The Fedora MinGW project’s mission is to provide an excellent development environment for Fedora users who wish to cross-compile their programs to run on Windows, minimizing the need to use Windows at all. In the past developers have had to port and compile all of the libraries and tools they have needed, and this huge effort has happened independently many times over. We aim to eliminate duplication of work for application developers by providing a range of libraries and development tools which have already been ported to the MinGW cross-compiler environment. This means that developers will not need to recompile the application stack themselves, but can concentrate just on the changes needed to their own application.

As of Fedora 17 a set of RPM macros and packages have been introduced which help packagers compile binaries for multiple targets. The targets Win32 and Win64 are supported.

In general terms, cross-compiled MinGW versions of packages which are already natively available in Fedora, should follow the native Fedora package as closely as possible. This means they should stay at the same version, include all the same patches as the native Fedora package, and be built with the same configuration options.

The MinGW SIG have written an RPM comparison tool which makes it possible to compare cross compiled MinGW packages with the Fedora native packages, in order to determine whether versions, patches and configuration are aligned.

Cross compiled MinGW packages must follow Fedora policy, except where noted in this document. Cross compiled packages go through the same review process, GIT admin process etc as other Fedora packages.

MinGW packages require special naming to denote the appropriate CPU architecture the binaries have been built for. There should never be a package prefixed with mingw- output during a build. The mingw- prefix is exclusive for RPM spec file names and the source RPM file name. The CPU architecture specific packages are created by sections with %files -n mingw32-foo or %files -n mingw64-foo.

The base packages provide a root filesystem, base libraries, binutils (basic programs like 'strip', 'ld' etc), the compiler (gcc) and the Win32/Win64 API. Packages may need to depend on one or more of these. In particular, almost all packages should BuildRequire mingw32-filesystem, mingw64-filesystem, mingw32-gcc and mingw64-gcc. The correct Requires flags will get added automatically when the %{?mingw_package_header} macro is mentioned in the spec file (as will be described later on in these guidelines)

The goal of the MinGW framework is to provide an easy way for package maintainers to build their packages for multiple targets using one .spec file. To aid developers in this several RPM macros have been developed which are part of the mingw-filesystem package. These RPM macros will be explained later on in these guidelines.

By default a MinGW package will be built for both the Win32 and Win64 targets.

When a package can only be built for either one of these targets this can be indicated by setting one of these:

Each cross compiled MinGW package which builds binaries for a specific target should put the binaries for that target in a separate subpackage. So if a package foo builds binaries for the Win32 and Win64 targets, then the source RPM should provide two subpackages named mingw32-foo and mingw64-foo.

This means that a spec file must contains %package and %files sections for all the targets.

If a package contains translations then all calls to the %find_lang must be replaced by %mingw_find_lang. This causes all translation filelists to be split in per-target filelists. For example: when a spec file contains something like this:

then two files will get created named mingw32-foo.lang and mingw64-foo.lang. These file lists can be included in the %files section for the targets:

[root]
+  |+
+  +- etc+
+  |   |+
+  |   +- rpm+
+  |       |+
+  |       +- macros.mingw+
+  |       +- macros.mingw32+
+  |       +- macros.mingw64+
+  |+
+  +- usr+
+      |+
+      +- bin   - Links to MinGW cross compiler toolchain+
+      |   |+
+      |   +- i686-w64-mingw32-cpp+
+      |   +- i686-w64-mingw32-gcc+
+      |   +- i686-w64-mingw32-g` + `+      |   +- x86_64-w64-mingw32-cpp+` + `+      |   +- x86_64-w64-mingw32-gcc+` + `+      |   +- x86_64-w64-mingw32-g
+      |   +- …​ etc..+
+      |+
+      +- lib+
+      |   |+
+      |   +- rpm+
+      |       |+
+      |       +- mingw-find-debuginfo.sh - extract debug information from Win32 and Win64 binaries+
+      |       +- mingw-find-lang.sh - generates per-target file lists containing translations+
+      |       +- mingw-find-provides.sh - extra DLL names+
+      |       +- mingw-find-requires.sh - discover required DLL names+
+      |+
+      +- i686-w64-mingw32  - root of mingw toolchain and binaries for the Win32 target - see next diagram+
+      +- x86_64-w64-mingw32  - root of mingw toolchain and binaries for the Win64 target - see next diagram+

/usr/i686-w64-mingw32
/usr/x86_64-w64-mingw32
+  |+
+  +- bin  - Binutils toolchain binaries for the target+
+  |   |+
+  |   +- ar+
+  |   +- as+
+  |   +- dlltool+
+  |   +- ld+
+  |   +- …​ etc …​+
+  |+
+  +- lib  - Binutils toolchain support libraries / files for the target+
+  |+
+  +- sys-root  - root for cross compiled MinGW binaries+
+      |+
+      +- mingw+
+          |+
+          +- bin     - cross-compiled MinGW binaries & runtime DLL parts+
+          +- etc     - configuration files+
+          +- include - include files for cross compiled MinGW libs+
+          +- lib     - cross-compiled static MinGW libraries & linktime DLL parts+
+          |   |+
+          |   +- pkgconfig  - pkg-config definitions for libraries+
+          |+
+          +- share+
+              |+
+              +- man+

The MinGW cross-compilers and binutils are Fedora binaries and are therefore placed in %{_bindir} (ie. /usr/bin) according to the FHS and Fedora guidelines.

The MinGW cross-compilers and binutils which generate i686 binaries for Windows are named:

The same binaries are present in %{_prefix}/i686-w64-mingw32/bin without any prefix in the name, ie:

The same also applies for the x86_64 target. This target uses 'x86_64-w64-mingw32' as prefix instead of 'i686-w64-mingw32'

The root filesystem contains Windows executables and DLLs and any other Windows-only files. It is necessary both because we need to store Windows libraries in order to link further libraries which depend on them, and also because MinGW requires a root filesystem location.

The location for Win32 target is provided by the macro:

And the Win64 target is provided by the macro:

The mingw-filesystem package provides a number of convenience macros for the cross compiled sysroot directories, and toolchain. It is mandatory to use these macros in all MinGW cross compiled packages submitted to Fedora.

In order to build binaries for multiple targets we have to call commands like ./configure and make multiple times (once for each target). If one has to write this all out in a spec file then it will lead to duplicate code. To reduce the amount of duplication, several RPM macros have been introduced to help with the compilation. These macros are %mingw_configure, %mingw_cmake, %mingw_cmake_kde4, %mingw_qmake_qt4, %mingw_qmake_qt5 and %mingw_make

These macros use out of source compilation to build binaries for all the targets. Almost all packages support out of source compilation or require slight patching. The only known exceptions to date are zlib and openssl. Packages which don’t support out of source compilation may require a different approach like performing everything in the %install phase. If you happen to stumble across a package which requires a different approach feel free to contact us on the Fedora MinGW mailing list

Some packages need to be built multiple times for each target. Examples of this are packages which have to be built once for a static version and once for a shared version. Such packages can add a custom suffix to the build directory used. Say you’ve got something like below:

This can be rewritten to something like this:

Most packages used the command make %{?_smp_mflags} to build the package. In the MinGW cross compiler framework you have to use %mingw_make %{?_smp_mflags} to build the package for all configured targets. As with the %mingw_configure macro you can also use the MINGW_BUILDDIR_SUFFIX environment variable to indicate a custom suffix to the build directory used

To install the package the command make install DESTDIR=$RPM_BUILD_ROOT was used in almost all cases. This can be rewritten to %mingw_make install DESTDIR=$RPM_BUILD_ROOT to install the package for all configured targets The environment variable MINGW_BUILDDIR_SUFFIX can also be used here

Some packages require some custom instructions before the files are ready to be packaged. Such code can remain as is. However, you may need to duplicate these instructions multiple times (for all configured targets).

If a package contains binaries which depend on a DLL provided by another package, these dependencies should be expressed in the form:

where foo.dll is the name of the DLL. The name must be converted to lowercase because Windows binaries contain case insensitive dependencies. The form 'mingw32(foo.dll)' should be used for Win32 binaries and the form 'mingw64(foo.dll)' for Win64 binaries.

Correct dependency generation is done automatically. Packagers should start their spec files with this line:

All binary packages should depend on mingw32-filesystem or mingw64-filesystem (depending on the files in the package). If the line mentioned above is used then it will be added automatically, so you don’t have to add it yourself

All specfiles should BuildRequire at least one of these (depending on the targets for which you want to build):

BuildRequires:  mingw32-filesystem >= minimum-version
BuildRequires:  mingw64-filesystem >= minimum-version

and any other BuildRequires that they need.

The minimum-version must be at least 95 or any later version which provides the functionality you need

All packages should have:

BuildArch: noarch

unless they contain Fedora native executables.

All libraries must be built as DLLs.

Because of the peculiarity of Windows, DLLs are stored in the %{mingw32_bindir} directory, along with a control file in the %{mingw32_libdir} directory. For example, for a library called foo there would be:

The foo.dll file is the main library, foo.dll.a is a stub linked to applications so they can find the library at runtime. All of these files are required in those locations in order to link successfully. The .dll may contain a version number although not always (eg. foo-0.dll).

Most libraries also provide executables. These can include executables which can be used to test or showcase the library in question (for example gtk3-demo.exe in mingw-gtk3). Other examples are helper executables which are used by the library itself internally (for example gspawn-win32-helper.exe in mingw-glib2).

Executables which are required for proper functionality of the libraries must be packaged in the matching mingw32/mingw64 subpackage. All other executables are discouraged, but may be packaged in optional (dependent) subpackages at a packager’s discretion.

There are various types of files which are simply duplicates of equivalent files found in Fedora native packages. These files should not be packaged in the MinGW package. The following files don’t need to be packaged in the MinGW package when their native counterpart already contains them: