Creating Universal Extensions for Perl, Python and Ruby

With the advent of the Intel processor to the Macintosh family, software needs to be compiled/linked to run on multiple architectures. In OS X v10.4 and previous, extensions built by perl, python and ruby would only normally build for the native architecture. In OS X v10.5 and later, extension are built universal by default, and this can be customized.

Building Universal

Including the 64-bit architectures, there are currently 4 architectures that can be built:


Architecture Name	Description
i386	Intel (32-bit)
ppc	PowerPC (32-bit)
ppc64	PowerPC (64-bit)
x86_64	Intel (64-bit)

For example, to tell the compiler and linker to build the two 32-bit architectures (which is the customary setting), the following command-line arguments would be used:

-arch i386 -arch ppc

Building Perl, Python and Ruby Extensions

The process of building perl, python and ruby extensions is similar to that on other platforms. For perl, it looks something like:

    
                % perl Makefile.PL
              
                % make
              
                % make install

For python, it looks something like:

% python setup.py install

And for ruby:

    
                % ruby extconf.rb
              
                % make
              
                % make install

All of the arguments to the compiler and linker are automatically generated, and since most other operating systems don’t have the concept of multiple architectures, perl, python and ruby don’t know how to deal with them. It is possible to force additional architecture arguments to be used by the compiler and linker, but it isn’t pretty.

For perl, overriding some Makefile variable works in many cases (though is not the only way):

    
                % perl Makefile.PL
              
                % make PASTHRU_INC='-arch i386 -arch ppc' LD='cc -arch i386 -arch ppc'
              
                % make install

Likewise, for python, this usually works:

    
                % env CFLAGS='-arch i386 -arch ppc' LDFLAGS='-arch i386 -arch ppc' python setup.py install

And for ruby:

    
                % env CFLAGS='-arch i386 -arch ppc' LDFLAGS='-arch i386 -arch ppc' ruby extconf.rb
              
                % make
              
                % make install

OS X v10.5 and later

In OS X v10.5 and later, the default for perl, python and ruby extensions is to build the two 32-bit architectures. In most cases, this is what is desired, so there will be no difference in the build procedures.

However, for those times when a different set of architectures is desired, a new environment variable can be used to change this. For example, to build a perl extension only for 32-bit PowerPC, you can use:

    
                % env ARCHFLAGS='-arch ppc' perl Makefile.PL
              
                % make
              
                % make install

or for python:

% env ARCHFLAGS='-arch ppc' python setup.py install

or for ruby:

    
                % env ARCHFLAGS='-arch ppc' ruby extconf.rb
              
                % make
              
                % make install

Or, you can set the ARCHFLAGS environment variable globally, and then just run the normal build/install commands.

Perl, Python, and Ruby Extensions Release Notes