GPS for waydroid containers

Use gpsd's implementation of the android.hardware.gnss service ¹ to provide the host's GPS data to the waydroid container. This allows apps inside the container to access location.

The gnss service running in the container will connect via TCP to the gpsd service running on the host using the gpsd client and reports basic location data and SV info to Android.

Building

Setup the build environment

Choose a distribution to build with, this doc assumes Debian trixie.

Install all dependencies listed on https://wiki.lineageos.org/emulator#install-the-build-packages. In addition install

• libncurses5 (which is no longer available in trixie, so take it from boowkworm)
• meson
• glslang-tools (unsure whether we need libglvnd-dev)
• python3-mako
• python3-pycparser
• python3-yaml

Setup ccache

To improve build speeds it might be advisable to use ccache. You might want to set the following variables

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

and set the cache size to some value, e.g., 10G

ccache -M 50G

and enabling compression

ccache -o compression=true

Setup LVM with caching

The build takes up some disk space, around 280GB. If you're using an HDD, you might want to consider setting up LVM caching using a quicker drive. See man lvmcache.

Building system and vendor images

Follow the instructions on https://docs.waydro.id/development/compile-waydroid-lineage-os-based-images. In short:

• Initialize the repository repo init -u https://github.com/LineageOS/android.git -b lineage-20.0 --git-lfs
• Sync it repo sync build/make
• Grab waydroid's local manifests and put them into the .repo/local_manifests/ directory wget -O - https://raw.githubusercontent.com/waydroid/android_vendor_waydroid/lineage-20/manifest_scripts/generate-manifest.sh | bash
• Copy this repo's 90-waydroid-gps.xml file to the .repo/local_manifests/ directory
• Sync all repositories repo sync
• Setup the build environment . build/envsetup.sh
• Apply the waydroid patches apply-waydroid-patches
• Apply this repo's patches. This currently has to be done manually.
  • Apply the patch to device/waydroid/waydroid

    cd device/waydroid/waydroid \
        && git apply <this-repo>/patches/device_waydroid_waydroid.patch
    

• Setup the build environment (unsure whether this actually is needed a second time) . build/envsetup.sh
• Prepare for the image you want to build lunch lineage_waydroid_x86_64-userdebug
• Build the system image make systemimage -j$(nproc --all)
• Build the vendor image make vendorimage -j$(nproc --all)

Use waydroid

• Install waydroid
• Copy system.img and vendor.img to /etc/waydroid-extra/images/
• Run waydroid init -f
• The waydroid container will attempt to connect to the host's gpsd via TCP. The lxc container should allow the outbound connection by default. The host/port to connect to must be configured during build through the service.gpsd.host and service.gpsd.port properties specified in device.mk. When unset, these will resolve to "localhost" and "2947", respectively. In the patch above the host to connect to is configured as 192.168.240.1, which is an IP address on one of the host's interfaces.
• Make sure the host's gpsd service is configured to listen on the IP address configured for the Android image.
  • If running via systemd, make sure the gpsd.socket unit is listening on the correct interface, e.g, by overriding the unit like so

    # /etc/systemd/system/gpsd.socket.d/override.conf
    [Socket]
    ListenStream=
    ListenStream=/run/gpsd.sock
    ListenStream=0.0.0.0:2947
    

    and add GPSD_OPTIONS="--listenany" to /etc/default/gpsd.

Footnotes

1. https://android.googlesource.com/platform/hardware/interfaces/+/refs/heads/main/gnss ↩