crossroad 0.5

Example: autotools

Let’s imagine you want to compile any software with a typical GNU compilation system, for Windows 64-bit.

1. First enter crossroad:

   $ crossroad w64

   Normally here your shell prompt will be modified at this point.

2. Enter your source code:

   $ cd /some/path/to/your/source/

   In a typical autotools project, you will have here access to a `configure` script, or with ways to build one, for instance by running an `autogen.sh` first.

3. Configure your build:

   $ crossroad configure

   There is no need to add a –prefix, a –host, or a –build. These are automatically and appropriately set up for you.

   Of course you should add any other option as you would normally do to your `configure` step. For instance if your project had a libjpeg dependency that you want to deactivate:

   $ crossroad configure –without-libjpeg

   See the ./configure –help of a project for listing of its available options.

4. Here the configure may fail if you miss any dependency. You may install many dependencies easily through crossroad. Crossroad relies on the Fedora MinGW project for this feature and provides basically a package manager for Windows cross-compiled packages (see the manual for more details on its features). Let’s say for instance that your project depends on glib. You could just run:

   $ crossroad install glib-devel

   Do this step as many times as necessary, until the configure step 3. succeeds. Then go to the next step.

5. Build:

   $ make
   $ make install

6. All done! Just exit your cross-compilation environment with ctrl-d or exit. To test your binaries on an actual Windows machine, crossroad provides 2 tools.

   1. Make a zip of your whole cross-compiled tree with the following:

      $ crossroad -c mysoftware.zip w64

      This will create a zip file mysoftware.zip that you can just move over to your test Windows OS. Then uncompress it, and set or update your PATH environment variable with the bin/ directory of this uncompressed prefix.

      Note: only zip format supported for the moment, since it is the most common compression format for Windows.

   2. If you are running Windows in a VM for instance, or are sharing partitions, you can just add a link in a shared directory. Just cd to the shared directory and run:

      $ crossroad -s w64 myproject

      This will create a symlink named myproject/ to the “w64” target. Since the directory is shared, it should be visible in Windows as a normal directory.

7. Then run your app, and enjoy!

Note: this has been tested with success on many GNU projects, cross-compiled for Windows: cairo, babl, GEGL, glib, GTK+, libpng, pango, freetype2, gdk-pixbuf and GIMP.

Example: CMake

CMake uses toolchain files. Crossroad prepared one for you, so you don’t have to worry about it. Simply replace the step (3) of the autotools example with this command:

$ crossroad cmake .

A common cmake usage is to create a build/ directory and build there. You can do so with crossroad, of course:

$ mkdir build; cd build
$ crossroad cmake ..

Alternatively crossroad allows also to use the curses interface of cmake:

$ crossroad ccmake .

The rest should be the same, and you can add any options to your build.

This has been tested with success on allegro 5, cross-compiled for Windows.

Example: other

It has not been tested with any other compilation system up to now. So it all depends what they require for a cross-compilation. But since a crossroad environment prepares a bunch of environment variables for you, and helps you download dependencies, no doubt it will already make your life easier.

The configure, cmake and ccmake command are simple wrappers around any ./configure script, and the cmake/ccmake commands, adding some default options (which crossroad prepared) for successful cross-compilation.

For instance crossroad configure is the equivalent of running:

$ ./configure --prefix=$CROSSROAD_PREFIX --host=$CROSSROAD_HOST --build=$CROSSROAD_BUILD

And crossroad cmake is nothing more than:

$ cmake . -DCMAKE_INSTALL_PREFIX:PATH=$CROSSROAD_PREFIX -DCMAKE_TOOLCHAIN_FILE=$CROSSROAD_CMAKE_TOOLCHAIN_FILE

Here is the list of useful, easy-to-remember and ready-to-use, environment variables, prepared by crossroad:

• $CROSSROAD_PREFIX;

• $CROSSROAD_HOST;

• $CROSSROAD_BUILD;

• $CROSSROAD_CMAKE_TOOLCHAIN_FILE.

• $CROSSROAD_PLATFORM

• $CROSSROAD_PLATFORM_NICENAME

What it means is that you can use these for other compilation system. You can also use your crossroad prefix, even for systems which do not require any compilation. Let’s say for instance you wish to include a pure python project in your build. No per-platform compilation is needed, but you still want to carry all the files in the same prefix. So just run:

$ ./setup.py –prefix=$CROSSROAD_PREFIX

and so on.

Note: as you may have guess `$CROSSROAD_PREFIX` encapsulates your new cross-build and all its dependencies. Though in most cases, you should not need to manually go there do anything, you still can (for instance to change software settings, etc.) with `cd $CROSSROAD_PREFIX`.