en/source/add-device.html

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<p>Use the information in this page to create the Makefiles for your device and
product. Please note, unlike the other pages in this section, the contents here
are applicable only when creating an entirely new device type and are intended
for company build and product teams only.</p>

<h2 id="build-layers">Understand Build Layers</h2>

<p>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, thus eliminating copying and
simplifying maintenance.</p>

<table>
 <tbody><tr>
  <th>Layer</th>
  <th>Example</th>
  <th>Description</th>
 </tr>
  <tr>
    <td>Product</td>
    <td>myProduct, myProduct_eu, myProduct_eu_fr, j2, sdk</td>
    <td>The product layer defines the feature specification of a shipping
    product such as the modules to build, locales supported, and the
    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 for
    all products, then creating product variants based on that base
    product. For example, you can have two products that differ only by
    their radios (CDMA vs GSM) inherit from the same base product that
    does not define a radio.
</td>

  </tr>
 <tr>
    <td>Board/Device</td>
    <td>sardine, trout, goldfish</td>
    <td>The device/board layer represents the physical layer of plastic on the
    device (i.e. the industrial design of the device). For example, North American
    devices probably include QWERTY keyboards whereas devices sold in France
    probably include AZERTY keyboards. 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.</td>
  </tr>
<tr>
    <td>Arch</td>
    <td>arm, x86, mips, arm64, x86_64, mips64</td>
    <td>The architecture layer describes the processor configuration and ABI
    (Application Binary Interface) running on the board. </td>
  </tr>
</table>

<h2 id="build-variants">Use Build Variants</h2>

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

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

<p>These are the currently-defined build variants:</p>

<table border=1>
<tr>
    <td>
        <code>eng</code>
    </td>
    <td>
        This is the default flavor.
<ul>
<li>Installs modules tagged with: <code>eng</code> and/or <code>debug</code>.</li>
<li>Installs modules according to the product definition files, in
addition to tagged modules.</li>
<li><code>ro.secure=0</code></li>
<li><code>ro.debuggable=1</code></li>
<li><code>ro.kernel.android.checkjni=1</code></li>
<li><code>adb</code> is enabled by default.</li>
</ul>
    </td>
</tr>
<tr>
    <td>
        <code>user</code>
    </td>
    <td>
        This is the flavor intended to be the final release bits.
<ul>
<li>Installs modules tagged with <code>user</code>.</li>
<li>Installs modules according to the product definition files, in
addition to tagged modules.</li>
<li><code>ro.secure=1</code> </li>
<li><code>ro.debuggable=0</code> </li>
<li><code>adb</code> is disabled by default.</li>
</ul>
    </td>
</tr>
<tr>
    <td>
        <code>userdebug</code>
    </td>
    <td>
        The same as <code>user</code>, except:
<ul>
<li>Also installs modules tagged with <code>debug</code>.</li>
<li><code>ro.debuggable=1</code></li>
<li><code>adb</code> is enabled by default.</li>
</ul>
    </td>
</tr>
</table>

<h2 id="use-resource-overlays">Customize the Build with Resource Overlays</h2>

<p>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 <code>PRODUCT_PACKAGE_OVERLAYS</code> 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.</p>

<p>The most commonly customized settings are contained in the file <a
href="https://android.googlesource.com/platform/frameworks/base/+/master/core/res/res/values/config.xml">frameworks/base/core/res/res/config.xml</a>.</p>

<p> To set up a resource overlay on this file, add the overlay directory to the
project buildfile, as follows:</p>

<pre class="devsite-click-to-copy">
PRODUCT_PACKAGE_OVERLAYS := device/<var>DEVICE_IMPLEMENTER</var>/<var>DEVICE_NAME</var>/overlay
</pre>

<p>or</p>

<pre class="devsite-click-to-copy">
PRODUCT_PACKAGE_OVERLAYS := vendor/<var>VENDOR_NAME</var>/overlay
</pre>

<p> Then, add an overlay file to the directory, for example:</p>

<pre class="devsite-click-to-copy">
vendor/foobar/overlay/frameworks/base/core/res/res/config.xml
</pre>

<p> Any strings or string arrays found in the overlay <code>config.xml</code> file replace
those found in the original file.</p>

<h2 id="build-a-product">Build a Product</h2>

<p>
There are many ways to organize the source files for your device. We'll briefly
go over how the Nexus 6 implementation was organized as an example, but you can
organize your source files and build the way you see fit.
</p>
<p>
Nexus 6 was implemented with a main device configuration named
<code>shamu</code>. 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
<code>device/moto/shamu</code> directory to see how all of this is setup.
</p>
<h3 id="makefiles">Write the Makefiles</h3>
<p>
  The following steps describe how to set up product Makefiles in a way similar
to that of the Nexus 6 product line:
</p>
<ol>
  <li>Create a <code>device/&lt;company_name&gt;/&lt;device_name&gt;</code> directory for your
  product. For example, <code>device/moto/shamu</code>. This directory will contain source code
  for your device along with the Makefiles to build them.
  </li>

  <li>Create a <code>device.mk</code> Makefile that declares the files and modules needed for the
  device. For an example, see <code>device/moto/shamu/device.mk</code>.
  </li>

  <li>Create a product definition Makefile to create a specific product based on the device. The
  following Makefile is taken from <code>device/moto/shamu/aosp_shamu.mk</code> as an example.
  Notice the product is inheriting from the
  <code>device/moto/shamu/device.mk</code> and
  <code>vendor/moto/shamu/device-vendor.mk</code> files via the Makefile while
  also declaring the product-specific information such as name, brand, and model.

<pre class="devsite-click-to-copy">
# Inherit from the common Open Source product configuration
$(call inherit-product, $(SRC_TARGET_DIR)/product/aosp_base_telephony.mk)

PRODUCT_NAME := aosp_shamu
PRODUCT_DEVICE := shamu
PRODUCT_BRAND := Android
PRODUCT_MODEL := AOSP on Shamu
PRODUCT_MANUFACTURER := motorola
PRODUCT_RESTRICT_VENDOR_FILES := true

$(call inherit-product, device/moto/shamu/device.mk)
$(call inherit-product-if-exists, vendor/moto/shamu/device-vendor.mk)

PRODUCT_NAME := aosp_shamu

PRODUCT_PACKAGES += \
    Launcher3
</pre>

    <p>
      See <a href="#prod-def">Product Definition Variables</a> for additional product-specific
      variables you can add to your Makefiles.
    </p>
  </li>

  <li>Create an <code>AndroidProducts.mk</code> file that points to the product's Makefiles. In
  this example, only the product definition Makefile is needed. The example below is from
  <code>device/moto/shamu/AndroidProducts.mk</code>:
<pre class="devsite-click-to-copy">
#
# This file should set PRODUCT_MAKEFILES to a list of product makefiles
# to expose to the build system.  LOCAL_DIR will already be set to
# the directory containing this file.
#
# This file may not rely on the value of any variable other than
# LOCAL_DIR; do not use any conditionals, and do not look up the
# value of any variable that isn't set in this file or in a file that
# it includes.
#

PRODUCT_MAKEFILES := \
    $(LOCAL_DIR)/aosp_shamu.mk
</pre>
  </li>

  <li>Create a <code>BoardConfig.mk</code> Makefile that contains board-specific configurations.
  For an example, see <code>device/moto/shamu/BoardConfig.mk</code>.
  </li>

  <li>Create a <code>vendorsetup.sh</code> file to add your product (a "lunch combo") to the build
  along with a <a href="#build-variants">build variant</a> separated by a dash. For example:
<pre class="devsite-click-to-copy">
add_lunch_combo <var>&lt;PRODUCT_NAME&gt;</var>-userdebug
</pre>
  </li>

  <li>At this point, you can create more product variants based on the same device.
  </li>

</ol>
<h3 id="prod-def">Set Product Definition Variables</h3>
<p>
  Product-specific variables are defined in the product's Makefile. Variables maintained in a
  product definition files include:
</p>
<table>
  <tbody>
    <tr>
      <th>
        Parameter
      </th>
      <th>
        Description
      </th>
      <th>
        Example
      </th>
    </tr>
    <tr>
      <td>
        PRODUCT_AAPT_CONFIG
      </td>
      <td>
        <code>aapt</code> configurations to use when creating packages
      </td>
      <td></td>
    </tr>
    <tr>
      <td>
        PRODUCT_BRAND
      </td>
      <td>
        The brand (e.g., carrier) the software is customized for, if any
      </td>
      <td></td>
    </tr>
    <tr>
      <td>
        PRODUCT_CHARACTERISTICS
      </td>
      <td>
        <code>aapt</code> characteristics to allow adding variant-specific resources to a package.
      </td>
      <td>
        tablet,nosdcard
      </td>
    </tr>
    <tr>
      <td>
        PRODUCT_COPY_FILES
      </td>
      <td>
        List of words like <code>source_path:destination_path</code>. The file at the source path
        should be copied to the destination path when building this product. The rules for the copy
        steps are defined in config/Makefile
      </td>
      <td></td>
    </tr>
    <tr>
      <td>
        PRODUCT_DEVICE
      </td>
      <td>
        Name of the industrial design. This is also the board name, and the build system uses it to locate the <code>BoardConfig.mk.</code>
      </td>
      <td>
        <code>tuna</code>
      </td>
    </tr>
    <tr>
      <td>
        PRODUCT_LOCALES
      </td>
      <td>
        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 PRODUCT_LOCALES is used as the product's default locale.
      </td>
      <td>
        <code>en_GB de_DE es_ES fr_CA</code>
      </td>
    </tr>
    <tr>
      <td>
        PRODUCT_MANUFACTURER
      </td>
      <td>
        Name of the manufacturer
      </td>
      <td>
        <code>acme</code>
      </td>
    </tr>
    <tr>
      <td>
        PRODUCT_MODEL
      </td>
      <td>
        End-user-visible name for the end product
      </td>
      <td></td>
    </tr>
    <tr>
      <td>
        PRODUCT_NAME
      </td>
      <td>
        End-user-visible name for the overall product. Appears in the Settings &gt; About screen.
      </td>
      <td></td>
    </tr>
    <tr>
      <td>
        PRODUCT_OTA_PUBLIC_KEYS
      </td>
      <td>
        List of Over the Air (OTA) public keys for the product
      </td>
      <td></td>
    </tr>
    <tr>
      <td>
        PRODUCT_PACKAGES
      </td>
      <td>
        Lists the APKs and modules to install.
      </td>
      <td>
        <code>Calendar Contacts</code>
      </td>
    </tr>
    <tr>
      <td>
        PRODUCT_PACKAGE_OVERLAYS
      </td>
      <td>
        Indicate whether to use default resources or add any product specific overlays
      </td>
      <td>
        <code>vendor/acme/overlay</code>
      </td>
    </tr>
    <tr>
      <td>
        PRODUCT_PROPERTY_OVERRIDES
      </td>
      <td>
        List of system property assignments in the format "key=value"
      </td>
      <td></td>
    </tr>
  </tbody>
</table>

<h3 id="ANDROID_VENDOR_KEYS">Set ANDROID_VENDOR_KEYS to connect over USB</h3>

<p>The <code>ANDROID_VENDOR_KEYS</code> environment variable enables device
manufacturers to access production builds over <code>adb</code>. Generate a key
for each release that every device will accept, store those internally (such as at
<code>vendor/oem-name/security/adb/</code>), and then use
<code>ANDROID_VENDOR_KEYS</code> to tell <code>adb</code> to use these canonical
keys rather than random keys.</p>

<p>Use the <code>ANDROID_VENDOR_KEYS</code> environment variable to
point to the directory containing the generated <code>adb</code> public and
private keys used for encryption. The private key is stored in file. The public
key is stored in file.pub. The <code>ANDROID_VENDOR_KEYS</code> environment
variable points to a file or directory where the generated key pairs are
stored.</p>

<p>This variable is set to a file or directory that contains 2048-bit RSA
authentication key pairs generated with the <code>adb keygen</code> file command.
These key pairs are in addition to the RSA key pairs generated by the ADB
server. An RSA key pair is needed when you use <code>adb</code> to connect over
USB for the first time.</p>

<p>You must accept the host computer's RSA key to explicitly grant
<code>adb</code> access to the device. By default key pairs generated by the
ADB server are stored in the following key store directories as
<code>adbkey</code> (private key) and <code>adbkey.pub</code> (public key):</p>

<p>For file locations, on MacOS, this will likely be:
<code>$HOME/.android</code>.  On Windows and Linux, this will be:
<code>%USERPOFILE%\.android</code>. On Windows, RSA authentication keys can
also be in <code>C:\Windows\System32\config\systemprofile\.android</code> in
some cases. When the ADB server needs a key, it first searches the ADB server
key store directory. If no keys are found, it then checks the
<code>ANDROID_VENDOR_KEYS</code> environment variable. If no keys are found,
the local ADB server generates and saves a new key pair in the ADB server key
store directory.</p>

<p class="note"><strong>Note:</strong> You can override the default directory
where the ADB server stores RSA keys by setting the
<code>ANDROID_SDK_HOME</code> environment variable. On the device, keys are
stored in the <code>/data/misc/adb/adb_keys/</code> file, and new authorized
keys are appended to the same file as you accept them.</p>

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