android_frameworks_base/docs/html-ndk/ndk/guides/ndk-build.jd

page.title=ndk-build
@jd:body

<div id="qv-wrapper">
    <div id="qv">
      <h2>On this page</h2>

      <ol>
        <li><a href="#int">Internals</a></li>
         <li><a href="#ifc">Invoking from the Command Line</a></li>
         <li><a href="#ife">Invoking from Eclipse</a></li>
         <li><a href="#6432">64-Bit and 32-Bit Toolchains</a></li>
         <li><a href="#req">Requirements</a></li>
          </ol>
        </li>
      </ol>
    </div>
  </div>

<p>The {@code ndk-build} file is a shell script introduced in Android NDK r4. Its purpose
is to invoke the right NDK build script.

<h2 id="int">Internals</h2>

<p>Running the {@code ndk-build} script is equivalent to running the following command:</p>

<pre class="no-pretty-print">
$GNUMAKE -f &lt;ndk&gt;/build/core/build-local.mk
&lt;parameters&gt;
</pre>

<p><code>$GNUMAKE</code> points to GNU Make 3.81 or later, and
<code>&lt;ndk&gt;</code> points to your NDK installation directory. You can use
this information to invoke ndk-build from other shell scripts, or even your own
make files.</p>

<h2 id="ifc">Invoking from the Command Line</h2>
<p>The {@code ndk-build} file lives in the top level the NDK installation directory. To run it
from the command line, invoke it while in or under your application project directory.
For example: </p>

<pre class="no-pretty-print">
cd &lt;project&gt;
$ &lt;ndk&gt;/ndk-build
</pre>

<p>In this example, <code>&lt;project&gt;</code> points to your
project’s root directory, and <code>&lt;ndk&gt;</code> is the directory where
you installed the NDK. As noted in <a
href="{@docRoot}ndk/guides/setup.html#install">Setup</a>, you can add {@code $NDK} to your
{@code PATH} to avoid having to type the whole filepath every time you use ndk-build.
Alternatively, you can create an alias.</p>
<p><a class="anchor" id="options"></a> </p>
<h3>Options</h3>
<p>All parameters to ndk-build are passed directly to the underlying GNU {@code make}
command that runs the NDK build scripts. Combine <code>ndk-build</code> and
options in the form <code>ndk-build &lt;option&gt;</code>. For example: </p>

<pre class="no-pretty-print">
$ ndk-build clean
</pre>

<p>The following options are available:</p>
<dl>
  <dt>{@code clean}</dt>
  <dd>Remove any previously generated binaries.</dd>
  <dt>{@code V=1}</dt>
  <dd>Launch build, and display build commands.<dd>
  <dt>{@code -B}</dt>
  <dd>Force a complete rebuild.</dd>
  <dt>{@code -B V=1}</dt>
  <dd>Force a complete rebuild, and display build commands.</dd>
  <dt>{@code NDK_LOG=1}</dd>
  <dd>Display internal NDK log messages (used for debugging the NDK itself).</dd>
  <dt>{@code NDK_DEBUG=1}</dt>
  <dd>Force a debuggable build (see <a href="#dvr">Table 1</a>).</dd>
  <dt>{@code NDK_DEBUG=0}</dt>
  <dd>Force a release build (see <a href="#dvr">Table 1</a>).</dd>
  <dt>{@code NDK_HOST_32BIT=1}</dt>
  <dd>Always use the toolchain in 32-bit mode (see <a href="#6432">64-bit and 32-bit
  Toolchains</a>).</dd>
  <dt>{@code NDK_APPLICATION_MK=&lt;file&gt;}</dt>
  <dd>Build, using a specific <code>Application.mk</code> file pointed to by the
  {@code NDK_APPLICATION_MK} variable.</dd>
  <dt>{@code -C &lt;project&gt;}</dt>
  <dd>Build the native code for the project path located at {@code &lt;project&gt;}. Useful if you
  don't want to {@code cd} to it in your terminal.</dd>
</dl>

<h2 id="ife">Invoking from Eclipse</h2>
<p>To build from Eclipse, make sure that you have configured it as described in
<a href="{@docRoot}ndk/guides/setup.html#configure">Setup</a>. If you
wish to build using the default <code>ndk-build</code> command, with no
options, you can just build your project just as you would any Android project.
To get Eclipse to add any of the options described above, follow these steps:</p>
<ol type="1">
<li>In the <em>Project Explorer</em> pane, right-click your project name.</li>
<li>Select <strong>Properties</strong>.</li>
<li>Click <strong>C/C++ Build</strong>.</li>
<li>Under the <em>Builder Settings</em> tab, uncheck <strong>Use default build command</strong>.</li>
<li>In the <em>Build command</em> field, enter the entire build string as if you were typing it on
the command line.</li>
<li>Click <strong>OK</strong>.</li>
</ol>
Figure 1 shows an example of an entered string.<br>
<br>
<img src="./images/NDK_build_string.png"
    srcset="./images/NDK_build_string@2x.png 2x"
    alt="enter the build string next to 'Build command'"
    height="152" width="501">
<p style="clear:both"><b>Figure 1.</b> Specifying a debug build from within
Eclipse</p>
<p><a class="anchor" id="dvr"></a> </p>
<h3>Debuggable versus Release builds</h3>
<p>Use the <code>NDK_DEBUG</code> option and, in certain cases,
{@code AndroidManifest.xml} to specify debug or release build,
optimization-related behavior, and inclusion of symbols. Table 1 shows the
results of each possible combination of settings.</p>
<p><em>Table 1.</em> Results of <code>NDK_DEBUG</code> (command line) and
<code>android:debuggable</code> (manifest) combinations.</p>
<table>
<tr>
<th></th><th>NDK_DEBUG=0 </th><th>NDK_DEBUG=1</th><th>NDK_DEBUG not specified
</th></tr>
<tr>
<td>android:debuggble="true" </td><td>Debug; Symbols; Optimized*1
</td><td>Debug; Symbols; Not optimized*2 </td><td>(same as NDK_DEBUG=1)
</td></tr>
<tr>
<td>android:debuggable="false"</td><td>Release; Symbols; Optimized
</td><td>Release; Symbols; Not optimized</td><td>Release; No symbols;
Optimized*3 </td></tr>
</table>
*1: Useful for profiling.<br>
*2: Default for running <a href="{@docRoot}ndk/guides/ndk-gdb.html">{@code ndk-gdb}</a>.<br>
*3: Default mode.<br>
<br>
<p class="note"><strong>Note:</strong> {@code NDK_DEBUG=0} is the equivalent of
{@code APP_OPTIM=release}, and complies with the GCC {@code -O2} option. {@code NDK_DEBUG=1} is the
equivalent of {@code APP_OPTIM=debug} in {@code Application.mk}, and complies with the GCC
{@code -O0} option. For more information about {@code APP_OPTIM}, see
<a href="{@docRoot}ndk/guides/application_mk.html">Application.mk</a>.</p>
<p>The syntax on the command line is, for example: </p>

<pre class="no-pretty-print">
$ ndk-build NDK_DEBUG=1
</pre>

<p>If you are using build tools from prior to SDK r8, you must also modify your
{@code AndroidManifest.xml} file to specify debug mode. The syntax for doing so resembles the
following:</p>

<pre class="no-pretty-print">&lt;application android:label="@string/app_name"
android:debuggable="true"&gt;
</pre>

From SDK r8 onward, you do not need to touch {@code AndroidManifest.xml}. Building a debug package
(e.g. with ant debug or the corresponding option of the ADT plugin) causes the tool automatically to
pick the native debug files generated with {@code NDK_DEBUG=1}.


<h2 id="6432">64-Bit and 32-Bit Toolchains</h2>
<p>Some toolchains come with both 64-bit and 32-bit versions. For example,
directories {@code &lt;ndk&gt;/toolchain/&lt;name&gt;/prebuilt/} and
{@code &lt;ndk&gt;/prebuilt/} may contain both {@code linux-x86} and
{@code linux-x86_64} folders for Linux tools in 32-bit and 64-bit modes,
respectively. The ndk-build script automatically chooses a 64-bit version of
the toolchain if the host OS supports it. You can force the use of a 32-bit
toolchain by using {@code NDK_HOST_32BIT=1} either in your environment or
on the ndk-build command line.</p>
<p>Note that 64-bit tools utilize host resources better (for instance, they are faster, and handle
larger programs), and they can still generate 32-bit binaries for Android.</p>

<h2 id="req">Requirements</h2>
<p>You need GNU Make 3.81 or later to use ndk-build or the NDK in general.
The build scripts will detect a non-compliant Make tool, and generate an error
message.</p>
<p>If you have GNU Make 3.81 installed, but the default <code>make</code>
command doesn’t launch it, define {@code GNUMAKE} in your environment to point to it
before launching ndk-build. For example: </p>

<pre class="no-pretty-print">
$ export GNUMAKE=/usr/local/bin/gmake
$ ndk-build
</pre>

<p>You can override other host prebuilt tools in {@code $NDK/prebuilt/&lt;OS&gt;/bin/}
with the following environment variables: </p>

<pre class="no-pretty-print">
$ export NDK_HOST_AWK=&lt;path-to-awk&gt;
$ export NDK_HOST_ECHO=&lt;path-to-echo&gt;
$ export NDK_HOST_CMP=&lt;path-to-cmp&gt;
</pre>