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openfoam/doc/cross-compile-mingw.md
2019-04-28 13:36:50 +02:00

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Notes for cross-compiling with mingw.

On openSUSE use the packages:

mingw64-cross-binutils
mingw64-cross-cpp
mingw64-cross-gcc
mingw64-cross-gcc-c++
mingw64-filesystem
mingw64-headers
mingw64-runtime

mingw64-libwinpthread1
mingw64-winpthreads-devel

mingw64-libfftw3
mingw64-fftw3-devel

This setup is missing zlib, so download that manually and compile as a static library.

CC="$(wmake -show-c) CFLAGS="$(wmake -show-cflags) ./configure --static

The resulting output files (zconf.h zlib.h) and (libz.a) either need to be installed in system locations where OpenFOAM can find it, or if they are to be shipped directly with OpenFOAM, they can also be placed in the src/OpenFOAM/include and platforms/XXX/lib paths.

When using the cross-compiled executables and libraries, additional runtime libraries are required. On openSUSE these are provided by the packages:

mingw64-libgcc_s_seh1
mingw64-libstdc++6

In a few locations within OpenFOAM, flex is used to generate code. The generated C++ code requires the FlexLexer.h header file. This is normally located under /usr/include/FlexLexer.h, which will be ignored by the cross-compiler.

As a fairly ugly hack, a copy of this file can be made in a standard project include location. For example,

mkdir src/OpenFOAM/lnInclude
cp /usr/include/FlexLexer.h src/OpenFOAM/lnInclude

The last point to consider when cross-compiling is the behaviour of the OpenFOAM tools used during compilation. These are found under wmake/src. When these are compiled they will create executables that work on the target platform (Windows), but not on the host platform.

The workaround:

  1. Activate the native OpenFOAM environment (Linux with system gcc) and use that to compile the build tools
wmake/src/Allmake

This can be skipped if you already have an existing OpenFOAM build.

  1. Activate the OpenFOAM for cross-compiling (Linux with mingw) and use that to compile the build tools
wmake/src/Allmake
  1. Copy the contents of the native platform build tools into the cross-compilation platform directory. For example,
cp wmake/platforms/linux64Gcc/* wmake/platforms/linux64Mingw/

The wmake/platforms/linux64Mingw/ directory should now contain native and cross-compiled tools:

dirToString
wmkdep
wmkdepend

dirToString.exe
wmkdep.exe
wmkdepend.exe

The native tools are the one that will (automatically) be used throughout the balance of the cross-compilation process.

Adjust paths for third-party sources. Eg, in etc/config.sh/FFTW you may wish to have the following:

fftw_version=fftw-system
export FFTW_ARCH_PATH=/usr/x86_64-w64-mingw32/sys-root/mingw

The settings for cross-compilation are normally defined in the etc/pref.sh file with contents like this:

# For mingw cross-compile

export WM_COMPILER=Mingw
export WM_MPLIB=MSMPI

export WM_LABEL_SIZE=32
# other settings...

Additional adjustments may be required in some other places. For example in etc/config.sh/FFTW

fftw_version=fftw-system
export FFTW_ARCH_PATH=/usr/x86_64-w64-mingw32/sys-root/mingw

Known limitations (2019-05-01)

  • No CGAL support (ie, no foamyHexMesh)
  • No ParaView plugin, runTimepostProcessing
  • reacting EulerFoam solvers have too many interdependencies and do not yet compile.