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 <p>As part of the Android 8.0 rearchitecture of the lower layers of the Android OS
 to support better modularity, devices running Android 8.0 must support binderized
 or passthrough HALs:</p>

 <ul>
 <li><strong>Binderized HALs</strong>. HALs expressed in HAL interface definition
 language (HIDL). These HALs replace both conventional and legacy HALs used in earlier versions of
 Android. In a Binderized HAL, the Android framework and HALs communicate with each other using
 binder inter-process communication (IPC) calls. All devices launching with Android 8.0 or later must
 support binderized HALs only.</li>

 <li><strong>Passthrough HALs</strong>. A HIDL-wrapped conventional or legacy
 HAL. These HALs wrap existing HALs and can serve the HAL in binderized and
 same-process (passthrough) modes. Devices upgrading to Android 8.0 can use
 passthrough HALs.</li>
 </ul>

 <h2 id=requirements>HAL mode requirements</h2>

 <table>
 <tbody>

 <tr>
 <th>Device</th>
 <th>Passthrough</th>
 <th>Binderized</th>
 </tr>

 <tr>
 <td><em>Launch with Android 8.0</em></td>
 <td>HALs listed in <a href="#passthrough">Passthrough HALs</a> must be
 passthrough.</td>
 <td>All other HALs are binderized (including HALs that are vendor
 extensions).</td>
 </tr>

 <tr>
 <td rowspan=2><em>Upgrade to Android 8.0</em></td>
 <td>HALs listed in <a href="#passthrough">Passthrough HALs</a> must be
 passthrough.</td>
 <td>HALs listed in <a href="#binderized">Binderized HALs</a> must be
 binderized.</td>
 </tr>

 <tr>
 <td colspan=2>All other HALs provided by the vendor image can be in passthrough
 OR binderized mode.</td>
 </tr>

 </tbody>
 </table>

 <h2 id=binderized>Binderized HALs</h2>
 <p>Android requires the following HALS to to be binderized on all Android
 devices regardless of whether they are launch devices or upgrade devices:</p>

 <ul>
 <li><code>android.hardware.biometrics.fingerprint@2.1</code>. Replaces
 <code>fingerprintd</code> which is no longer in Android 8.0.</li>
 <li><code>android.hardware.configstore@1.0</code>. New in Android 8.0.</li>
 <li><code>android.hardware.dumpstate@1.0</code>. The original interface provided
 by this HAL could not be shimmed and was changed. Because of this,
 <code>dumpstate_board</code> must be re-implemented on a given device (this is
 an optional HAL).</li>
 <li><code>android.hardware.graphics.allocator@2.0</code>. Required to be
 binderized in Android 8.0 so file descriptors don't have to be shared between
 trusted and untrusted processes.</li>
 <li><code>android.hardware.radio@1.0</code>. Replaces the interface provided by
 <code>rild</code> which lives in its own process.</li>
 <li><code>android.hardware.usb@1.0</code>. New in Android 8.0.</li>
 <li><code>android.hardware.wifi@1.0</code>. New in Android 8.0, replaces the
 legacy Wi-Fi HAL library that was loaded into <code>system_server</code>.</li>
 <li><code>android.hardware.wifi.supplicant@1.0</code>. A HIDL interface over the
 existing <code>wpa_supplicant</code> process.</li>
 </ul>

 <p class=note><strong>NOTE</strong>: Android provides the following HIDL
 interfaces which will always be in binderized mode:
 <code>android.frameworks.*</code>, <code>android.system.*</code> , and
 <code>android.hidl.*</code> (except for <code>android.hidl.memory@1.0</code>
 as described below).</p>

 <h2 id=passthrough>Passthrough HALs</h2>
 <p>Android requires the following HALs to be in passthrough mode on all Android
 devices regardless of whether they are launch devices or upgrade devices:</p>

 <ul>
 <li><code>android.hardware.graphics.mapper@1.0</code>. Maps memory into the
 process it lives in.</li>
 <li><code>android.hardware.renderscript@1.0</code>. Passes items in the same
 process (equivalent to <code>openGL</code>).</li>
 </ul>
 <p>All HALs not listed above must be binderized for launch devices.</p>

 <h2 id=same-process>Same-Process HALs</h2>
 <p>Same-Process HALs (SP-HALs) always open in the same process in which they are
 used. They include all HALs not expressed in HIDL as well as some that are
 <strong>not</strong> binderized. Membership in the SP-HAL set is controlled only
 by Google, with no exceptions.</p>

 <p>SP-HALs include the following:</p>

 <ul>
 <li><code>openGL</code></li>
 <li><code>Vulkan</code></li>
 <li><code>android.hidl.memory@1.0</code> (provided by the Android system, always
 passthrough)</li>
 <li><code>android.hardware.graphics.mapper@1.0</code>.</li>
 <li><code>android.hardware.renderscript@1.0</code></li>
 </ul>

 <h2 id=legacy>Conventional &amp; legacy HALs</h2>

 <p>Conventional HALs (deprecated in Android 8.0) are interfaces that conform to a
 specific named and versioned application binary interface (ABI). The bulk of
 Android system interfaces
 (<a href="https://android.googlesource.com/platform/hardware/libhardware/+/master/include/hardware/camera3.h">camera</a>,
 <a href="https://android.googlesource.com/platform/hardware/libhardware/+/master/include/hardware/audio.h">audio</a>,
 <a href="https://android.googlesource.com/platform/hardware/libhardware/+/master/include/hardware/sensors.h">sensors</a>,
 etc.) are in the form of conventional HALs, which are defined under
 <a href="https://android.googlesource.com/platform/hardware/libhardware/+/master/include/hardware">hardware/libhardware/include/hardware</a>.</p>

 <p>Legacy HALs (also deprecated in Android 8.0) are interfaces that predate
 conventional HALs. A few important subsystems (Wi-Fi, Radio Interface Layer, and
 Bluetooth) are legacy HALs. While there's no uniform or standardized way to
 describe a legacy HAL, anything predating Android 8.0 that is not a conventional
 HAL is a legacy HAL. Parts of some legacy HALs are contained in
 <a href="https://android.googlesource.com/platform/hardware/libhardware_legacy/+/master">libhardware_legacy</a>,
 while other parts are interspersed throughout the codebase.</p>

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 </html>
	<html devsite>
	<head>
	<title>HAL Types</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>As part of the Android 8.0 rearchitecture of the lower layers of the Android OS
	to support better modularity, devices running Android 8.0 must support binderized
	or passthrough HALs:</p>

	<ul>
	<li><strong>Binderized HALs</strong>. HALs expressed in HAL interface definition
	language (HIDL). These HALs replace both conventional and legacy HALs used in earlier versions of
	Android. In a Binderized HAL, the Android framework and HALs communicate with each other using
	binder inter-process communication (IPC) calls. All devices launching with Android 8.0 or later must
	support binderized HALs only.</li>

	<li><strong>Passthrough HALs</strong>. A HIDL-wrapped conventional or legacy
	HAL. These HALs wrap existing HALs and can serve the HAL in binderized and
	same-process (passthrough) modes. Devices upgrading to Android 8.0 can use
	passthrough HALs.</li>
	</ul>

	<h2 id=requirements>HAL mode requirements</h2>

	<table>
	<tbody>

	<tr>
	<th>Device</th>
	<th>Passthrough</th>
	<th>Binderized</th>
	</tr>

	<tr>
	<td><em>Launch with Android 8.0</em></td>
	<td>HALs listed in <a href="#passthrough">Passthrough HALs</a> must be
	passthrough.</td>
	<td>All other HALs are binderized (including HALs that are vendor
	extensions).</td>
	</tr>

	<tr>
	<td rowspan=2><em>Upgrade to Android 8.0</em></td>
	<td>HALs listed in <a href="#passthrough">Passthrough HALs</a> must be
	passthrough.</td>
	<td>HALs listed in <a href="#binderized">Binderized HALs</a> must be
	binderized.</td>
	</tr>

	<tr>
	<td colspan=2>All other HALs provided by the vendor image can be in passthrough
	OR binderized mode.</td>
	</tr>

	</tbody>
	</table>

	<h2 id=binderized>Binderized HALs</h2>
	<p>Android requires the following HALS to to be binderized on all Android
	devices regardless of whether they are launch devices or upgrade devices:</p>

	<ul>
	<li><code>android.hardware.biometrics.fingerprint@2.1</code>. Replaces
	<code>fingerprintd</code> which is no longer in Android 8.0.</li>
	<li><code>android.hardware.configstore@1.0</code>. New in Android 8.0.</li>
	<li><code>android.hardware.dumpstate@1.0</code>. The original interface provided
	by this HAL could not be shimmed and was changed. Because of this,
	<code>dumpstate_board</code> must be re-implemented on a given device (this is
	an optional HAL).</li>
	<li><code>android.hardware.graphics.allocator@2.0</code>. Required to be
	binderized in Android 8.0 so file descriptors don't have to be shared between
	trusted and untrusted processes.</li>
	<li><code>android.hardware.radio@1.0</code>. Replaces the interface provided by
	<code>rild</code> which lives in its own process.</li>
	<li><code>android.hardware.usb@1.0</code>. New in Android 8.0.</li>
	<li><code>android.hardware.wifi@1.0</code>. New in Android 8.0, replaces the
	legacy Wi-Fi HAL library that was loaded into <code>system_server</code>.</li>
	<li><code>android.hardware.wifi.supplicant@1.0</code>. A HIDL interface over the
	existing <code>wpa_supplicant</code> process.</li>
	</ul>

	<p class=note><strong>NOTE</strong>: Android provides the following HIDL
	interfaces which will always be in binderized mode:
	<code>android.frameworks.</code>, <code>android.system.</code> , and
	<code>android.hidl.*</code> (except for <code>android.hidl.memory@1.0</code>
	as described below).</p>

	<h2 id=passthrough>Passthrough HALs</h2>
	<p>Android requires the following HALs to be in passthrough mode on all Android
	devices regardless of whether they are launch devices or upgrade devices:</p>

	<ul>
	<li><code>android.hardware.graphics.mapper@1.0</code>. Maps memory into the
	process it lives in.</li>
	<li><code>android.hardware.renderscript@1.0</code>. Passes items in the same
	process (equivalent to <code>openGL</code>).</li>
	</ul>
	<p>All HALs not listed above must be binderized for launch devices.</p>

	<h2 id=same-process>Same-Process HALs</h2>
	<p>Same-Process HALs (SP-HALs) always open in the same process in which they are
	used. They include all HALs not expressed in HIDL as well as some that are
	<strong>not</strong> binderized. Membership in the SP-HAL set is controlled only
	by Google, with no exceptions.</p>

	<p>SP-HALs include the following:</p>

	<ul>
	<li><code>openGL</code></li>
	<li><code>Vulkan</code></li>
	<li><code>android.hidl.memory@1.0</code> (provided by the Android system, always
	passthrough)</li>
	<li><code>android.hardware.graphics.mapper@1.0</code>.</li>
	<li><code>android.hardware.renderscript@1.0</code></li>
	</ul>

	<h2 id=legacy>Conventional & legacy HALs</h2>

	<p>Conventional HALs (deprecated in Android 8.0) are interfaces that conform to a
	specific named and versioned application binary interface (ABI). The bulk of
	Android system interfaces
	(<a href="https://android.googlesource.com/platform/hardware/libhardware/+/master/include/hardware/camera3.h">camera</a>,
	<a href="https://android.googlesource.com/platform/hardware/libhardware/+/master/include/hardware/audio.h">audio</a>,
	<a href="https://android.googlesource.com/platform/hardware/libhardware/+/master/include/hardware/sensors.h">sensors</a>,
	etc.) are in the form of conventional HALs, which are defined under
	<a href="https://android.googlesource.com/platform/hardware/libhardware/+/master/include/hardware">hardware/libhardware/include/hardware</a>.</p>

	<p>Legacy HALs (also deprecated in Android 8.0) are interfaces that predate
	conventional HALs. A few important subsystems (Wi-Fi, Radio Interface Layer, and
	Bluetooth) are legacy HALs. While there's no uniform or standardized way to
	describe a legacy HAL, anything predating Android 8.0 that is not a conventional
	HAL is a legacy HAL. Parts of some legacy HALs are contained in
	<a href="https://android.googlesource.com/platform/hardware/libhardware_legacy/+/master">libhardware_legacy</a>,
	while other parts are interspersed throughout the codebase.</p>

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