1. Download AOSP source code

Sync the source code from repository (e.g., Tsinghua mirror).

repo init -u https://mirrors.tuna.tsinghua.edu.cn/git/AOSP/platform/manifest -b android-11.0.0_r25 # The version name is after "-b"

repo sync # Or use "repo sync -j8" where j8 represents using 8 threads.

2. Download and install device drivers

• You can find drivers for Nexus and Pixel series on the website. It is important to note that each driver has a specific code that needs to correspond with the build number of the AOSP source code you have downloaded.

• After decompression, you will get two shell files. Copy them to the root directory of the downloaded AOSP source code.

• Execute the two extracted shell files. When prompted for a license, press enter to agree. Use the spacebar to scroll to the end and enter "I ACCEPT".

3. Prepare environment for compliling

• Execute source build/envsetup.sh to set up the necessary environment variables in the shell.
• Execute make clean to clear previous compilation results.
• To select a build target, use the lunch command. The syntax is as follows:

lunch product_name-build_variant 
# the "product_name" part is the device alias, while "build_variant" part refers to the specific variant. 
# For example: lunch aosp_coral-userdebug

You can find a list of product builds here, while the variants include: user, userdebug, and eng.

4. Compile source code

m -j32 # Enable 32-thread compilation

Compiling AOSP source code is a memory and time-intensive task. It is recommended to use a high-configured server and a separate thread window for the process.

5. Flash the image into a Android device

• Find an unused Android smartphone with an unlocked Bootloader (each model has its own method, tutorials can be found easily online).
• Configure the fastboot tool in the computer system, you can either compile it using the make fastboot command in the aosp directory or download it directly from the website.
• Enter fastboot mode on your phone, you can either press the corresponding key combination during startup or use the following command:

adb reboot bootloader

• Make sure to install Android USB driver on your computer to avoid the situation where the device cannot be found after the phone restarts.
• Set the environment variable ANDROID_PRODUCT_OUT on your computer to the directory of the compiled image, such as "....../aosp/out/target/product/coral".
• Navigate to the image directory on your computer and proceed with the flashing process:

cd ..../aosp/out/target/product/coral

fastboot flashall -w

• After the flashing process is complete, the phone will automatically power on and enter the new system.