Cross compile configuration

[Manu343726]

The current scripts only do the standard calls to b2 and the bootstrapper to get the Boost binaries from the CMake setup being run.

Any thoughts about how this setup should look like?

[pfultz2]

You can see here how MXE cross compiles boost for windows. It basically creates a user-config.bjam file, like this:

echo 'using gcc : mxe : $(TARGET)-g++ : <rc>$(TARGET)-windres <archiver>$(TARGET)-ar <ranlib>$(TARGET)-ranlib ;' > '$(1)/user-config.jam'

But rather than guess the names from the target, you can get the names from cmake variables: CMAKE_CXX_COMPILER, CMAKE_RC_COMPILER, CMAKE_RANLIB and CMAKE_AR variables.

[Manu343726]

Thanks Paul, it's a good reference.

I'm actually guessing the toolset from the CMAKE_CXX_VARIABLE, my problem is more on the way of "How user code should look like?" How the user may expect this to be called/requested?

Maybe:

$ bii cpp:configure -DBII_BOOST_CROSS_COMPILE=ON -DBII_BOOST_TOOLSET=gcc-arm -DBII_BOOST_TARGET_OS=linux

Note the BII_BOOST_TOOLSET variable already exists.

[pfultz2]

The user shouldn't need to define any extra variables, except maybe one for address-model, but that could probably could be inferred from the compiler name.

-DBII_BOOST_CROSS_COMPILE=ON

Use CMAKE_CROSSCOMPILING variable instead.

-DBII_BOOST_TOOLSET=gcc-arm

Infer from CMAKE_SYSTEM_NAME and CMAKE_CXX_COMPILER.

-DBII_BOOST_TARGET_OS=linux

Infer from CMAKE_SYSTEM_NAME.

Now for some esoteric systems, the user might need to define these variables; they can't be inferred(considering this is open source they can just open a PR for it). However, most likely they will define these extra variables in their cmake toolchain file. So then they can just call:

bii cpp:configure -DCMAKE_TOOLCHAIN_FILE=toolchain-mingw.cmake

Or call:

bii cpp:configure

If they add the toolchain file to their bii settings file.

[Manu343726]

I'm missing a +1 button on comments. Thanks for all the info.