Introduction

Building a custom Android ROM allows you to create a personalized version of Android, tailored to your preferences, free from bloatware, and potentially running the latest version on older devices. Using the Android Open Source Project (AOSP), you can build, customize, and flash your own ROM. This guide walks you through the process for beginners, assuming some familiarity with Linux and basic coding concepts.

Prerequisites

Before you start, ensure you have the following:

• A 64-bit Linux PC (Ubuntu recommended) with at least 64GB RAM(recommended), 500GB storage(SSD preferred for faster builds).
• A compatible Android device with an unlocked bootloader and USB cable.
• Basic knowledge of Git, Linux commands, and Android terminology (e.g., bootloader, recovery).
• Internet connection for downloading source code (up to 100GB for AOSP).

Warning: Building and flashing a custom ROM can brick your device if not done correctly. Proceed with caution and back up all data.

Step 1: Set Up Your Build Environment

You’ll need to install necessary tools and configure your Linux system.

1. Install Dependencies: On Ubuntu, run the following to install required packages:

sudo apt-get update
sudo apt-get install openjdk-8-jdk git-core gnupg flex bison gperf build-essential \
zip curl zlib1g-dev gcc-multilib g++-multilib libc6-dev-i386 lib32ncurses5-dev \
lib32z1-dev libgl1-mesa-dev libxml2-utils xsltproc unzip python3
                    

2. Install Repo Tool: Download and configure the Git Repo tool to manage AOSP source code:

mkdir ~/bin
curl https://storage.googleapis.com/git-repo-downloads/repo > ~/bin/repo
chmod a+x ~/bin/repo
export PATH=~/bin:$PATH
                    

3. Configure Git: Set up your Git identity:

git config --global user.email "your.email@example.com"
git config --global user.name "Your Name"
                    

These steps prepare your system to download and build AOSP.

Step 2: Download AOSP Source Code

Download the AOSP source for your desired Android version (e.g., Android 15, codename Baklava):

mkdir ~/android
cd ~/android
repo init -u https://android.googlesource.com/platform/manifest -b android-latest-release
repo sync -c -j4
                    

The repo sync command may take hours depending on your internet speed. The -j4 flag limits parallel downloads to 4 for stability.

Step 3: Obtain Device-Specific Binaries

AOSP doesn’t include proprietary drivers (e.g., for your device’s camera or GPU). Download binaries for your device from the AOSP drivers page or your manufacturer’s website. For example, for a Google Pixel XL:

• Visit the AOSP drivers page.
• Download and extract the vendor image and hardware binaries for your device and Android version.
• Run the self-extracting scripts in the root of your AOSP directory (~/android).

These binaries are placed in the vendor/ directory.

Step 4: Build the ROM

Compile the AOSP source to create a system image:

cd ~/android
source build/envsetup.sh
lunch aosp_codename-userdebug
m
                    

Replace codename with your device’s actual codename (e.g., akita for Google Pixel 8a). The build will take time depending on your hardware. The resulting images are in ~/android/out/target/product/codename/.

Step 5: Flash the ROM

Flash the built ROM to your device:

1. Unlock Bootloader: Enable Developer Options and OEM unlocking in your device settings, then run:

adb reboot bootloader
fastboot flashing unlock