1.2 Features

GNU Mach is not the most advanced microkernel known to the planet, nor is it the fastest or smallest, but it has a rich set of interfaces and some features which make it useful as the base of the Hurd system.

it's free software

Anybody can use, modify, and redistribute it under the terms of the GNU General Public License (see Copying). GNU Mach is part of the GNU system, which is a complete operating system licensed under the GPL.

it's built to survive

As a microkernel, GNU Mach doesn't implement a lot of the features commonly found in an operating system, but only the bare minimum that is required to implement a full operating system on top of it. This means that a lot of the operating system code is maintained outside of GNU Mach, and while this code may go through a complete redesign, the code of the microkernel can remain comparatively stable.

it's scalable

Mach is particularly well suited for SMP and network cluster techniques. Thread support is provided at the kernel level, and the kernel itself takes advantage of that. Network transparency at the IPC level makes resources of the system available across machine boundaries (with NORMA IPC, currently not available in GNU Mach).

it exists

The Mach microkernel is real software that works Right Now. It is not a research or a proposal. You don't have to wait at all before you can start using and developing it. Mach has been used in many operating systems in the past, usually as the base for a single UNIX server. In the GNU system, Mach is the base of a functional multi-server operating system, the Hurd.