# Modify the Qualcomm Device Loader source using devtool

The following examples show the `devtool` usage for Qualcomm software components.

- Kernel: See [Use Yocto to develop kernel](https://docs.qualcomm.com/bundle/publicresource/topics/80-80022-3/kernel-development.html#yocto-kernel-support).
- QDL tool: Use the `devtool` to modify the QDL source in the workspace created.

devtool modify qdl
        INFO: Source tree extracted to <workspace>/build/workspace/sources/qdl
        INFO: Using source tree as build directory since that would be the default for this recipe
        INFO: Recipe qdl now set up to build from <workspace>/build/workspace/sources/qdl
        Copy to clipboard

    1. Check-out the following tree locally:

tree -L 2 build/workspace/
            build/workspace/
            ├── appends
            │   └── qdl_git.bbappend
            ├── conf
            │   └── layer.conf
            ├── README
            └── sources
                └── qdl
            Copy to clipboard
    2. Inspect the checked-out QDL source-tree:

ls workspace/sources/qdl/
            firehose.c  LICENSE  Makefile  patch.c  patch.h  program.c  program.h  qdl.c  qdl.h  README  sahara.c  ufs.c  ufs.h  util.c
            Copy to clipboard
    3. Change the source tree under `workspace/sources/qdl/` and build
your changes:

devtool build qdl
            devtool build-image qcom-multimedia-image
            Copy to clipboard

    The generated images are in the path `build/tmp/deploy/images/rb3gen2-core-kit/qcom-multimedia-image`.
- Weston: Use the devtool to modify Weston in the workspace created.

devtool modify weston
        INFO: Adding local source files to srctree...
        INFO: Source tree extracted to <workspace>/build/workspace/sources/weston
        INFO: Recipe weston now set up to build from <workspace>/build/workspace/sources/weston
        Copy to clipboard

    1. Check-out the following tree locally:

tree -L 2 build/workspace/
            build/workspace/
            ├── appends
            │   └── weston_10.0.2.bbappend
            ├── conf
            │   └── layer.conf
            ├── README
            └── sources
                └── weston
            Copy to clipboard
    2. Inspect the checked-out Weston source-tree:

ls workspace/sources/weston/
            clients           COPYING      desktop-shell     include      libweston          meson.build        oe-local-files  pipewire    releasing.rst  tests  weston.ini.in
            compositor        data         doc               ivi-shell    libweston-desktop  meson_options.txt  oe-logs         protocol    remoting       tools  xwayland
            CONTRIBUTING.rst  DCO-1.1.txt  fullscreen-shell  kiosk-shell  man                notes.txt          oe-workdir      README.rst  shared         wcap
            Copy to clipboard
    3. Change the source tree under `workspace/sources/weston/` and
build your changes:

devtool build weston
            devtool build-image qcom-multimedia-image
            Copy to clipboard

    The generated images are in the path `build/tmp/deploy/images/rb3gen2-core-kit/qcom-multimedia-image`.

Last Published: May 10, 2026

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