| <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 and application software. This section describes |
| the structure of the update packages and the tools provided to build |
| them. It is intended for developers who want to make the OTA update |
| system work on new Android devices and those who are building update |
| packages for use with released devices. OTA updates are designed to |
| upgrade the underlying operating system and the read-only apps installed |
| on the system partition; these updates do <em>not</em> affect |
| applications installed by the user from Google Play. |
| </p> |
| |
| <h2 id="ab_updates">A/B updates</h2> |
| |
| <p> |
| Modern A/B devices have two copies of each partition, A and B. Devices |
| apply the 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 called <em>streaming A/B</em>. A/B updates are also |
| known as <em>seamless updates</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>. |
| </p> |
| |
| <h2 id="nonab_updates">Non-A/B updates</h2> |
| |
| <p> |
| Older devices have a special 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> |
| |
| </body> |
| </html> |
