Merge "Remove obsolete sync directories for SAC"HEAD master main

author: Gina Dimino <gdimino@google.com> 2021-07-15 23:27:11 +0000
committer: Gerrit Code Review <noreply-gerritcodereview@google.com> 2021-07-15 23:27:11 +0000
commit: 72e0ae8d8207042452f75874221103f4f6b3014a (patch)
tree: 7fa97b880b85be7de5b713d233cdc407c20b88cd /en/devices/architecture/vndk/build-system.html
parent: e55b3193405187e091a4ac7730ef04360ec04504 (diff)
parent: fc5fc0e74df003b0ee454d3418b88cd722282c49 (diff)
download: source.android.com-master.tar.gz
1 files changed, 0 insertions, 892 deletions
diff --git a/en/devices/architecture/vndk/build-system.html b/en/devices/architecture/vndk/build-system.html
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-<html devsite>
-  <head>
-    <title>VNDK Build System Support</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>
-  In Android 8.1 and higher, the build system has built-in VNDK support. When
-  VNDK support is enabled, the build system checks the dependencies between
-  modules, builds a vendor-specific variant for vendor modules, and
-  automatically installs those modules into designated directories.
-</p>
-
-<h2 id=vndk-build-support-example>VNDK build support example</h2>
-
-<p>
-  In this example, the <code>Android.bp</code> module definition defines a
-  library named <code>libexample</code>. The <code>vendor_available</code>
-  property indicates framework modules and vendor modules may depend on
-  <code>libexample</code>:
-</p>
-
-<p>
-  <img src="../images/treble_vndk_androidbp.png" alt="libexample vendor_available:true and vndk.enabled:true" />
-</p>
-<figcaption>
-  <strong>Figure 1.</strong> VNDK support enabled
-</figcaption>
-
-<p>
-  Both the framework executable <code>/system/bin/foo</code> and the vendor
-  executable <code>/vendor/bin/bar</code> depend on <code>libexample</code> and
-  have <code>libexample</code> in their <code>shared_libs</code> properties.
-</p>
-
-<p>
-  If <code>libexample</code> is used by both framework modules and vendor
-  modules, two variants of <code>libexample</code> are built. The core variant
-  (named after <code>libexample</code>) is used by framework modules and the
-  vendor variant (named after <code>libexample.vendor</code>) is used by vendor
-  modules. The two variants are installed into different directories:
-</p>
-
-<ul>
-  <li>The core variant is installed into
-  <code>/system/lib[64]/libexample.so</code>.</li>
-  <li>The vendor variant is installed into
-  <code>/system/lib[64]/vndk/libexample.so</code> because
-  <code>vndk.enabled</code> is <code>true</code>.</li>
-</ul>
-
-<p>
-  For more details, see <a href="#module-definition">Module definition</a>.
-</p>
-
-<h2 id="configuring-build-support">Configuring build support</h2>
-
-<p>
-  To enable full build system support for a product device, add
-  <code>BOARD_VNDK_VERSION</code> to <code>BoardConfig.mk</code>:
-</p>
-
-<pre class="prettyprint">BOARD_VNDK_VERSION := current</pre>
-
-<p>
-  This setting has a <strong>global</strong> effect: When defined in
-  <code>BoardConfig.mk</code>, all modules are checked. As there is no mechanism
-  to blacklist or whitelist an offending module, you should clean all
-  unnecessary dependencies before adding <code>BOARD_VNDK_VERSION</code>. You
-  can test and compile a module by setting <code>BOARD_VNDK_VERSION</code> in
-  your environment variables:
-</p>
-
-<pre class="prettyprint">$ BOARD_VNDK_VERSION=current m module_name.vendor</pre>
-
-<p>When <code>BOARD_VNDK_VERSION</code> is enabled, several default global
-  header search paths are <em>removed</em>. These include:
-</p>
-
-<ul>
- <li><code>frameworks/av/include</code></li>
- <li><code>frameworks/native/include</code></li>
- <li><code>frameworks/native/opengl/include</code></li>
- <li><code>hardware/libhardware/include</code></li>
- <li><code>hardware/libhardware_legacy/include</code></li>
- <li><code>hardware/ril/include</code></li>
- <li><code>libnativehelper/include</code></li>
- <li><code>libnativehelper/include_deprecated</code></li>
- <li><code>system/core/include</code></li>
- <li><code>system/media/audio/include</code></li>
-</ul>
-
-<p>
-  If a module depends on the headers from these directories, you must specify
-  (explicitly) the dependencies with <code>header_libs</code>,
-  <code>static_libs</code>, and/or <code>shared_libs</code>.
-</p>
-
-<h2 id="module-definition">Module definition</h2>
-
-<p>
-  To build Android with <code>BOARD_VNDK_VERSION</code>, you must revise the
-  module definition in either <code>Android.mk</code> or
-  <code>Android.bp</code>. This section describes different kinds of module
-  definitions, several VNDK-related module properties, and dependency checks
-  implemented in the build system.
-</p>
-
-<h3 id="vendor-modules">Vendor modules</h3>
-
-<p>
-  Vendor modules are vendor-specific executables or shared libraries that
-  must be installed into a vendor partition. In <code>Android.bp</code> files,
-  vendor modules must set vendor or proprietary property to <code>true</code>.
-  In <code>Android.mk</code> files, vendor modules must set
-  <code>LOCAL_VENDOR_MODULE</code> or <code>LOCAL_PROPRIETARY_MODULE</code> to
-  <code>true</code>.
-</p>
-
-<p>
-  If <code>BOARD_VNDK_VERSION</code> is defined, the build system disallows
-  dependencies between vendor modules and framework modules and emits errors if:
-</p>
-
-<ul>
- <li>a module without <code>vendor:true</code> depends on a module with
- <code>vendor:true</code>, or</li>
- <li>a module with <code>vendor:true</code> depends on a
- non-<code>llndk_library</code> module that has neither
- <code>vendor:true</code> nor <code>vendor_available:true</code>.</li>
-</ul>
-
-<p>
-  The dependency check applies to <code>header_libs</code>,
-  <code>static_libs</code>, and <code>shared_libs</code> in
-  <code>Android.bp</code>, and to <code>LOCAL_HEADER_LIBRARIES</code>,
-  <code>LOCAL_STATIC_LIBRARIES</code> and <code>LOCAL_SHARED_LIBRARIES</code> in
-  <code>Android.mk</code>.
-</p>
-
-<h3 id="ll-ndk">LL-NDK</h3>
-
-<p>
-  LL-NDK shared libraries are shared libraries with stable ABIs. Both framework
-  and vendor modules share the same and the latest implementation. For each
-  LL-NDK shared library, <code>Android.bp</code> contains a
-  <code>llndk_library</code> module definition:
-</p>
-
-<pre class="prettyprint">
-llndk_library {
-    name: "libvndksupport",
-    symbol_file: "libvndksupport.map.txt",
-}
-</pre>
-
-<p>
-  This module definition specifies a module name and a symbol file that
-  describes the symbols visible to vendor modules. For example:
-</p>
-
-<pre class="prettyprint">
-LIBVNDKSUPPORT {
-  global:
-    android_load_sphal_library; # vndk
-    android_unload_sphal_library; # vndk
-  local:
-    *;
-};
-</pre>
-
-<p>
-  Based on the symbol file, the build system generates a stub shared library for
-  vendor modules, which link with these libraries when
-  <code>BOARD_VNDK_VERSION</code> is enabled. A symbol is included in the stub
-  shared library only if it:
-</p>
-
-<ul>
- <li>Is not defined in the section end with <code>_PRIVATE</code> or
- <code>_PLATFORM</code>,</li>
- <li>Does not have <code>#platform-only</code> tag, and</li>
- <li>Does not have <code>#introduce*</code> tags or the tag matches with the
- target.</li>
-</ul>
-
-<aside class="note">
-  <strong>Note</strong>: Vendors must not define their own LL-NDK shared
-  libraries because vendor modules won't be able to find them in
-  <a href="/setup/build/gsi">Generic System Image (GSI)</a>.
-</aside>
-
-<h3 id="vndk">VNDK</h3>
-
-<p>
-  In <code>Android.bp</code> files, <code>cc_library</code>,
-  <code>cc_library_static</code>, <code>cc_library_shared</code>, and
-  <code>cc_library_headers</code> module definitions support three VNDK-related
-  properties: <code>vendor_available</code>, <code>vndk.enabled</code>, and
-  <code>vndk.support_system_process</code>.
-</p>
-
-<p>
-  If <code>vendor_available</code> or <code>vndk.enabled</code> is
-  <code>true</code>, two variants (<em>core</em> and <em>vendor</em>) may be
-  built. The core variant should be treated as a framework module and the vendor
-  variant should be treated as a vendor module. If some framework modules depend
-  on this module, the core variant is built. If some vendor modules
-  depend on this module, the vendor variant is built. The build system enforces
-  the following dependency checks:
-</p>
-
-<ul>
- <li>The core variant is always framework-only and inaccessible to vendor
- modules.</li>
- <li>The vendor variant is always inaccessible to framework modules.</li>
- <li>All dependencies of the vendor variant, which are specified in
- <code>header_libs</code>, <code>static_libs</code>, and/or
- <code>shared_libs</code>, must be either an <code>llndk_library</code> or a
- module with <code>vendor_available</code> or <code>vndk.enabled</code>.</li>
- <li>If <code>vendor_available</code> is <code>true</code>, the vendor variant
- is accessible to all vendor modules.</li>
- <li>If <code>vendor_available</code> is <code>false</code>, the vendor variant
- is accessible only to other VNDK or VNDK-SP modules (i.e., modules with
- <code>vendor:true</code> cannot link <code>vendor_available:false</code>
- modules).</li>
-</ul>
-
-<p>
-  The default installation path for <code>cc_library</code> or
-  <code>cc_library_shared</code> is determined by the following rules:
-</p>
-
-<ul>
- <li>The core variant is installed to <code>/system/lib[64]</code>.</li>
- <li>The vendor variant installation path may vary:
-  <ul>
-    <li>If <code>vndk.enabled</code> is <code>false</code>, the vendor variant
-    is installed into <code>/vendor/lib[64]</code>.</li>
-    <li>If <code>vndk.enabled</code> is <code>true</code>,
-    <code>vndk.support_system_process</code> can be either <code>true</code> or
-    <code>false</code>. If:
-  <ul>
-    <li><code>false</code>, the vendor variant is installed into
-    <code>/system/lib[64]/vndk-${VER}</code>.</li>
-    <li><code>true</code>, the vendor variant is installed to
-    <code>/system/lib[64]/vndk-sp-${VER}</code>.</li>
-    </ul>
-   </li>
-  </ul>
- </li>
-</ul>
-
-<p>
-  The table below summarizes how the build system handles the vendor variants:
-</p>
-<table>
- <tr>
-  <th>vendor_available</th>
-  <th style="text-align: center">vndk<br>enabled</th>
-  <th style="text-align: center">vndk<br>support_same_process</th>
-  <th>Vendor variant descriptions</th>
- </tr>
-
- <tr>
-  <td rowspan="4"><code>true</code></td>
-  <td rowspan="2"><code>false</code></td>
-  <td><code>false</code></td>
-  <td>The vendor variants are <em>VND-ONLY</em>. Shared libraries are
-  installed into <code>/vendor/lib[64]</code>.</td>
- </tr>
-
- <tr>
-  <td><code>true</code></td>
-  <td><em>Invalid</em> (Build error)</td>
- </tr>
-
- <tr>
-  <td rowspan="2"><code>true</code></td>
-  <td><code>false</code></td>
-  <td>The vendor variants are <em>VNDK</em>. Shared libraries are installed
-  to <code>/system/lib[64]/vndk-${VER}</code>.</td>
- </tr>
-
- <tr>
-  <td><code>true</code></td>
-  <td>The vendor variants are <em>VNDK-SP</em>. Shared libraries are
-  installed to <code>/system/lib[64]/vndk-sp-${VER}</code>.</td>
- </tr>
-
- <tr>
-  <td rowspan="4"><p><code>false</code></p></td>
-  <td rowspan="2"><p><code>false</code></p></td>
-  <td><p><code>false</code></p></td>
-  <td><p>No vendor variants. This module is <em>FWK-ONLY</em>.</p></td>
- </tr>
-
- <tr>
-  <td><code>true</code></td>
-  <td><em>Invalid</em> (Build error)</td>
- </tr>
-
- <tr>
-  <td rowspan="2"><code>true</code></td>
-  <td><code>false</code></td>
-  <td>The vendor variants are <em>VNDK-Private</em>. Shared libraries are
-  installed to <code>/system/lib[64]/vndk-${VER}</code>.These must not be
-  directly used by vendor modules.</td>
- </tr>
-
- <tr>
-  <td><code>true</code></td>
-  <td>The vendor variants are <em>VNDK-SP-Private</em>. Shared libraries are
-  installed to <code>/system/lib[64]/vndk-sp-${VER}</code>. These must not be
-  directly used by vendor modules.</td>
- </tr>
-</table>
-
-<aside class="note">
-  <strong>Note</strong>: Vendors may set <code>vendor_available</code> to their
-  modules but must not set <code>vndk.enabled</code> or
-  <code>vndk.support_system_process</code> because the modules won't be able
-  to find them in the <a href="/setup/build/gsi">Generic System Image (GSI)</a>.
-</aside>
-
-<h3 id="vndk-extensions">VNDK extensions</h3>
-
-<p>
-  VNDK extensions are VNDK shared libraries with additional APIs. Extensions are
-  installed to <code>/vendor/lib[64]/vndk[-sp]</code> (without version suffix)
-  and override the original VNDK shared libraries at runtime.
-</p>
-
-<h4 id="defining-vndk-extensions">Defining VNDK extensions</h4>
-
-<p>
-  In Android 9 and higher, <code>Android.bp</code> natively supports VNDK
-  extensions. To build a VNDK extension, define another module with a
-  <code>vendor:true</code> and an <code>extends</code> property:
-</p>
-
-<pre class="prettyprint">
-cc_library {
-    name: "libvndk",
-    vendor_available: true,
-    vndk: {
-        enabled: true,
-    },
-}
-
-cc_library {
-    name: "libvndk_ext",
-    vendor: true,
-    vndk: {
-        enabled: true,
-        extends: "libvndk",
-    },
-}
-</pre>
-
-<p>
-  A module with <code>vendor:true</code>, <code>vndk.enabled:true</code>, and
-  <code>extends</code> properties defines the VNDK extension:</p>
-
-<ul>
- <li>The <code>extends</code> property must specify a base VNDK shared library
-  name (or VNDK-SP shared library name).</li>
-  <li>VNDK extensions (or VNDK-SP extensions) are named after the base module
-  names from which they extend. For example, the output binary of
-  <code>libvndk_ext</code> is <code>libvndk.so</code> instead of
-  <code>libvndk_ext.so</code>.</li>
-  <li>VNDK extensions are installed into <code>/vendor/lib[64]/vndk</code>.</li>
-  <li>VNDK-SP extensions are installed into
-  <code>/vendor/lib[64]/vndk-sp</code>.</li>
-  <li>The base shared libraries must have both <code>vndk.enabled:true</code>
-  and <code>vendor_available:true</code>.</li>
-</ul>
-
-<p>
-  A VNDK-SP extension must extend from a VNDK-SP shared library
-  (<code>vndk.support_system_process</code> must be equal):
-</p>
-
-<pre class="prettyprint">
-cc_library {
-    name: "libvndk_sp",
-    vendor_available: true,
-    vndk: {
-        enabled: true,
-        support_system_process: true,
-    },
-}
-
-cc_library {
-    name: "libvndk_sp_ext",
-    vendor: true,
-    vndk: {
-        enabled: true,
-        extends: "libvndk_sp",
-        support_system_process: true,
-    },
-}
-</pre>
-
-<p>
-  VNDK extensions (or VNDK-SP extensions) may depend on other vendor shared
-  libraries:
-</p>
-
-<pre class="prettyprint">
-cc_library {
-    name: "libvndk",
-    vendor_available: true,
-    vndk: {
-        enabled: true,
-    },
-}
-
-cc_library {
-    name: "libvndk_ext",
-    vendor: true,
-    vndk: {
-        enabled: true,
-        extends: "libvndk",
-    },
-    shared_libs: [
-        "libvendor",
-    ],
-}
-
-cc_library {
-    name: "libvendor",
-    vendor: true,
-}
-</pre>
-
-<aside class="note">
-  <strong>Note:</strong> Similar to SP-HAL-Dep, VNDK-SP extensions and their
-  dependencies (including vendor libraries) must be labeled as
-  <code>same_process_hal_file</code> in sepolicy.
-</aside>
-
-<h4 id="using-vndk-extensions">Using VNDK extensions</h4>
-
-<p>
-  If a vendor module depends on additional APIs defined by VNDK extensions, the
-  module must specify the name of the VNDK extension in its
-  <code>shared_libs</code> property:
-</p>
-
-<pre class="prettyprint">
-// A vendor shared library example
-cc_library {
-    name: "libvendor",
-    vendor: true,
-    shared_libs: [
-        "libvndk_ext",
-    ],
-}
-
-// A vendor executable example
-cc_binary {
-    name: "vendor-example",
-    vendor: true,
-    shared_libs: [
-        "libvndk_ext",
-    ],
-}
-</pre>
-
-<p>
-  If a vendor module depends on VNDK extensions, those VNDK extensions are
-  installed to <code>/vendor/lib[64]/vndk[-sp]</code> automatically. If a module
-  no longer depends on a VNDK extension, add a clean step to
-  <code>CleanSpec.mk</code> to remove the shared library. For example:
-</p>
-
-<pre class="prettyprint">
-$(call add-clean-step, rm -rf $(TARGET_OUT_VENDOR)/lib/libvndk.so)
-</pre>
-
-<h3 id="conditional-compilation">Conditional compilation</h3>
-
-<p>
-  This section describes how to deal with the <em>subtle differences</em> (e.g.
-  adding or removing a feature from one of the variants) between the following
-  three VNDK shared libraries:
-</p>
-
-<ul>
-  <li>Core variant (e.g. <code>/system/lib[64]/libexample.so</code>)</li>
-  <li>Vendor variant (e.g.
-  <code>/system/lib[64]/vndk[-sp]-${VER}/libexample.so</code>)</li>
-  <li>VNDK extension (e.g. <code>/vendor/lib[64]/vndk[-sp]/libexample.so</code>)
-  </li>
-</ul>
-
-
-<h4 id="conditional-cflags">Conditional compiler flags</h4>
-
-<p>
-  The Android build system defines <code>__ANDROID_VNDK__</code> for vendor
-  variants and VNDK extensions by default. You may guard the code
-  with the C preprocessor guards:
-</p>
-
-<pre class="prettyprint">
-void all() { }
-
-#if !defined(__ANDROID_VNDK__)
-void framework_only() { }
-#endif
-
-#if defined(__ANDROID_VNDK__)
-void vndk_only() { }
-#endif
-</pre>
-
-<p>
-  In addition to <code>__ANDROID_VNDK__</code>, different <code>cflags</code> or
-  <code>cppflags</code> may be specified in <code>Android.bp</code>. The
-  <code>cflags</code> or <code>cppflags</code> specified in
-  <code>target.vendor</code> is specific to the vendor variant.
-</p>
-
-<p>
-  For example, the following <code>Android.bp</code> defines
-  <code>libexample</code> and <code>libexample_ext</code>:
-</p>
-
-<pre class="prettyprint">
-cc_library {
-    name: "libexample",
-    srcs: ["src/example.c"],
-    vendor_available: true,
-    vndk: {
-        enabled: true,
-    },
-    target: {
-        vendor: {
-            cflags: ["-DLIBEXAMPLE_ENABLE_VNDK=1"],
-        },
-    },
-}
-
-cc_library {
-    name: "libexample_ext",
-    srcs: ["src/example.c"],
-    vendor: true,
-    vndk: {
-        enabled: true,
-        extends: "libexample",
-    },
-    cflags: [
-        "-DLIBEXAMPLE_ENABLE_VNDK=1",
-        "-DLIBEXAMPLE_ENABLE_VNDK_EXT=1",
-    ],
-}
-</pre>
-
-<p>
-  And this is the code listing of <code>src/example.c</code>:
-</p>
-
-<pre class="prettyprint">
-void all() { }
-
-#if !defined(LIBEXAMPLE_ENABLE_VNDK)
-void framework_only() { }
-#endif
-
-#if defined(LIBEXAMPLE_ENABLE_VNDK)
-void vndk() { }
-#endif
-
-#if defined(LIBEXAMPLE_ENABLE_VNDK_EXT)
-void vndk_ext() { }
-#endif
-</pre>
-
-<p>
-  According to these two files, the build system generates shared libraries
-  with following exported symbols:
-</p>
-
-<table>
- <tr>
-  <th>Installation path</th>
-  <th>Exported symbols</th>
- </tr>
-
- <tr>
-  <td><code>/system/lib[64]/libexample.so</code></td>
-  <td><code>all</code>, <code>framework_only</code></td>
- </tr>
-
- <tr>
-  <td><code>/system/lib[64]/vndk-${VER}/libexample.so</code></td>
-  <td><code>all</code>, <code>vndk</code></td>
- </tr>
-
- <tr>
-  <td><code>/vendor/lib[64]/vndk/libexample.so</code></td>
-  <td><code>all</code>, <code>vndk</code>, <code>vndk_ext</code></td>
- </tr>
-</table>
-
-
-<h4 id="exported-symbols">Requirements on the exported symbols</h4>
-
-<p>
-  The <a href="/devices/architecture/vndk/abi-stability">VNDK ABI checker</a>
-  compares the ABI of <em>VNDK vendor variants</em> and
-  <em>VNDK extensions</em> to the reference ABI dumps under
-  <code>prebuilts/abi-dumps/vndk</code>.
-</p>
-
-<ul>
-  <li>Symbols exported by <em>VNDK vendor variants</em> (e.g.
-  <code>/system/lib[64]/vndk-${VER}/libexample.so</code>) must be identical
-  to (not the supersets of) the symbols defined in ABI dumps.</li>
-
-  <li>Symbols exported by <em>VNDK extensions</em> (e.g.
-  <code>/vendor/lib[64]/vndk/libexample.so</code>) must be supersets of the
-  symbols defined in ABI dumps.</li>
-</ul>
-
-<p>
-  If <em>VNDK vendor variants</em> or <em>VNDK extensions</em> fail to follow
-  the requirements above, VNDK ABI checker emits build errors and stops the
-  build.
-</p>
-
-
-<h4 id="excluding">Excluding source files or shared libraries from vendor variants</h4>
-
-<p>
-  To exclude source files from the vendor variant, add them to the
-  <code>exclude_srcs</code> property. Similarly, to ensure shared libraries are
-  not linked with the vendor variant, add those libraries to the
-  <code>exclude_shared_libs</code> property. For example:
-</p>
-
-<pre class="prettyprint">
-cc_library {
-    name: "libexample_cond_exclude",
-    srcs: ["fwk.c", "both.c"],
-    shared_libs: ["libfwk_only", "libboth"],
-    target: {
-        vendor: {
-            exclude_srcs: ["fwk.c"],
-            exclude_shared_libs: ["libfwk_only"],
-        },
-    },
-}
-</pre>
-
-<p>
-  In this example, the core variant of <code>libexample_cond_exclude</code>
-  includes the code from <code>fwk.c</code> and <code>both.c</code> and depends
-  on the shared libraries <code>libfwk_only</code> and <code>libboth</code>. The
-  vendor variant of <code>libexample_cond_exclude</code> includes only the code
-  from <code>both.c</code> because <code>fwk.c</code> is excluded by the
-  <code>exclude_srcs</code> property. Similarly,
-  <code>libexample_cond_exclude</code> depends only on the shared library
-  <code>libboth</code> because <code>libfwk_only</code> is excluded by the
-  <code>exclude_shared_libs</code> property.
-</p>
-
-<h4 id="export-headers-from-vndk-extension">Export headers from VNDK extensions</h4>
-
-<p>
-  A VNDK extension may add new classes or new functions to a VNDK shared
-  library. It is suggested to keep those declarations in independent headers
-  and avoid changing the existing headers.
-</p>
-
-<p>
-  For example, a new header file
-  <code>include-ext/example/ext/feature_name.h</code> is created for the VNDK
-  extension <code>libexample_ext</code>:
-</p>
-
-<ul>
-  <li>Android.bp</li>
-  <li><strong>include-ext/example/ext/feature_name.h</strong></li>
-  <li>include/example/example.h</li>
-  <li>src/example.c</li>
-  <li><strong>src/ext/feature_name.c</strong></li>
-</ul>
-
-<p>
-  In the following <code>Android.bp</code>, <code>libexample</code> exports
-  only <code>include</code>, whereas <code>libexample_ext</code> exports both
-  <code>include</code> and <code>include-ext</code>. This ensures
-  <code>feature_name.h</code> won't be incorrectly included by the users of
-  <code>libexample</code>:
-</p>
-
-<pre class="prettyprint">
-cc_library {
-    name: "libexample",
-    srcs: ["src/example.c"],
-    export_include_dirs: ["include"],
-    vendor_available: true,
-    vndk: {
-        enabled: true,
-    },
-}
-
-cc_library {
-    name: "libexample_ext",
-    srcs: [
-        "src/example.c",
-        "src/ext/feature_name.c",
-    ],
-    export_include_dirs: [
-        "include",
-        "include-ext",
-    ],
-    vendor: true,
-    vndk: {
-        enabled: true,
-        extends: "libexample",
-    },
-}
-</pre>
-
-<p>
-  If separating extensions to independent header files is not feasible, an
-  alternative is to add <code>#ifdef</code> guards. However, make sure that all
-  VNDK extension users add the define flags. You may define
-  <code>cc_defaults</code> to add define flags to <code>cflags</code> and link
-  shared libraries with <code>shared_libs</code>.
-</p>
-
-<p>
-  For example, to add a new member function <code>Example2::get_b()</code> to
-  the VNDK extension <code>libexample2_ext</code>, you must modify the existing
-  header file and add a <code>#ifdef</code> guard:
-</p>
-
-<pre class="prettyprint">
-#ifndef LIBEXAMPLE2_EXAMPLE_H_
-#define LIBEXAMPLE2_EXAMPLE_H_
-
-class Example2 {
- public:
-  Example2();
-
-  void get_a();
-
-#ifdef LIBEXAMPLE2_ENABLE_VNDK_EXT
-  void get_b();
-#endif
-
- private:
-  void *impl_;
-};
-
-#endif  // LIBEXAMPLE2_EXAMPLE_H_
-</pre>
-
-<p>
-  A <code>cc_defaults</code> named <code>libexample2_ext_defaults</code> is
-  defined for the users of <code>libexample2_ext</code>:
-</p>
-
-<pre class="prettyprint">
-cc_library {
-    name: "libexample2",
-    srcs: ["src/example2.cpp"],
-    export_include_dirs: ["include"],
-    vendor_available: true,
-    vndk: {
-        enabled: true,
-    },
-}
-
-cc_library {
-    name: "libexample2_ext",
-    srcs: ["src/example2.cpp"],
-    export_include_dirs: ["include"],
-    vendor: true,
-    vndk: {
-        enabled: true,
-        extends: "libexample2",
-    },
-    cflags: [
-        "-DLIBEXAMPLE2_ENABLE_VNDK_EXT=1",
-    ],
-}
-
-cc_defaults {
-    name: "libexample2_ext_defaults",
-    shared_libs: [
-        "libexample2_ext",
-    ],
-    cflags: [
-        "-DLIBEXAMPLE2_ENABLE_VNDK_EXT=1",
-    ],
-}
-</pre>
-
-<p>
-  The users of <code>libexample2_ext</code> may simply include
-  <code>libexample2_ext_defaults</code> in their <code>defaults</code>
-  property:
-</p>
-
-<pre class="prettyprint">
-cc_binary {
-    name: "example2_user_executable",
-    defaults: ["libexample2_ext_defaults"],
-    vendor: true,
-}
-</pre>
-
-
-
-<h3 id="product-packages">Product packages</h3>
-
-<p>
-  In the Android build system, the variable <code>PRODUCT_PACKAGES</code>
-  specifies the executables, shared libraries, or packages that should be
-  installed into the device. The transitive dependencies of the specified
-  modules are implicitly installed into the device as well.
-</p>
-
-<p>
-  If <code>BOARD_VNDK_VERSION</code> is enabled, modules with
-  <code>vendor_available</code> or <code>vndk.enabled</code> get special
-  treatment. If a framework module depends on a module with
-  <code>vendor_available</code> or <code>vndk.enabled</code>, the core variant
-  is included in the transitive installation set. Similarly, if a vendor module
-  depends on a module with <code>vendor_available</code> or
-  <code>vndk.enabled</code>, the vendor variant is included in the transitive
-  installation set.
-</p>
-
-<p>
-  When the dependencies are invisible to the build system (e.g. shared libraries
-  that may be opened with <code>dlopen()</code> in runtime), you should specify
-  the module names in <code>PRODUCT_PACKAGES</code> to install those modules
-  explicitly.
-</p>
-
-<p>
-  If a module has <code>vendor_available</code> or <code>vndk.enabled</code>,
-  the module name stands for its core variant. To explicitly specify the
-  vendor variant in <code>PRODUCT_PACKAGES</code>, append a <code>.vendor</code>
-  suffix to the module name. For example:
-</p>
-
-<pre class="prettyprint">
-cc_library {
-    name: "libexample",
-    srcs: ["example.c"],
-    vendor_available: true,
-}
-</pre>
-
-<p>
-  In this example, <code>libexample</code> stands for
-  <code>/system/lib[64]/libexample.so</code> and <code>libexample.vendor</code>
-  stands for <code>/vendor/lib[64]/libexample.so</code>. To install
-  <code>/vendor/lib[64]/libexample.so</code>, add <code>libexample.vendor</code>
-  to <code>PRODUCT_PACKAGES</code>:
-</p>
-
-<pre class="prettyprint">PRODUCT_PACKAGES += libexample.vendor</pre>
-
-  </body>
-</html>
author	Gina Dimino <gdimino@google.com>	2021-07-15 23:27:11 +0000
committer	Gerrit Code Review <noreply-gerritcodereview@google.com>	2021-07-15 23:27:11 +0000
commit	72e0ae8d8207042452f75874221103f4f6b3014a (patch)
tree	7fa97b880b85be7de5b713d233cdc407c20b88cd /en/devices/architecture/vndk/build-system.html
parent	e55b3193405187e091a4ac7730ef04360ec04504 (diff)
parent	fc5fc0e74df003b0ee454d3418b88cd722282c49 (diff)
download	source.android.com-master.tar.gz