Target Images

When you complete a project, you must build a target image that your users can install on their target platform. You do this by packaging all the artifacts that make up the complete target image:

Board Support Packages (BSPs)
the core OS and utilities
HTML5 apps
Qt runtime
HMI
Browser/WebKit
other binaries

Typically, you wouldn't build all of these components yourself. Instead, you have these prebuilt binaries available in your development environment when you install the QNX CAR platform.

Artifact Organization

When designing a system, you choose how to organize artifacts into one or more IFS files and partition images. Partition images are then combined to produce target images:

Image filesystems (IFS) (or .ifs files) are created by mkifs. An IFS is a single binary that is loaded into RAM, generally on bootup by a bootloader or IPL. IFS files are usually quite minimal and contain only the drivers and libraries needed to start the kernel and mount additional partitions. Because an IFS is loaded into RAM and the files in it are more difficult to upgrade than files on a regular filesystem, an IFS is usually used only for startup code and a few key libraries, especially libraries that need to load early in the boot process to speed up boot time or improve performance. In the case of the QNX CAR platform, for example, everything required to start a minimal system and display the backup camera is stored in an IFS, but the HMI and apps are loaded from a storage device. The primary IFS is automatically mounted to /proc/boot.
Partition images (or .image files) are created by mkxfs. These files contain the contents of a partition that are written to a storage device. A system might consist of a number of partitions. For example, an SD image for the QNX CAR platform contains 3 partitions: a FAT16 partition for booting and 2 QNX6 partitions (one for system data and another for user data). Partition images can contain a variety of file types including IFS files. For the QNX CAR platform, the primary IFS is stored in a FAT16 partition because most targets are capable of reading FAT16 with their default bootloader.
Partition images are combined to produce target images (or .img files). A target image (also referred to as a disk image or system image) contains an entire target system—a partition table and the partition contents—and so is convenient to install. You can load a target image directly onto a storage medium such as an SD card without having to modify partition information.

System Generation

In general terms, to generate a system image for the QNX CAR platform, you perform the following steps:

Develop the .build files that contain the scripts and files used by mkifs.
Run mkifs to generate IFS files.
Determine all the files to include in each partition and develop .build files to be used by mkxfs.
Run mkxfs to generate all the partition images.
Run diskimage to generate the partition table and write all the partition images to a single .img file.

Because generating the various files is time-consuming and error-prone, this isn't the process we recommend. Instead, the QNX CAR platform includes an mksysimage.py script that handles the entire process of generating a system image. In fact, the mksysimage.py script supports multiple platforms and a number of configurations per platform. For example, in the case of OMAP5432, the mksysimage.py script produces images for SD card, EMMC, and EMMC + SATA SSD. For more information on mksysimage.py, see the following sections: