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<html devsite>
<head>
<title>Building Kernels</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>
This page details how to build only the
<a href="/devices/architecture/kernel/">kernel</a>. The following instructions
assume you have not downloaded all of AOSP; if you have already done so, you
can skip the <code>git clone</code> steps except the step that downloads the
kernel sources.
</p>
<p>All examples in this section use the
<a href="devices.html#hikey-boards">hikey</a> kernel.</p>
<h2 id="figuring-out-which-kernel-to-build">Selecting a kernel</h2>
<p>This table lists the name and locations of the kernel sources and binaries:
<table>
<tr>
<th>Device</th>
<th>Binary location</th>
<th>Source location</th>
<th>Build configuration</th>
</tr>
<tr>
<td>blueline</td>
<td>device/google/crosshatch-kernel</td>
<td><a href="#building-b1c1">instructions</a></td>
<td>b1c1_defconfig</td>
</tr>
<tr>
<td>crosshatch</td>
<td>device/google/crosshatch-kernel</td>
<td><a href="#building-b1c1">instructions</a></td>
<td>b1c1_defconfig</td>
</tr>
<tr>
<td>taimen</td>
<td>device/google/wahoo-kernel</td>
<td>kernel/msm</td>
<td>wahoo_defconfig</td>
</tr>
<tr>
<td>walleye</td>
<td>device/google/wahoo-kernel</td>
<td>kernel/msm</td>
<td>wahoo_defconfig</td>
</tr>
<tr>
<td>easel</td>
<td>N/A</td>
<td>kernel/arm64</td>
<td>mnh_prod_defconfig</td>
</tr>
<tr>
<td>marlin</td>
<td>device/google/marlin-kernel</td>
<td>kernel/msm</td>
<td>marlin_defconfig</td>
</tr>
<tr>
<td>sailfish</td>
<td>device/google/marlin-kernel</td>
<td>kernel/msm</td>
<td>marlin_defconfig</td>
</tr>
<tr>
<td>hikey</td>
<td>device/linaro/hikey-kernel</td>
<td>kernel/hikey-linaro</td>
<td>hikey_defconfig</td>
</tr>
<tr>
<td>angler</td>
<td>device/huawei/angler-kernel</td>
<td>kernel/msm</td>
<td>angler_defconfig</td>
</tr>
<tr>
<td>bullhead</td>
<td>device/lge/bullhead-kernel</td>
<td>kernel/msm</td>
<td>bullhead_defconfig</td>
</tr>
<tr>
<td>shamu</td>
<td>device/moto/shamu-kernel</td>
<td>kernel/msm</td>
<td>shamu_defconfig</td>
</tr>
<tr>
<td>fugu</td>
<td>device/asus/fugu-kernel</td>
<td>kernel/x86_64</td>
<td>fugu_defconfig</td>
</tr>
<tr>
<td>volantis</td>
<td>device/htc/flounder-kernel</td>
<td>kernel/tegra</td>
<td>flounder_defconfig</td>
</tr>
<tr>
<td>hammerhead</td>
<td>device/lge/hammerhead-kernel</td>
<td>kernel/msm</td>
<td>hammerhead_defconfig</td>
</tr>
<tr>
<td>flo</td>
<td>device/asus/flo-kernel/kernel</td>
<td>kernel/msm</td>
<td>flo_defconfig</td>
</tr>
<tr>
<td>deb</td>
<td>device/asus/flo-kernel/kernel</td>
<td>kernel/msm</td>
<td>flo_defconfig</td>
</tr>
<tr>
<td>manta</td>
<td>device/samsung/manta/kernel</td>
<td>kernel/exynos</td>
<td>manta_defconfig</td>
</tr>
<tr>
<td>mako</td>
<td>device/lge/mako-kernel/kernel</td>
<td>kernel/msm</td>
<td>mako_defconfig</td>
</tr>
<tr>
<td>grouper</td>
<td>device/asus/grouper/kernel</td>
<td>kernel/tegra</td>
<td>tegra3_android_defconfig</td>
</tr>
<tr>
<td>tilapia</td>
<td>device/asus/grouper/kernel</td>
<td>kernel/tegra</td>
<td>tegra3_android_defconfig</td>
</tr>
<tr>
<td>maguro</td>
<td>device/samsung/tuna/kernel</td>
<td>kernel/omap</td>
<td>tuna_defconfig</td>
</tr>
<tr>
<td>toro</td>
<td>device/samsung/tuna/kernel</td>
<td>kernel/omap</td>
<td>tuna_defconfig</td>
</tr>
<tr>
<td>panda</td>
<td>device/ti/panda/kernel</td>
<td>kernel/omap</td>
<td>panda_defconfig</td>
</tr>
<tr>
<td>stingray</td>
<td>device/moto/wingray/kernel</td>
<td>kernel/tegra</td>
<td>stingray_defconfig</td>
</tr>
<tr>
<td>wingray</td>
<td>device/moto/wingray/kernel </td>
<td>kernel/tegra</td>
<td>stingray_defconfig</td>
</tr>
<tr>
<td>crespo</td>
<td>device/samsung/crespo/kernel</td>
<td>kernel/samsung</td>
<td>herring_defconfig</td>
</tr>
<tr>
<td>crespo4g</td>
<td>device/samsung/crespo/kernel</td>
<td>kernel/samsung</td>
<td>herring_defconfig</td>
</tr>
</table>
<p>After determining the device project you want to work with, view the git log
for the kernel binary. Device projects use the form
<code>device/<var>VENDOR</var>/<var>NAME</var></code>.</p>
<pre class="devsite-click-to-copy">
<code class="devsite-terminal">git clone https://android.googlesource.com/kernel/hikey-linaro</code>
<code class="devsite-terminal">cd hikey-linaro</code>
<code class="devsite-terminal">git log --max-count=1 kernel</code>
</pre>
<p>The commit message for the kernel binary contains a partial git log of the
kernel sources used to build the binary. The first entry in the log is the most
recent (the one used to build the kernel). Make a note of the commit message
as you will need it in a later step.</p>
<h2 id="id-version">Identifying kernel version</h2>
<p>To determine the kernel version used in a system image, run the following
command against the kernel file:</p>
<pre class="devsite-terminal devsite-click-to-copy">
dd if=kernel bs=1 skip=$(LC_ALL=C grep -a -b -o $'\x1f\x8b\x08\x00\x00\x00\x00\x00' kernel | cut -d ':' -f 1) | zgrep -a 'Linux version'
</pre>
<p>For Nexus 5 (hammerhead), the command is:</p>
<pre class="devsite-terminal devsite-click-to-copy">
dd if=zImage-dtb bs=1 skip=$(LC_ALL=C od -Ad -x -w2 zImage-dtb | grep 8b1f | cut -d ' ' -f1 | head -1) | zgrep -a 'Linux version'
</pre>
<h2 id="downloading-sources">Downloading sources</h2>
<p>Download the source for the kernel you want to build using the appropriate
<code>git clone</code> command. For example, the following command clones the
<code>common</code> kernel, a generic, customizable kernel:</p>
<pre class="devsite-terminal devsite-click-to-copy">
git clone https://android.googlesource.com/kernel/common
</pre>
<p>A full list of the kernel projects can be found in the
<a href="https://android.googlesource.com/kernel">Kernel</a> directory. Below
are some of the commonly used kernels and their respective <code>git clone</code>
commands.</p>
<p>The <code>exynos</code> project has the kernel sources for Nexus 10, and can
be used as a starting point for work on Samsung Exynos chipsets.</p>
<pre class="devsite-terminal devsite-click-to-copy">git clone https://android.googlesource.com/kernel/exynos</pre>
<p>The <code>goldfish</code> project contains the kernel sources for the
emulated platforms.</p>
<pre class="devsite-terminal devsite-click-to-copy">git clone https://android.googlesource.com/kernel/goldfish</pre>
<p>The <code>hikey-linaro</code> project is used for HiKey reference boards,
and can be used as a starting point for work on HiSilicon 620 chipsets.</p>
<pre class="devsite-terminal devsite-click-to-copy">git clone https://android.googlesource.com/kernel/hikey-linaro</pre>
<p>The <code>msm</code> project has the sources for ADP1, ADP2, Nexus One,
Nexus 4, Nexus 5, Nexus 6, Nexus 5X, Nexus 6P, Nexus 7 (2013), Pixel, and
Pixel XL, and can be used as a starting point for work on Qualcomm MSM chipsets.</p>
<pre class="devsite-terminal devsite-click-to-copy">git clone https://android.googlesource.com/kernel/msm</pre>
<p>The <code>omap</code> project is used for PandaBoard and Galaxy Nexus, and
can be used as a starting point for work on TI OMAP chipsets.</p>
<pre class="devsite-terminal devsite-click-to-copy">git clone https://android.googlesource.com/kernel/omap</pre>
<p>The <code>samsung</code> project is used for Nexus S, and can be used as a
starting point for work on Samsung Hummingbird chipsets.</p>
<pre class="devsite-terminal devsite-click-to-copy">git clone https://android.googlesource.com/kernel/samsung</pre>
<p>The <code>tegra</code> project is for Xoom, Nexus 7 (2012), Nexus 9, and can
be used as a starting point for work on NVIDIA Tegra chipsets.</p>
<pre class="devsite-terminal devsite-click-to-copy">git clone https://android.googlesource.com/kernel/tegra</pre>
<p>The <code>x86_64</code> project has the kernel sources for Nexus Player, and
can be used as a starting point for work on Intel x86_64 chipsets.</p>
<pre class="devsite-terminal devsite-click-to-copy">git clone https://android.googlesource.com/kernel/x86_64</pre>
<h2 id="building">Building the kernel manually</h2>
<p>When you know the last commit message for a kernel and have successfully
downloaded the kernel source and prebuilt gcc, you are ready to build the
kernel. The following build commands use the hikey kernel:</p>
<pre class="devsite-click-to-copy">
<code class="devsite-terminal">export ARCH=arm64</code>
<code class="devsite-terminal">export CROSS_COMPILE=aarch64-linux-android-</code>
<code class="devsite-terminal">cd hikey-linaro</code>
<code class="devsite-terminal">git checkout -b android-hikey-linaro-4.1 origin/android-hikey-linaro-4.1</code>
<code class="devsite-terminal">make hikey_defconfig</code>
<code class="devsite-terminal">make</code>
</pre>
<p>To build a different kernel, simply replace <code>hikey-linaro</code> with
the name of the kernel you want to build.</p>
<p>The image outputs to the <code>arch/arm64/boot/Image</code> directory; the
kernel binary outputs to the
<code>arch/arm64/boot/dts/hisilicon/hi6220-hikey.dtb</code> fle. Copy the
<code>Image</code> directory and the <code>hi6220-hikey.dtb</code> file to the
<code>hikey-kernel</code> directory.</p>
<p>Alternatively, you can include the <code>TARGET_PREBUILT_KERNEL</code>
variable while using <code>make bootimage</code> (or any other <code>make</code>
command line that builds a boot image). This variable is supported by all
devices as it is set up via <code>device/common/populate-new-device.sh</code>.
For example:</p>
<pre class="devsite-terminal devsite-click-to-copy">
export TARGET_PREBUILT_KERNEL=$your_kernel_path/arch/arm/boot/zImage-dtb
</pre>
<p class="note"><strong>Note:</strong> Kernel names differ by device. To locate
the correct filename for your kernel, refer to
<code>device/<var>VENDOR</var>/<var>NAME</var></code> in the kernel source.</p>
<h2 id="building-b1c1">Building Pixel 3 (blueline) and Pixel 3 XL (crosshatch) kernels</h2>
<p>For Pixel 3 and Pixel 3 XL, the kernel source is separated into multiple
projects. Use <a href="/setup/develop/repo#init">repo</a> to download the
kernel source for the appropriate branch (as of this writing, <code><var>VERSION</var></code> should be
<code>4.9-pie-qpr1</code>):</p>
<pre class="devsite-terminal devsite-click-to-copy">repo init -u https://android.googlesource.com/platform/manifest -b android-msm-bluecross-$<var>VERSION</var></pre>
<pre class="devsite-terminal devsite-click-to-copy">repo sync</pre>
<p>Then build the kernel with:</p>
<pre class="devsite-terminal devsite-click-to-copy">sh build/build.sh</pre>
</body>
</html>
|
