building Android
http://source.android.com/source/building.html
The following instructions to build the Android source tree apply to allbranches, including
master. The basic sequence of build commandsis as follows:
Note: If you're building Android 6.0 or later,please see Compiling with Jack for information on thisnew default toolchain.
Set up environment
Initialize the environment with the envsetup.sh script. Notethat replacing
source with . (a single dot) saves a few characters,and the short form is more commonly used in documentation.
$ source build/envsetup.sh
or
$ . build/envsetup.sh
Choose a Target
Choose which target to build with lunch. The exact configuration can be passed asan argument. For example, the following command:
$ lunch aosp_arm-eng
refers to a complete build for the emulator, with all debugging enabled.
If run with no arguments lunch will prompt you to choose a target from the menu.
All build targets take the form BUILD-BUILDTYPE, where the
BUILD is a codenamereferring to the particular feature combination.
The BUILDTYPE is one of the following:
| Buildtype | Use |
|---|---|
| user | limited access; suited for production |
| userdebug | like "user" but with root access and debuggability; preferred for debugging |
| eng | development configuration with additional debugging tools |
For more information about building for and running on actual hardware, seeRunning Builds.
Build the code
Build everything with make. GNU make can handle paralleltasks with a
-jN argument, and it's common to use a number oftasks N that's between 1 and 2 times the number of hardwarethreads on the computer being used for the build. For example, on adual-E5520 machine (2 CPUs, 4 cores per CPU, 2 threads per core),the fastest
builds are made with commands between make -j16 andmake -j32.
$ make -j4
Run It!
You can either run your build on an emulator or flash it on a device. Please note that you have already selected your build target with
lunch, and it is unlikely at best to run on a different target than it was built for.
Flash a Device
To flash a device, you will need to use fastboot, which should be included in your path after a successful build. Place the device in fastboot mode either manually by holding the appropriate key combination at boot, or from the shell with
$ adb reboot bootloader
Once the device is in fastboot mode, run
$ fastboot flashall -w
The -w option wipes the /data partition on the device; this is useful for your first time flashing a particular device but is otherwise unnecessary.
For more information about building for and running on actual hardware, seeRunning Builds.
Emulate an Android Device
The emulator is added to your path automatically by the build process. To run the emulator, type
$ emulator
Using ccache
ccache is a compiler cache for C and C++ that can help make builds faster.In the root of the source tree, do the following:
$ export USE_CCACHE=1
$ export CCACHE_DIR=/<path_of_your_choice>/.ccache
$ prebuilts/misc/linux-x86/ccache/ccache -M 50G
The suggested cache size is 50-100G.
On Linux, you can watch ccache being used by doing the following:
$ watch -n1 -d prebuilts/misc/linux-x86/ccache/ccache -s
On Mac OS, you should replace linux-x86 with darwin-x86.
When using Ice Cream Sandwich (4.0.x) or older, you should replaceprebuilts/misc with
prebuilt.
Troubleshooting Common Build Errors
Wrong Java Version
If you are attempting to build a version of Android inconsistent with yourversion of Java,
make will abort with a message such as
************************************************************
You are attempting to build with the incorrect version
of java.
Your version is: WRONG_VERSION.
The correct version is: RIGHT_VERSION.
Please follow the machine setup instructions at
https://source.android.com/source/download.html
************************************************************
This may be caused by:
-
Failing to install the correct JDK as specified in JDK Requirements.
-
Another JDK previously installed appearing in your path. Prepend the correct JDK to the beginning of your PATH or remove the problematic JDK.
Python Version 3
Repo is built on particular functionality from Python 2.x and is unfortunately incompatible with Python 3. In order to use repo, please install Python 2.x:
$ apt-get install python
Case Insensitive Filesystem
If you are building on an HFS filesystem on Mac OS, you may encounter an error such as
************************************************************
You are building on a case-insensitive filesystem.
Please move your source tree to a case-sensitive filesystem.
************************************************************
Please follow the instructions in Initializing the Build Environment for creating a case-sensitive disk image.
No USB Permission
On most Linux systems, unprivileged users cannot access USB ports by default. If you see a permission denied error, follow the instructionsInitializing the Build Environment for configuring USB access.
If adb was already running and cannot connect to the device aftergetting those rules set up, it can be killed with
adb kill-server.That will cause adb to restart with the new configuration.
