# Debug

This information explains how to customize the Yocto-based
workspace, and resolve general problems and issues.

## Debug tools

`packagegroup-core-tools-debug` defined in the `<workspace>/layers/poky/meta`
directory adds debug tools as part of `rootfs`.
The `<workspace>/layers/meta-qcom-hwe/recipes-devtools` directory contains the appended package group recipe as
`packagegroup-core-tools-debug.bbappend`. This append file adds
`ltrace`, `perf`, `sysstat`, and `valgrind` tools to this package group.
For more information, see [Debug Linux user
space issues](https://docs.qualcomm.com/bundle/publicresource/topics/80-80021-12/using_open_source_debug_tools.html).

## Create a build for debugging

To generate a debug build, run the following command:

kas shell meta-qcom/ci/<machine-name>.yml:meta-qcom/ci/<distro-name.yml>:meta-qcom/ci/linux-qcom-6.18.yml:meta-qcom/ci/debug.yml
    bitbake qcom-multimedia-image
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To understand which kernel defconfig and config fragments are used
when `DEBUG_BUILD` is set to **1**, see Kernel recipe, under [Kernel recipes](https://docs.qualcomm.com/doc/80-80021-27/topic/meta_qcom.html#kernel-recipes).

The following code snippet from `recipes-kernel/linux/linux-qcom_6.18.bb` enables the debug configuration fragment for the kernel being built:

KBUILD_CONFIG_EXTRA:append = " ${@oe.utils.vartrue('DEBUG_BUILD', '${S}/kernel/configs/debug.config', '', d)}"
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## Verify QDL and ModemManager

If you are using a Linux distribution with `systemd`,
use the `systemctl` command to stop `ModemManager`.
The following is an example from Ubuntu 22.04:

1. To verify the `ModemManager` status, run the following command:

systemctl status ModemManager
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ModemManager.service - Modem Manager
        Loaded: loaded (/lib/systemd/system/ModemManager.service; enabled; vendor preset: enabled)
        Active: active (running) since Tue 2023-11-28 16:28:15 IST; 3 months 4 days ago
        Main PID: 1338 (ModemManager)
        Tasks: 3 (limit: 4915)
        CGroup: /system.slice/ModemManager.service
                └─1338 /usr/sbin/ModemManager --filter-policy=strict
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ps aux | grep -i modemmanager
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root      1338  0.0  0.0 434332  9544 ?        Ssl   2023  10:39 /usr/sbin/ModemManager --filter-policy=strict
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2. To stop `ModemManager`, run the following command:

systemctl stop ModemManager
        systemctl status ModemManager
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ModemManager.service - Modem Manager
        Loaded: loaded (/lib/systemd/system/ModemManager.service; enabled; vendor preset: enabled)
        Active: inactive (dead) since Sun 2024-03-03 20:08:32 IST; 4s ago
        Process: 1338 ExecStart=/usr/sbin/ModemManager --filter-policy=strict (code=exited, status=0/SUCCESS)
        Main PID: 1338 (code=exited, status=0/SUCCESS)
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3. The `ps aux` command doesn’t show any entry for
`/usr/sbin/ModemManager`. If you need `ModemManager`, you must
restart it after the flashing is complete and verify if it has
started:

systemctl start ModemManager
        systemctl status ModemManager
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ModemManager.service - Modem Manager
        Loaded: loaded (/lib/systemd/system/ModemManager.service; enabled; vendor preset: enabled)
        Active: active (running) since Sun 2024-03-03 20:11:46 IST; 43s ago
        Main PID: 14785 (ModemManager)
        Tasks: 3 (limit: 4915)
        CGroup: /system.slice/ModemManager.service
                └─14785 /usr/sbin/ModemManager --filter-policy=strict
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ps aux | grep -i modemmanager
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root     14785  4.6  0.0 434332  9160 ?        Ssl  20:11   0:00 /usr/sbin/ModemManager --filter-policy=strict
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## Verify newly added layer excluded from build

If BitBake didn’t parse a newly added layer, the recipes from that layer aren’t included in the image.

1. Run the following command, and verify that you see the layer in the output:

bitbake -e | grep ^BBLAYERS=
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2. If you can’t find the layer, confirm the contents of the `conf/bblayers.conf` file to ensure that the layer is included.

Last Published: Mar 17, 2026

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