lohriialo/device_arpi_rpi4

This guide applies to

Raspberry Pi 4
Android 11 in Tablet mode

Establish build environment :

Ubuntu 18.04.5 LTS (Bionic Beaver) is the recommended build environment, more details read through the AOSP guide https://source.android.com/setup/build/initializing

Required build tools :

sudo apt-get install git-core gnupg flex bison build-essential zip curl zlib1g-dev gcc-multilib g++-multilib libc6-dev-i386 lib32ncurses5-dev x11proto-core-dev libx11-dev lib32z1-dev libgl1-mesa-dev libxml2-utils xsltproc unzip fontconfig kpartx python-mako
git config --global user.name "Your Name"
git config --global user.email "you@example.com"

Installing Repo tool :

Repo tool is required to sync AOSP source code, more details https://source.android.com/setup/develop/repo

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

Sync AOSP source code with Raspberry Pi 4 device tree :

Syncing Android 11 source code, more details https://github.com/android-rpi/local_manifests

mkdir WORKING_DIRECTORY
cd WORKING_DIRECTORY
repo init -u https://android.googlesource.com/platform/manifest -b android-11.0.0_r27
git clone https://github.com/android-rpi/local_manifests .repo/local_manifests -b arpi-11
repo sync -j4

(Optional) if network error :

More rarely, Linux clients experience connectivity issues, getting stuck in the middle of downloads (typically during receiving objects). It's been reported that tweaking the settings of the TCP/IP stack and using non-parallel commands can improve the situation. You need root access to modify the TCP setting:

sudo sysctl -w net.ipv4.tcp_window_scaling=0
repo sync -j1

Patch framework source

Now that we have the source code synced, we need to modify a few things for it to properly work with a Raspberry Pi 4

Apply arpi-11 patch
Change to modify keyboard layout to include power menu, edit key 63 F5 to key 63 POWER at /device/arpi/rpi4/Generic.kl

Patch boot from USB instead of SdCard

Default boot mode is via SD card but for better performance if you want to boot from a USB drive(SSD/Pendrive 3.0 etc), change the boot mode to USB. Modify the file at /device/arpi/rpi4/fstab.rpi4

edit /dev/block/mmcblk0p2 to /dev/block/sda2
edit /dev/block/mmcblk0p3 to /dev/block/sda3
edit /dev/block/mmcblk0p4 to /dev/block/sda4

Build Raspberry Pi 4 Kernel

This build uses the kernel from arpi-5.4.y branch

If not already installed, make sure to install kernel build tools sudo apt install gcc-aarch64-linux-gnu libssl-dev
cd /kernel/arpi
ARCH=arm64 scripts/kconfig/merge_config.sh arch/arm64/configs/bcm2711_defconfig kernel/configs/android-base.config kernel/configs/android-recommended.config
ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- make Image.gz
ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- DTC_FLAGS="-@" make broadcom/bcm2711-rpi-4-b.dtb
ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- DTC_FLAGS="-@" make overlays/vc4-kms-v3d-pi4.dtbo

Build AOSP source

Now that we have everything ready, let's build Android 10 image for Raspberry Pi 4. Usually it takes a couple of hours for the build to complete depending on the speed of your machine. For more details read AOSP build instructions http://source.android.com/source/building.html

cd WORKING_DIRECTORY
source build/envsetup.sh
lunch rpi4-eng
make ramdisk systemimage vendorimage
(Or a single command : source build/envsetup.sh && lunch rpi4-eng && make ramdisk systemimage vendorimage)

If build host machine has a good number of CPU cores, use -j[n] option with make to increase the build speed, example use 4 cpu core:

make -j4 ramdisk systemimage vendorimage

Build errors?

(Only if machine is 8GB RAM or less, allocate atleast 6GB to jvm else chances of running into build error

If error is Exception in thread "main" java.lang.OutOfMemoryError: Java heap space use export _JAVA_OPTIONS="-Xmx8g"
If error is Picked up _JAVA_OPTIONS: -Xmx8g Killed use -j1

Create Android 11 Image

cd device/arpi/rpi4
sudo ./mkimg.sh

Note: Depending on system.img size, change system partition size mkimg.sh

Flash Image to SD Card or USB pendrive or SSD

balena Etcher https://www.balena.io/etcher/
Raspberry Pi Imager https://www.raspberrypi.org/downloads

lohriialo / device_arpi_rpi4