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.
Understanding 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.
|Product||myProduct, myProduct_eu, myProduct_eu_fr, j2, sdk||The product layer defines the feature specification of a shipping product such as the modules to build, locales supported, and configuration for various locales. In other words, this is the name of the overall product. Product-specific variables are defined in product definition makefiles. A product can inherit from other product definitions, which simplifies maintenance. A common method is to create a base product that contains features that apply to all products, then create product variants based on that base product. For example, two products that differ only by their radios (CDMA versus GSM) can inherit from the same base product that doesn't define a radio.|
|Board/device||marlin, blueline, coral||The board/device layer represents the physical layer of plastic on the device (that is, the industrial design of the device). This layer also represents the bare schematics of a product. These include the peripherals on the board and their configuration. The names used are merely codes for different board/device configurations.|
|Arch||arm, x86, arm64, x86_64||The architecture layer describes the processor configuration and application binary interface (ABI) running on the board.|
Using 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
which can be one or more values of
If a module doesn't specify a tag (by
tag defaults to
optional. An optional module is installed only if
it's required by the product configuration with
These are the currently defined build variants.
This is the default flavor.
The variant intended to be the final release bits.
The same as
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
dex2oatfor 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.
Customizing 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
PRODUCT_PACKAGE_OVERLAYS := vendor/vendor-name/overlay
Then, add an overlay file to the directory, for example:
Any strings or string arrays found in the overlay
config.xml file replace
those found in the original file.
Building 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.
Writing product makefiles
The following steps describe how to set up product makefiles in a way similar to that of the Pixel product line:
- 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.
- Create a
device.mkmakefile that declares the files and modules needed for the device. For an example, see
- 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.mkas an example. Notice that the product inherits from the
vendor/google/marlin/device-vendor-marlin.mkfiles 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.
- Create an
AndroidProducts.mkfile 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
- Create a
BoardConfig.mkmakefile that contains board-specific configurations. For an example, see
- For Android 9 and lower only, create a
vendorsetup.shfile to add your product (a "lunch combo") to the build along with a build variant separated by a dash. For example:
- At this point, you can create more product variants based on the same device.
Setting 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.
||The brand (for example, carrier) the software is customized for, if any.|
List of words like
Name of the industrial design. This is also the board name, and the build system uses it
A space-separated list of two-letter language code, two-letter country code pairs that
describe several settings for the user, such as the UI language and time, date, and
currency formatting. The first locale listed in
||Name of the manufacturer.||
||End-user-visible name for the end product.|
||End-user-visible name for the overall product. Appears in the Settings > About screen.|
||List of over-the-air (OTA) public keys for the product.|
||List of the APKs and modules to install.||Calendar contacts|
||Indicates whether to use default resources or add any product specific overlays.||
List of the system property assignments in the format
Configuring the 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.
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_LOCALESvariable; 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.
- Inclusive filter:
Enabling 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
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.
Setting ADB_VENDOR_KEYS to connect over USB
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:
- Generate a key pair using
adb keygen. For Google devices, Google generates a new key pair for each new OS version.
- Check the key pairs in, somewhere in the source tree. Google stores them in
vendor/google/security/adb/, for example.
- Set the build variable
PRODUCT_ADB_KEYSto point to your key directory. Google does this by adding an
Android.mkfile 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
environment variable to point to the directory in which the key pairs are stored.
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