Building the System

The basic sequence of build commands is as follows:


Initialize the environment with the[/code] 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/ [/code][/code]

$ . build/ [/code][/code]

Choose a Target

Choose which target to build with 

lunch[/code]. The exact configuration can be passed as an argument, e.g.

$ lunch full-eng [/code][/code]
The example above refers to a complete build for the emulator, with all debugging enabled.

If run with no arguments 

lunch[/code] 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
full emulator fully configured with all languages, apps, input methods
full_maguro maguro
full[/code] build running on Galaxy Nexus GSM/HSPA+ ("maguro")
full_panda panda
full[/code] build running on PandaBoard ("panda")

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[/code]. GNU make can handle parallel tasks with a 

-jN[/code] 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[/code] and 

make -j32[/code].

$ make -j4 [/code][/code]

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[/code], 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[/code], 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 [/code][/code]
Once the device is in fastboot mode, run

$ fastboot flashall -w [/code][/code]

-w[/code] option wipes the 

/data[/code] 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 [/code][/code]

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 [/code][/code]
You can watch ccache being used by doing the following:

$ watch -n1 -d prebuilt/linux-x86/ccache/ccache -s [/code][/code]
On OSX, you should replace 

linux-x86[/code] with 


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[/code] 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 ************************************************************ [/code][/code]
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:/} [/code][/code]

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 [/code][/code]

Gmake Version 3.82

There is a bug in 

make[/code] 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. ************************************************************ [/code][/code]
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 Initializingpage 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[/code]. That will cause adb to restart with the new configuration.