This section describes how to set up your local work environment to buildthe Android source files. You will need to use Linux or Mac OS. Building underWindows is not currently supported.

For an overview of the entire code-review and code-update process, see Life of a Patch.

Choosing a Branch

Some of the requirements for your build environment are determined by whichversion of the source code you plan to compile. SeeBuild Numbers for a full listing of branches you maychoose from. You may also choose to download and build the latest source code(called "master"), in which case you will simply omit the branch specificationwhen you initialize the repository.

Once you have selected a branch, follow the appropriate instructions below toset up your build environment.

Setting up a Linux build environment

These instructions apply to all branches, including master.

The Android build is routinely tested in house on recent versions ofUbuntu LTS (12.04), but most distributions should have the requiredbuild tools available. Reports of successes or failures on otherdistributions are welcome.

For Gingerbread (2.3.x) and newer versions, including the masterbranch, a 64-bit environment is required. Older versions can becompiled on 32-bit systems.

Note: See the Downloading andBuilding page for the list of hardware and software requirements. Thenfollow the detailed instructions for Ubuntu and Mac OS below.

Installing the JDK

The master branch of Android in the Android Open Source Project (AOSP)requires Java 7. On Ubuntu, use OpenJDK.

Java 7: For the latest version of Android

$ sudo apt-get update
$ sudo apt-get install openjdk-7-jdk

Optionally, update the default Java version by running:

$ sudo update-alternatives --config java
$ sudo update-alternatives --config javac

If you encounter version errors for Java, set itspath as described in the WrongJava Version section.

To develop older versions of Android, download and install the corresponding version of the Java JDK:
Java 6: for Gingerbread through KitKat
Java 5: for Cupcake through Froyo

Note: The lunch command in the build step will ensure that the Sun JDK isused instead of any previously installed JDK.

Installing required packages (Ubuntu 12.04)

You will need a 64-bit version of Ubuntu. Ubuntu 12.04 is recommended.Building using an older version of Ubuntu is not supported on master or recent releases.

$ sudo apt-get install git gnupg flex bison gperf build-essential 
  zip curl libc6-dev libncurses5-dev:i386 x11proto-core-dev 
  libx11-dev:i386 libreadline6-dev:i386 libgl1-mesa-glx:i386 
  libgl1-mesa-dev g++-multilib mingw32 tofrodos 
  python-markdown libxml2-utils xsltproc zlib1g-dev:i386
$ sudo ln -s /usr/lib/i386-linux-gnu/mesa/libGL.so.1 /usr/lib/i386-linux-gnu/libGL.so

Installing required packages (Ubuntu 14.04)

Building on Ubuntu 14.04 is experimental at the moment but will eventually become the recommendedenvironment.

$ sudo apt-get install bison g++-multilib git gperf libxml2-utils

Installing required packages (Ubuntu 10.04 -- 11.10)

Building on Ubuntu 10.04-11.10 is no longer supported, but may be useful for building olderreleases of AOSP.

$ sudo apt-get install git-core gnupg flex bison gperf build-essential 
  zip curl zlib1g-dev libc6-dev lib32ncurses5-dev ia32-libs 
  x11proto-core-dev libx11-dev lib32readline5-dev lib32z-dev 
  libgl1-mesa-dev g++-multilib mingw32 tofrodos python-markdown 
  libxml2-utils xsltproc

On Ubuntu 10.10:

$ sudo ln -s /usr/lib32/mesa/libGL.so.1 /usr/lib32/mesa/libGL.so

On Ubuntu 11.10:

$ sudo apt-get install libx11-dev:i386

Configuring USB Access

Under GNU/linux systems (and specifically under Ubuntu systems),regular users can't directly access USB devices by default. Thesystem needs to be configured to allow such access.

The recommended approach is to create a file/etc/udev/rules.d/51-android.rules (as the root user) and to copythe following lines in it. <username> must be replaced by theactual username of the user who is authorized to access the phonesover USB.

# adb protocol on passion (Nexus One)
SUBSYSTEM=="usb", ATTR{idVendor}=="18d1", ATTR{idProduct}=="4e12", MODE="0600", OWNER="<username>"
# fastboot protocol on passion (Nexus One)
SUBSYSTEM=="usb", ATTR{idVendor}=="0bb4", ATTR{idProduct}=="0fff", MODE="0600", OWNER="<username>"
# adb protocol on crespo/crespo4g (Nexus S)
SUBSYSTEM=="usb", ATTR{idVendor}=="18d1", ATTR{idProduct}=="4e22", MODE="0600", OWNER="<username>"
# fastboot protocol on crespo/crespo4g (Nexus S)
SUBSYSTEM=="usb", ATTR{idVendor}=="18d1", ATTR{idProduct}=="4e20", MODE="0600", OWNER="<username>"
# adb protocol on stingray/wingray (Xoom)
SUBSYSTEM=="usb", ATTR{idVendor}=="22b8", ATTR{idProduct}=="70a9", MODE="0600", OWNER="<username>"
# fastboot protocol on stingray/wingray (Xoom)
SUBSYSTEM=="usb", ATTR{idVendor}=="18d1", ATTR{idProduct}=="708c", MODE="0600", OWNER="<username>"
# adb protocol on maguro/toro (Galaxy Nexus)
SUBSYSTEM=="usb", ATTR{idVendor}=="04e8", ATTR{idProduct}=="6860", MODE="0600", OWNER="<username>"
# fastboot protocol on maguro/toro (Galaxy Nexus)
SUBSYSTEM=="usb", ATTR{idVendor}=="18d1", ATTR{idProduct}=="4e30", MODE="0600", OWNER="<username>"
# adb protocol on panda (PandaBoard)
SUBSYSTEM=="usb", ATTR{idVendor}=="0451", ATTR{idProduct}=="d101", MODE="0600", OWNER="<username>"
# adb protocol on panda (PandaBoard ES)
SUBSYSTEM=="usb", ATTR{idVendor}=="18d1", ATTR{idProduct}=="d002", MODE="0600", OWNER="<username>"
# fastboot protocol on panda (PandaBoard)
SUBSYSTEM=="usb", ATTR{idVendor}=="0451", ATTR{idProduct}=="d022", MODE="0600", OWNER="<username>"
# usbboot protocol on panda (PandaBoard)
SUBSYSTEM=="usb", ATTR{idVendor}=="0451", ATTR{idProduct}=="d00f", MODE="0600", OWNER="<username>"
# usbboot protocol on panda (PandaBoard ES)
SUBSYSTEM=="usb", ATTR{idVendor}=="0451", ATTR{idProduct}=="d010", MODE="0600", OWNER="<username>"
# adb protocol on grouper/tilapia (Nexus 7)
SUBSYSTEM=="usb", ATTR{idVendor}=="18d1", ATTR{idProduct}=="4e42", MODE="0600", OWNER="<username>"
# fastboot protocol on grouper/tilapia (Nexus 7)
SUBSYSTEM=="usb", ATTR{idVendor}=="18d1", ATTR{idProduct}=="4e40", MODE="0600", OWNER="<username>"
# adb protocol on manta (Nexus 10)
SUBSYSTEM=="usb", ATTR{idVendor}=="18d1", ATTR{idProduct}=="4ee2", MODE="0600", OWNER="<username>"
# fastboot protocol on manta (Nexus 10)
SUBSYSTEM=="usb", ATTR{idVendor}=="18d1", ATTR{idProduct}=="4ee0", MODE="0600", OWNER="<username>"

Those new rules take effect the next time a device is plugged in.It might therefore be necessary to unplug the device and plug itback into the computer.

This is known to work on both Ubuntu Hardy Heron (8.04.x LTS) andLucid Lynx (10.04.x LTS). Other versions of Ubuntu or othervariants of GNU/linux might require different configurations.

Setting up ccache

You can optionally tell the build to use the ccache compilation tool.Ccache acts as a compiler cache that can be used to speed-up rebuilds.This works very well if you do "make clean" often, or if you frequentlyswitch between different build products.

Put the following in your .bashrc or equivalent.

export USE_CCACHE=1

By default the cache will be stored in ~/.ccache.If your home directory is on NFS or some other non-local filesystem,you will want to specify the directory in your .bashrc as well.

export CCACHE_DIR=<path-to-your-cache-directory>

The suggested cache size is 50-100GB.You will need to run the following command once you have downloadedthe source code:

prebuilts/misc/linux-x86/ccache/ccache -M 50G

When building Ice Cream Sandwich (4.0.x) or older, ccache is ina different location:

prebuilt/linux-x86/ccache/ccache -M 50G

This setting is stored in the CCACHE_DIR and is persistent.

Using a separate output directory

By default, the output of each build is stored in the out/subdirectory of the matching source tree.

On some machines with multiple storage devices, builds arefaster when storing the source files and the output onseparate volumes. For additional performance, the outputcan be stored on a filesystem optimized for speed insteadof crash robustness, since all files can be re-generatedin case of filesystem corruption.

To set this up, export the OUT_DIR_COMMON_BASE variableto point to the location where your output directorieswill be stored.

export OUT_DIR_COMMON_BASE=<path-to-your-out-directory>

The output directory for each separate source tree will benamed after the directory holding the source tree.

For instance, if you have source trees as /source/master1and /source/master2 and OUT_DIR_COMMON_BASE is set to/output, the output directories will be /output/master1and /output/master2.

It's important in that case to not have multiple sourcetrees stored in directories that have the same name,as those would end up sharing an output directory, withunpredictable results.

This is only supported on Jelly Bean (4.1) and newer,including the master branch.

Setting up a Mac OS build environment

In a default installation, Mac OS runs on a case-preserving but case-insensitivefilesystem. This type of filesystem is not supported by git and will cause somegit commands (such as "git status") to behave abnormally. Because of this, werecommend that you always work with the AOSP source files on a case-sensitivefilesystem. This can be done fairly easily using a disk image, discussed below.

Once the proper filesystem is available, building the master branch in a modernMac OS environment is very straightforward. Earlier branches, including ICS,require some additional tools and SDKs.

Creating a case-sensitive disk image

You can create a case-sensitive filesystem within your existing Mac OS environmentusing a disk image. To create the image, launch DiskUtility and select "New Image". A size of 25GB is the minimum tocomplete the build, larger numbers are more future-proof. Using sparse imagessaves space while allowing to grow later as the need arises. Be sure to select"case sensitive, journaled" as the volume format.

You can also create it from a shell with the following command:

# hdiutil create -type SPARSE -fs 'Case-sensitive Journaled HFS+' -size 40g ~/android.dmg

This will create a .dmg (or possibly a .dmg.sparsefile) file which, once mounted, acts as a drive with the required formatting for Android development. For a disk image named "android.dmg" stored in your home directory, you can add the following to your ~/.bash_profile to mount the image when you execute "mountAndroid":

# mount the android file image
function mountAndroid { hdiutil attach ~/android.dmg -mountpoint /Volumes/android; }

Once mounted, you'll do all your work in the "android" volume. You can eject it (unmount it) just like you would with an external drive.

Installing the JDK

The master and 5.0.x branches of Android in the Android Open Source Project (AOSP)require Java 7. On Mac OS, use jdk-7u71-macosx-x64.dmg.

To develop for versions of Android Gingerbread through KitKat, download andinstall the Java 6 version of the Java JDK.

Master branch

To build the latest source in a Mac OS environment, you will need an Intel/x86machine running MacOS 10.8 (Mountain Lion) or later, along with Xcode4.5.2 or later including the Command Line Tools.

Branch 5.0.x and earlier branches

To build 5.0.x and earlier source in a Mac OS environment, you will need an Intel/x86machine running MacOS 10.8 (Mountain Lion), along with Xcode4.5.2 and Command Line Tools.

Branch 4.4.x and earlier branches

To build 4.2.x and earlier source in a Mac OS environment, you will need an Intel/x86machine running MacOS 10.6 (Snow Leopard) or MacOS 10.7 (Lion), along with Xcode4.2 (Apple's Developer Tools). Although Lion does not come with a JDK, it shouldinstall automatically when you attempt to build the source.

The remaining sections for Mac OS apply only to those who wish to buildearlier branches.

Branch 4.0.x and all earlier branches

To build android-4.0.x and earlier branches in a Mac OS environment, you need anIntel/x86 machine running MacOS 10.5 (Leopard) or MacOS 10.6 (Snow Leopard). Youwill need the MacOS 10.5 SDK.

Installing required packages

• Install Xcode from the Apple developer site.We recommend version 3.1.4 or newer, i.e. gcc 4.2.Version 4.x could cause difficulties.If you are not already registered as an Apple developer, you will have tocreate an Apple ID in order to download.

• Install MacPorts from macports.org.

  Note: Make sure that /opt/local/bin appears in your path BEFORE /usr/bin. If not, add

  export PATH=/opt/local/bin:$PATH
  

  to your ~/.bash_profile.

• Get make, git, and GPG packages from MacPorts:

  $ POSIXLY_CORRECT=1 sudo port install gmake libsdl git-core gnupg
  

  If using Mac OS 10.4, also install bison:

  $ POSIXLY_CORRECT=1 sudo port install bison
  

Reverting from make 3.82

For versions of Android before ICS, there is a bug in gmake 3.82 that prevents android from building. You can install version 3.81 using MacPorts by taking the following steps:

• Edit /opt/local/etc/macports/sources.conf and add a line that says

  file:///Users/Shared/dports
  

  above the rsync line. Then create this directory:

  $ mkdir /Users/Shared/dports
  

• In the new dports directory, run

  $ svn co --revision 50980 http://svn.macports.org/repository/macports/trunk/dports/devel/gmake/ devel/gmake/
  

• Create a port index for your new local repository:

  $ portindex /Users/Shared/dports
  

• Finally, install the old version of gmake with

  $ sudo port install gmake @3.81
  

Setting a file descriptor limit

On MacOS the default limit on the number of simultaneous file descriptors open is too low and a highly parallel build process may exceed this limit.

To increase the cap, add the following lines to your ~/.bash_profile:

# set the number of open files to be 1024
ulimit -S -n 1024

Next: Download the source

Your build environment is good to go! Proceed to downloading the source.