Android Customizing the Linux kernel

From Variscite Wiki
VAR-SOM-MX6 - N7.1.1 - Customizing the Linux kernel

1 Making changes to kernel configuration

$ cd ~/var_n_711_100/n_711_100_build/vendor/variscite/kernel_imx/
$ make ARCH=arm mrproper
$ make ARCH=arm imx_v7_var_android_defconfig
$ make ARCH=arm menuconfig

Navigate the menu and select the desired kernel functionalities, save the new configuration and exit.
Then, save the new configuration as the default configuration:

$ make ARCH=arm savedefconfig
$ cp arch/arm/configs/imx_v7_var_android_defconfig arch/arm/configs/imx_v7_var_android_defconfig.orig 
$ cp defconfig arch/arm/configs/imx_v7_var_android_defconfig

2 Making changes to the device tree

For example, edit the following file:

  • VAR-SOM-MX6 : ~/var_n_711_100/n_711_100_build/vendor/variscite/kernel_imx/arch/arm/boot/dts/imx6qdl-var-som.dtsi
  • DART-MX6: ~/var_n_711_100/n_711_100_build/vendor/variscite/kernel_imx/arch/arm/boot/dts/imx6qdl-var-dart.dtsi

For example, if you want to make changes related to the SPI configuration you can refer to: SPI

3 Build a new boot.img

When you perform changes to the kernel, you may build boot.img solely instead of building the whole Android.

$ cd ~/var_n_711_100/n_711_100_build
$ source build/envsetup.sh
$ lunch -userdebug
$ make bootimage

4 Flashing the boot image to the target

Run the following to boot the device into fastboot mode and reflash the boot image:

$ adb reboot bootloader
$ sudo `which fastboot` flash bootout/target/product/var_mx6/boot-<setup-name>.img
Replace setup-name as per above table.
$ sudo `which fastboot` reboot