“Real-time Free Software solutions are moving forward with the
first release of ADEOS[1], a hardware abstraction layer allowing a
real-time kernel and a general purpose kernel to co-exist. RTAI[2]
will eventually use ADEOS services, thus offering a real-time
kernel based on a principle clearly different from the 5,995,745 US
Patent[3].“ADEOS implements a combination of principles[4] published in
the early nineties. A core idea was described in the SPACE 1991[5]
proposal and consists of a tiny layer that dispatches the hardware
resources between multiple concurrent operating systems. ADEOS is a
nanokernel that can service a real-time kernel with the highest
priority and a general purpose kernel with the lowest priority.
Some Free Software real-time solutions favored a different approach
where the real-time kernel runs the general purpose operating
system, as described in claims 1 and 7 of the 5,995,745 US Patent
(1996).“Philippe Gerum implemented ADEOS and released it under the GNU
GPL in June 3, 2002[1]. “My primary motivation was to be able to
keep contributing Free Software using a patent free technology. My
work was directly inspired by Karim Yaghmour’s[6] paper published
in February 2001[4]. It grounded the implementation onto an
original and solid theoretical background” says Philippe
Gerum…”