build-android-kernel-with-gnu-toolchain.md

Build PixelExperience kernel for whyred (xiaomi_sdm660) with GNU toolchain

Preparation

1. download kernel source: https://github.com/PixelExperience-Devices/kernel_xiaomi_sdm660/tree/thirteen

2. download cross compile toolchain: https://developer.arm.com/downloads/-/arm-gnu-toolchain-downloads

   • AArch32 GNU/Linux target with hard float (arm-none-linux-gnueabihf)
     • arm-gnu-toolchain-12.2.rel1-x86_64-arm-none-linux-gnueabihf.tar.xz
   • AArch64 GNU/Linux target (aarch64-none-linux-gnu)
     • arm-gnu-toolchain-12.2.rel1-x86_64-aarch64-none-linux-gnu.tar.xz

3. install necessary dev library:

   sudo apt-get install libssl-dev
   

Build

1. unzip the kernel source and the tool chain;

2. set the necessary environment variables:

   export ARCH=arm64
   export CROSS_COMPILE=/home/zhaojr/android/toolchain-gnu/arm-gnu-toolchain-12.2.rel1-x86_64-aarch64-none-linux-gnu/bin/aarch64-none-linux-gnu-
   export CROSS_COMPILE_ARM32=/home/zhaojr/android/toolchain-gnu/arm-gnu-toolchain-12.2.rel1-x86_64-arm-none-linux-gnueabihf/bin/arm-none-linux-gnueabihf-
   

3. run build command:

   make O=out whyred_defconfig
   
   # disable "-Werror" flag which makes all warnings into errors
   sed -i 's/CONFIG_CC_WERROR=y/CONFIG_CC_WERROR=n/' out/.config
   
   # remove "-Werror" flag for "qcacld" driver
   sed -i '/-Werror/d' drivers/staging/qcacld-3.0/Kbuild
   
   make -j4 O=out
   

4. if you want to debug the wlan driver, set the debug flag:

   # set debug flag for "drivers/staging/qcacld-3.0/" and "drivers/staging/qca-wifi-host-cmn/"
   make -j4 O=out BUILD_DEBUG_VERSION=1
   

Flash kernel

The build takes about 15 minutes, and the generated kernel image is ./out/arch/arm64/boot/Image.gz-dtb, use "Anykernel" to flash the kernel.

nice