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Android_boot_image_editor/README.md

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# Nexus_boot_image_editor
[![Build Status](https://travis-ci.org/cfig/Nexus_boot_image_editor.svg?branch=master)](https://travis-ci.org/cfig/Nexus_boot_image_editor)
Utilies for editing Nexus(or Nexus compatible) devices boot.img , then you don't need full Android source code to edit your boot images.
## Prerequisite
#### Host OS requirement:
The unpacking task only works on Linux, the packing task can work on Linux & OSX.
So the recommended OS is Linux.
#### Target Android requirement:
(1) Targeted boot.img MUST follows AOSP [verified boot flow](https://source.android.com/security/verifiedboot/index.html), which means it packs linux kernel and rootfs together, then sign it with OEM/USER keys.
(2) These utilities are known to work for Nexus (or Nexus compatible) boot.img for the following Android releases:
Branch: master
- Android AOSP master
Branch: Marshmallow
- Marshmallow (API Level 23)
- Lollipop (API Level 21,22)
You can get a full [Android version list](https://source.android.com/source/build-numbers.html) here.
## Usage
Get tools via git:
git clone https://github.com/cfig/Nexus_boot_image_editor.git
cd Nexus_boot_image_editor
Then put your boot.img at **$(CURDIR)/boot.img**, then start gradle 'unpack' task:
cp <original_boot_image> boot.img
./gradew unpack
Your get the flattened kernel and /root filesystem under **$(CURDIR)/build/unzip\_boot**:
build/unzip_boot/
├── bootimg.cfg
├── kernel
└── root
Then you can edit the actual file contents, like rootfs or kernel.
Now, pack the boot.img again
./gradew pack
You get the repacked boot.img at $(CURDIR):
boot.img.signed
## Advanced usage for ROM developers
If you have full Android source code, and have set up environment by envsetup/lunch, then the "pack" task will use $ANDROID\_PRODUCT\_OUT/root as rootfs.
. build/envsetup.sh
lunch xx-userdebug
cd <path_to_Nexus_boot_image_editor>
./gradew pack
If you have a rooted Android device connected via adb, you can also flash it with "flash" task:
./gradew flash
This will update the updated boot.img to /dev/block/by-name/boot.
## example & test
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](https://dl.google.com/dl/android/aosp/bullhead-mda89e-factory-29247942.tgz), you can take it as a quick start.