Building the System
The basic sequence of build commands is as follows:
Initialize
Initialize the environment with the envsetup.sh script. Note that 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 as an argument, e.g.
$ lunch full-eng The example above 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 codename referring to the particular feature combination:
| Build name | Device | Notes |
|---|---|---|
| generic | emulator | lowest-common denominator |
| full | emulator | fully configured with all languages, apps, input methods |
| full_crespo | crespo | full build running on Nexus S ("crespo") |
and 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, see Building for devices
Build the Code
Build everything with make. GNU make can handle parallel tasks with a -jN argument, and it's common to use a number of tasks N that's between 1 and 2 times the number of hardware threads on the computer being used for the build. E.g. on a dual-E5520 machine (2 CPUs, 4 cores per CPU, 2 threads per core), the fastest builds are made with commands between make -j16 and make -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, see Building for devices
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 $ prebuilt/linux-x86/ccache/ccache -M 20G You can watch ccache being used by doing the following:
$ watch -n1 -d prebuilt/linux-x86/ccache/ccache -s On OSX, you should replace linux-x86 with darwin-x86.
Troubleshooting Common Build Errors
Wrong Java Version
If you are attempting to build froyo or earlier with Java 1.6, or gingerbread or later with Java 1.5, 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 http://source.android.com/download ************************************************************ This may be caused by
-
failing to install the correct JDK as specified on the Initializing page. Building Android requires Sun JDK 5 or 6 depending on which release you are building.
-
another JDK that you previously installed appearing in your path. You can remove the offending JDK from your path with:
$ export PATH=${PATH/\/path\/to\/jdk\/dir:/}
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 Gmake Version 3.82
There is a bug in make version 3.82 on Mac OS that prevents building Android.
TODO: what the error looks like with GNU make 3.82 on older builds that don't explicitly detect it.
Follow the instructions on the Initializing page for reverting GNU make from 3.82 to 3.81.
Case Insensitive Filesystem
If you are building on an HFS filesystem on Mac OS X, 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 on the Initializing page 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 instructions on the Initializing page for configuring USB access.
If adb was already running and cannot connect to the device after getting those rules set up, it can be killed with adb kill-server. That will cause adb to restart with the new configuration.