Development

Build Android Kernel and Run on QEMU with Minimal Environment: Step by Step

Get the Android Linux kernel named "Goldfish". Build. Get initrd or ext4 device image. Run QEMU.

Alexandr Fadeev

Dec 16, 2018 • 1 min read

Short Recipe

git clone https://android.googlesource.com/kernel/goldfish kernel/goldfish
cd ./kernel/goldfish
git checkout -b android-4.4-dev origin/android-4.4
make defconfig
make -j4
wget https://storage.googleapis.com/syzkaller/wheezy.img
qemu-system-x86_64 -m 1GB -kernel arch/x86/boot/bzImage -hda wheezy.img -append "root=/dev/sda"

Step by Step

Get the Android Linux kernel named "Goldfish" adapted to run under emulator (see Building Kernels | Android Open Source Project):
```
git clone https://android.googlesource.com/kernel/goldfish kernel/goldfish
```
Enter the directory. It is empty.
```
cd ./kernel/goldfish
```

List the branches and select any of them.

git branch -a
* master
  remotes/origin/android-4.14
  remotes/origin/android-4.4   # <- Linux kernel 4.4.

Checkout.

git checkout -b android-4.4-dev origin/android-4.4

Build.
```
make defconfig
make -j4
```
Result is here: arch/x86/boot/bzImage.

Install QEMU.

sudo apt install qemu

or just

sudo apt install qemu-system-x86

Run Android Linux kernel with initrd.
Create initrd RAM disk.
```
mkinitramfs -o initrd
```
Run QEMU.
```
qemu-system-x86_64 -m 1GB -kernel arch/x86/boot/bzImage -initrd initrd
```
Give to QEMU some additional RAM memory -m 1GB to not get an error message like "Kernel panic - Not syncing: No working init found."
Run Android Linux kernel with ext4 image.
Download 1GB wheezy.img.
Wheezy image is a R/W image of Debian 7 with 656 MB of a free space. It is suitable for QEMU and also if you're going to run syzkaller further.
```
wget https://storage.googleapis.com/syzkaller/wheezy.img
```
Run QEMU.
```
qemu-system-x86_64 -m 1GB -kernel arch/x86/boot/bzImage -hda wheezy.img -append "root=/dev/sda"
```
Login: root. Password: empty.