

We would like to announce the first public release of the FeS2 simulator. FeS2 is a timing-first, multiprocessor, x86 simulator, implemented as a module for Virtutech Simics.


  • (12/02/2010) Very nice FeS2 and Simics tutorials posted by Simha Sethumadhavan and his students
  • (03/13/2009) 64-bit version of FeS2 released (svn r95)
  • (10/01/2008) Multiprocessor version of FeS2 released (svn r50)
  • (06/02/2008) Initial release of the FeS2 uniprocessor model (svn r30)
  • (03/02/2008) Poster presented at ASPLOS 2008

FeS2 Features

  • Open sourced under GPLv2
  • Accurate execution-driven timing-model that includes a cache hierarchy, branch predictors and a superscalar out-of-order core.
  • Simulates the x86 ISA
    • Enables research to use tools that only exist on x86 or are much more mature on x86 (e.g. Pin, Apache Harmony). It also enables the evaluation of applications that are only available as x86 binaries (e.g. Microsoft Word, Adobe Photoshop).
  • Full-system simulation (i.e. simulates both user code and the operating system)
    • Necessary to correctly evaluate multi-threaded applications. Multi-threaded applications are both affected by operating-system thread-scheduling and communicate via operating-system mechanisms such as signals.
  • Multiprocessor memory model
    • Relevant to many areas of research, FeS2 provides a detailed and flexible memory system timing model. The memory model is provided by Ruby (leveraged from a pre-release version of GEMS).
  • Timing-first simulation methodology
    • The known-good functional model provided by Simics can run any x86 application and operating system thereby enabling their evaluation with the mostly-correct FeS2 timing model (which was easier to implement).
  • Micro-operation based core model
    • Decodes x86 instructions into RISC like micro-operations (uops) as is done in high-performance x86 implementations. The decoding of x86 instructions into uops and the functional implementation of the uops is implemented using code leveraged from PTLsim.