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What is POSIX? Why POSIX conformance is important for embedded real-time developers

Next: POSIX.1, .1b and .1c

What is POSIX®? POSIX is the Portable Operating System Interface, the open operating interface standard accepted world-wide. It is produced by IEEE and recognized by ISO and ANSI.

LynuxWorks™ has been committed to the POSIX standard for the past 20 years
LynxOS real-time operating system.

The LynxOS® real-time operating system is certified POSIX-conformant and also supports all of the routines in POSIX.1b and POSIX.1c.

ICI came to LynxOS for its POSIX conformance after an earlier project team was unable to port one of its Solaris™-based military software projects to a non-POSIX conformant operating system (VxWorks®). Read the full story.

POSIX support assures code portability between systems and is increasingly mandated for commercial applications and government contracts. For instance, the USA's Joint Technical Architecture—Army (JTA-A) standards set specifies that conformance to the POSIX specification is critical to support software interoperability.

POSIX conformance is worth more than POSIX compliance

POSIX conformance is what real-time embedded developers are usually looking for. POSIX conformance means that the POSIX.1 standard is supported in its entirety. In the case of the LynxOS real-time operating system, the routines of the POSIX.1b and POSIX.1c subsets are also supported.

Certified POSIX conformance exists when conformance is certified by an accredited, independent certification authority. For example, LynxOS has been certified conformant to POSIX 1003.1-1996 by Mindcraft, Inc. and tested against FIPS 151-2 (Federal Information Processing Standard).

POSIX compliance is a less powerful label, and could merely mean that a product provides partial POSIX support. "POSIX compliance" means that documentation is available that shows which POSIX features are supported and which are not.

  • Be wary of claims like POSIX operating system or 95% POSIX, which do not specify POSIX conformance.
  • Remember that POSIX compliance does not always mean that all POSIX-defined features are supported.

Always ask for proof of POSIX conformance

The IEEE stipulates that a conformance document must be made available for products which claim POSIX conformance. Please browse our LynxOS POSIX documentation here — PDF file (954 kB).

The LynxOS real-time operating system is certified POSIX-conformant and also supports all of the routines in POSIX.1b and POSIX.1c. We subject LynxOS to our test suites for POSIX.1, POSIX.1b, and POSIX.1c. A failure from any POSIX call in our test suites is considered a bug and is kicked back to engineering for repair.

Next: POSIX.1, .1b and .1c

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Security white papers
Separation Kernels Enable Rapid Development of Trustworthy Systems
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Coming Together of Safety and (Cyber) Security Changes Demands in RTOS Market
Separation kernels and secure hypervisors will be evermore in demand as safety and certification will be required in more and more applications. Governments are already working on infrastructures deploying this type of technology. (October 2012)
Building in RTOS Support for Safety- & Security-Critical Systems
LynuxWorks explains the differences between safety-critical and security-critical applications and how to meet their demanding requirements with the LynxOS-178 RTOS and the LynxSecure hypervisor. (EE Times Design, August 2011)
Enhancing Application Performance on Multicore Systems
Tips on optimizing a multicore real-time system, including virtualization, avoiding synchronization and concurrency while maximizing application parallelism. (Military Embedded Systems, February 2011)
Hardware Virtualization puts a new spin on Secure Systems
Real-time determinism and military security don't have to be separate realities. A combination of a secure separation kernel and an embedded hypervisor enables whole new levels of system security. (COTS Journal, October 2010)
Using a Separation Kernel to add Military-Grade Security to Legacy Systems
A challenge for the software designer is how to integrate modern military-grade software programs into legacy software designed long before security standards were predominant in system requirements. (VME Critical Systems, Summer 2010)
Virtualization: Keeping Embedded Software safe and Secure in an Unsafe World
A new, secure methodology is needed to separate systems of different security levels which run on shared resources—without compromising the performance of legacy systems. (EE Times, June 2010)
Secure Virtualization Combines Traditional Desktop OSs and Embedded RTOSes in Military Embedded Systems
Advances in software and hardware technologies now make it feasible to use both embedded and desktop operating systems in a secure military system. (Military Embedded Systems, May 2010)
DO-178B Provides Certification Safety net
Developers of commercial avionics software must demonstrate compliance with DO-178 guidelines. The FAA has issued additional guidance for so-called DO-178B Reusable Software Components (RSCs as defined in AC20-148), which allow for reuse of certifications. (COTS Journal, November 2009)
Designing Safety-critical Avionics Software Using open Standards
Safety-critical avionics systems have continually grown more complex and software-intensive. Regulatory authorities and avionics manufacturers have responded with guidance such as DO-178B and RSC to ensure that software performs safely, with controlled development cost. (Boards and Solutions, September 2009)
Two Different Realms: RTOS Support for Safety-critical vs. Security-critical Systems
Safety- and security-critical system functions are evolving simultaneously, with different yet similar requirements. Modern RTOSes are stepping up to meet these needs. (VME and Critical Systems, June 2009)
Virtualization Makes Better use of Open-source OSes and apps
With the introduction of the embedded hypervisor, embedded systems can avoid certain performance or licensing issues inherent to open-source OSes and applications. (EE Times, March 23, 2009)
Secure Virtualization Technology can Extend the life of Legacy Systems
By combining the concept of virtualization and security, one can consolidate multiple legacy systems running on heterogeneous operating systems onto a single host system with high-assurance security. (Military Embedded Systems, January/February 2009)
Virtual Machines: Intel's CPU Extensions Transform Virtualization
Virtualization has traditionally presented its share of design challenges in information-assurance-based systems. But now, Intel's VT-x and VT-d CPU extensions are changing the game and showing potential to become the de facto path to virtualization. (Military Embedded Systems, January 2009)
Separation Kernel for a Secure Real-time Operating System
The technical foundation adopted for the so-called MILS architecture is a separation kernel like LynxSecure, which permits multiple functions to be realised on a common set of physical resources without unwanted mutual interference. (Boards and Solutions Magazine, February 2008)
Advances in Virtualization aid Information Assurance
Advances in the newest Intel® processors are making virtualization much easier to implement in security applications than ever before. (Embedded Computing Design, January 2008)
Protecting our most Vital Systems
Some significant defence programmes are already committed to a new approach to high-threat, high-asset-value systems. Rance DeLong explains MILS. (Components in Electronics, April 2007)
Perspectives: Security and the Separation Kernel
Today's avionics systems are designed to support more than one application, using a partitioned operating system and memory management units to ensure applications have adequate separation. (Avionics Magazine, April 2007)
MILS: An Architecture for Security, Safety, and Real Time
The unrelenting growth and integration of embedded controls, information processing, and communications has created a need for systems that provide robust protection for resources and services in the face of serious threats. (Embedded Technology Magazine, November 2006)
Partitioning Operating Systems Versus Process-based Operating Systems
Partitioning operating systems are the latest buzz, while processes, by contrast, have been around for over 30 years. Both provide memory protection, however, the intent behind them is very different.
DO-178B and the Common Criteria: Future Security Levels
Although there are similarities between the airborne safety-critical requirements in RTCA/DO-178B and the Common Criteria, ISO 14508, compliance with the higher levels of security in the Common Criteria demands meeting additional security requirements. (COTS Journal, April 2006)
Reusing Safety-Critical Software Components
Safety-critical systems often operate together as a single "system-of-systems," making it important that they meet the most stringent and rigorous requirements for safety-criticality. The failure of one module in a system could create other failures or vulnerabilities, or worse yet, failure of the system as a whole. (COTS Journal, August 2005)
Using the Microprocessor MMU for Software Protection in Real-Time Systems
With minimal impact to overall system performance, user tasks and the kernel can be protected from accidental corruption by using multiple protected address spaces.
Improving code Migration and Reuse
The unrelenting growth and integration of embedded controls, information processing, and communications has created a need for systems that provide robust protection for resources and services in the face of serious threats. (Embedded Computing Design, August 2006)
FCS Program Rolls Forward in Formation
A wireless data network, with advanced communications and technologies, links soldiers with 18 new, lightweight manned and unmanned ground vehicles, unmanned aircraft, sensors and weapons—and it's all in one program. (COTS Journal, June 2005)
Secure Operating Systems for Deeply Embedded Devices
As we add more intelligence to our embedded devices, we find that they are becoming increasingly integrated into our information technology infrastructure. Though system security is not a new concept, security-in-depth is a new paradigm developers are now starting to address. (RTC Magazine, September 2004)
LynxSecure Separation Kernel and Embedded Hypervisor LynxOS-SE Embedded RTOS Luminosity Eclipse-based IDE
LynxOS Embedded RTOS RTOS: LynxOS-178 for software certification

 

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