Building for Emulator/AVD

Introduction

In case you don’t have an officially supported device, don’t want to test changes on your daily driver, or are just someone who wants to test apps with LineageOS-specific features, we’ve still got you covered.

These instructions will help you build an emulator-compatible version of LineageOS, ready to run on your computer. If you want to use Android Studio/AVD there are also instructions for packing up/installing your custom build instead of the default AOSP images that Google provides.

What you’ll need

Let’s begin!

Build LineageOS

Install the platform-tools

If you haven’t previously installed adb and fastboot, you can download them from Google. Extract it running:

unzip platform-tools-latest-linux.zip -d ~

Now you have to add adb and fastboot to your PATH. Open ~/.profile and add the following:

# add Android SDK platform tools to path
if [ -d "$HOME/platform-tools" ] ; then
    PATH="$HOME/platform-tools:$PATH"
fi

Then, run source ~/.profile to update your environment.

Install the build packages

Several packages are needed to build LineageOS. You can install these using your distribution’s package manager.

To build LineageOS, you’ll need:

For Ubuntu versions older than 20.04 (focal), install also:

While for Ubuntu versions older than 16.04 (xenial), install:

Java

Different versions of LineageOS require different JDK (Java Development Kit) versions.

* Ubuntu 16.04 and newer do not have OpenJDK 1.7 in the standard package repositories. See the Ask Ubuntu question “How do I install openjdk 7 on Ubuntu 16.04 or higher?”. Note that the suggestion to use PPA openjdk-r is outdated (the PPA has never updated their offering of openjdk-7-jdk, so it lacks security fixes); skip that answer even if it is the most upvoted.

Create the directories

You’ll need to set up some directories in your build environment.

To create them:

mkdir -p ~/bin
mkdir -p ~/android/lineage

The ~/bin directory will contain the git-repo tool (commonly named “repo”) and the ~/android/lineage directory will contain the source code of LineageOS.

Install the repo command

Enter the following to download the repo binary and make it executable (runnable):

curl https://storage.googleapis.com/git-repo-downloads/repo > ~/bin/repo
chmod a+x ~/bin/repo

Put the ~/bin directory in your path of execution

In recent versions of Ubuntu, ~/bin should already be in your PATH. You can check this by opening ~/.profile with a text editor and verifying the following code exists (add it if it is missing):

# set PATH so it includes user's private bin if it exists
if [ -d "$HOME/bin" ] ; then
    PATH="$HOME/bin:$PATH"
fi

Then, run source ~/.profile to update your environment.

Configure git

Given that repo requires you to identify yourself to sync Android, run the following commands to configure your git identity:

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

Turn on caching to speed up build

Make use of ccache if you want to speed up subsequent builds by running:

export USE_CCACHE=1
export CCACHE_EXEC=/usr/bin/ccache

and adding that line to your ~/.bashrc file. Then, specify the maximum amount of disk space you want ccache to use by typing this:

ccache -M 50G

where 50G corresponds to 50GB of cache. This needs to be run once. Anywhere from 25GB-100GB will result in very noticeably increased build speeds (for instance, a typical 1hr build time can be reduced to 20min). If you’re only building for one device, 25GB-50GB is fine. If you plan to build for several devices that do not share the same kernel source, aim for 75GB-100GB. This space will be permanently occupied on your drive, so take this into consideration.

You can also enable the optional ccache compression. While this may involve a slight performance slowdown, it increases the number of files that fit in the cache. To enable it, run:

ccache -o compression=true

Initialize the LineageOS source repository

The following branches have been tested for building emulator images:

Enter the following to initialize the repository:

cd ~/android/lineage
repo init -u https://github.com/LineageOS/android.git -b lineage-18.1

Download the source code

To start the download of the source code to your computer, type the following:

repo sync

The LineageOS manifests include a sensible default configuration for repo, which we strongly suggest you use (i.e. don’t add any options to sync). For reference, our default values are -j 4 and -c. The -j 4 part implies be four simultaneous threads/connections. If you experience problems syncing, you can lower this to -j 3 or -j 2. On the other hand, -c makes repo to pull in only the current branch instead of all branches that are available on GitHub.

Start the build

Time to start building! Now, type:

source build/envsetup.sh
lunch lineage_<arch>-eng
mka

<arch> can be one of the following:

Notably, as of LineageOS 18.1 one can also build Android TV format verions of each arch above, the options for this are as follows:

For starting, x86 is recommended, as your computer can run it natively using hardware acceleration.

Instead of eng one can also target userdebug, the latter is used by official AOSP emulator images, but ADB and communiction with the emulator will need to be enabled first.

Running the emulator

Assuming the build completed without errors, type the following in the terminal window the build ran in:

emulator

The emulator will fire up and you’ll see the LineageOS boot animation. After some time, it will finish booting up and be ready to use.

Success! So… what’s next?

You’ve done it! Welcome to the elite club of self-builders. You’ve built your operating system from scratch, from the ground up. You are the master/mistress of your domain… and hopefully you’ve learned a bit on the way and had some fun too.

Exporting for use in Android Studio/AVD

In case you want to run the emulator image independently from the system/terminal you built it in, you are able to export the built image into a format that can be used by Android Studio/AVD. To do that, run the following command in the same terminal that you originally started the build in:

mka sdk_addon

If you now look into the out/host/linux-x86/sdk_addon directory, you will find a ZIP file (ending in -img.zip) that contains all the necessary files for running the emulator image externally.

To deploy the build into your Android Studio installation, move the contained folder (which is named after the architecture that you built for) into a subfolder of /path/to/android/sdk/system-images. AOSP uses the following path name by default, but you are free to make up your own as well:

system-images/android-<sdk version>/<tag>/<arch> (where <tag> is one of default/google_apis/google_apis_playstore)

LineageOS emulator builds will use the tag lineage by default (visible as “LineageOS” in the images list).

As long as you haven’t moved the folder directly into system-images, the emulator image should now show up in the of the lists of images when creating a new virtual Android device.