Docs: Changes to source.android.com

  - 207940242 One more fix: add header for Television Requirements. by Gina Dimino <gdimino@google.com>
  - 207936055 Update health README link. by Android Partner Docs <noreply@android.com>
  - 207929938 Errata run for Android 9 CDD. by Gina Dimino <gdimino@google.com>
  - 207897850 Fix typos in Develop and Configure index pages by Kenneth Lau <kennethlau@google.com>
  - 207813977 Devsite localized content from translation request 958913. by Android Partner Docs <noreply@android.com>
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  - 207796341 Fixing the URL for the CDD link in versions file. by Gina Dimino <gdimino@google.com>
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  - 207775888 Update links to AOSP by Kenneth Lau <kennethlau@google.com>
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  - 207611166 Add Background Restrictions into Release Notes. by Christina Nguyen <cqn@google.com>
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PiperOrigin-RevId: 207940242
Change-Id: I3dee204c744e2e6062ac56810b88aefabf84636a

1 files changed, 392 insertions, 65 deletions

diff --git a/en/devices/architecture/dto/compile.html b/en/devices/architecture/dto/compile.html
index 65e3cbc2..aea2f3bc 100644
--- a/en/devices/architecture/dto/compile.html
+++ b/en/devices/architecture/dto/compile.html
@@ -1,10 +1,12 @@
-<html devsite>
-  <head>
-    <title>Compiling &amp; Verifying</title>
-    <meta name="project_path" value="/_project.yaml" />
-    <meta name="book_path" value="/_book.yaml" />
-  </head>
-  <body>
+<html devsite="">
+<head>
+  <title>Compiling & Verifying</title>
+  <meta name="project_path" value="/_project.yaml">
+  <meta name="book_path" value="/_book.yaml">
+</head>
+
+<body>
+   {% include "_versions.html" %}
   <!--
       Copyright 2017 The Android Open Source Project
 
@@ -21,83 +23,408 @@
       limitations under the License.
   -->
 
-<p>You can use Device Tree Compiler (DTC) to compile the Device Tree Source
-files. However, before applying the overlay DT on the target main DT, you should
-also verify the result by simulating the behavior of DTO.</p>
 
-<h2 id=compile>Compiling with DTC</h2>
-<p>When using <code>dtc</code> to compile <code>.dts</code>, you must add option
-<code>-@</code> to add a <code>__symbols__</code> node in the resulting
-<code>.dtbo</code>. The <code>__symbols__</code> node contains a list of all
-nodes that are marked with a label, which the DTO library can use for
-references.</p>
+  <p>You can use Device Tree Compiler (DTC) to compile the Device Tree Source
+  files. However, before applying the overlay DT on the target main DT, you
+  should also verify the result by simulating the behavior of DTO.</p>
+
+
+  <h2 id="compile">Compiling with DTC</h2>
+
+
+  <p>When using <code>dtc</code> to compile <code>.dts</code>, you must add
+  option <code>-@</code> to add a <code>__symbols__</code> node in the
+  resulting <code>.dtbo</code>. The <code>__symbols__</code> node contains a
+  list of all nodes that are marked with a label, which the DTO library can use
+  for references.</p>
 
-<p>Sample command to build main DT <code>.dts</code>:</p>
 
-<pre class="devsite-terminal">
+  <p>Sample command to build main DT <code>.dts</code>:</p>
+
+  <pre class="devsite-terminal">
 dtc -@ -O dtb -o my_main_dt.dtb my_main_dt.dts
 </pre>
 
-<p>Sample command to build the overlay DT <code>.dts</code>:</p>
+  <p>Sample command to build the overlay DT <code>.dts</code>:</p>
 
-<pre class="devsite-terminal">
+  <pre class="devsite-terminal">
 dtc -@ -O dtb -o my_overlay_dt.dtbo my_overlay_dt.dts
 </pre>
 
-<p class="note"><strong>Note:</strong> If you encounter the DTC build error:
-<code>invalid option --'@'</code>, you might need to update your DTC version.
-Upstream of AOSP, the official DTC supports DTO as of
-<a href="https://github.com/dgibson/dtc/tree/v1.4.4" class="external">version
-1.4.4</a> and most patches are merged after December 2016. For DTO support, we
-recommend using the
-<code><a href="https://android.googlesource.com/platform/external/dtc/" class="external">external/dtc</code></a>
-in AOSP, which is synced with the latest DTC (with DTO patches merged as
-needed).</p>
-
-<h2 id=verify>Verify DTO results on the host</h2>
-<p>Verification can help you identify errors that might occur when placing the
-overlay DT on the main DT. Before updating the target, you can verify the
-result of overlaying DT on the host by simulating the behavior of DTO using
-<code>/include/</code> in <code>.dts</code>.</p>
-
-<p class="note"><strong>Note:</strong> <code>/include/</code> does NOT support
-the use of <code>__overlay__</code> in overlay DT sources.</p>
-
-<p><img src="../images/treble_dto_simulate.png"></p>
-<p><strong>Figure 1.</strong> Use syntax <code>/include/</code> to simulate DTO
-on the host.</p>
-
-<ol>
-<li>Create a copy of the overlay <code>.dts</code>. In the copy, remove the
-first line header. Example:
-<pre>
+  <aside class="note"><strong>Note:</strong> If you encounter the DTC build error:
+  <code>invalid option --'@'</code>, you might need to update your DTC version.
+  Upstream of AOSP, the official DTC supports DTO as of <a href=
+  "https://github.com/dgibson/dtc/tree/v1.4.4" class="external">version
+  1.4.4</a> and most patches are merged after December 2016. For DTO support,
+  we recommend using the <code><a href=
+  "https://android.googlesource.com/platform/external/dtc/" class=
+  "external">external/dtc</a></code> in AOSP, which is synced with the latest DTC
+  (with DTO patches merged as needed).</aside>
+
+
+  <h2 id="verify">Verify DTO results on the host</h2>
+
+
+  <p>Verification can help you identify errors that might occur when placing
+  the overlay DT on the main DT. Before updating the target, you can verify the
+  result of overlaying DT on the host by simulating the behavior of DTO using
+  <code>/include/</code> in <code>.dts</code>.</p>
+
+
+  <aside class="note"><strong>Note:</strong> <code>/include/</code> does NOT
+  support the use of <code>__overlay__</code> in overlay DT sources.</aside>
+
+
+  <p><img src="../images/treble_dto_simulate.png">
+  </p>
+
+
+  <figcaption><strong>Figure 1.</strong> Use syntax <code>/include/</code> to simulate
+  DTO on the host</figcaption>
+
+
+  <ol>
+    <li>Create a copy of the overlay <code>.dts</code>. In the copy, remove the
+    first line header. Example:
+
+      <pre>
 /dts-v1/;
 /plugin/;
-</pre>
-Save the file as <code>my_overlay_dt_wo_header.dts</code> (or any filename you
-want).</li>
+</pre>Save the file as <code>my_overlay_dt_wo_header.dts</code> (or any
+filename you want).
+    </li>
 
-<li>Create a copy of the main <code>.dts</code>. In the copy, after the last
-line, append the include syntax for the file you created in step 1. For example:
-<pre>
+
+    <li>Create a copy of the main <code>.dts</code>. In the copy, after the
+    last line, append the include syntax for the file you created in step 1.
+    For example:
+
+      <pre>
 /include/ "my_overlay_dt_wo_header.dts"
-</pre>
-Save the file as <code>my_main_dt_with_include.dts</code> (or any filename you
-want).</li>
+</pre>Save the file as <code>my_main_dt_with_include.dts</code> (or any
+filename you want).
+    </li>
+
+
+    <li>Use <code>dtc</code> to compile
+    <code>my_main_dt_with_include.dts</code> to get the merged DT, which should
+    be the same result as DTO. For example:
 
-<li>Use <code>dtc</code> to compile <code>my_main_dt_with_include.dts</code> to
-get the merged DT, which should be the same result as DTO. For example:
-<pre class="devsite-terminal">
+      <pre class="devsite-terminal">
 dtc -@ -O dtb -o my_merged_dt.dtb my_main_dt_with_include.dts
 </pre>
-</li>
+    </li>
 
-<li>Use <code>dtc</code> to dump <code>my_merged_dt.dto</code>.
-<pre class="devsite-terminal">
+
+    <li>Use <code>dtc</code> to dump <code>my_merged_dt.dto</code>.
+
+      <pre class="devsite-terminal">
 dtc -O dts -o my_merged_dt.dts my_merged_dt.dtb
 </pre>
-</li>
-</ol>
+    </li>
+  </ol>
+
+
+  <h2 id="verifying-DTO-in-p">Verifying DTO in Android {{ androidPVersionNumber }}</h2>
+
+
+  <p>Android {{ androidPVersionNumber}} requires a Device Tree Blob Overlay
+  (DTBO) partition. To add nodes or make changes to the properties in the SoC
+  DT, the bootloader must dynamically overlay a device specific DT over
+  the SoC DT.</p>
+
+
+  <h3 id="indicating-applied-overlays">Indicating applied overlays</h3>
+
+
+  <p>To enable the <a href="/compatibility/vts/">
+  Vendor Test Suite (VTS)</a> to assess the correctness of overlay
+  application, vendors must add a new kernel command line parameter
+  <code>androidboot.dtbo_idx</code> that indicates the overlays selected from
+  the DTBO partition. For example, the parameter <code>androidboot.
+  dtbo_idx=x,y,z</code> reports <code>x</code>, <code>y</code> and
+  <code>z</code> as the zero-based indices of the Device Tree Overlays (DTOs)
+  from the DTBO partition applied (in that order) by the bootloader to the base
+  Device Tree (DT).</p>
+
+
+  <p>Overlays can apply to nodes from the main device tree or add new nodes,
+  but <strong>cannot</strong> refer to a node added in a previous overlay. This
+  restriction is necessary because the overlay application does not merge the
+  overlay symbol table with the main DT symbol table (not merging avoids
+  conflicts in symbol names and complication of dependencies between
+  overlays).</p>
+
+
+  <h4 id="example-invalid-overlays">Example: Invalid overlays</h4>
+
+
+  <p>In this example, <code>overlay_2.dts</code> refers to node
+  <strong><code>e</code></strong> , which was added by
+  <code>overlay_1.dts</code>. After <code>overlay_1</code> is applied to the
+  main DT, if an attempt is made to apply <code>overlay_2</code> to the
+  resultant DT, the overlay application will fail with an error that the symbol
+  <strong><code>e</code></strong> is not present in the symbol table for the
+  base DT.</p>
+
+
+  <table>
+    <tr>
+      <th width="33%">main.dts</th>
+
+      <th>overlay_1.dts</th>
+
+      <th>overlay_2.dts</th>
+
+    </tr>
+    <tr>
+      <td>
+        <pre>
+<strong>[main.dts]</strong>
+
+/dts-v1/;
+
+/ {
+  a: a {};
+  b: b {};
+  c: c {};
+};
+</pre>
+  </td>
+
+        <td>
+          <pre>
+<strong>[overlay_1.dts]</strong>
+
+/dts-v1/;
+/plugin/;
+
+&amp;b { ref1 =  <&a>;
+    e: e {
+        prop = <0x0a>;
+        phandle = <0x04>;
+    };
+};
+</pre>
+</td>
+
+      <td>
+<pre>
+<strong>[overlay_2.dts]</strong>
+
+/dts-v1/;
+/plugin/;
+
+/* invalid! */
+<font color="red">&amp;e</font> {
+    prop = <0x0b>;
+};
+</pre>
+      </td>
+    </tr>
+  </table>
+
+
+  <h4 id="example-valid-overlays">Example: Valid overlays</h4>
+
+
+  <p>In this example, <code>overlay_2.dts</code> refers only to node
+  <strong><code>b</code></strong> from the main DTS. When
+  <code>overlay_1</code> is applied to the base DT, then followed by the
+  application of <code>overlay_2</code>, the value of property
+  <strong><code>prop</code></strong> in node <strong><code>e</code></strong>
+  (set by <code>overlay_1.dts</code>) is overwritten by the value set by
+  <code>overlay_2.dts</code>.</p>
+
+
+  <table>
+    <tr>
+      <th width="33%">main.dts</th>
+
+      <th>overlay_1.dts</th>
+
+      <th>overlay_2.dts</th>
+
+    </tr>
+
+
+    <tr>
+      <td>
+      <pre>
+<strong>[final.dts]</strong>
+
+/dts-v1/;
+
+/ {
+  a: a {};
+  b: b {};
+  c: c {};
+};
+</pre>
+        </td>
+
+      <td>
+      <pre>
+<strong>[overlay_1.dts]</strong>
+
+/dts-v1/;
+/plugin/;
+
+
+&amp;b { ref1 =  <&a>;
+     e {
+          prop = <0x0c>;
+      };
+};
+</pre>
+        </td>
+
+      <td>
+      <pre>
+<strong>[overlay_2.dts]</strong>
+
+/dts-v1/;
+/plugin/;
+
+/* valid */
+<font color="blue">&amp;b</font> { ref1 =  <&c>;
+     e {
+          prop = <0x0d>;
+      };
+};
+</pre>
+      </td>
+    </tr>
+  </table>
+
+
+  <h3 id="implementing-the-dtbo-partition">Implementing the DTBO partition</h3>
+
+
+  <p>To implement the required DTBO partition, ensure the bootloader can do the
+  following:</p>
+
+
+  <ol>
+    <li>Identify the board it is running on and select the corresponding
+    overlay(s) to be applied.</li>
+
+
+    <li>Append the <code>androidboot.dtbo_idx</code> parameter to the kernel
+    command line.
+
+      <ul>
+        <li>The parameter must indicate, the zero-based indices of the DTOs
+        from the DTBO partition image it applied to the base DT (in the same
+        order).</li>
+
+
+        <li>The indices must refer to the position of the overlay in the DTBO
+        partition.</li>
+      </ul>
+    </li>
+  </ol>
+
+
+  <p>For details on the structure of the DTBO partition, refer to <a href=
+  "https://source.android.com/devices/architecture/dto/">Device Tree
+  Overlays</a> on source.android.com.</p>
+
+
+  <h3 id="validating-the-dtbo-partition">Validating the DTBO partition</h3>
+
+
+  <p>You can use VTS to verify the following:</p>
+
+
+  <ul>
+    <li>Existence of the kernel command line parameter
+    <code>androidboot.dtbo_idx</code> (by checking that <code>Init</code> has
+    automatically set up the corresponding <code>ro.boot.dtbo_idx</code> system
+    property).</li>
+
+
+    <li>Validity of the <code>ro.boot.dtbo_idx</code> system property (by
+    checking that the property specifies at least one valid DTBO image
+    index).</li>
+
+
+    <li>Validity of the DTBO partition (also verifies the overlays in the DTBO
+    partition that are applied to the base DT).</li>
+
+
+    <li>Additional nodes or property changes in the resulting DT are presented
+    to the Linux kernel.</li>
+  </ul>
+
+
+  <p>For example, in the following overlays and final DT, adding
+  <code>androidboot.dtbo_idx=5,3</code> to the kernel command line passes
+  validation but adding <code>androidboot.dtbo_idx=3,5</code> to the kernel
+  command line does not pass validation.</p>
+
+
+  <table>
+    <tr>
+      <th width="50%">Overlay DT at index 3</th>
+
+
+      <th>Overlay DT at index 5</th>
+
+<tr>
+<td>
+<pre>
+<strong>[overlay_1.dts]</strong>
+
+/dts-v1/;
+/plugin/;
+
+&amp;c <strong>{ prop = <0xfe>; }</strong>;
+</pre>
+      </td>
+
+      <td>
+      <pre>
+<strong>[overlay_2.dts]</strong>
+
+/dts-v1/;
+/plugin/;
+
+&amp;c { prop = <0xff>; };
+</pre>
+        </td>
+    </tr>
+
+<table>
+    <tr>
+   <th>Final DT</th>
+
+   <tr>
+   <td>
+   <pre>
+/dts-v1/;
+/ {
+
+	a {
+		phandle = <0x1>;
+	};
+
+	b {
+		phandle = <0x2>;
+	};
+
+	c {
+		phandle = <0x3>;
+		<strong>prop = <0xfe></strong>;
+	};
+
+	__symbols__ {
+		a = "/a";
+		b = "/b";
+		c = "/c";
+	};
+};
 
-  </body>
+  </table>
+</body>
 </html>