GNU Mach

GNU Mach is an implementation of the Mach microkernel. It is the default microkernel in the GNU Hurd. GNU Mach runs on IA-32 machines. GNU Mach is maintained by developers on the GNU project. It is distributed under the terms of the GNU General Public License (GPL).
History.
Early versions of the Hurd were developed on top of CMU's Mach 3.0.
In 1994, CMU stopped working on Mach, and the GNU Project switched to the University of Utah's Mach 4. The kernel known as "GNU Mach" was derived from Mach 4 once Utah stopped development. The first ChangeLog entry by Thomas Bushnell (rather than by a Utah researcher) is from 16 December 1996.
In 2002, Roland McGrath branched the OSKit-Mach branch from GNU Mach 1.2, intending to replace all the device drivers and some of the hardware support with code from OSKit. After the release of GNU Mach 1.3, this branch was intended to become the GNU Mach 2.0 main line; however, as of 2006, OSKit-Mach is not being developed.
GNU Mach 1.4 was released on 27 September 2013, eleven years after 1.3.