1. Android build
  - Download original android source code ( android-8.0.0_r7 ) from http://source.android.com
    (
      $repo init -u https://android.googlesource.com/platform/manifest -b android-8.0.0_r7
      $repo sync -cdq -j12 --no-tags
      $repo start android-8.0.0_r7 --all 
    )

  - And, merge the source into the android source code
  - Run following scripts to build android
    a) source build/envsetup.sh
    b) lunch 1
    c) make -j4
  - When you compile the android source code, you have to add google original prebuilt source(toolchain) into the android directory.
  - After build, you can find output at out/target/product/generic

2. Kernel Build  
  - Uncompress using following command at the android directory

        a) tar -xvzf *_Oreo_Kernel.tar.gz

  - When you compile the kernel source code, you have to add google original prebuilt source(toolchain) into the android directory.
  - Run following scripts to build kernel
  
    a) cd kernel/msm-4.4
    b) mkdir -p out
    c) export CROSS_COMPILE=../../../prebuilts/gcc/linux-x86/aarch64/aarch64-linux-android-4.9/bin/aarch64-linux-android- 
    d) make ARCH=arm64 O=./out joan_global_com-perf_defconfig 
    e) make ARCH=arm64 O=./out KERNEL_COMPRESSION_SUFFIX=gz -j4

	* "-j4" : The number, 4, is the number of multiple jobs to be invoked simultaneously. 
	- After build, you can find the build image(Image.gz) at kernel/msm-4.4/out/arch/arm/boot 
