News & Press

Green Hills Software's INTEGRITY RTOS Begins POSIX Conformance Certification

Securely Partitioned RTOS Increases Reliability and Security of POSIX Applications

OPEN GROUP FORUM, SAN DIEGO, CA-February 2, 2004— Green Hills Software, Inc., the market leader in royalty-free real-time operating systems (RTOS), today announced that it has extended the POSIX support in its INTEGRITY RTOS to include all interfaces and functionality necessary for conformance to the latest, 2003 POSIX.1 System Interfaces specification (IEEE standard 1003.1). Demonstrating Green Hills Software's continued commitment to open standards, it has started the process of certifying conformance under the "POSIX Certified by the IEEE and The Open Group" program.

POSIX defines a standard Linux and UNIX compatible interface between application software and an underlying operating system. The use of POSIX allows organizations to leverage their software investment across disparate projects that use different POSIX compliant operating systems. "The Navy's Open Architecture initiative utilizes POSIX as a means for providing portable software that can be used across Naval surface, subsurface and air platforms," said United States Navy Captain Thomas J. Strei, Director of Architecture and Technologies in the Program executive Office for Integrated Warfare Systems. "Commercial Off the Shelf (COTS) compliant POSIX products are needed to carry out the Navy's Open Architecture vision."

The INTEGRITY RTOS supplements POSIX memory protection with secure partitioning, allowing developers to build much more reliable and secure applications than previously possible with Linux and traditional POSIX operating systems. Memory protection only prevents one task from inadvertently corrupting the memory used by another. Secure partitioning guarantees that each task has the resources needed to run correctly, including memory and processor bandwidth. This ensures that errant or malicious tasks, or a denial of service attack, will not result in resource starvation.

Superior Alternative to Embedded Linux

"The INTEGRITY RTOS provides everything that developers are looking for from embedded Linux—POSIX interfaces, robust networking support, no royalties and source code availability—but the INTEGRITY RTOS is orders of magnitude smaller, faster, more reliable and more secure," said Dan O'Dowd, founder and chief executive officer of Green Hills Software. "With its significantly better development tools support, the INTEGRITY RTOS also enables manufacturers to get devices to market much faster and with much lower costs. Moreover, manufacturers who embed the INTEGRITY RTOS do not have to disclose their source code, as mandated by the General Public License that governs Linux, nor are they exposed to the risk of intellectual property contamination inherent in Linux."

"POSIX support in the INTEGRITY RTOS is highly optimized for embedded and real-time systems," added David Kleidermacher, vice president of engineering for Green Hills Software. "The POSIX memory footprint in the INTEGRITY RTOS is under 150 kilobytes, less than one-tenth the memory required by Linux. And unlike other operating systems that disable interrupts and preemption, the INTEGRITY RTOS is able to provably guarantee worst-case interrupt response times in the hundreds of nanoseconds and task switch times of about one microsecond, several hundred times faster than Linux."


POSIX support in the INTEGRITY RTOS has been extended to the newest specification, "IEEE Std 1003.1, 2003 Edition, Standard for Information Technology-Portable Operating System Interface (POSIX)." The INTEGRITY RTOS now provides over 1,000 functions that comprise the standard System Interfaces, including multiprocessing, threads, signals, file system interfaces, access control, pipes, queues, asynchronous I/O and timers.

Newly added interfaces include fork() and exec(), the standard multiprocessing primitives in Linux and UNIX systems. Most RTOSes lack an analog to fork() and exec(), making it extremely difficult to port applications not written specifically for an embedded system. The addition of fork() and exec() to the INTEGRITY RTOS provides developers with a high level of portability for UNIX and Linux applications.

For higher performance multiprocessing, the INTEGRITY RTOS also includes the posix_spawn() interface, which was added to the most recent POSIX specification. The posix_spawn() function can usually replace sequential calls to fork() and exec() with a single, much faster operation.

Under the POSIX certification program, the INTEGRITY RTOS will be validated against a POSIX test suite to prove its conformance.


POSIX support for the INTEGRITY RTOS is planned for release in April 2004, after POSIX certification has been received. The initial release will support the PowerPC, ARM, XScale, MIPS, x86/Pentium, and ColdFire target processors and Windows, Linux, Solaris, and HP-UX development hosts.

About Green Hills Software

Founded in 1982, Green Hills Software is the technology leader for real-time operating systems and software development tools for 32- and 64-bit embedded systems. The royalty-free INTEGRITY RTOS, compilers, MULTI and AdaMULTI integrated development environments, TimeMachine debugger and hardware probe product line offer a complete development solution that addresses embedded systems from the lowest cost consumer products to the most safety-critical aircraft flight systems. Green Hills Software is headquartered in Santa Barbara, CA, with European headquarters in the United Kingdom.

Green Hills Software, the Green Hills logo, MULTI, INTEGRITY, AdaMULTI, and TimeMachine are trademarks or registered trademarks of Green Hills Software, Inc. in the U.S. and/or internationally. All other trademarks and products are the property of their respective owners.

North American Sales Contact: Green Hills Software, Inc., 30 West Sola Street, Santa Barbara, CA 93101, Tel: 805-965-6044, Fax: 805-965-6343, Website:, Email:

International Sales Contact: Green Hills Software Ltd., Dolphin House, St. Peter Street, Winchester Hampshire SO23 8BW, United Kingdom, Tel: +44 (0)1962 829820, Fax: +44 (0)1962 890300, Email:

Media Contacts:
Green Hills Software, Inc.
Lynn J. Robinson
(805) 965-6044

Patterson & Associates
Barbara Stewart
(480) 488-6909