1 <html devsite> 2 <head> 3 <title>Building Kernels</title> 4 <meta name="project_path" value="/_project.yaml" /> 5 <meta name="book_path" value="/_book.yaml" /> 6 </head> 7 <body> 8 <!-- 9 Copyright 2017 The Android Open Source Project 10 11 Licensed under the Apache License, Version 2.0 (the "License"); 12 you may not use this file except in compliance with the License. 13 You may obtain a copy of the License at 14 15 http://www.apache.org/licenses/LICENSE-2.0 16 17 Unless required by applicable law or agreed to in writing, software 18 distributed under the License is distributed on an "AS IS" BASIS, 19 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 20 See the License for the specific language governing permissions and 21 limitations under the License. 22 --> 23 24 25 26 <p>This page details how to build only the kernel. The following instructions 27 assume you have not downloaded all of AOSP; if you have already done so, you can 28 skip the <code>git clone</code> steps except the step that downloads the kernel 29 sources.</p> 30 31 <p>All examples in this section use the 32 <a href="/source/devices.html#hikey-boards">hikey</a> kernel.</p> 33 34 <h2 id="figuring-out-which-kernel-to-build">Selecting a kernel</h2> 35 <p>This table lists the name and locations of the kernel sources and binaries: 36 <table> 37 <tr> 38 <th>Device</th> 39 <th>Binary location</th> 40 <th>Source location</th> 41 <th>Build configuration</th> 42 </tr> 43 <tr> 44 <td>marlin</td> 45 <td>device/google/marlin-kernel</td> 46 <td>kernel/msm</td> 47 <td>marlin_defconfig</td> 48 </tr> 49 <tr> 50 <td>sailfish</td> 51 <td>device/google/marlin-kernel</td> 52 <td>kernel/msm</td> 53 <td>marlin_defconfig</td> 54 </tr> 55 <tr> 56 <td>hikey</td> 57 <td>device/linaro/hikey-kernel</td> 58 <td>kernel/hikey-linaro</td> 59 <td>hikey_defconfig</td> 60 </tr> 61 <tr> 62 <td>angler</td> 63 <td>device/huawei/angler-kernel</td> 64 <td>kernel/msm</td> 65 <td>angler_defconfig</td> 66 </tr> 67 <tr> 68 <td>bullhead</td> 69 <td>device/lge/bullhead-kernel</td> 70 <td>kernel/msm</td> 71 <td>bullhead_defconfig</td> 72 </tr> 73 <tr> 74 <td>shamu</td> 75 <td>device/moto/shamu-kernel</td> 76 <td>kernel/msm</td> 77 <td>shamu_defconfig</td> 78 </tr> 79 <tr> 80 <td>fugu</td> 81 <td>device/asus/fugu-kernel</td> 82 <td>kernel/x86_64</td> 83 <td>fugu_defconfig</td> 84 </tr> 85 <tr> 86 <td>volantis</td> 87 <td>device/htc/flounder-kernel</td> 88 <td>kernel/tegra</td> 89 <td>flounder_defconfig</td> 90 </tr> 91 <tr> 92 <td>hammerhead</td> 93 <td>device/lge/hammerhead-kernel</td> 94 <td>kernel/msm</td> 95 <td>hammerhead_defconfig</td> 96 </tr> 97 <tr> 98 <td>flo</td> 99 <td>device/asus/flo-kernel/kernel</td> 100 <td>kernel/msm</td> 101 <td>flo_defconfig</td> 102 </tr> 103 <tr> 104 <td>deb</td> 105 <td>device/asus/flo-kernel/kernel</td> 106 <td>kernel/msm</td> 107 <td>flo_defconfig</td> 108 </tr> 109 <tr> 110 <td>manta</td> 111 <td>device/samsung/manta/kernel</td> 112 <td>kernel/exynos</td> 113 <td>manta_defconfig</td> 114 </tr> 115 <tr> 116 <td>mako</td> 117 <td>device/lge/mako-kernel/kernel</td> 118 <td>kernel/msm</td> 119 <td>mako_defconfig</td> 120 </tr> 121 <tr> 122 <td>grouper</td> 123 <td>device/asus/grouper/kernel</td> 124 <td>kernel/tegra</td> 125 <td>tegra3_android_defconfig</td> 126 </tr> 127 <tr> 128 <td>tilapia</td> 129 <td>device/asus/grouper/kernel</td> 130 <td>kernel/tegra</td> 131 <td>tegra3_android_defconfig</td> 132 </tr> 133 <tr> 134 <td>maguro</td> 135 <td>device/samsung/tuna/kernel</td> 136 <td>kernel/omap</td> 137 <td>tuna_defconfig</td> 138 </tr> 139 <tr> 140 <td>toro</td> 141 <td>device/samsung/tuna/kernel</td> 142 <td>kernel/omap</td> 143 <td>tuna_defconfig</td> 144 </tr> 145 <tr> 146 <td>panda</td> 147 <td>device/ti/panda/kernel</td> 148 <td>kernel/omap</td> 149 <td>panda_defconfig</td> 150 </tr> 151 <tr> 152 <td>stingray</td> 153 <td>device/moto/wingray/kernel</td> 154 <td>kernel/tegra</td> 155 <td>stingray_defconfig</td> 156 </tr> 157 <tr> 158 <td>wingray</td> 159 <td>device/moto/wingray/kernel </td> 160 <td>kernel/tegra</td> 161 <td>stingray_defconfig</td> 162 </tr> 163 <tr> 164 <td>crespo</td> 165 <td>device/samsung/crespo/kernel</td> 166 <td>kernel/samsung</td> 167 <td>herring_defconfig</td> 168 </tr> 169 <tr> 170 <td>crespo4g</td> 171 <td>device/samsung/crespo/kernel</td> 172 <td>kernel/samsung</td> 173 <td>herring_defconfig</td> 174 </tr> 175 </table> 176 177 <p>After determining the device project you want to work with, view the git log 178 for the kernel binary. Device projects use the form 179 <code>device/<var>VENDOR</var>/<var>NAME</var></code>.</p> 180 181 <pre class="devsite-click-to-copy"> 182 <code class="devsite-terminal">git clone https://android.googlesource.com/kernel/hikey-linaro</code> 183 <code class="devsite-terminal">cd hikey-linaro</code> 184 <code class="devsite-terminal">git log --max-count=1 kernel</code> 185 </pre> 186 187 <p>The commit message for the kernel binary contains a partial git log of the 188 kernel sources used to build the binary. The first entry in the log is the most 189 recent (the one used to build the kernel). Make a note of the commit message 190 as you will need it in a later step.</p> 191 192 <h2 id="id-version">Identifying kernel version</h2> 193 194 <p>To determine the kernel version used in a system image, run the following 195 command against the kernel file:</p> 196 197 <pre class="devsite-terminal devsite-click-to-copy"> 198 dd if=kernel bs=1 skip=$(LC_ALL=C grep -a -b -o $'\x1f\x8b\x08\x00\x00\x00\x00\x00' kernel | cut -d ':' -f 1) | zgrep -a 'Linux version' 199 </pre> 200 201 <p>For Nexus 5 (hammerhead), the command is:</p> 202 <pre class="devsite-terminal devsite-click-to-copy"> 203 dd if=zImage-dtb bs=1 skip=$(LC_ALL=C od -Ad -x -w2 zImage-dtb | grep 8b1f | cut -d ' ' -f1 | head -1) | zgrep -a 'Linux version' 204 </pre> 205 206 207 <h2 id="downloading-sources">Downloading sources</h2> 208 <p>Download the source for the kernel you want to build using the appropriate 209 <code>git clone</code> command. For example, the following command clones the <code>common</code> kernel, a generic, customizable kernel:</p> 210 <pre class="devsite-terminal devsite-click-to-copy"> 211 git clone https://android.googlesource.com/kernel/common 212 </pre> 213 214 <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> 215 216 <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> 217 <pre class="devsite-terminal devsite-click-to-copy">git clone https://android.googlesource.com/kernel/exynos</pre> 218 219 <p>The <code>goldfish</code> project contains the kernel sources for the emulated platforms.</p> 220 <pre class="devsite-terminal devsite-click-to-copy">git clone https://android.googlesource.com/kernel/goldfish</pre> 221 222 <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> 223 <pre class="devsite-terminal devsite-click-to-copy">git clone https://android.googlesource.com/kernel/hikey-linaro</pre> 224 225 <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> 226 <pre class="devsite-terminal devsite-click-to-copy">git clone https://android.googlesource.com/kernel/msm</pre> 227 228 <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> 229 <pre class="devsite-terminal devsite-click-to-copy">git clone https://android.googlesource.com/kernel/omap</pre> 230 231 <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> 232 <pre class="devsite-terminal devsite-click-to-copy">git clone https://android.googlesource.com/kernel/samsung</pre> 233 234 <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> 235 <pre class="devsite-terminal devsite-click-to-copy">git clone https://android.googlesource.com/kernel/tegra</pre> 236 237 <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> 238 <pre class="devsite-terminal devsite-click-to-copy">git clone https://android.googlesource.com/kernel/x86_64</pre> 239 240 <h2 id="building">Building the kernel</h2> 241 <p>When you know the last commit message for a kernel and have successfully 242 downloaded the kernel source and prebuilt gcc, you are ready to build the 243 kernel. The following build commands use the hikey kernel:</p> 244 <pre class="devsite-click-to-copy"> 245 <code class="devsite-terminal">export ARCH=arm64</code> 246 <code class="devsite-terminal">export CROSS_COMPILE=aarch64-linux-android-</code> 247 <code class="devsite-terminal">cd hikey-linaro</code> 248 <code class="devsite-terminal">git checkout -b android-hikey-linaro-4.1 origin/android-hikey-linaro-4.1</code> 249 <code class="devsite-terminal">make hikey_defconfig</code> 250 <code class="devsite-terminal">make</code> 251 </pre> 252 253 <p>To build a different kernel, simply replace <code>hikey-linaro</code> with 254 the name of the kernel you want to build.</p> 255 256 <p>The image outputs to the <code>arch/arm64/boot/Image</code> directory; the 257 kernel binary outputs to the 258 <code>arch/arm64/boot/dts/hisilicon/hi6220-hikey.dtb</code> fle. Copy the 259 <code>Image</code> directory and the <code>hi6220-hikey.dtb</code> file to the 260 <code>hikey-kernel</code> directory.</p> 261 262 <p>Alternatively, you can include the <code>TARGET_PREBUILT_KERNEL</code> 263 variable while using <code>make bootimage</code> (or any other <code>make</code> 264 command line that builds a boot image). This variable is supported by all 265 devices as it is set up via <code>device/common/populate-new-device.sh</code>. 266 For example:</p> 267 268 <pre class="devsite-terminal devsite-click-to-copy"> 269 export TARGET_PREBUILT_KERNEL=$your_kernel_path/arch/arm/boot/zImage-dtb 270 </pre> 271 272 <p class="note"><strong>Note:</strong> Kernel names differ by device. To locate 273 the correct filename for your kernel, refer to 274 <code>device/<var>VENDOR</var>/<var>NAME</var></code> in the kernel source.</p> 275 276 </body> 277 </html> 278
