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How to create QBSPs from Yocto builds

Published on Friday December 14, 2018 by Piippo Samuli in Embedded Dev Loop Qt qt creator QBSP Qt for Device Creation Yocto yocto project | Comments

In Qt for Device Creation 5.12.0, we have enabled additional content installation via QBSPs (Qt Board Support Packages). A QBSP combines toolchain, target device images and set of Qt Creator configurations for particular device into a single file that can be easily shared and installed using the Qt online installer or the Maintenance tool. Technically a QBSP is an archived repository created by the Qt Installer Framework, and it's creation is now fully integrated into the Yocto builds that are used to create the Boot to Qt Software Stack content.

For all the target devices currently supported in the meta-boot2qt layer, you can create a QBSP simply by issuing a bitbake command:

bitbake meta-b2qt-embedded-qbsp

This will first build both the toolchain and the image, and then package those into a QBSP file with the required Qt Creator configurations. The resulting QBSP file is located in tmp/deploy/qbsp/ folder in your Yocto build environment. The QBSP packaging respects the SDKMACHINE variable, so that if you use environment variable SDKMACHINE=i686-mingw32, a Windows toolchain is packaged into the QBSP.

The Yocto integration is implemented in two classes that can be used even if your target device has not been otherwise integrated into the meta-boot2qt layer. By inheriting the classes and setting up the required variables, you can have a QBSP with your own image for your own target device.

qbsp-image.bbclass

The QBSP will need a suitable device image to include in the package and to achieve this you will need to inherit qbsp-image.bbclass in the image recipe you want to use. You can control the content of the package with variable QBSP_IMAGE_CONTENT. By default Boot to Qt images include a .img file and a .conf file used by the Flashing Wizard.

inherit qbsp-image

QBSP_IMAGE_CONTENT = "\
${IMAGE_LINK_NAME}.img \
${IMAGE_LINK_NAME}.conf \
"

qbsp.bbclass

qbsp.bbclass is the main class that handles the creation of the QBSP and you can control the various aspects of it through variables. Most important ones are the dependencies to the toolchain and image task using QBSP_SDK_TASK and QBSP_IMAGE_TASK variables.

For the Boot to Qt Software Stack, this is done in the meta-b2qt-embedded-qbsp.bb recipe:

inherit qbsp

VERSION_SHORT = "${@d.getVar('PV').replace('.','')}"
QBSP_NAME = "Boot2Qt ${PV}"
QBSP_MACHINE = "${@d.getVar('MACHINE').replace('-','')}"
QBSP_INSTALLER_COMPONENT = "embedded.b2qt.${VERSION_SHORT}.yocto.${QBSP_MACHINE}"
QBSP_INSTALL_PATH = "/${PV}/Boot2Qt/${MACHINE}"

QBSP_SDK_TASK = "meta-toolchain-b2qt-embedded-qt5-sdk"
QBSP_IMAGE_TASK = "b2qt-embedded-qt5-image"

Rest of the variables are then used to control how the installer shows the component and where they are installed. You can optionally also, e.g., add an EULA to the package, which the user would need to accept before they can install the components. You can find this and all the other information about the QBSP specific variables in the documentation.

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