This project was initially started as a userspace testbed for kernel
and embedded development. In particular, some of this work has been
reused in the X15 and GNU/Hurd projects, which are licensed under GPLv3+
and GPLv2 respectively. Some of it is also used in proprietary software.

As a result, files found both in this library (under a BSD license) and
GPL covered projects (under a GPL license) are actually double licensed.
They can be reused from this library under the 2-clause BSD license.

On the other hand, files licensed under the GPLv3+ aren't double licensed.
As a special exception, they may be reused in the GNU/Hurd project under
the GPLv2 license.