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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.
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.
Data structures
The first thing we need to understand is the data structures used to control the operation of the library.
resmgr_attr_t control structure
The control structure (type resmgr_attr_t) is passed to the resmgr_attach() function, which puts the resource manager's path into the general pathname space and binds requests on this path to a dispatch handle.
The data structure sizing parameters
These two parameters are used to control various sizes of messaging areas.

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.
      - 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.
        Data structures
        The first thing we need to understand is the data structures used to control the operation of the library.
        resmgr_attr_t control structure
        The control structure (type resmgr_attr_t) is passed to the resmgr_attach() function, which puts the resource manager's path into the general pathname space and binds requests on this path to a dispatch handle.
        The other_func message handler
        In general, you should avoid using this member. This member, if non-NULL, represents a routine that will get called with the current message received by the resource manager library when it doesn't recognize the message.
        The data structure sizing parameters
        These two parameters are used to control various sizes of messaging areas.
        The flags parameter
        This parameter gives additional information to the resource manager library.
        resmgr_connect_funcs_t connect table
        When the resource manager library receives a message, it looks at the type of message and sees if it can do anything with it. In the base layer, there are two tables that affect this behavior: The resmgr_connect_funcs_t table, which contains a list of connect message handlers, and the resmgr_io_funcs_t table, which contains a similar list of I/O message handlers.
        resmgr_io_funcs_t I/O table
        The I/O table is very similar in spirit to the connect functions table shown above.
        The resmgr_context_t internal context block
        Finally, one data structure is used by the lowest layer of the library to keep track of information that it needs to know about. You should view the contents of this data structure as read-only, (except for the iov member).
        Resource manager structure
        Now that we've seen the data structures, we can discuss interactions between the parts that you'd supply to actually make your resource manager do something.
        POSIX-layer data structures
        There are three data structures that relate to the POSIX-layer support routines. As far as the base layer is concerned, you can use any data structures you want; it's the POSIX layer that requires you to conform to a certain content and layout. The benefits delivered by the POSIX layer are well worth this tiny constraint. As we'll see later, you can add your own content to the structures as well.
      - 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.

The data structure sizing parameters

QNX SDP8.0Getting Started with the QNX OSDeveloperUser

These two parameters are used to control various sizes of messaging areas.

The nparts_max parameter controls the size of the dynamically allocated iov member in the resource manager library context block (of type resmgr_context_t, see below). You'd typically adjust this member if you were returning more than a one-part IOV from some of your handling functions. Note that it has no effect on the incoming messages—this is only used on outgoing messages.

The msg_max_size parameter controls how much buffer space the resource manager library should set aside as a receive buffer for the message. The resource manager library will set this value to be at least as big as the header for the biggest message it will be receiving. This ensures that when your handler function gets called, it will be passed the entire header of the message. Note, however, that the data (if any) beyond the current header is not guaranteed to be present in the buffer, even if the msg_max_size parameter is large enough.

Page updated: March 05, 2025