``libffi`` is notoriously messy to install and use --- to the point that
CPython includes its own copy to avoid relying on external packages.
-CFFI does the same for Windows, but (so far) not for other platforms.
+CFFI does the same for Windows, but not for other platforms (which should
+have their own working libffi's).
Modern Linuxes work out of the box thanks to ``pkg-config``. Here are some
(user-supplied) instructions for other platforms.