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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.
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.
Optimizing the runtime linker

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.
      - Choosing the OS version for building programs
        Whether you're using the command line or the IDE, you can install multiple versions of QNX SDP and build programs for multiple versions of QNX OS.
      - Making your code more portable
        To help you create portable applications, the QNX OS lets you compile for specific standards and include OS-specific code.
      - Cross-development
        In this section, we'll describe how to compile and debug a QNX OS system. Your QNX OS system might be anything from a deeply embedded turnkey system to a powerful multiprocessor server. You'll develop the code to implement your system using development tools running on a supported cross-development platform.
      - Overriding compiler options specified in makefiles
        You can specify compiler options in the shell environment where you run the make utility, to override the options specified in standard makefiles.
      - Using libraries
        When you're developing code, you almost always make use of a library, a collection of code modules that you or someone else has already developed (and hopefully debugged).
      - Linking your modules
        To link your application against a library, use the -l option to qcc, omitting the lib prefix and any extension from the library's name. For example, to link against libsocket, specify -l socket.
      - Optimizing the runtime linker
        Lazy binding
        Lazy binding (also known as lazy linking or on-demand symbol resolution) is the process by which symbol resolution isn't done until a symbol is actually used. Functions can be bound on-demand, but data references can't.
        RTLD_LAZY
        RTLD_LAZY is a flag that you can pass to dlopen() when you load a shared object.
        Lazy loading
        Lazy dependency loading (or on-demand dependency loading) is a method of loading the required objects when they're actually required.
        Diagnostics and debugging
        When you're developing a complex application, it may become difficult to understand how the runtime linker lays out the internal link maps and scopes of resolution. To help determine what exactly the runtime linker is doing, you can use the DL_DEBUG environment variable to make the linker display diagnostic messages.
        Environment variables
      - Debugging in a cross-development environment
      - Auditing builds
        QNX provides tools that you can use to gather information about build artifacts, including which shared libraries a binary needs, the package it belongs to, and the command-line options that were used to build it.
      - A simple debug session
    - 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) filesystem, 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.
    - 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 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.
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.

Optimizing the runtime linker

QNX SDP8.0Programmer's GuideDeveloper

The runtime linker supports the following features that you can use to optimize the way it resolves and relocates symbols:

The term lazy in all of them can cause confusion, so let's compare them briefly before looking at them in detail:

Lazy binding is the process by which symbol resolution is deferred until a symbol is actually used.
RTLD_LAZY indicates to the runtime linker that an a loaded object might have unresolved symbols that it shouldn't worry about resolving. It's up to the developer to load the objects that define the symbols before calling any functions that use the symbols.
Lazy loading modifies the lookup scope and avoids loading objects (or even looking them up) before the linker needs to search them for a symbol.

RTLD_LAZY doesn't imply anything about whether dependencies are loaded; it says where a symbol is looked up. It allows the looking up of symbols that are subsequently opened with the RTLD_GLOBAL flag, when looking up a symbol in an RTLD_LAZY-opened object and its resolution scope fails. The term resolution scope is intentional since we don't know what it is by just looking at RTLD_LAZY; it differs depending on whether you specify RTLD_WORLD, RTLD_LAZYLOAD, or both.

Page updated: August 09, 2024