en/devices/tech/ota/index.html - platform/docs/source.android.com - Git at Google

 <html devsite>
   <head>
     <title>OTA Updates</title>
     <meta name="project_path" value="/_project.yaml" />
     <meta name="book_path" value="/_book.yaml" />
   </head>
   <body>
   <!--
       Copyright 2017 The Android Open Source Project

       Licensed under the Apache License, Version 2.0 (the "License");
       you may not use this file except in compliance with the License.
       You may obtain a copy of the License at

           http://www.apache.org/licenses/LICENSE-2.0

       Unless required by applicable law or agreed to in writing, software
       distributed under the License is distributed on an "AS IS" BASIS,
       WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
       See the License for the specific language governing permissions and
       limitations under the License.
   -->


     <p>
       Android devices in the field can receive and install over-the-air (OTA)
       updates to the system, application software, and time zone rules. This
       section describes the structure of update packages and the tools provided
       to build them. It is intended for developers who want to make OTA updates
       work on new Android devices and those who want to build update packages
       for released devices.
     </p>

     <p>OTA updates are designed to upgrade the underlying operating system, the
       read-only apps installed on the system partition, and/or time zone rules;
       these updates do <em>not</em> affect applications installed by the user
       from Google Play.
     </p>

     <h2 id="ab_updates">A/B (Seamless) system updates</h2>
     <p>
       Modern Android devices have two copies of each partition (A and B) and can
       apply an update to the currently unused partition while the system is
       running but idle. A/B devices do not need space to download the update
       package because they can apply the update as they read it from the
       network; this is known as <em>streaming A/B</em>. For more information
       about OTA updates for A/B devices, see
       <a href="/devices/tech/ota/ab/index.html">A/B (Seamless) System
       Updates</a>. For a sample app that provides examples on using Android
       system update APIs (i.e., <code>update_engine</code>) to install A/B
       updates, refer to
       <a href="https://android.googlesource.com/platform/bootable/recovery/+/master/updater_sample/"
       class="external">SystemUpdaterSample</a> (app details available in
       <a href="https://android.googlesource.com/platform/bootable/recovery/+/master/updater_sample/README.md"
       class="external"><code>updater_sample/README.md</code></a>).
     </p>

     <h2 id="nonab_updates">Non-A/B system updates</h2>
       <p>
         Older Android devices have a dedicated recovery partition containing the
         software needed to unpack a downloaded update package and apply the
         update to the other partitions. For more information, see
         <a href="/devices/tech/ota/nonab/index.html">Non-A/B System Updates</a>.
       </p>

       <h2 id=time-zone-updates>Time zone rule updates</h2>
       <p>
         As of Android 8.1, OEMs can push updated time zone rules data to devices
         without requiring a system update. This mechanism enables users to
         receive timely updates (thus extending the useful lifetime of an Android
         device) and OEMs to test time zone updates independently of system image
         updates. For details, see
         <a href="/devices/tech/config/timezone-rules">Time Zone Rules</a>.
       </p>

   </body>
 </html>
	<html devsite>
	<head>
	<title>OTA Updates</title>
	<meta name="project_path" value="/_project.yaml" />
	<meta name="book_path" value="/_book.yaml" />
	</head>
	<body>
	<!--
	Copyright 2017 The Android Open Source Project

	Licensed under the Apache License, Version 2.0 (the "License");
	you may not use this file except in compliance with the License.
	You may obtain a copy of the License at

	http://www.apache.org/licenses/LICENSE-2.0

	Unless required by applicable law or agreed to in writing, software
	distributed under the License is distributed on an "AS IS" BASIS,
	WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	See the License for the specific language governing permissions and
	limitations under the License.
	-->



	<p>
	Android devices in the field can receive and install over-the-air (OTA)
	updates to the system, application software, and time zone rules. This
	section describes the structure of update packages and the tools provided
	to build them. It is intended for developers who want to make OTA updates
	work on new Android devices and those who want to build update packages
	for released devices.
	</p>

	<p>OTA updates are designed to upgrade the underlying operating system, the
	read-only apps installed on the system partition, and/or time zone rules;
	these updates do <em>not</em> affect applications installed by the user
	from Google Play.
	</p>

	<h2 id="ab_updates">A/B (Seamless) system updates</h2>
	<p>
	Modern Android devices have two copies of each partition (A and B) and can
	apply an update to the currently unused partition while the system is
	running but idle. A/B devices do not need space to download the update
	package because they can apply the update as they read it from the
	network; this is known as <em>streaming A/B</em>. For more information
	about OTA updates for A/B devices, see
	<a href="/devices/tech/ota/ab/index.html">A/B (Seamless) System
	Updates</a>. For a sample app that provides examples on using Android
	system update APIs (i.e., <code>update_engine</code>) to install A/B
	updates, refer to
	<a href="https://android.googlesource.com/platform/bootable/recovery/+/master/updater_sample/"
	class="external">SystemUpdaterSample</a> (app details available in
	<a href="https://android.googlesource.com/platform/bootable/recovery/+/master/updater_sample/README.md"
	class="external"><code>updater_sample/README.md</code></a>).
	</p>

	<h2 id="nonab_updates">Non-A/B system updates</h2>
	<p>
	Older Android devices have a dedicated recovery partition containing the
	software needed to unpack a downloaded update package and apply the
	update to the other partitions. For more information, see
	<a href="/devices/tech/ota/nonab/index.html">Non-A/B System Updates</a>.
	</p>

	<h2 id=time-zone-updates>Time zone rule updates</h2>
	<p>
	As of Android 8.1, OEMs can push updated time zone rules data to devices
	without requiring a system update. This mechanism enables users to
	receive timely updates (thus extending the useful lifetime of an Android
	device) and OEMs to test time zone updates independently of system image
	updates. For details, see
	<a href="/devices/tech/config/timezone-rules">Time Zone Rules</a>.
	</p>

	</body>
	</html>