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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.
Programming
Programmer's Guide
The QNX OS Programmer's Guide covers a variety of topics that might interest developers who are building applications that will run under the QNX OS.
Handling Hardware Interrupts
This chapter explains the QNX OS mechanisms for quickly reacting to hardware events.
Interrupt Service Thread (IST)
Servicing the hardware
The above discussion may lead you to the conclusion that level-sensitive is good; edge-triggered is bad. However, another issue comes into play.

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.
- OS Components & Operations
- Graphics
- Programming
  - Getting Started with the QNX OS
    Getting Started with the QNX OS: A Guide for Realtime Programmers is intended to introduce you to the QNX OS and help you develop applications and resource managers for it.
  - Programmer's Guide
    The QNX OS Programmer's Guide covers a variety of topics that might interest developers who are building applications that will run under the QNX OS.
    - Compiling and Debugging
      Let's start by looking at some things you should consider when you start to write a program for the QNX OS.
    - QNX OS Architecture and Concepts
      The QNX OS architecture consists of the microkernel and several cooperating processes. These processes communicate with each other via various forms of interprocess communication (IPC). Message passing is the primary form of IPC in QNX OS.
    - Processes
      Your applications should be written in a way that reflects the architecture of the QNX OS—as a set of cooperating processes. In this chapter, we see how to start processes (also known as creating processes) from code, how to terminate them, and how to detect their termination.
    - Multicore Processing
      Multiprocessing systems, whether discrete or multicore, can greatly improve your applications' performance.
    - Working with Access Control Lists (ACLs)
      Some filesystems, such as the Power-Safe (fs-qnx6.so) and QNX compressed filesystems, extend file permissions with Access Control Lists, which are based on the withdrawn IEEE POSIX 1003.1e and 1003.2c draft standards.
    - Understanding the Microkernel's Concept of Time
      Whether you're working with timers or simply getting the time of day, it's important that you understand how the OS works with time.
    - Handling Hardware Interrupts
      This chapter explains the QNX OS mechanisms for quickly reacting to hardware events.
      - Attaching and detaching interrupts
        In order to handle interrupts, the software must tell the OS that it wants to associate a thread or an event with a particular source of interrrupts, a hardware interrupt request (IRQ).
      - Interrupt Service Thread (IST)
        Determining the source of the interrupt
        Depending on your hardware configuration, there may actually be multiple hardware sources associated with an interrupt. This issue is a function of your specific hardware and bus type. This characteristic (plus good programming style) mandates that your IST ensure that the hardware associated with it actually caused the interrupt.
        Servicing the hardware
        The above discussion may lead you to the conclusion that level-sensitive is good; edge-triggered is bad. However, another issue comes into play.
        Thread or event
        Should you associate a thread directly with an interrupt (InterruptAttachThread()) or associate an event (InterruptAttachEvent())?
      - Problems with shared interrupts
        It's possible for different devices to share an interrupt (for example if you've run out of hardware interrupt lines), but we don't recommend you do this with hardware that will be generating a lot of interrupts. We also recommend you not share interrupts with drivers that you don't have complete source control over, because you need to be sure that the drivers process interrupts properly.
    - Working with Memory
      (or The Persistence of Memory, with a nod to Salvador Dali) In the Process Manager chapter of the System Architecture guide, we looked at how the OS manages memory. This chapter describes how you can work with memory.
    - Freedom from Hardware and Platform Dependencies
      The QNX OS can run on many different hardware platforms. The way in which applications can access peripheral devices and how data is stored varies between platforms. This chapter explains our solutions for minimizing the impact of such platform dependencies.
    - Conventions for Recursive Makefiles and Directories
      In this chapter, we'll look at the supplementary files used in the QNX OS development environment. Although we use the standard make command to create libraries and executables, we also use some of our own conventions in the Makefile syntax.
    - Glossary
  - Writing a Resource Manager
- 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.

Servicing the hardware

QNX SDP8.0Programmer's GuideDeveloper

The above discussion may lead you to the conclusion that level-sensitive is good; edge-triggered is bad. However, another issue comes into play.

In an edge-triggered environment, there's no such requirement, because the interrupt won't be noticed again until it transits from clear to asserted.

Note:

Since the range of hardware attached to an interrupt source can be very diverse, the specific how-to's of servicing the interrupt are beyond the scope of this document—this really depends on what your hardware requires you to do.

Page updated: March 05, 2025