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QNX Software Development Platform
OS Components
Building Embedded Systems
The Building Embedded Systems guide is intended for developers who are developing or building BSPs for QNX OS embedded systems.
Initial Program Loaders (IPLs)
IPLs first set up the minimum environment needed to execute their compiled C code, then find the OS image and load it into memory, and then jump to the QNX startup code.

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QNX Software Development Platform
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  The System Architecture guide accompanies the QNX OS and is intended for both application developers and end-users.
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    The Boot Optimization Guide describes techniques you can use to reduce the time from your board's initial power on until you have a fully functional QNX system running on the board.
  - Building Embedded Systems
    The Building Embedded Systems guide is intended for developers who are developing or building BSPs for QNX OS embedded systems.
    - Overview
      QNX systems are built from the QNX OS standard release components, the architecture- and board-specific files provided in QNX BSPs, and customer and third-party components.
    - Working with QNX BSPs
      Before you attempt to write a new BSP or modify an existing one, it is helpful to know how to use a BSP.
    - Initial Program Loaders (IPLs)
      IPLs first set up the minimum environment needed to execute their compiled C code, then find the OS image and load it into memory, and then jump to the QNX startup code.
      - From reset to startup
        Due to the different board architectures and processes handled by the board firmware, IPLs for x86 and ARM platforms are very different.
      - x86 disk boot IPLs
        IPLs for x86 processors are board-agnostic and support x86_64 boards.
      - ARM IPLs
        IPLs for ARM are board-specific. This means that a great deal of work is usually required to adapt an IPL written for one ARM board so it can be used on another ARM board.
      - Image storage
        The media on which the bootable OS image is stored, and how it is stored (compressed or not) determine what the IPL must do with the image.
      - The startup header
        The startup header (or boot header) structure is defined in startup.h.
      - Customizing an IPL
        If you need to write a custom IPL, it's best to work from an existing one, and preferably one for an SoC similar to the one you are using for your project.
      - Optimizing an IPL
        You can use a variety of strategies to optimize an IPL.
    - Startup Programs
      The first program to run in a bootable OS image is the startup program; it completes the system configuration, then launches the OS kernel.
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      Kernel callouts are standalone pieces of code (or code fragments) that the kernel uses to perform hardware-specific functions. These callouts don't need to be statically linked to the kernel.
    - System Page
      The system page contains essential information about the system, including the system page's size, information about the hardware platform (including IRQs and the CPU), the cache size, and the location of kernel callouts in memory.
    - OS Images
      OS images are files that contains the OS, your executables, and any data files that might be related to your programs.
    - OS Image Buildfiles
      You can edit OS image buildfiles to configure OS images.
    - IPL Library
      The IPL library contains a set of routines for building a custom IPL.
    - Startup Library
      The startup library contains a rich set of routines ranging from high-level functions called by main() to utility functions for performing specific startup tasks.
    - Debugging QNX Embedded Systems
      The microkernel architecture of QNX OS means that debugging QNX embedded systems can be different from debugging other embedded systems.
    - Sample Buildfiles
      This appendix contains sample buildfiles that you can modify to support your hardware platform and your implementation requirements.
    - Glossary
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- Utilities & Libraries
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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 OS applications and systems.
Typographical Conventions, Support, and Licensing
This section describes the typographical conventions used throughout the documentation and explains how to obtain technical support.

Initial Program Loaders (IPLs)

QNX SDP8.0Building Embedded SystemsConfigurationDeveloper

IPLs first set up the minimum environment needed to execute their compiled C code, then find the OS image and load it into memory, and then jump to the QNX startup code.

An IPL is minimalist; it uses as little code as possible to get the startup code to run. An IPL performs the following tasks, in sequence:

Complete hardware initializations, if needed.
Set up a stack for the C-language environment.
Find and validate the OS image.
Load the OS image into memory.
Jump to the startup code in the OS image.

An IPL can be stored on either a linearly mapped device, such as a NOR Flash memory device, or a non-linearly mapped device, such as an eMMC, SD card, or SPI NOR Flash device. Like the board architecture, the type of memory device on which the IPL and the OS image are stored determines the design of the IPL (see the next section and Image storage later in this chapter).

Factors affecting IPL design

The design and content of an IPL are affected by numerous factors, including:

Board: IPLs are target architecture-specific. IPLs for x86 processors and ARM processors are very different (see From reset to startup).; In addition to being architecture-specific, an IPL is specific to the board (and even the board variant) that it runs on. It must be customized so that it knows how to configure the memory controller, set the clocks, and perform other hardware initializations.
Supported removeable media: The type of removable media that the board retrieves the boot image from determines the boot strategies and techniques that the IPL can use.; Although linear media are supported, non-linear media (for example, USB key or onboard eMMC, NOR flash, or NAN flash) have become the most common options.
Size of the storage media: Whether the IFS image is compressed or uncompressed depends on the size and performance of the storage media.

Page updated: May 17, 2024