Add a new device

Use the information in this page to create the makefiles for your device and product.

Each new Android module must have a configuration file to direct the build system with module metadata, compile-time dependencies, and packaging instructions. Android uses the Soong build system. See Building Android for more information about the Android build system.

Understand build layers

The build hierarchy includes the abstraction layers that correspond to the physical makeup of a device. These layers are described in the table below. Each layer relates to the one above it in a one-to-many relationship. For example, an architecture can have more than one board and each board can have more than one product. You may define an element in a given layer as a specialization of an element in the same layer, which eliminates copying and simplifies maintenance.

Use build variants

When building for a particular product, it's useful to have minor variations on the final release build. In a module definition, the module can specify tags with LOCAL_MODULE_TAGS, which can be one or more values of optional (default), debug, and eng.

If a module doesn't specify a tag (by LOCAL_MODULE_TAGS), its tag defaults to optional. An optional module is installed only if it's required by the product configuration with PRODUCT_PACKAGES.

These are the currently defined build variants.

Guidelines for userdebug

Running userdebug builds in testing helps device developers understand the performance and power of in-development releases. To maintain consistency between user and userdebug builds, and to achieve reliable metrics in builds used for debugging, device developers should follow these guidelines:

• userdebug is defined as a user build with root access enabled, except:
  • userdebug-only apps that are run only on-demand by the user
  • Operations that run only during idle maintenance (on charger/fully charged), such as using dex2oatd versus dex2oat for background compiles
• Don't include features that are enabled/disabled by default based on the build type. Developers are discouraged from using any form of logging that affects battery life, such as debug logging or heap dumping.
• Any debugging features that are enabled by default in userdebug should be clearly defined and shared with all developers working on the project. You should enable debugging features only on a limited-time basis until the issue you're trying to debug is resolved.

Customize the build with resource overlays

The Android build system uses resource overlays to customize a product at build time. Resource overlays specify resource files that are applied on top of the defaults. To use resource overlays, modify the project buildfile to set PRODUCT_PACKAGE_OVERLAYS to a path relative to your top-level directory. That path becomes a shadow root searched along with the current root when the build system searches for resources.

The most commonly customized settings are contained in the file frameworks/base/core/res/res/values/config.xml.

To set up a resource overlay on this file, add the overlay directory to the project buildfile using one of the following:

PRODUCT_PACKAGE_OVERLAYS := device/device-implementer/device-name/overlay

or

PRODUCT_PACKAGE_OVERLAYS := vendor/vendor-name/overlay

Then, add an overlay file to the directory, for example:

vendor/foobar/overlay/frameworks/base/core/res/res/values/config.xml

Any strings or string arrays found in the overlay config.xml file replace those found in the original file.

Build a product

You can organize the source files for your device in many different ways. Here's a brief description of one way to organize a Pixel implementation.

Pixel is implemented with a main device configuration named marlin. From this device configuration, a product is created with a product definition makefile that declares product-specific information about the device such as the name and model. You can view the device/google/marlin directory to see how all of this is set up.

Write product makefiles

The following steps describe how to set up product makefiles in a way similar to that of the Pixel product line:

1. Create a device/<company-name>/<device-name> directory for your product. For example, device/google/marlin. This directory will contain source code for your device along with the makefiles to build them.
2. Create a device.mk makefile that declares the files and modules needed for the device. For an example, see device/google/marlin/device-marlin.mk.
3. Create a product definition makefile to create a specific product based on the device. The following makefile is taken from device/google/marlin/aosp_marlin.mk as an example. Notice that the product inherits from the device/google/marlin/device-marlin.mk and vendor/google/marlin/device-vendor-marlin.mk files through the makefile while also declaring the product-specific information such as name, brand, and model.

   # Inherit from the common Open Source product configuration
   $(call inherit-product, $(SRC_TARGET_DIR)/product/core_64_bit.mk)
   $(call inherit-product, $(SRC_TARGET_DIR)/product/aosp_base_telephony.mk)
   
   PRODUCT_NAME := aosp_marlin
   PRODUCT_DEVICE := marlin
   PRODUCT_BRAND := Android
   PRODUCT_MODEL := AOSP on msm8996
   PRODUCT_MANUFACTURER := Google
   PRODUCT_RESTRICT_VENDOR_FILES := true
   
   PRODUCT_COPY_FILES += device/google/marlin/fstab.common:$(TARGET_COPY_OUT_VENDOR)/etc/fstab.marlin
   
   $(call inherit-product, device/google/marlin/device-marlin.mk)
   $(call inherit-product-if-exists, vendor/google_devices/marlin/device-vendor-marlin.mk)
   
   PRODUCT_PACKAGES += \
       Launcher3QuickStep \
       WallpaperPicker
   

   See Setting product definition variables for additional product-specific variables that you can add to your makefiles.

4. Create an AndroidProducts.mk file that points to the product's makefiles. In this example, only the product definition makefile is needed. The example below is from device/google/marlin/AndroidProducts.mk (which contains both marlin, the Pixel, and sailfish, the Pixel XL, which shared most configuration):

   PRODUCT_MAKEFILES := \
   	$(LOCAL_DIR)/aosp_marlin.mk \
   	$(LOCAL_DIR)/aosp_sailfish.mk
   
   COMMON_LUNCH_CHOICES := \
   	aosp_marlin-userdebug \
   	aosp_sailfish-userdebug
   

5. Create a BoardConfig.mk makefile that contains board-specific configurations. For an example, see device/google/marlin/BoardConfig.mk.
6. For Android 9 and lower only, create a vendorsetup.sh file to add your product (a "lunch combo") to the build along with a build variant separated by a dash. For example:

   add_lunch_combo <product-name>-userdebug
   

7. At this point, you can create more product variants based on the same device.

Set product definition variables

Product-specific variables are defined in the product's makefile. The table shows some of the variables maintained in a product definition file.

Configure default system language and locale filter

Use this information to configure the default language and system locale filter, then enable the locale filter for a new device type.

Properties

Configure both the default language and the system locale filter using dedicated system properties:

• ro.product.locale: for setting the default locale. This is initially set to the first locale in the PRODUCT_LOCALES variable; you can override that value. (For more information, see the Setting product definition variables table.)
• ro.localization.locale_filter: for setting a locale filter, using a regular expression applied to locale names. For example:
  • Inclusive filter: ^(de-AT|de-DE|en|uk).* - allows only German (Austria and Germany variants), all English variants of English, and Ukrainian
  • Exclusive filter: ^(?!de-IT|es).* - excludes German (Italy variant), and all variants of Spanish.

Enable the locale filter

To enable the filter, set the ro.localization.locale_filter system property string value.

By setting the filter property value and the default language through oem/oem.prop during factory calibration you can configure restrictions without baking the filter into the system image. You ensure that these properties are picked up from the OEM partition by adding them to the PRODUCT_OEM_PROPERTIES variable as indicated below:

# Delegation for OEM customization
PRODUCT_OEM_PROPERTIES += \
    ro.product.locale \
    ro.localization.locale_filter

Then in production the actual values are written to oem/oem.prop, to reflect the target requirements. With this approach, the default values are retained during the factory reset, so the initial settings look exactly like a first setup to the user.

Set ADB_VENDOR_KEYS to connect over USB

The ADB_VENDOR_KEYS environment variable enables device manufacturers to access debuggable builds (-userdebug and -eng, but not -user) over adb without manual authorization. Normally adb generates a unique RSA authentication key for each client computer, which it will send to any connected device. This is the RSA key shown in the adb authorization dialog. As an alternative you can build known keys into the system image and share them with the adb client. This is useful for OS development and especially for testing because it avoids the need to manually interact with the adb authorization dialog.

To create vendor keys, one person (usually a release manager) should:

1. Generate a key pair using adb keygen. For Google devices, Google generates a new key pair for each new OS version.
2. Check the key pairs in, somewhere in the source tree. Google stores them in vendor/google/security/adb/, for example.
3. Set the build variable PRODUCT_ADB_KEYS to point to your key directory. Google does this by adding an Android.mk file in the key directory that says PRODUCT_ADB_KEYS := $(LOCAL_PATH)/$(PLATFORM_VERSION).adb_key.pub, which helps ensure that we remember to generate a new key pair for each OS version.

Here's the makefile Google uses in the directory where we store our checked-in key pairs for each release:

PRODUCT_ADB_KEYS := $(LOCAL_PATH)/$(PLATFORM_VERSION).adb_key.pub

ifeq ($(wildcard $(PRODUCT_ADB_KEYS)),)
  $(warning ========================)
  $(warning The adb key for this release)
  $(warning )
  $(warning   $(PRODUCT_ADB_KEYS))
  $(warning )
  $(warning does not exist. Most likely PLATFORM_VERSION in build/core/version_defaults.mk)
  $(warning has changed and a new adb key needs to be generated.)
  $(warning )
  $(warning Please run the following commands to create a new key:)
  $(warning )
  $(warning   make -j8 adb)
  $(warning   LOGNAME=android-eng HOSTNAME=google.com adb keygen $(patsubst %.pub,%,$(PRODUCT_ADB_KEYS)))
  $(warning )
  $(warning and upload/review/submit the changes)
  $(warning ========================)
  $(error done)
endif

To use these vendor keys, an engineer only needs to set the ADB_VENDOR_KEYS environment variable to point to the directory in which the key pairs are stored. This tells adb to try these canonical keys first, before falling back to the generated host key that requires manual authorization. When adb can't connect to an unauthorized device, the error message will suggest that you set ADB_VENDOR_KEYS if it's not already set.