Customizing Linux Kernel #
Updating Defconfig #
Default kernel defconfig is
arch/arm64/configs/imx8mq_trucrux_defconfig
Default path to kernal
build_xwayland/tmp/work/imx8mq-trux-q01-fslc-linux/linux-trucrux/5.4.142+gitAUTOINC+<commit id>/git/
Kernel can be customized using bitbake menuconfig command
$ cd ~/CodeSetup/ $ source setup-environment build_xwayland $ bitbake -c menuconfig virtual/kernel
Now customize kernel by selecting options using
"*" = build in "M" = Modular " " = not selected
once finished save and exit.
The .config file is stored in
~/CodeSetup/build_xwayland/tmp/work/imx8mq-trux-q01-fslc-linux/linux-fslc-trucrux/5.4.142-r0/build/.config
Once the configuration is done the file has to be saved as a defconfig file. To save configuration as a defconfig file
$ bitbake -c savedefconfig virtual/kernel
The defconfig will be saved in
~/CodeSetup/build_xwayland/tmp/work/imx8mq-trux-q01-fslc-linux/linux-fslc-trucrux/5.4.142-r0/build/defconfig
now to apply the defconfig during kernel build, copy defconfig file to “meta-trucrux/recipies-kernel/linux/files/” as shown below.
If “files” directory is not present, create a new “files” directory
$ cd CodeSetup/build_xwayland/tmp/work/imx8mq-trux-q01-fslc-linux/linux-fslc-trucrux/5.4.142-r0/build $ cp defconfig ~/CodeSetup/sources/meta-trucrux/recipies-kernel/linux/files/
Create a bbappend file
$ cd CodeSetup/sources/meta-trucrux/recipes-kernel/linux/ $ touch linux-trucrux_%.bbappend $ vi linux-trucrux_%.bbappend
now add the following lines in bbappend file
SRC_URI += "file://defconfig"
KBUILD_DEFCONFIG_imx8mq-trux-q01 = "${WORKDIR}/defconfig"
bitbake linux kernel
$ bitbake linux-trucrux
Customizing Source Code #
To make changes in source code creating a local_repos is recommended.
$ cd ~/CodeSetup $ mkdir local_repos $ git clone https://github.com/Trucrux/linux-fslc-trucrux.git -b v5.4.142_dunfell
now use git to create a branch or make changes in same branch (creating new branch is recommended)
Make required changes in the kernel.
To include the changes during kernel build create a bbappend file as shown below:
$ cd ~/CodeSetup/sources/meta-trucrux/recipies-kernel/linux $ touch linux-trucrux_5.4.bbappend
(ignore if bbappend is already exist)
and append the following in bbappend file
KERNEL_SRC = "git://${BSPDIR}/local_repos/linux-fslc-trucrux;protocol=file"
SRCBRANCH = "< branch name > "
SRCREV = "The commit id you'd like to use"
bitbake linux kernel
$ bitbake linux-trucrux
NOTE: bbappend files apply changes during runtime
DTSI and DTS files for SOM and DVP board #
Path : arch/arm64/boot/dts/freescale/
