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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.
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.
High Availability Manager
The High Availability Manager (HAM) provides a mechanism for monitoring processes and services on your system.
HAM hierarchy
The High Availability Manager consists of three main components.

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.
  - 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.
    - An OS for HA
      If you had to design an HA-capable OS from the ground up, would you start with a single executable environment? In this simple, high-performance design, all OS components, device drivers, applications, the works, would all run without memory protection in kernel mode.
    - Custom hardware support
      While many operating systems provide HA support in a hardware-specific way (e.g., via PCI Hot Plug), QNX OS isn't tied to PCI. Your particular HA system may be built on a custom chassis, in which case an OS that offers a PCI-based HA solution may not address your needs at all.
    - High Availability Manager
      The High Availability Manager (HAM) provides a mechanism for monitoring processes and services on your system.
      - The HAM and the Guardian
        As a self-monitoring manager, the HAM is resilient to internal failures. If, for whatever reason, the HAM itself is stopped abnormally, it can immediately and completely reconstruct its own state. A mirror process called the Guardian perpetually stands ready and waiting to take over the HAM's role. Since all state information is maintained in shared memory, the Guardian can assume the exact same state that the original HAM was in before the failure.
      - HAM hierarchy
        The High Availability Manager consists of three main components.
        Entities
        Entities are the fundamental units of observation/monitoring in the system.
        Conditions
        Conditions are associated with entities; a condition represents the entity's state.
        Actions
        Actions are associated with conditions. Actions are executed when the appropriate conditions are true with respect to a specific entity.
      - Publishing autonomously detected conditions
        Entities or other components in the system can inform the HAM about conditions (events) that they deem interesting, and the HAM in turn can deliver these conditions (events) to other components in the system that have expressed interest in (subscribed to) them.
      - Subscribing to autonomously published conditions
        To express their interest in events published by other components, subscribers can use the ham_condition_state() and ham_condition_raise() API calls.
      - The HAM as a filesystem
        Effectively, the HAM's internal state is like a hierarchical filesystem, where entities are like directories, conditions associated with those entities are like subdirectories, and actions inside those conditions are like leaf nodes of this tree structure.
      - Multistage recovery
        The HAM can perform a multistage recovery, executing several actions in a certain order. This technique is useful whenever strict dependencies exist between various actions in a sequence. In most cases, recovery requires more than a single restart mechanism in order to properly restore the system's state to what it was before a failure.
      - HAM API
        The basic mechanism to talk to the HAM is to use its API. This API is implemented as a library that you can link against. The library is thread-safe and cancellation-safe.
  - 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.

HAM hierarchy

QNX SDP8.0System ArchitectureDeveloperUser

The High Availability Manager consists of three main components.

Page updated: March 05, 2025