csrc/crosstool-ng-1.20.0/COPYING

Unless otherwise stated in individual files, this work is licensed to you under
the following terms.

- Files in docs/ are available under the Creative Commons Attribution, Share
  Alike (by-sa), v2.5, to be found there:
    licenses.d/by-sa/deed.en     (human-readable summary)
    licenses.d/by-sa/legalcode   (legal code, the full license)
    
- Files found in patches/*/ are available under the same license as the
  upstream software they apply to.

  That means that you can't use those patches if you were licensed the
  software under a specific license which is not the one the software is
  commonly available under.

  As an example, if you ever managed to get the Linux kernel under a license
  other than the GPLv2, you are not allowed to use the Linux kernel patches
  coming with crosstool-NG, as those are available under the GPLv2, which is
  the license the Linux kernel is most commonly available under.

  As a convenience, the GNU Lesser General Public License (LGPL) v2.1 (for the
  patches against glibc, uClibc, and some other libraries) is available there:
    licenses.d/lgpl.txt

- Other files not covered by the above licenses, and not covered by an
  individual license specified in the file itself, or an accompanying file,
  are available under the GNU General Public License (GPL), v2, to be found
  here:
    licenses.d/gpl.txt

- Also, I want to clarify one point. If you build a toolchain with crosstool-NG
  and you happen to sell, deliver, or otherwise publish this toolchain to a
  third party, I consider crosstool-NG as being part of the sources needed to
  rebuild the afore-mentioned toolchain, alongside with all other source code
  that third party is otherwise entitled to receive, due to other licenses of
  the different components. See licenses.d/gpl.txt, section 3, which reads:
   > For an executable work, complete source code means [...], plus the
   > scripts used to control compilation and installation of the executable.

  In short: crosstool-NG is the part refered to as "the scripts to control
  compilation and installation of the executable", it being the toolchain in
  our case; and as such you must make it available, in conformance to the
  GPLv2, see above.

  Also, if you have local patches that you apply to the different components
  (either manualy, or by instructing crosstool-NG to do so), you will have to
  make those patches available alongside with your toolchain, to comply with
  the licenses of the components impacted by your patches.