The AOSP build process is fairly well understood by now: sync the source code, add device-specific drivers and kernel, and build the target image. I had built AOSP before to debug certain issues, but official support for Pixel 3 XL only goes up to Android 12. Recently, while working on Chromium development, I needed to test WebView on a newer platform, so I used LineageOS 21 for the build instead.

Prerequisites

Assumes a configured AOSP build environment:

Syncing AOSP Source

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mkdir ~/aosp
cd ~/aosp
repo init --partial-clone -b android-12.0.0_r34 -u https://android.googlesource.com/platform/manifest
repo sync -c -j8

Obtaining Drivers

  1. Look up the Pixel 3 XL (codename crosshatch) on the Build Numbers page to find the latest Build ID, e.g., SP1A.210812.016.C2
  2. Download the corresponding drivers from Google Drivers
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mkdir vendor_backup && cd vendor_backup
wget https://dl.google.com/dl/android/aosp/google_devices-crosshatch-sp1a.210812.016.c2-a4e274b7.tgz
wget https://dl.google.com/dl/android/aosp/qcom-crosshatch-sp1a.210812.016.c2-00a7f1f3.tgz

tar xvf qcom-crosshatch-*.tgz
tar xvf google_devices-crosshatch-*.tgz
./extract-google_devices-crosshatch.sh
./extract-qcom-crosshatch.sh
mv vendor/ ../

Building and Flashing

Refer to the Building AOSP documentation:

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cd ~/aosp
source build/envsetup.sh
# Choose Pixel 3 XL (crosshatch) as the build target
# user/userdebug/eng select different build types
lunch aosp_crosshatch-userdebug

# Start the build
m

# Flash the device
export ANDROID_PRODUCT_OUT='/home/haoxiqiang/workspace/aosp/out/target/product/crosshatch'
adb reboot fastboot
fastboot flashall -w

For differences between user, userdebug, and eng build types, see the official documentation.

Building with LineageOS

For newer Android versions, LineageOS provides excellent device support:

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repo init --partial-clone -u https://github.com/LineageOS/android.git -b lineage-21.0 --git-lfs
repo sync -c -j8

See the LineageOS Build Wiki for detailed instructions.

References