crosstool-pio uses Crosstool-NG to build tools for PlatformIO (pio).

Crosstool-NG aims at building toolchains. Toolchains are an essential
component in a software development project. It will compile, assemble and
link the code that is being developed. Some pieces of the toolchain will
eventually end up in the resulting binaries:  static libraries are but an
example.

Refer to (http://crosstool-ng.github.io/docs/) for more information on how
to configure, install and use crosstool-NG.
