Building the ART Module

ART is built as a module in the form of an APEX package, com.android.art.apex. That package can be installed with adb install on a device running Android S or later. It is also included in the system partition (in the system/apex directory) of platform releases, to ensure it is always available.

The recommended way to build the ART Module is to use the master-art manifest, which only has the sources and dependencies required for the module.

Currently it is also possible to build ART directly from sources in a platform build, i.e. as has been the traditional way up until Android S. However that method is being phased out.

The ART Module is available as a debug variant, com.android.art.debug.apex, which has extra internal consistency checks enabled, and some debug tools. A device cannot have both the non-debug and debug variants installed at once - it may not boot then.

com.google.android.art.apex (note .google.) is the Google signed variant of the module. It is also mutually exclusive with the other ones.

Building as a module on master-art

1. Check out the master-art tree:

   repo init -b master-art -u <repository url>
   

   See the Android source access instructions for further details.

2. Set up the development environment:

   lunch art_module_<arch>
   export TARGET_BUILD_APPS=com.android.art
   export SOONG_ALLOW_MISSING_DEPENDENCIES=true
   

   For Google internal builds, specify instead the Google signed variant of the product and module:

   lunch mainline_modules_<arch>
   export TARGET_BUILD_APPS=com.google.android.art
   export SOONG_ALLOW_MISSING_DEPENDENCIES=true
   

   <arch> is the device architecture, one of arm, arm64, x86, or x86_64. Regardless of the device architecture, the build also includes the usual host architectures, and 64/32-bit multilib for the 64-bit products.

   To build the debug variant of the module, specify com.android.art.debug for TARGET_BUILD_APPS instead. It is also possible to list both.

   TODO(b/179779520): Provide a better setup command.

3. Build the module:

   m
   

4. Install the module and reboot:

   adb install out/target/product/module_<arch>/system/apex/com.android.art.apex
   adb reboot
   

   The name of the APEX file depends on what you put in TARGET_BUILD_APPS.

Building as part of the base system image

NOTE: This method of building is slated to be obsoleted in favor of the module build on master-art above (b/172480617).

1. Check out a full Android platform tree and lunch the appropriate product the normal way.

2. Ensure the ART Module is built from source:

   export SOONG_CONFIG_art_module_source_build=true
   

   If this isn't set then the build may use prebuilts of the ART Module that may be older than the sources.

3. Build the system image the normal way, for example:

   m droid
   

Updating prebuilts

Prebuilts are used for the ART Module dependencies that have sources outside the master-art manifest. Conversely the ART Module is (normally) a prebuilt when used in platform builds of the base system image.

The locations of the prebuilts are:

• prebuilts/runtime/mainline for prebuilts and SDKs required to build the ART Module.

  See prebuilts/runtime/mainline/README.md for instructions on how to update them.

• packages/modules/ArtPrebuilt for the ART Module APEX packages.

• prebuilts/module_sdk/art for the ART Module SDK and other tools, needed to build platform images and other modules that depend on the ART Module.

To update the ART Module prebuilts in the two last locations:

1. Ensure the changes that need to go into the prebuilt are submitted.

2. Wait for a new build on branch aosp-master-art, target aosp_art_module.

3. In a full platform tree, run:

   packages/modules/ArtPrebuilt/update-art-module-prebuilts.py \
     --build <build id> --upload
   

   This will download the prebuilts from the given <build id> (an integer number), create a CL topic, and upload it to Gerrit. Get it reviewed and submit. Please do not make any file changes locally.