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 the MIT license) and GPL covered projects (under a GPL license) are actually double licensed. They can be reused from this library under the MIT license. Some older copies may be found under a 2-clause BSD license.