Home
QNX Software Development Platform
QNX SDP is a cross-compiling and debugging environment, including an IDE and command-line tools, for building binary images and programs for target boards running the QNX OS 8.0.
System Architecture
The System Architecture guide accompanies the QNX OS and is intended for both application developers and end-users.
Resource Managers
To give the QNX OS a great degree of flexibility, to minimize the runtime memory requirements of the final system, and to cope with the wide variety of devices that may be found in a custom embedded system, the OS allows user-written processes to act as resource managers that can be started and stopped dynamically.
How do client programs talk to resource managers?
Since the QNX OS is a distributed, microkernel OS with virtually all nonkernel functionality provided by user-installable programs, a clean and well-defined interface is required between client programs and resource managers.
Communication via native IPC
Once a resource manager has established its pathname prefix, it will receive messages whenever any client program tries to do an open(), read(), write(), etc. on that pathname.

QNX Momentics IDE User's Guide
This User's Guide describes version 8.0 of the Integrated Development Environment (IDE) that's part of the QNX Tool Suite.
QNX Software Development Platform
QNX SDP is a cross-compiling and debugging environment, including an IDE and command-line tools, for building binary images and programs for target boards running the QNX OS 8.0.
- Quickstart Guide
- System Architecture
  The System Architecture guide accompanies the QNX OS and is intended for both application developers and end-users.
  - The Philosophy of the QNX OS
    The primary goal of the QNX OS is to deliver the open systems POSIX API in a robust, scalable form suitable for a wide range of systems—from tiny, resource-constrained embedded systems to high-end distributed computing environments. The OS supports several processor families, including x86 and ARM.
  - The QNX OS Microkernel
    The microkernel implements the core POSIX features used in embedded realtime systems, along with the fundamental QNX OS message-passing services.
  - Interprocess Communication (IPC)
    Interprocess Communication (IPC) plays a fundamental role in the transformation of the microkernel from an embedded realtime kernel into a full-scale POSIX operating system. As various service-providing processes are added to the microkernel, IPC is the glue that connects those components into a cohesive whole.
  - The Microkernel Instrumentation
    The microkernel (procnto-smp-instr) is equipped with a sophisticated tracing and profiling mechanism that lets you monitor your system's execution in real time. This instrumentation works on both single-CPU and SMP systems.
  - Process Manager
    The Process Manager can create and manage multiple POSIX processes, each of which may contain multiple POSIX threads.
  - Dynamic Linking
    In a typical system, a number of programs will be running. Each program relies on a number of functions, some of which will be standard C library functions, like printf(), malloc(), write(), etc.
  - Resource Managers
    To give the QNX OS a great degree of flexibility, to minimize the runtime memory requirements of the final system, and to cope with the wide variety of devices that may be found in a custom embedded system, the OS allows user-written processes to act as resource managers that can be started and stopped dynamically.
    - How do client programs talk to resource managers?
      Since the QNX OS is a distributed, microkernel OS with virtually all nonkernel functionality provided by user-installable programs, a clean and well-defined interface is required between client programs and resource managers.
      - Why write a resource manager?
      - The types of resource managers
      - Communication via native IPC
        Once a resource manager has established its pathname prefix, it will receive messages whenever any client program tries to do an open(), read(), write(), etc. on that pathname.
    - Resource manager architecture
    - Summary
      By supporting pathname space mapping, by having a well-defined interface to resource managers, and by providing a set of libraries for common resource manager functions, the QNX OS offers the developer unprecedented flexibility and simplicity in developing drivers for new hardware—a critical feature for many embedded systems.
  - Filesystems
    The QNX OS provides a rich variety of filesystems. Like most service-providing processes in the OS, these filesystems execute outside the kernel; applications use them by communicating via messages generated by the shared-library implementation of the POSIX API.
  - Character I/O
    A key requirement of any realtime operating system is high-performance character I/O.
  - Networking Architecture
    As with other service-providing processes in the QNX OS, the networking services execute outside the kernel. Developers are presented with a single unified interface, regardless of the configuration and number of networks involved.
  - TCP/IP Networking
    Our TCP/IP stack is included in the io-sock networking stack and uses the common FreeBSD API.
  - High Availability
    The term High Availability (HA) is commonly used in telecommunications and other industries to describe a system's ability to remain up and running without interruption for extended periods of time.
  - What is Real Time and Why Do I Need It?
    Real time is an often misunderstood—and misapplied—property of operating systems. This appendix provides a summary of some of the critical elements of realtime computing and discusses a few design considerations and benefits.
  - Glossary
- OS Components & Operations
- Graphics
- Programming
- System Security Guide
  The QNX System Security Guide is intended for both system integrators who are responsible for the security of a QNX OS system and developers who want to create a QNX OS resource manager free from vulnerabilities.
- Utilities & Libraries
- Migrating to QNX OS 8.0
QNX Software in the Cloud
QNX Software in the Cloud enables developers to use the QNX OS in the Amazon cloud environment.
QNX Toolkit for Visual Studio Code
This User's Guide describes the QNX^® Toolkit for Visual Studio Code. The guide introduces you to the QNX Toolkit by explaining the QNX development environment and how to build, run, and debug your QNX^® Operating System (OS) applications and systems.
QNX Hypervisor User's Guide
This User's Guide explains the QNX hypervisor architecture and provides instructions for installing and running a QNX Hypervisor system, changing system components and configuration, and using hypervisor features such as virtual devices (vdevs).
Typographical Conventions, Support, and Licensing
This section describes the typographical conventions used throughout the documentation, explains how to obtain technical support, and provides some information about licensing.

Communication via native IPC

QNX SDP8.0System ArchitectureDeveloperUser

Once a resource manager has established its pathname prefix, it will receive messages whenever any client program tries to do an open(), read(), write(), etc. on that pathname.

For example, after devc-ser* has taken over the pathname /dev/ser1, and a client program executes:

fd = open ("/dev/ser1", O_RDONLY);

the client's C library will construct an io_open message, which it then sends to the devc-ser* resource manager via IPC.

Some time later, when the client program executes:

read (fd, buf, BUFSIZ);

the client's C library constructs an io_read message, which is then sent to the resource manager.

A key point is that all communications between the client program and the resource manager are done through native IPC messaging. This allows for a number of unique features:

A well-defined interface to application programs. In a development environment, this allows a very clean division of labor for the implementation of the client side and the resource manager side.
A simple interface to the resource manager. Since all interactions with the resource manager go through native IPC, and there are no special back door hooks or arrangements with the OS, the writer of a resource manager can focus on the task at hand, rather than worry about all the special considerations needed in other operating systems.

Note:

All QNX OS device drivers and filesystems are implemented as resource managers. This means that everything that a native QNX OS device driver or filesystem can do, a user-written resource manager can do as well.

Consider FTP filesystems, for instance. Here a resource manager would take over a portion of the pathname space (e.g., /ftp) and allow users to cd into FTP sites to get files. For example, cd /ftp/rtfm.mit.edu/pub would connect to the FTP site rtfm.mit.edu and change directory to /pub. After that point, the user could open, edit, or copy files.

Application-specific filesystems would be another example of a user-written resource manager. Given an application that makes extensive use of disk-based files, a custom tailored filesystem can be written that works with that application and delivers superior performance.

The possibilities for custom resource managers are limited only by the application developer's imagination.

Page updated: March 05, 2025