PROCESSES AND VIRTUAL MEMORY

LynxOS: Full implementation of POSIX.1, .1b and .1c.
POSIX is such an integral part of LynxOS that we ship it with a copy of the O'Reilly POSIX manual. Moreover, LynxOS' support for POSIX is one of the reasons we were able to build-in the Linux ABI-compatibility that LynxOS is known for.

In addition to the POSIX®.1 specification, the LynxOS® real-time operating system (RTOS) also fully implements the POSIX.1b and POSIX.1c subsets:

1. POSIX.1: POSIX core services (the feature set usually found in UNIX® operating systems)
2. POSIX.1b: real-time extensions
3. POSIX.1c: thread extensions

While LynxOS fully supports the POSIX.1b and POSIX.1c subsets, many operating systems only partially support them—if at all.

For example, "traditional" RTOSes usually implement portions of POSIX.1b and POSIX.1c, but they may lack many of the core POSIX.1 features such as fork(). Then there are operating systems like UNIX and Linux®, which are by nature very close to the POSIX.1 specification, but which rarely implement all of the real-time and thread extensions of POSIX.1b and POSIX.1c.

POSIX.1 Core Services (incorporates Standard ANSI C) Process Creation and Control Signals Floating Point Exceptions Segmentation Violations Illegal Instructions Bus Errors Timers File and Directory Operations Pipes C Library (Standard C) I/O Port Interface and Control There are standardized tests approved by the IEEE for POSIX.1 conformance. POSIX.1 is the feature set most commonly found in UNIX operating systems, and the POSIX test suite was the means used to insure that UNIX operating systems are interoperable. LynxOS first passed the official NIST POSIX-conformance test suite FIPS 151-1, and was later recertified to the more stringent FIPS 151-2. The official sites for certified POSIX conformant products are: http://www.nist.gov/itl/div897/ctg/posix/finalreg4.htm (FIPS 151-2 validated products 1997 and earlier) http://standards.ieee.org/regauth/posix/posix2.html (FIPS 151-2 validated products 1997 and later)

POSIX.1b Real-time extensions POSIX.1c Threads extensions Priority Scheduling Real-Time Signals Clocks and Timers Semaphores Message Passing Shared Memory Asynch and Synch I/O Memory Locking Thread Creation, Control, and Cleanup Thread Scheduling Thread Synchronization Signal Handling Currently, the NIST POSIX-conformance test suites do not cover the POSIX.1b and POSIX.1c extensions. However, a group of test suites is provided by the Open Group instead. These may be downloaded from: http://www.opengroup.org/testing/downloads.html

 

For a complete list of POSIX.1, POSIX.1b and POSIX.1c function calls, visit here.

 

"But is it POSIX-conformant?"

POSIX for embedded developers What is POSIX? POSIX.1, .1b and .1c POSIX Function Calls Reference Processes and Virtual Memory Parent-Child Processes Threads in POSIX Signals in POSIX LynxOS: POSIX-conformant RTOS POSIX PDF BROCHURE (170 kB) POSIX TRAINING: Real-time system course O'REILLY PROGRAMMING GUIDES for LynuxWorks operating systems POSIX Programmers Guide Pthreads Programming POSIX.4 Programmers Guide A savvy engineer just needs to ask a few quick questions about an operating system in order to determine if it might fully support the POSIX standards. "Does each process in the operating system reside in a different name space and have its own symbols table? "Does the operating system support the fork() call?" "Can the operating system distinguish between threads and processes?" "Does the operating system support signals?"

PROCESSES AND VIRTUAL MEMORY