Compiling Linux Kernel for Pixel 2 devices -- Bash script

wahoo_mybuild.sh

#!/bin/bash
# Purpose: Script for building AOSP code and Linux kernel for walleye using open-source toolchains. 
# Author: [email protected]
# License: Gnu GPL v. 2
# License is same as Linux kernel license, since the code helps compile the Linux kernel for a device
# Change these directory paths to point to your aosp and NDK folders.

# reference: https://www.digitalocean.com/community/tutorials/how-to-build-android-roms-on-ubuntu-16-04
# edited by thinkycx 201809
export KERNEL=/root/AOSP/msm
export AOSP=/root/AOSP/android-8.0.0_r33
export CROSS_COMPILE=/root/AOSP/tools/aarch64-linux-android-4.9/bin/aarch64-linux-android-  # ~/ndk/android-ndk-r16b/toolchains/aarch64-linux-android-4.9/prebuilt/linux-x86_64/bin/aarch64-linux-android-

export USER=root # building AOSP needs USER env but in docker there is no USER env
export MAKE_NUM=80 #cpu number*2 `nproc`
export USE_CCACHE=1
export CCACHE_MEM_SIZE=100G
export ANDROID_JACK_VM_ARGS="-Xmx16g -Dfile.encoding=UTF-8 -XX:+TieredCompilation"

# Change these if you are building for something other than walleye (Pixel 2) as needed.
export KERNELNAME=wahoo
export TARGETBUILD=walleye
export ARCH=arm64
export SUBARCH=arm64
export CLANG_TRIPLE=aarch64-linux-gnu-
export CLANG_PREBUILT_BIN=$AOSP/prebuilts/clang/host/linux-x86/clang-4053586/bin
export CC_CMD=${CLANG_PREBUILT_BIN}/clang

# These likely would not have to be changed.
export PATH=$PATH:$AOSP/prebuilts/misc/linux-x86/dtc:$AOSP/prebuilts/misc/linux-x86/libufdt

build_aosp()
{
    set -x
    cp arch/arm64/boot/dtbo.img $AOSP/device/google/${KERNELNAME}-kernel 
    cp arch/arm64/boot/Image.lz4-dtb $AOSP/device/google/${KERNELNAME}-kernel
    set +x
    # Uncomment if other drivers need to be also updated. The following paths are specific to walleye and may need
    # changes for your specific device.
    cp drivers/input/touchscreen/stm/*.ko $AOSP/device/google/${KERNELNAME}-kernel
    cp drivers/power/*.ko $AOSP/device/google/wahoo-kernel
    cp drivers/input/touchscreen/synaptics_dsx_htc/*.ko $AOSP/device/google/${KERNELNAME}-kernel
    cp drivers/input/touchscreen/lge/*.ko $AOSP/device/google/${KERNELNAME}-kernel
    cp drivers/input/touchscreen/lge/lgsic/*.ko $AOSP/device/google/${KERNELNAME}-kernel
    
    # use ccache
    if [ ${USE_CCACHE} -eq 1 ];then
        echo "use ccache -M ${CCACHE_MEM_SIZE}"
        prebuilts/misc/linux-x86/ccache/ccache -M ${CCACHE_MEM_SIZE}
    fi
 
    echo "Running lunch and make for ${TARGETBUILD}-userdebug in the $AOSP folder"
    pushd .
    cd $AOSP  || return 1
    . build/envsetup.sh || return 1
    lunch aosp_${TARGETBUILD}-userdebug || return 1
    # Alternative 1: Builds everything
    make -j${MAKE_NUM} || return 1
    # Alternative 2: The following may work if only the kernel is being updated
    # make bootimage
    popd
    return 0
}

flash_image()
{
    echo "Attempting to flash image..."
    pushd .
    cd $AOSP
    . build/envsetup.sh
    lunch aosp_${TARGETBUILD}-userdebug || return 1
    set -x
    adb reboot bootloader || return 1
    sleep 10
    echo "fastboot flashall -w"
    fastboot flashall -w || return 1
    set +x
    popd
    echo "Attempt to flash image done..."
}

build_kernel()
{
    cd ${KERNEL}
    # Make walleye_defconfig or appropriate kernel configuration file
    set -x
    echo "Building kernel: make ${KERNELNAME}_defconfig"
    make ${KERNELNAME}_defconfig

    echo "apt-get install ... for kernel dependency"
    apt-get install bc -y
    apt-get install liblz4-tool -y 

    # Build the kernel, using clang if needed.
    if [ -z "${CC_CMD}" ];
    then
        # echo "Building kernel: make V=1 -j40"
        # make V=1 -j40 || exit 1
        echo "Building kernel: make -j${MAKE_NUM}"
        make -j${MAKE_NUM} || exit 1
    else
        # echo "Building kernel: make V=1 CC=${CC_CMD} -j40"
        # make V=1 CC=${CC_CMD} -j40 || exit 1
        echo "Building kernel: make -j${MAKE_NUM}"
        make -j${MAKE_NUM} || exit 1
    fi
    set +x
}

build_kernel || exit 1

# Copy the kernel files to the AOSP tree and build it.
build_aosp || exit 1

# Flash the image to the connected device over adb. The device must be authorized for adb.
# flash_image || exit 1

comment

• set -x

Prints a trace of simple commands, for commands, case commands, select commands, and arithmetic for commands and their arguments or associated word lists after they are expanded and before they are executed.

• pushd .
• popd
  change directory

Hi, here you have mentioned that your Pixel was unresponsive after flashing the compiled kernel. Could you solve that problem and how? Can you help me please.

I could solve the problem, so mentioning the solution here, in case it comes handy to anyone. So I was using the original factory image for Pixel 2 (walleye-opm2.171026.006.c1). Apparently, this image has some issue with the touchscreen, so when I was modifying the boot.img over it, the touchscreen was not responding. It was a guess work but when I flashed the new Android Pie image (walleye-ppr2.181005.003) and flashed the modified image using boot.img from this factory image, everything worked just fine.