1 page.title=Building Kernels 2 @jd:body 3 4 <!-- 5 Copyright 2015 The Android Open Source Project 6 7 Licensed under the Apache License, Version 2.0 (the "License"); 8 you may not use this file except in compliance with the License. 9 You may obtain a copy of the License at 10 11 http://www.apache.org/licenses/LICENSE-2.0 12 13 Unless required by applicable law or agreed to in writing, software 14 distributed under the License is distributed on an "AS IS" BASIS, 15 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 16 See the License for the specific language governing permissions and 17 limitations under the License. 18 --> 19 <div id="qv-wrapper"> 20 <div id="qv"> 21 <h2>In this document</h2> 22 <ol id="auto-toc"> 23 </ol> 24 </div> 25 </div> 26 27 <p>This page details how to build only the kernel. The following instructions 28 assume you have not downloaded all of AOSP; if you have already done so, you can 29 skip the <code>git clone</code> steps except the step that downloads the kernel 30 sources.</p> 31 32 <p>All examples in this section use the 33 <a href="{@docRoot}source/devices.html#hikey-boards">hikey</a> kernel.</p> 34 35 <h2 id="figuring-out-which-kernel-to-build">Selecting a kernel</h2> 36 <p>This table lists the name and locations of the kernel sources and binaries: 37 <table> 38 <tr> 39 <th>Device</th> 40 <th>Binary location</th> 41 <th>Source location</th> 42 <th>Build configuration</th> 43 </tr> 44 <tr> 45 <td>marlin</td> 46 <td>device/google/marlin-kernel</td> 47 <td>kernel/msm</td> 48 <td>marlin_defconfig</td> 49 </tr> 50 <tr> 51 <td>sailfish</td> 52 <td>device/google/marlin-kernel</td> 53 <td>kernel/msm</td> 54 <td>marlin_defconfig</td> 55 </tr> 56 <tr> 57 <td>hikey</td> 58 <td>device/linaro/hikey-kernel</td> 59 <td>kernel/hikey-linaro</td> 60 <td>hikey_defconfig</td> 61 </tr> 62 <tr> 63 <td>angler</td> 64 <td>device/huawei/angler-kernel</td> 65 <td>kernel/msm</td> 66 <td>angler_defconfig</td> 67 </tr> 68 <tr> 69 <td>bullhead</td> 70 <td>device/lge/bullhead-kernel</td> 71 <td>kernel/msm</td> 72 <td>bullhead_defconfig</td> 73 </tr> 74 <tr> 75 <td>shamu</td> 76 <td>device/moto/shamu-kernel</td> 77 <td>kernel/msm</td> 78 <td>shamu_defconfig</td> 79 </tr> 80 <tr> 81 <td>fugu</td> 82 <td>device/asus/fugu-kernel</td> 83 <td>kernel/x86_64</td> 84 <td>fugu_defconfig</td> 85 </tr> 86 <tr> 87 <td>volantis</td> 88 <td>device/htc/flounder-kernel</td> 89 <td>kernel/tegra</td> 90 <td>flounder_defconfig</td> 91 </tr> 92 <tr> 93 <td>hammerhead</td> 94 <td>device/lge/hammerhead-kernel</td> 95 <td>kernel/msm</td> 96 <td>hammerhead_defconfig</td> 97 </tr> 98 <tr> 99 <td>flo</td> 100 <td>device/asus/flo-kernel/kernel</td> 101 <td>kernel/msm</td> 102 <td>flo_defconfig</td> 103 </tr> 104 <tr> 105 <td>deb</td> 106 <td>device/asus/flo-kernel/kernel</td> 107 <td>kernel/msm</td> 108 <td>flo_defconfig</td> 109 </tr> 110 <tr> 111 <td>manta</td> 112 <td>device/samsung/manta/kernel</td> 113 <td>kernel/exynos</td> 114 <td>manta_defconfig</td> 115 </tr> 116 <tr> 117 <td>mako</td> 118 <td>device/lge/mako-kernel/kernel</td> 119 <td>kernel/msm</td> 120 <td>mako_defconfig</td> 121 </tr> 122 <tr> 123 <td>grouper</td> 124 <td>device/asus/grouper/kernel</td> 125 <td>kernel/tegra</td> 126 <td>tegra3_android_defconfig</td> 127 </tr> 128 <tr> 129 <td>tilapia</td> 130 <td>device/asus/grouper/kernel</td> 131 <td>kernel/tegra</td> 132 <td>tegra3_android_defconfig</td> 133 </tr> 134 <tr> 135 <td>maguro</td> 136 <td>device/samsung/tuna/kernel</td> 137 <td>kernel/omap</td> 138 <td>tuna_defconfig</td> 139 </tr> 140 <tr> 141 <td>toro</td> 142 <td>device/samsung/tuna/kernel</td> 143 <td>kernel/omap</td> 144 <td>tuna_defconfig</td> 145 </tr> 146 <tr> 147 <td>panda</td> 148 <td>device/ti/panda/kernel</td> 149 <td>kernel/omap</td> 150 <td>panda_defconfig</td> 151 </tr> 152 <tr> 153 <td>stingray</td> 154 <td>device/moto/wingray/kernel</td> 155 <td>kernel/tegra</td> 156 <td>stingray_defconfig</td> 157 </tr> 158 <tr> 159 <td>wingray</td> 160 <td>device/moto/wingray/kernel </td> 161 <td>kernel/tegra</td> 162 <td>stingray_defconfig</td> 163 </tr> 164 <tr> 165 <td>crespo</td> 166 <td>device/samsung/crespo/kernel</td> 167 <td>kernel/samsung</td> 168 <td>herring_defconfig</td> 169 </tr> 170 <tr> 171 <td>crespo4g</td> 172 <td>device/samsung/crespo/kernel</td> 173 <td>kernel/samsung</td> 174 <td>herring_defconfig</td> 175 </tr> 176 </table> 177 178 <p>After determining the device project you want to work with, view the git log 179 for the kernel binary. Device projects use the form 180 <code>device/<vendor>/<name></code>.</p> 181 182 <pre><code>$ git clone https://android.googlesource.com/kernel/hikey-linaro 183 $ cd hikey-linaro 184 $ git log --max-count=1 kernel 185 </code></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><code>$ dd if=kernel bs=1 skip=$(LC_ALL=C grep -a -b -o $'\x1f\x8b\x08\x00\x00\x00\x00\x00' kernel | cut -d ':' -f 1) | zgrep -a 'Linux version' 198 </code></pre> 199 200 <p>For Nexus 5 (hammerhead), the command is:</p> 201 <pre><code>$ dd if=zImage-dtb bs=1 skip=$(LC_ALL=C od -Ad -x -w2 zImage-dtb | grep 8b1f | cut -d ' ' -f1 | head -1) | zgrep -a 'Linux version' 202 </code></pre> 203 204 205 <h2 id="downloading-sources">Downloading sources</h2> 206 <p>Download the source for the kernel you want to build using the appropriate 207 <code>git clone</code> command:</p> 208 209 <pre><code>$ git clone https://android.googlesource.com/kernel/common.git 210 $ git clone https://android.googlesource.com/kernel/hikey-linaro 211 $ git clone https://android.googlesource.com/kernel/x86_64.git 212 $ git clone https://android.googlesource.com/kernel/exynos.git 213 $ git clone https://android.googlesource.com/kernel/goldfish.git 214 $ git clone https://android.googlesource.com/kernel/msm.git 215 $ git clone https://android.googlesource.com/kernel/omap.git 216 $ git clone https://android.googlesource.com/kernel/samsung.git 217 $ git clone https://android.googlesource.com/kernel/tegra.git 218 </code></pre> 219 220 <ul> 221 <li>The <code>goldfish</code> project contains the kernel sources for the 222 emulated platforms.</li> 223 <li>The <code>msm</code> project has the sources for ADP1, ADP2, Nexus One, 224 Nexus 4, Nexus 5, Nexus 6, Nexus 5X, Nexus 6P, Nexus 7 (2013), Pixel, 225 and Pixel XL, and can be used 226 as a starting point for work on Qualcomm MSM chipsets.</li> 227 <li>The <code>omap</code> project is used for PandaBoard and Galaxy Nexus, 228 and can be used as a starting point for work on TI OMAP chipsets.</li> 229 <li>The <code>samsung</code> project is used for Nexus S, and can be used as a 230 starting point for work on Samsung Hummingbird chipsets.</li> 231 <li>The <code>tegra</code> project is for Xoom, Nexus 7 (2012), Nexus 9, 232 and can be used as a starting point for work on NVIDIA Tegra chipsets.</li> 233 <li>The <code>exynos</code> project has the kernel sources for Nexus 10, 234 and can be used as a starting point for work on Samsung Exynos chipsets.</li> 235 <li>The <code>x86_64</code> project has the kernel sources for Nexus Player, 236 and can be used as a starting point for work on Intel x86_64 chipsets.</li> 237 <li>The <code>hikey-linaro</code> project is used for HiKey reference boards, 238 and can be used as a starting point for work on HiSilicon 620 chipsets.</li> 239 </ul> 240 241 <h2 id="downloading-a-prebuilt-gcc">Downloading a prebuilt gcc</h2> 242 <p>Ensure the prebuilt toolchain is in your path:</p> 243 <pre>$ export PATH=$(pwd)/prebuilts/gcc/linux-x86/arm/arm-eabi-4.6/bin:$PATH</pre> 244 <p>or</p> 245 <pre>$ export PATH=$(pwd)/prebuilts/gcc/darwin-x86/arm/arm-eabi-4.6/bin:$PATH</pre> 246 247 <p>On a Linux host, if you don't have an Android source tree, you can download 248 the prebuilt toolchain from: 249 <pre>$ git clone https://android.googlesource.com/platform/prebuilts/gcc/linux-x86/arm/arm-eabi-4.6</pre> 250 251 <h2 id="building">Building the kernel</h2> 252 <p>When you know the last commit message for a kernel and have successfully 253 downloaded the kernel source and prebuilt gcc, you are ready to build the 254 kernel. The following build commands use the hikey kernel:</p> 255 <pre><code>$ export ARCH=arm64 256 $ export CROSS_COMPILE=aarch64-linux-android- 257 $ cd hikey-linaro 258 $ git checkout -b android-hikey-linaro-4.1 origin/android-hikey-linaro-4.1 259 $ make hikey_defconfig 260 $ make 261 </code></pre> 262 263 <p>To build a different kernel, simply replace <code>hikey-linaro</code> with 264 the name of the kernel you want to build.</p> 265 266 <p>The image outputs to the <code>arch/arm64/boot/Image</code> directory; the 267 kernel binary outputs to the 268 <code>arch/arm64/boot/dts/hisilicon/hi6220-hikey.dtb</code> fle. Copy the 269 <code>Image</code> directory and the <code>hi6220-hikey.dtb</code> file to the 270 <code>hikey-kernel</code> directory.</p> 271 272 <p>Alternatively, you can include the <code>TARGET_PREBUILT_KERNEL</code> 273 variable while using <code>make bootimage</code> (or any other <code>make</code> 274 command line that builds a boot image). This variable is supported by all 275 devices as it is set up via <code>device/common/populate-new-device.sh</code>. 276 For example:</p> 277 278 <pre><code>$ export TARGET_PREBUILT_KERNEL=$your_kernel_path/arch/arm/boot/zImage-dtb 279 </code></pre> 280 281 <p class="note"><strong>Note:</strong> Kernel names differ by device. To locate 282 the correct filename for your kernel, refer to 283 <code>device/<vendor>/<name></code> in the kernel source.</p> 284
