#https://usmile.at/blog/how-to-build-android-kernel
#https://gist.github.com/tangabc/a7767b5b22d2b44062e1b9636ba9f711

sudo apt install gcc-arm-linux-gnueabi build-essential git make libncurses5 libncurses5-dev python2 libssl-dev gcc-aarch64-linux-gnu bc
#sudo dpkg --add-architecture i386
#sudo apt install libc6:i386 libncurses5:i386 libstdc++6:i386 libz-dev:i386 

mkdir kernel
cd kernel

#get moto x4 kernel source
wget "https://github.com/MotorolaMobilityLLC/kernel-msm/archive/MMI-PPVS29.266-45-6.tar.gz"
tar xzvf MMI-PPVS29.266-45-6.tar.gz

#get toolchain
#git clone https://android.googlesource.com/platform/prebuilt
git clone https://android.googlesource.com/platform/prebuilts/gcc/linux-x86/aarch64/aarch64-linux-android-4.8

#set compile vars
export ARCH=arm64
export SUBARCH=arm64
# export CROSS_COMPILE=<path to toolchain from googlesource>/toolchains/arm-eabi-4.4.3/bin/arm-eabi-
#export CROSS_COMPILE=$PWD/prebuilt/linux-x86/toolchains/arm-eabi-4.4.3/bin/arm-eabi-
#export CROSS_COMPILE=/usr/bin/aarch64-linux-gnu-
export CROSS_COMPILE=/root/kernel/aarch64-linux-android-4.8/bin/aarch64-linux-android-

cd kernel-msm-MMI-PPVS29.266-45-6
make defconfig
//optional for configuration of the kernel
# make menuconfig

make -j4 #number of cpu cores