Compiling M5

M5 runs on Linux and OpenBSD, but should be easily portable to other Unix-like OSes. Cross-endian support has been mostly added, however this has not been extensively tested. All the syscall emulation (_SE) targets support running regardless of host/target endianess, however at present ALPHA_FS does not fully support big endian machines.

Required Software

To build M5, you will need the following software:

• g++ version 3.0 or newer. Once upon a time, M5 built with g++ 2.95, but it probably doesn't anymore.
• Python, version 2.4 or newer.
• SCons, version 0.96.91 or newer.
• SWIG, version 1.3.28 or newer.

SCons is a powerful replacement for make. See here[1], to download SCons, and here for installation instructions. Note that you can install SCons in your home directory using the '--prefix=' option (see here for details) or use SCons Local if you do not have administrator privileges on the machine you are trying to compile on.

The regression tester and a few utility scripts are written in Perl, but Perl is not strictly necessary to build the simulator.

Possible Targets

M5 can build many binaries each for a different guest architecture, simulation mode, and use. The currently available architectures are: ALPHA, SPARC, and MIPS, which are self explanatory.

Each of these can built in two simulation modes:

• FS - Full System mode. In this mode a complete system is simulated including a kernel, I/O devices, etc. It currently only works with the ALPHA architecture.
• SE - Syscall Emulation mode. This mode simulates statically compiled binaries by functionally emulating any syscall they make. .

Possible Binaries

• m5.debug - A binary used for debugging without any optimizations. Since no optimizations are done this binary is compiled the fastest, however since no optimizations are done it executes very slowly. (-g3 -gdwarf-2 -O0).
• m5.opt - A binary with debugging and optimization. This binary executes much faster than the debug binary and still provides all the debugging facility of the debug version. However when debugging source code it can be more difficult to use that the debug target. (-g -O3)
• m5.prof - This binary is like the opt target, however it also includes profiling support suitable for use with gprof. (-O3 -g -pg).
• m5.fast - This binary is the fastest binary and all debugging support is removed from the binary (trace flags for example). (-O3 -DNDEBUG)

Source Tree

Once you have obtained and unpacked the M5 sources, the root of your of your M5 source tree should have three directories:

• src - This directory contains the sources for the simulator itself.
• ext - This directory contains external packages used by M5 that are not commonly installed on systems.
• configs - This directory contains sample script files that can be used to run M5 and as a starting place for your own configurations.
• docs - This directory has the doxygen output in it and any other interesting bits documentation we have
• util - This directory has random programs that are used in conjunction with M5 such as Python scripts to process data in an DB, submit jobs to a batch processing system, etc.
• system - This directory contains platform dependent code such as BIOS, hypervisor, that someone using M5 may want to modify.

There are multiple architectures, modes and binaries that M5 can build.

• Architectures

  ALPHA 

  Alpha ISA

  SPARC 

  SPARC ISA

  MIPS 

  MIPS ISA

• Types

  FS 

  A binary for full system simulation. This currently only works with the ALPHA target.

  SE 

  A binary for syscall emulation.

• Target

  debug 

  A binary with no optimization and all debugging features (g++ -ggdb -g3 -O0 -DDEBUG)

  opt 

  A binary with optimization and all debugging features (g++ -ggdb -g3 -O5 -DDEBUG)

  fast 

  A binary with optimization and no debugging features (g++ -ggdb -g3 -O5 -DNO_DEBUG)

  prof 

  A binary with optimization that generates profile output suitable to use with gprof

Starting in the root of this tree, you can build M5 and test your build using the following commands.

% cd m5
% scons build/<arch>_<type>/m5.<target>

scons: Reading SConscript files ...
Checking for C header file fenv.h... yes
Building in /tmp/newmem/build/ALPHA_FS
Options file /tmp/newmem/build/options/ALPHA_FS not found,
  using defaults in build_opts/ALPHA_FS
Compiling in ALPHA_FS with MySQL support.
scons: done reading SConscript files.
scons: Building targets ...
g++ -o build/ALPHA_FS/base/circlebuf.do -c -pipe -fno-strict-aliasing
    -Wall -Wno-sign-compare -Werror -Wundef -g3 -gdwarf-2 -O0
    -DTHE_ISA=ALPHA_ISA -DDEBUG -Iext/dnet -I/usr/include/python2.4
    -Ibuild/libelf/include -I/usr/include/mysql -Ibuild/ALPHA_FS
    build/ALPHA_FS/base/circlebuf.cc
...

If your output looked like the above, then congratulations, you've complied M5!

Each configuration is built in a separate subdirectory of m5/build. For each configuration, the various flavors of binaries are built in the same directory. The default binary that you built above is ALPHA_SE/m5.debug. You can build other binaries by specifying them on the scons command line, e.g. 'scons ALPHA_SE/m5.opt' or 'scons ALPHA_FS/m5.debug'.