An outspoken open source detractor has paid Linux a back-handed compliment. Green Hills Software (GHS), known for diatribes against Linux in military/aerospace applications, is shipping “Padded Cell technology” (PCT) intended to enable the company's proprietary real-time operating system (RTOS) to take advantage of the wealth of Linux application software.

Green Hills's colorful CEO Dan O'Dowd first lashed out against Linux in January, when he predicted the death of the Linux development tools market in a lively EE Time guest editorial. O'Dowd subsequently penned a series of press releases calling linux a national security threat, among other things. Now, it appears that GHS has been forced to support Linux applications under an “If you can't beat 'em, join 'em” scenario.

O'Dowd says his company has achieved a kind of Linux application binary compatibility through technology that enables Linux applications to run under Linux, which in turn runs in user space under GHS's Integrity RTOS. The approach appears to be similar to that taken by ADEOS, a resource sharing multi-OS environment often used with RTLinux.

A true Linux application binary interface (ABI), meanwhile, is available from LynuxWorks for its LynxOS RTOS, and another has been promised by Sun for Solaris. And, LynuxWorks and MontaVista have long shipped ABIs for VxWorks applications.

PCT implements a “virtual computer” in a user-mode application that runs on top of Integrity. Multiple PCT applications can run concurrently on a single physical computer, each hosting its own guest OS. According to GHS, an “impenetrable wall” surrounds each virtual computer, preventing “errant, insecure, or malicious code” from compromising precious system security or reliability. “Like a padded cell, Integrity PC prevents Linux and other insecure and unreliable software from harming the rest of a system, while also limiting the harm it can do to itself,” states O'Dowd.

GHS says PCT enables the incorporation of “legacy applications and traditional operating systems, such as Linux,” into high-security and high-reliability applications. It says PCT frees users from porting chores, and facilitates tracking upstream application updates. It says customer Boeing is already using PCT in several military applications.

Features claimed by GHS include:

• Guest OSes and apps run as user mode, and cannot alter the hardware's configuration
• Hardware memory protection prevents PCT apps from reading or writing memory not explicity allocated to them
• All I/O, including network communications, can be monitored by the host RTOS
• Resource guarantees can be configured for each virtual computer and host RTOS
• Deterministic real-time performance is provided by host RTOS
• Graphical configuration and visualization tools included

O'Dowd said, “With Integrity PC, users of enterprise operating systems can upgrade to a secure foundation without having to re-implement their existing applications. Legacy operating systems and applications can safely co-exist with totally reliable and security-critical applications running natively.”

Availability

Integrity PC is available now on PowerPC processors, with support for Linux as a guest OS.

 
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