Real-Time Linux Inside Defense Industry

Lockheed Martin Space Systems is going open source for simulation testing.

The defense contractor will use Concurrent’s real-time RedHawk Linux operating system for the U.S. Army’s Theater High Altitude Area Defense (THAAD) program, a strategic missile defense subsystem simulation testing program.

Financial terms of the deal were not publicly disclosed.

Lockheed Martin will use RedHawk in hardware-in-the-loop (HIL) simulation testing, which allows for testing of components in a, “closed loop that is
reproducible, systematic, fast and more reliable than actual bench testing.”

RedHawk is not a new Linux distribution, but rather a
series of enhancements on top of Red Hat Enterprise Linux that provides real-
time “deterministic” capabilities to the OS.

Concurrent’s director of real-time marketing, Gary Beerman,
defined deterministic as the ability for a user to run an application or
scenario in the same time and be able to repeat the same scenario without
anything else interrupting it.

He told that almost everything in the RedHawk OS is Red Hat Enterprise Linux, albeit booted with the RedHawk kernel and its extensions.

RedHawk’s Linux kernel includes a priority preemptive scheduler, a higher
level of real-time determinism and capability to do process shielding. The
RedHawk extensions also enable users to partition applications to run on a
particular processor inside of multi-processor systems.

The user interface enables users to schedule tasks so that when the application comes
up it can be locked onto a particular processor and no other application in
the system can use that processor.

“That is one of the great strengths of RedHawk,” Beerman said. “By better controlling the resources of the system you can
better guarantee the determinism of how an application is going to run.”

The RedHawk Linux solution as shipped by Concurrent actually includes the
standard Red Hat Enterprise Linux installation CDs, though support is
handled via Concurrent. Beerman noted that Concurrent already has existing
support contract in place with Red Hat.

There weren’t any major technical objections to Lockheed’s use of Linux, though there was a legal objection. Beerman said that
Lockheed’s corporate lawyers had a concern about the GPL licensing.

When code is linked against GPL licensed code, a concern exists that all
the code then must be open and available to everyone. Beerman explained that
Lockheed’s corporate lawyers were concerned about the potential of having to
open up their military programs for the world to see.

“The only thing that they had to be made aware of was that if they link
against GPL licensed code, some of their code could then also fall under GPL
licensing rules, which really means they need to link against LGPL,” Beerman

The LGPL, or Lesser GPL, allows for non-free libraries to be linked
against it. Concurrent however was able to alleviate the legal concerns with
a technical solution.

“We have a tool that shows them on regular Linux systems which libraries
are GPL and which ones are not,” Beerman said.

Concurrent’s RedHawk isn’t the only Linux effort to improve the real-time
capabilities of Linux.

MontaVisa Linux has been spearheading the development
of and open source real-time extensions patch for Linux for over a year
and recently included its work in a new release.

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