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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
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.
Resource Managers
In this chapter, we'll take a look at what you need to understand in order to write a resource manager. Resource managers are another distintive feature of QNX OS that allow you to access services through standard POSIX calls.
What is a resource manager?
A resource manager is simply a program with some well-defined characteristics.
Examples of resource managers
Before we get carried away, let's take a look at a couple of examples and see how they abstract some service. We'll look at an actual piece of hardware (a serial port) and something much more abstract (a filesystem).

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.
    - Processes and Threads
      This chapter explains the concepts behind processes and threads, and the challenges of synchronization and scheduling. A thread is a flow of execution, and a process is a collection of threads. In the QNX OS, the schedulable entity is a thread, not a process.
    - Message Passing
      In this chapter, we'll look at the most distinctive feature of QNX OS, message passing. Message passing lies at the heart of the operating system's microkernel architecture, giving the OS its modularity.
    - Interrupts
      In this chapter, we'll take a look at interrupts, how we deal with them under QNX OS, their impact on scheduling and realtime, and some interrupt-management strategies.
    - Resource Managers
      In this chapter, we'll take a look at what you need to understand in order to write a resource manager. Resource managers are another distintive feature of QNX OS that allow you to access services through standard POSIX calls.
      - What is a resource manager?
        A resource manager is simply a program with some well-defined characteristics.
        Examples of resource managers
        Before we get carried away, let's take a look at a couple of examples and see how they abstract some service. We'll look at an actual piece of hardware (a serial port) and something much more abstract (a filesystem).
        Characteristics of resource managers
        As we saw in our examples (above), the key to the flexibility of the resource managers is that all the functionality of the resource manager is accessed using standard POSIX function calls—we didn't use special functions when talking to the serial port. But what if you need to do something special, something very device-specific?
      - The client's view
        We've already seen a hint of what the client expects. It expects a file-descriptor-based interface, using standard POSIX functions.
      - The resource manager's view
        Let's look at things from the resource manager's perspective.
      - The resource manager library
        Before we get too far into all the issues surrounding resource managers, we have to get acquainted with the QNX OS resource manager library.
      - Writing a resource manager
        Now that we've introduced the basics—how the client looks at the world, how the resource manager looks at the world, and an overview of the two cooperating layers in the library, it's time to focus on the details.
      - Handler routines
        Not all outcalls correspond to client messages—some are synthesized by the kernel, and some by the library.
      - Alphabetical listing of connect and I/O functions
        This section gives an alphabetical listing of the connect and I/O function entry points that you can fill in (the two tables passed to resmgr_attach()). Remember that if you simply call iofunc_func_init(), all these entries will be filled in with the appropriate defaults; you'd want to modify a particular entry only if you wish to handle that particular message. In the Examples section, below, you'll see some examples of the common functions.
      - Examples
        I'm now going to show you a number of cookbook examples you can cut and paste into your code, to use as a basis for your projects. These aren't complete resource managers—you'll need to add the thread pool and dispatch skeleton shown immediately below, and ensure that your versions of the I/O functions are placed into the I/O functions table after you've done the iofunc_func_init(), in order to override the defaults!
      - Advanced topics
        Now that we've covered the basics of resource managers, it's time to look at some more complicated aspects.
      - Summary
        Writing a resource manager is by far the most complicated task that we've discussed in this book.
    - Sample Programs
      This appendix contains the complete versions of some of the sample programs discussed in this book.
    - Glossary
  - 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.
  - 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.

Examples of resource managers

QNX SDP8.0Getting Started with the QNX OSDeveloperUser

Before we get carried away, let's take a look at a couple of examples and see how they abstract some service. We'll look at an actual piece of hardware (a serial port) and something much more abstract (a filesystem).

Serial port

On a typical system, there usually exists some way for a program to transmit output and receive input from a serial, RS-232-style hardware interface. This hardware interface consists of a bunch of hardware devices, including a UART (Universal Asynchronous Receiver Transmitter) chip which knows how to convert the CPU's parallel data stream into a serial data stream and vice versa.

In this case, the service being provided by the serial resource manager is the capability for a program to send and receive characters on a serial port.

We say that an abstraction occurs, because the client program (the one ultimately using the service) doesn't know (nor does it care about) the details of the UART chip and its implementation. All the client program knows is that to send some characters it should call the fprintf() function, and to receive some characters it should call the fgets() function. Notice that we used standard, POSIX function calls to interact with the serial port.

Filesystem

As another example of a resource manager, let's examine the filesystem. This consists of a number of cooperating modules: the filesystem itself, the block I/O driver, and the disk driver.

The service being offered here is the capability for a program to read and write characters on some medium. The abstraction that occurs is the same as with the serial port example above—the client program can still use the exact same function calls (e.g., the fprintf() and fgets() functions) to interact with a storage medium instead of a serial port. In fact, the client really doesn't know or need to know which resource manager it's interacting with.

Page updated: March 05, 2025