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- 161541119 Updates to 7.1 CDD by gdimino <gdimino@google.com> - 161436702 Update CTS downloads for 7.1 R7, 7.0 R11, 6.0 R20, 5.1 R21 by claym <claym@google.com> - 161410924 Cloned from CL 160326297 by 'g4 patch'. by claym <claym@google.com> - 161246895 Fix typo KM_TAG_USER_SECURE_ID by blamb <blamb@google.com> - 161235192 Clarify guide is for platform, add note for app developers by claym <claym@google.com> - 161217654 Fix typos in "bootloader" references by claym <claym@google.com> - 161131051 SAC FB: Make verified boot flash lock and unlock commands... by daroberts <daroberts@google.com> - 161106942 Remove Jack recommendation by claym <claym@google.com> - 161102887 Correct typo in July 2017 bulletin by daroberts <daroberts@google.com> - 161098528 Update build numbers for Jul security releases by Android Partner Docs <noreply@android.com> - 161094346 Update July 2017 security bulletin with AOSP links by daroberts <daroberts@google.com> - 161017723 Add warnings about incompatibility of FBE and adoptable s... by claym <claym@google.com> - 160996093 Docs: Nav changes to prep for O + new framework image by hvm <hvm@google.com> - 160984727 Devsite localized content from translation request 76cba1... by Android Partner Docs <noreply@android.com> - 160984408 Add instructions to check for device security update by daroberts <daroberts@google.com> - 160971202 July 2017 Security bulletin updates by daroberts <daroberts@google.com> - 160958735 Update audit2allow commands by daroberts <daroberts@google.com> - 160567793 Redirect old Dumpsys pages to DAC by claym <claym@google.com> - 160553240 Devsite localized content from translation request 29dc8d... by Android Partner Docs <noreply@android.com> - 160550105 Use a SHA-256 checksum, not a SHA-1 checksum, for the lat... by Android Partner Docs <noreply@android.com> - 160448356 Add researcher attribution for CVE-2017-0574 by daroberts <daroberts@google.com> - 160342125 Publish localized June security bulletin by daroberts <daroberts@google.com> - 160293585 Devsite localized content from translation request 3cdce1... by Android Partner Docs <noreply@android.com> - 160292361 Adds link to go/sac-guide at top of README for Googlers. by blamb <blamb@google.com> - 160281439 Include a mention of --cbr in the using-repo docs. by Android Partner Docs <noreply@android.com> PiperOrigin-RevId: 161541119 Change-Id: I24270f922ca979327303fd1776d90657095c57a4
author: Ruslan Piasetskyi <ruslan.piasetskyi@gmail.com> 2017-07-11 09:49:32 -0700
committer: Clay Murphy <claym@google.com> 2017-07-11 14:09:17 -0700
commit: 7b7ac1c38b6987cc7a1f9f307bc6d099a470e76f (patch)
tree: b16206b32b153c3edb1744b655b1a3bfdeb7af91 /en/devices/architecture
parent: 4a5bcd6fa800faafbe7272d39266e21dc26edf39 (diff)
download: source.android.com-7b7ac1c38b6987cc7a1f9f307bc6d099a470e76f.tar.gz
6 files changed, 292 insertions, 0 deletions
diff --git a/en/devices/architecture/hal.html b/en/devices/architecture/hal.html
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+<html devsite>
+  <head>
+    <title>Hardware Abstraction Layer (HAL)</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>A HAL defines a standard interface for hardware vendors to implement,
+which enables Android to be agnostic about lower-level driver implementations.
+Using a HAL allows you to implement functionality without affecting or modifying
+the higher level system. HAL implementations are packaged into modules and
+loaded by the Android system at the appropriate time.</p>
+
+<img src="../images/ape_fwk_hal.png">
+
+<p class="img-caption"><strong>Figure 1.</strong> HAL components</p>
+
+<p>You must implement the corresponding HAL (and driver) for the specific
+hardware your product provides. HAL implementations are typically built into
+shared library modules (<code>.so</code> files), but as Android does not mandate
+a standard interaction between a HAL implementation and device drivers, you can
+do what is best for your situation. However, to enable the Android system to
+correctly interact with your hardware, you <strong>must</strong> abide by the
+contract defined in each hardware-specific HAL interface.</p>
+
+<p>To guarantee that HALs have a predictable structure, each hardware-specific
+HAL interface has properties defined in
+<code>hardware/libhardware/include/hardware/hardware.h</code>. This interface
+allows the Android system to load correct versions of your HAL modules in a
+consistent way. A HAL interface consists of two components: modules and devices.
+</p>
+
+<h2 id="hal-module">HAL modules</h2>
+<p>A module represents your packaged HAL implementation, which is stored as a
+shared library (<code>.so file</code>). The
+<code>hardware/libhardware/include/hardware/hardware.h</code> header file
+defines a struct (<code>hw_module_t</code>) that represents a module and
+contains metadata such as the version, name, and author of the module. Android
+uses this metadata to find and load the HAL module correctly.</p>
+
+<p>In addition, the <code>hw_module_t</code> struct contains a pointer to
+another struct, <code>hw_module_methods_t</code>, that contains a pointer to
+an open function for the module. This open function is used to initiate
+communication with the hardware for which the HAL is serving as an abstraction.
+Each hardware-specific HAL usually extends the generic <code>hw_module_t</code>
+struct with additional information for that specific piece of hardware. For
+example, in the camera HAL, the <code>camera_module_t</code> struct contains a
+<code>hw_module_t</code> struct along with other camera-specific function
+pointers:</p>
+
+<pre class="devsite-click-to-copy">
+typedef struct camera_module {
+    hw_module_t common;
+    int (*get_number_of_cameras)(void);
+    int (*get_camera_info)(int camera_id, struct camera_info *info);
+} camera_module_t;
+</pre>
+
+<p>When you implement a HAL and create the module struct, you must name it
+<code>HAL_MODULE_INFO_SYM</code>. Example from the Nexus 9 audio HAL:</p>
+
+<pre class="devsite-click-to-copy">
+struct audio_module HAL_MODULE_INFO_SYM = {
+    .common = {
+        .tag = HARDWARE_MODULE_TAG,
+        .module_api_version = AUDIO_MODULE_API_VERSION_0_1,
+        .hal_api_version = HARDWARE_HAL_API_VERSION,
+        .id = AUDIO_HARDWARE_MODULE_ID,
+        .name = "NVIDIA Tegra Audio HAL",
+        .author = "The Android Open Source Project",
+        .methods = &hal_module_methods,
+    },
+};
+</pre>
+
+<h2 id="hal-device">HAL devices</h2>
+<p>A device abstracts the hardware of your product. For example, an audio
+module can contain a primary audio device, a USB audio device, or a Bluetooth
+A2DP audio device.</p>
+
+<p>A device is represented by the <code>hw_device_t</code> struct. Similar to a
+module, each type of device defines a detailed version of the generic
+<code>hw_device_t</code> that contains function pointers for specific features
+of the hardware. For example, the <code>audio_hw_device_t</code> struct type
+contains function pointers to audio device operations:</p>
+
+<pre class="devsite-click-to-copy">
+struct audio_hw_device {
+    struct hw_device_t common;
+
+    /**
+     * used by audio flinger to enumerate what devices are supported by
+     * each audio_hw_device implementation.
+     *
+     * Return value is a bitmask of 1 or more values of audio_devices_t
+     */
+    uint32_t (*get_supported_devices)(const struct audio_hw_device *dev);
+  ...
+};
+typedef struct audio_hw_device audio_hw_device_t;
+</pre>
+
+<p>In addition to these standard properties, each hardware-specific HAL
+interface can define more of its own features and requirements. For details,
+see the <a href="/reference/hal/">HAL reference documentation</a> as well as
+the individual instructions for each HAL.</p>
+
+<h2 id="hal-building">Building HAL modules</h2>
+<p>HAL implementations are built into modules (<code>.so</code>) files and are
+dynamically linked by Android when appropriate. You can build your modules by
+creating <code>Android.mk</code> files for each of your HAL implementations
+and pointing to your source files. In general, your shared libraries must be
+named in a specific format so they can be found and loaded properly. The naming
+scheme varies slightly from module to module, but follows the general pattern
+of: <code>&lt;module_type&gt;.&lt;device_name&gt;</code>.
+</p>
+
+<p>For details on setting up the build for each HAL, see the HAL-specific
+documentation through the Porting section of this website.</p>
+
+  </body>
+</html>
diff --git a/en/devices/architecture/images/ape_fwk_hal.png b/en/devices/architecture/images/ape_fwk_hal.png
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diff --git a/en/devices/architecture/images/treble_blog_after.png b/en/devices/architecture/images/treble_blog_after.png
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diff --git a/en/devices/architecture/images/treble_blog_before.png b/en/devices/architecture/images/treble_blog_before.png
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diff --git a/en/devices/architecture/index.html b/en/devices/architecture/index.html
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+<html devsite>
+  <head>
+    <title>Architecture</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 system architecture contains the following components:
+</p>
+
+<img src="../images/ape_fwk_all.png">
+
+<p class="img-caption"><strong>Figure 1.</strong> Android system architecture</p>
+
+<h2 id="application-framework">Application framework</h2>
+
+<p>The application framework is used most often by application developers. As a
+hardware developer, you should be aware of developer APIs as many map directly
+to the underlying HAL interfaces and can provide helpful information about
+implementing drivers.</p>
+
+<h2 id="binder-ipc">Binder IPC</h2>
+<p>The Binder Inter-Process Communication (IPC) mechanism allows the application
+framework to cross process boundaries and call into the Android system services
+code. This enables high level framework APIs to interact with Android system
+services. At the application framework level, this communication is hidden from
+the developer and things appear to "just work".</p>
+
+<h2 id="system-services">System services</h2>
+<p>System services are modular, focused components such as Window Manager,
+Search Service, or Notification Manager. Functionality exposed by application
+framework APIs communicates with system services to access the underlying
+hardware. Android includes two groups of services: <em>system</em> (such as
+Window Manager and Notification Manager) and <em>media</em> (services involved
+in playing and recording media).</p>
+
+<h2 id="hal">Hardware abstraction layer (HAL)</h2>
+<p>A HAL defines a standard interface for hardware vendors to implement,
+which enables Android to be agnostic about lower-level driver implementations.
+Using a HAL allows you to implement functionality without affecting or modifying
+the higher level system. HAL implementations are packaged into modules and
+loaded by the Android system at the appropriate time. For details, see
+<a href="/devices/architecture/hal.html">Hardware Abstraction Layer (HAL)</a>.
+</p>
+
+<h2 id="Linux-kernel">Linux kernel</h2>
+<p>Developing your device drivers is similar to developing a typical Linux
+device driver. Android uses a version of the Linux kernel with a few special
+additions such as wake locks (a memory management system that is more aggressive
+in preserving memory), the Binder IPC driver, and other features important for a
+mobile embedded platform. These additions are primarily for system functionality
+and do not affect driver development.</p>
+
+<p>You can use any version of the kernel as long as it supports the required
+features (such as the binder driver). However, we recommend using the latest
+version of the Android kernel. For details, see
+<a href="/source/building-kernels.html">Building Kernels</a>.</p>
+
+  </body>
+</html>
diff --git a/en/devices/architecture/treble.html b/en/devices/architecture/treble.html
new file mode 100644
index 00000000..343858df
--- /dev/null
+++ b/en/devices/architecture/treble.html
@@ -0,0 +1,73 @@
+<html devsite>
+  <head>
+    <title>Treble</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>The upcoming Android O release includes Project Treble, a major re-architect
+of the Android OS framework designed to make it easier, faster, and less costly
+for manufacturers to update devices to a new version of Android.</p>
+
+<h2 id=about-treble>Android updates</h2>
+<p>Project Treble separates the vendor implementation (device-specific,
+lower-level software written by silicon manufacturers) from the Android OS
+framework via a new vendor interface.</p>
+
+<p>In Android 7.x and earlier, no formal vendor interface exists so device
+makers must update large portions of the Android code to move a device to a
+newer version of Android:</p>
+
+<img src="images/treble_blog_before.png">
+
+<p class="img-caption"><strong>Figure 1.</strong> Pre-Treble Android update
+environment</p>
+
+<p>With Treble, a new stable vendor interface provides access to the
+hardware-specific parts of Android, enabling device makers to deliver new
+Android releases simply by updating the Android OS framework&mdash;without any
+additional work required from the silicon manufacturers:</p>
+
+<img src="images/treble_blog_after.png">
+
+<p class="img-caption"><strong>Figure 2.</strong> Treble Android update
+environment</p>
+
+<h2 id=testing-treble>Testing Treble</h2>
+<p>To ensure forward compatibility of the vendor implementation, the new vendor
+interface will be validated by the Vendor Test Suite (VTS), which is analogous
+to the <a href="/compatibility/cts/">Compatibility Test Suite (CTS)</a>. VTS is
+already launched and can be used to automate HAL and OS kernel testing even in
+pre-Treble environments; for details, see
+<a href="/devices/tech/test_infra/tradefed/fundamentals/vts">Systems Testing
+With VTS</a>.</p>
+
+<h2 id=launching-treble>Coming soon</h2>
+<p>Project Treble is coming to all new devices launching with Android O and
+beyond, and the new architecture is already running on the Developer Preview of
+O for Pixel phones. When Android O launches, we'll have full details here (on
+<a href="https://source.android.com/">source.android.com</a>). In the interim,
+you can find more details on Treble over at the
+<a href="https://android-developers.googleblog.com/2017/05/here-comes-treble-modular-base-for.html">Android
+Developers Blog</a>.</p>
+
+
+  </body>
+</html>
author	Ruslan Piasetskyi <ruslan.piasetskyi@gmail.com>	2017-07-11 09:49:32 -0700
committer	Clay Murphy <claym@google.com>	2017-07-11 14:09:17 -0700
commit	7b7ac1c38b6987cc7a1f9f307bc6d099a470e76f (patch)
tree	b16206b32b153c3edb1744b655b1a3bfdeb7af91 /en/devices/architecture
parent	4a5bcd6fa800faafbe7272d39266e21dc26edf39 (diff)
download	source.android.com-7b7ac1c38b6987cc7a1f9f307bc6d099a470e76f.tar.gz