1.. SPDX-License-Identifier: CC-BY-SA-2.0-UK 2 3********************** 4Kernel Development FAQ 5********************** 6 7Common Questions and Solutions 8============================== 9 10Here are some solutions for common questions. 11 12How do I use my own Linux kernel ``.config`` file? 13-------------------------------------------------- 14 15Refer to the 16":ref:`kernel-dev/common:changing the configuration`" 17section for information. 18 19How do I create configuration fragments? 20---------------------------------------- 21 22A: Refer to the 23":ref:`kernel-dev/common:creating configuration fragments`" 24section for information. 25 26How do I use my own Linux kernel sources? 27----------------------------------------- 28 29Refer to the 30":ref:`kernel-dev/common:working with your own sources`" 31section for information. 32 33How do I install/not-install the kernel image on the root filesystem? 34--------------------------------------------------------------------- 35 36The kernel image (e.g. ``vmlinuz``) is provided by the 37``kernel-image`` package. Image recipes depend on ``kernel-base``. To 38specify whether or not the kernel image is installed in the generated 39root filesystem, override ``RRECOMMENDS:${KERNEL_PACKAGE_NAME}-base`` to include or not 40include "kernel-image". See the 41":ref:`dev-manual/common-tasks:appending other layers metadata with your layer`" 42section in the 43Yocto Project Development Tasks Manual for information on how to use an 44append file to override metadata. 45 46How do I install a specific kernel module? 47------------------------------------------ 48 49Linux kernel modules are packaged individually. To ensure a 50specific kernel module is included in an image, include it in the 51appropriate machine :term:`RRECOMMENDS` variable. 52These other variables are useful for installing specific modules: 53- :term:`MACHINE_ESSENTIAL_EXTRA_RDEPENDS` 54- :term:`MACHINE_ESSENTIAL_EXTRA_RRECOMMENDS` 55- :term:`MACHINE_EXTRA_RDEPENDS` 56- :term:`MACHINE_EXTRA_RRECOMMENDS` 57 58For example, set the following in the ``qemux86.conf`` file to include 59the ``ab123`` kernel modules with images built for the ``qemux86`` 60machine:: 61 62 MACHINE_EXTRA_RRECOMMENDS += "kernel-module-ab123" 63 64For more information, see the 65":ref:`kernel-dev/common:incorporating out-of-tree modules`" section. 66 67How do I change the Linux kernel command line? 68---------------------------------------------- 69 70The Linux kernel command line is 71typically specified in the machine config using the :term:`APPEND` variable. 72For example, you can add some helpful debug information doing the 73following:: 74 75 APPEND += "printk.time=y initcall_debug debug" 76 77