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The meta-qcom metadata layer is hosted at git.yoctoproject.org and provides recipes to build the Qualcomm BSP. Use the recipes from the meta-qcom layer to build the software image. This layer also provides support for enabling Qualcomm devices. Note This guide uses the QCM6490 and QCS6490 hardware SoCs interchangeably. The rb3gen2-core-kit.conf and machine configuration files defined in the meta-qcom/conf/machine/ directory support the QCM6490, QCS6490, and QCS5430 hardware SoCs.

BitBake classes

For an introduction to the BitBake classes, see classes-recipe and classes.

Machine configurations

The Qualcomm Linux machine configuration files are available on GitHub. The files located in the meta-qcom/conf/machine/include directory define and set the required BitBake variables, which are commonly used by machine configurations defined by the Qualcomm BSP. The following table provides an overview of these files.

Machine configuration files for development kits based on QCS6490

Machine configuration files for development kits based on IQ-9075 and IQ-9100

Machine configuration files for development kits based on IQ-8275

Machine configuration files for development kits based on IQ-615

Machine configuration files for IQ-X5121 and IQ-X7181

Kernel command-line

The recipes-kernel/images/esp-qcom-image.bb sets the UKI_CMDLINE variable. This variable is passed as a –cmdline= to ukify tool while generating a UKI image. The meta-qcom/conf/machine/include/qcom-base.inc sets variables QCOM_BOOTIMG_ROOTFS and SERIAL_CONSOLES which are used to compose the UKI_CMDLINE variable.

Include DTB and DTB overlay

The KERNEL_DEVICETREE variable is used to package the required DTBs and DTB overlays into a FIT image. This variable is configured in the individual machine configuration files located in meta-qcom/conf/machine. For example, the conf/machine/rb3gen2-core-kit.conf file sets the KERNEL_DEVICETREE variable, thereby selecting the appropriate DTB: rb3gen2-core-kit.conf The following code block shows how KERNEL_DEVICETREE is set.
The DTB and DTB overlay listed are packaged into a FIT image using the FIT_DTB_COMPATIBLE entries in the conf/machine/include/fit-dtb-compatible.inc file.
This results in a FIT image generated with configuration as follows:

Firmware recipes

Qualcomm Linux firmware recipe files are available on GitHub. When the Qualcomm Linux source code is synced, the firmware recipes are available in the <workspace>/meta-qcom/recipes-bsp/firmware-boot,<workspace>/meta-qcom/recipes-bsp/hexagon-dsp-binaries directories.

Boot firmware binaries

Critical boot firmware images are required to boot the device. The following firmware recipe provides the hardware SoC-specific boot firmware. After generating the build, the firmware binaries in these zip files are available for flashing in the following directory: <workspace>/build/tmp/deploy/images/<machine-name>/<image-name>.qcomflash/

Subsystem firmware binaries

Qualcomm Linux includes firmware binaries that are loaded and run on the corresponding subsystems. As the Qualcomm hardware SoC boots up, individual subsystems run the firmware as they come out of reset. The linux-firmware recipe provides upstream firmware packages and installs them in the /usr/lib/firmwaredirectory. The linux-firmware_%.bb recipe does the following:
  1. Fetches the subsystem firmware binaries.
  2. Unpacks the tar file.
  3. Installs the firmware in /usr/lib/firmware/.

DSP libraries

User space utilities refer to the digital signal processor (DSP) libraries, which must be available in the rootfsimage. The following firmware recipes provide the hardware SoC-specific DSP libraries: The hexagon-dsp-binaries_%.bb recipe does the following:
  1. Fetches the DSP libraries from the GitHub repository.
  2. Unpacks the zip file.
  3. Installs the DSP libraries in rootfs.

Installation of boot, subsystem, and dspso

When Qualcomm Linux is built, the build system uses the firmware recipes to deploy the firmware based on the MACHINE_ESSENTIAL_EXTRA_RRECOMMENDS configuration variable, which is set in the machine configuration file. For example, in conf/machine/iq-9075-evk.conf, see the inclusion of packagegroup-iq-9075-evk-firmware in the MACHINE_ESSENTIAL_EXTRA_RRECOMMENDS variable:
Note The packagegroup-iq-9075-evk recipe present in the <workspace>/meta-qcom/recipes-bsp/packagegroups/ directory. It groups the firmware recipes to generate the image. When Qualcomm Linux is built, based on the configuration in the machine configuration and the package group recipe file, the respective firmware recipes from the <workspace>meta-qcom/recipes-bsp/firmware directory are built.

Kernel recipes

The Linux kernel recipes used by Qualcomm Linux are in <workspace>/meta-qcom/recipes-kernel/linux. Qualcomm Linux supports the long-term support (LTS) Qualcomm Linux kernel v6.18.x. In the meta-qcom layer, there are two kernel recipes: linux-qcom_6.18.bblinux-qcom-rt_6.18.bb
Kernel configuration The Qualcomm Linux kernel recipe uses a different set of kernel configuration and fragments.

Licenses

The licenses for recipes in meta-qcom are listed at <workspace>/meta-qcom/licenses.
Yocto can automatically create SPDX SBOM documents based on image creation. To enable this feature, follow the steps:
  1. Inherit the create-spdx class in local.conf as follows:
  2. After you inherit the class, rebuild the image with the BitBake command:
You can find the SPDX output in the following directories:
  • For each recipe, the generated files are available in the tmp/deploy/spdx/<machine> directory.
  • The top-level SPDX output file is in the tmp/deploy/images/<machine>/ directory.

Next steps