How to download and compile Android kernel goldfish ?

Prerequisites

Assuming that we already downloaded the android-ndk-r12b and sdk.

:~/utils$ ls
android-ndk-r12b android-sdk-linux bin goldfish nexus7

And then we need to set up the environment.
Or you can download the vm having been set up directly. [1]

1. Edit ~/.bashrc

# add Android SDK Tools to the path
export ANDROID_SDK=~/utils/android-sdk-linux
export PATH=$PATH:$ANDROID_SDK/tools:$ANDROID_SDK/platform-tools

# add other custom utilities to the path
export PATH=$PATH:~/utils/bin

# set up debugging paths
export PATH=$PATH:~/utils/android-ndk-r12b/prebuilt/android-arm64/gdbserver/:~/utils/android-ndk-r12b/prebuilt/linux-x86_64/bin/

# add toolchain to the path
export PATH=$PATH:~/utils/android-ndk-r12b/toolchains/x86_64-4.9/prebuilt/linux-x86_64/bin:~/utils/android-ndk-r12b/toolchains/aarch64-linux-android-4.9/prebuilt/linux-x86_64/bin:~/utils/android-ndk-r12b/prebuilt/android-arm64:~/utils/android-ndk-r12b/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64/bin:~/utils/android-ndk-r12b:~/utils/arm-eabi-4.8/bin:~/utils/android-ndk-r10e

export A24_INCLUDE=~/utils/android-ndk-r12b/platforms/android-24/arch-arm64/usr/include/
export A24_LINK=~/utils/android-ndk-r12b/platforms/android-24/arch-arm64/usr/lib/
export A24_SYSROOT=~/utils/android-ndk-r12b/platforms/android-24/arch-arm64/


export A23_INCLUDE=~/utils/android-ndk-r12b/platforms/android-23/arch-arm64/usr/include/
export A23_LINK=~/utils/android-ndk-r12b/platforms/android-23/arch-arm64/usr/lib/
export A23_SYSROOT=~/utils/android-ndk-r12b/platforms/android-23/arch-arm64/

Then

$source ~/.bashrc

2. Download android-kernel-goldfish

$git clone http://android.googlesource.com/kernel/goldfish.git   
$git branch -a  
$git checkout -b debug-android-goldfish-3.18 remotes/origin/android-goldfish-3.18

3. Compile kernel

$make ARCH=arm64 ranchu_defconfig $make -j8 ARCH=arm64 CROSS_COMPILE=aarch64-linux-android-
hint: adding an alias to your ~/.bashrc file:

alias armmake="make -j16 KCFLAGS=-ggdb3 ARCH=arm64 CROSS_COMPILE=aarch64-linux-android-"

4. Create the emulator

Create an Android Virtual Device (AVD), and install a custom 3.18 kernel in it.

Run android avd from the terminal
Add a new AVD by clicking "Create"
Pick a suitable name (we chose w4118avd)
Choose a Galaxy Nexus device
Target and CPU/ABI should self populate
Pick a "Skin with dynamic hardware controls"
Give at least 1500MB of RAM and a 256MB VM Heap
Tick on "Use Host GPU"

Once your AVD is set up, you can start it from the terminal with

$emulator @avdname -show-kernel

You need to open it with default kernel firstly; otherwise, it cannot start it by above emulator command.

• Hardware acceleration must be enabled in your VM settings for the AVD to boot.
• The AVD can take up to 10 minutes to boot. If the AVD fails to boot, try restarting your VM and your Host machine and allocating more memory to the VM. Giving more RAM to the AVD can also be helpful.
• If the emulator shows a completely black screen with a "Process System isn‘t responding", click on Wait a few times and you will get to the home screen soon.

5. Start the emulator

After compiling, you can start the emulator again.

$emulator @w4118avd -kernel arch/arm64/boot/Image -show-kernel -no-window -verbose -netfast

On x86_64 emulator

$make ARCH=x86_64 x86_64_ranchu_defconfig
$make -j16 ARCH=x86_64 CROSS_COMPILE=x86_64-linux-android- 2>&1 |tee kernel_make.out

$emulator -verbose @x86 -kernel arch/x86/boot/bzImage -show-kernel -no-window -qemu --enable-kvm 2>&1 | tee boot_errors

On armv7-32bit

kernel : android-goldfish-3.10
rom : android 7.0
toolchain : arm-eabi-4.8 (doesn‘t include in ndk-r12b)
command :

$make ARCH=arm ranchu_defconfig
$make -j16 ARCH=arm KCFLAGS=-ggdb3 CROSS_COMPILE=arm-eabi-
$emulator @arm32 -kernel arch/arm/boot/zImage -show-kernel -no-window -verbose -netfast

On x86 (not used)

kernel : android-goldfish-3.10
rom : android 7.0
command :
edit .config:

  │    [*] KGDB: kernel debugger  --->   
  │ │    [*] Compile the kernel with debug info                                     │ │  
  │ │    [*]   Provide GDB scripts for kernel debugging                  

$make ARCH=x86 i386_ranchu_defconfig
$make -j7 KCFLAGS=-ggdb3 ARCH=x86 

$emulator @x86 -kernel arch/x86/boot/bzImage -show-kernel -no-window -verbose -netfast

Kernel and ROM matched table

Other useful command

#### Android Stop Emulator from Command Line
    adb emu kill
#### Get the kernel messages
    adb shell dmesg
    adb shell cat /proc/kmsg
#### Redirecting kernel logs:
    For Windows:‐> adb shell cat /proc/kmsg > kernelmsg.txt
    For Linux:‐‐> adb shell cat /proc/kmsg | tee ‐a kernelmsg.txt
    

stop-emulators.sh

#!/bin/bash
for ((PORT=5554; PORT<=5584; PORT+=2)); do
    echo killing emulator-$PORT...
    adb -s emulator-$PORT emu kill
done

ref :

[1]
[2]
[3]
[4]
[5]