This page details how to build only the
kernel. The following instructions
assume you have not downloaded all of AOSP; if you have already done so, you
can skip the git clone steps except the step that downloads the
kernel sources.
All examples in this section use the hikey kernel.
Selecting a kernel
This table lists the name and locations of the kernel sources and binaries:
| Device | Binary location | Source location | Build configuration |
|---|---|---|---|
| taimen | device/google/wahoo-kernel | kernel/msm | wahoo_defconfig |
| walleye | device/google/wahoo-kernel | kernel/msm | wahoo_defconfig |
| easel | N/A | kernel/arm64 | mnh_prod_defconfig |
| marlin | device/google/marlin-kernel | kernel/msm | marlin_defconfig |
| sailfish | device/google/marlin-kernel | kernel/msm | marlin_defconfig |
| hikey | device/linaro/hikey-kernel | kernel/hikey-linaro | hikey_defconfig |
| angler | device/huawei/angler-kernel | kernel/msm | angler_defconfig |
| bullhead | device/lge/bullhead-kernel | kernel/msm | bullhead_defconfig |
| shamu | device/moto/shamu-kernel | kernel/msm | shamu_defconfig |
| fugu | device/asus/fugu-kernel | kernel/x86_64 | fugu_defconfig |
| volantis | device/htc/flounder-kernel | kernel/tegra | flounder_defconfig |
| hammerhead | device/lge/hammerhead-kernel | kernel/msm | hammerhead_defconfig |
| flo | device/asus/flo-kernel/kernel | kernel/msm | flo_defconfig |
| deb | device/asus/flo-kernel/kernel | kernel/msm | flo_defconfig |
| manta | device/samsung/manta/kernel | kernel/exynos | manta_defconfig |
| mako | device/lge/mako-kernel/kernel | kernel/msm | mako_defconfig |
| grouper | device/asus/grouper/kernel | kernel/tegra | tegra3_android_defconfig |
| tilapia | device/asus/grouper/kernel | kernel/tegra | tegra3_android_defconfig |
| maguro | device/samsung/tuna/kernel | kernel/omap | tuna_defconfig |
| toro | device/samsung/tuna/kernel | kernel/omap | tuna_defconfig |
| panda | device/ti/panda/kernel | kernel/omap | panda_defconfig |
| stingray | device/moto/wingray/kernel | kernel/tegra | stingray_defconfig |
| wingray | device/moto/wingray/kernel | kernel/tegra | stingray_defconfig |
| crespo | device/samsung/crespo/kernel | kernel/samsung | herring_defconfig |
| crespo4g | device/samsung/crespo/kernel | kernel/samsung | herring_defconfig |
After determining the device project you want to work with, view the git log
for the kernel binary. Device projects use the form
device/VENDOR/NAME.
git clone https://android.googlesource.com/kernel/hikey-linarocd hikey-linarogit log --max-count=1 kernel
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.
Identifying kernel version
To determine the kernel version used in a system image, run the following command against the kernel file:
dd if=kernel bs=1 skip=$(LC_ALL=C grep -a -b -o $'\x1f\x8b\x08\x00\x00\x00\x00\x00' kernel | cut -d ':' -f 1) | zgrep -a 'Linux version'
For Nexus 5 (hammerhead), the command is:
dd if=zImage-dtb bs=1 skip=$(LC_ALL=C od -Ad -x -w2 zImage-dtb | grep 8b1f | cut -d ' ' -f1 | head -1) | zgrep -a 'Linux version'
Downloading sources
Download the source for the kernel you want to build using the appropriate
git clone command. For example, the following command clones the
common kernel, a generic, customizable kernel:
git clone https://android.googlesource.com/kernel/common
A full list of the kernel projects can be found in the
Kernel directory. Below
are some of the commonly used kernels and their respective git clone
commands.
The exynos project has the kernel sources for Nexus 10, and can
be used as a starting point for work on Samsung Exynos chipsets.
git clone https://android.googlesource.com/kernel/exynos
The goldfish project contains the kernel sources for the
emulated platforms.
git clone https://android.googlesource.com/kernel/goldfish
The hikey-linaro project is used for HiKey reference boards,
and can be used as a starting point for work on HiSilicon 620 chipsets.
git clone https://android.googlesource.com/kernel/hikey-linaro
The msm 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.
git clone https://android.googlesource.com/kernel/msm
The omap project is used for PandaBoard and Galaxy Nexus, and
can be used as a starting point for work on TI OMAP chipsets.
git clone https://android.googlesource.com/kernel/omap
The samsung project is used for Nexus S, and can be used as a
starting point for work on Samsung Hummingbird chipsets.
git clone https://android.googlesource.com/kernel/samsung
The tegra project is for Xoom, Nexus 7 (2012), Nexus 9, and can
be used as a starting point for work on NVIDIA Tegra chipsets.
git clone https://android.googlesource.com/kernel/tegra
The x86_64 project has the kernel sources for Nexus Player, and
can be used as a starting point for work on Intel x86_64 chipsets.
git clone https://android.googlesource.com/kernel/x86_64
Building the kernel
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:
export ARCH=arm64export CROSS_COMPILE=aarch64-linux-android-cd hikey-linarogit checkout -b android-hikey-linaro-4.1 origin/android-hikey-linaro-4.1make hikey_defconfigmake
To build a different kernel, simply replace hikey-linaro with
the name of the kernel you want to build.
The image outputs to the arch/arm64/boot/Image directory; the
kernel binary outputs to the
arch/arm64/boot/dts/hisilicon/hi6220-hikey.dtb fle. Copy the
Image directory and the hi6220-hikey.dtb file to the
hikey-kernel directory.
Alternatively, you can include the TARGET_PREBUILT_KERNEL
variable while using make bootimage (or any other make
command line that builds a boot image). This variable is supported by all
devices as it is set up via device/common/populate-new-device.sh.
For example:
export TARGET_PREBUILT_KERNEL=$your_kernel_path/arch/arm/boot/zImage-dtb
Note: Kernel names differ by device. To locate
the correct filename for your kernel, refer to
device/VENDOR/NAME in the kernel source.