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This tool focuses on editing Android boot.img(also recovery.img, and vbmeta.img).

Linux or Mac. Also need python 2.x and jdk 8.

(1) Target boot.img MUST follows AOSP verified boot flow, either Boot image signature in VBoot 1.0 or AVB HASH footer (a.k.a. AVB) in VBoot 2.0.

Supported images:

• boot.img
• recovery.img (also recovery-two-step.img)
• vbmeta.img (also vbmeta_system.img, vbmeta_vendor.img etc.)
• dtbo.img (only 'unpack' is supported)

(2) These utilities are known to work for Nexus/Pixel boot.img for the following Android releases:

• AOSP master
• Lollipop (5.0) - Q preview

Clone this repo with minimal depth:

git clone https://github.com/cfig/Android_boot_image_editor.git --depth=1

Put your boot.img to current directory, then start gradle 'unpack' task:

cp <original_boot_image> boot.img
./gradlew unpack

Your get the flattened kernel and /root filesystem under ./build/unzip_boot:

build/unzip_boot/
├── boot.img.avb.json (AVB only)
├── bootimg.json (boot image info)
├── kernel
├── second       (2nd bootloader, if exists)
├── dtb          (dtb, if exists)
├── dtbo         (dtbo, if exists)
└── root

Then you can edit the actual file contents, like rootfs or kernel. Now, pack the boot.img again

./gradlew pack

You get the repacked boot.img at $(CURDIR):

boot.img.signed

If you are working with recovery.img, the steps are similar:

cp <original_recovery_image> recovery.img
./gradlew unpack
./gradlew pack

And you get recovery.img.signed

An example boot.img has been placed at src/test/resources/boot.img, which is extracted from Nexus 5x(code: bullhead) factory images from Google, you can take it as a quick start.

Read layout of Android boot.img. We now support both VB 1.0 and AVB 2.0 layouts.

boot_signer https://android.googlesource.com/platform/system/extras

bouncycastle https://android.googlesource.com/platform/external/bouncycastle

cpio / fs_config https://android.googlesource.com/platform/system/core

AVB https://android.googlesource.com/platform/external/avb/

mkbootimg https://android.googlesource.com/platform/system/core/+/master/mkbootimg/

Android version list https://source.android.com/source/build-numbers.html

kernel info extractor https://android.googlesource.com/platform/build/+/refs/heads/master/tools/extract_kernel.py

mkdtboimg https://android.googlesource.com/platform/system/libufdt/

libsparse https://android.googlesource.com/platform/system/core/+/refs/heads/master/libsparse/