.. SPDX-License-Identifier: CC-BY-SA-2.0-UK ********************** Kernel Development FAQ ********************** Common Questions and Solutions ============================== Here are some solutions for common questions. How do I use my own Linux kernel ``.config`` file? -------------------------------------------------- Refer to the ":ref:`kernel-dev/common:changing the configuration`" section for information. How do I create configuration fragments? ---------------------------------------- A: Refer to the ":ref:`kernel-dev/common:creating configuration fragments`" section for information. How do I use my own Linux kernel sources? ----------------------------------------- Refer to the ":ref:`kernel-dev/common:working with your own sources`" section for information. How do I install/not-install the kernel image on the root filesystem? --------------------------------------------------------------------- The kernel image (e.g. ``vmlinuz``) is provided by the ``kernel-image`` package. Image recipes depend on ``kernel-base``. To specify whether or not the kernel image is installed in the generated root filesystem, override ``RRECOMMENDS:${KERNEL_PACKAGE_NAME}-base`` to include or not include "kernel-image". See the ":ref:`dev-manual/layers:appending other layers metadata with your layer`" section in the Yocto Project Development Tasks Manual for information on how to use an append file to override metadata. How do I install a specific kernel module? ------------------------------------------ Linux kernel modules are packaged individually. To ensure a specific kernel module is included in an image, include it in the appropriate machine :term:`RRECOMMENDS` variable. These other variables are useful for installing specific modules: - :term:`MACHINE_ESSENTIAL_EXTRA_RDEPENDS` - :term:`MACHINE_ESSENTIAL_EXTRA_RRECOMMENDS` - :term:`MACHINE_EXTRA_RDEPENDS` - :term:`MACHINE_EXTRA_RRECOMMENDS` For example, set the following in the ``qemux86.conf`` file to include the ``ab123`` kernel modules with images built for the ``qemux86`` machine:: MACHINE_EXTRA_RRECOMMENDS += "kernel-module-ab123" For more information, see the ":ref:`kernel-dev/common:incorporating out-of-tree modules`" section. How do I change the Linux kernel command line? ---------------------------------------------- The Linux kernel command line is typically specified in the machine config using the :term:`APPEND` variable. For example, you can add some helpful debug information doing the following:: APPEND += "printk.time=y initcall_debug debug"