原始网站https://source.android.com/source/initializing.html强调一下，该设置适用于SDK ，可以避免很多莫名其妙的问题。

Initializing a Build Environment

The "Getting Started" section describes how to set up your local work environment, how to use Repo to get the Android files, and how to build the files on your machine.  To build the Android source files, you will need to use Linux or Mac OS. Building under Windows is not currently supported.

Note: The source download is approximately 8.5GB in size.You will need over 30GB free to complete a single build, andup to 100GB (or more) for a full set of builds.

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 (10.04), 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: It is also possible to build Android in a virtual machine.If you are running Linux in a virtual machine, you will need atleast 16GB of RAM/swap and 30GB or more of disk space in order tobuild the Android tree.

Detailed instructions for Ubuntu and MacOS follow. In general you will need:

• Python 2.5 -- 2.7, which you can download from python.org.
• GNU Make 3.81 -- 3.82, which you can download from gnu.org,
• JDK 6 if you wish to build Gingerbread or newer; JDK 5 for Froyo or older.  You can download both from java.sun.com.
• Git 1.7 or newer. You can find it at git-scm.com.

Installing the JDK

The Sun JDK is no longer in Ubuntu's main package repository.  In order to download it, you need to add the appropriate repository and indicate to the system which JDK should be used.

Java 6: for Gingerbread and newer

注意，该网址已经失效

更改为

即可

Java 5: for Froyo and older

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 10.04 -- 11.10)

You will need a 64-bit version of Ubuntu.  Ubuntu 10.04 is recommended.Building using a newer version of Ubuntu is currently only experimentallysupported and is not guaranteed to work on branches other than master.

On Ubuntu 10.10:

On Ubuntu 11.10:

Installing required packages (Ubuntu 12.04)

Building on Ubuntu 12.04 is currently only experimentally supported and is notguaranteed to work on branches other than master.

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. must be replaced by theactual username of the user who is authorized to access the phonesover USB.

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.

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.

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

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.

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 X build environment

In a default installation, OS X 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 modernOS X 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 OS X 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:

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":

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.

Master branch

To build the latest 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 X only apply 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

  1	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

  1	$ 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

  1	$ 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

  1	file:///Users/Shared/dports

  above the rsync line.  Then create this directory:

  $ mkdir /Users/Shared/dports

  1	$ 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/

  1	$ 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

  1	$ portindex /Users/Shared/dports

• Finally, install the old version of gmake with
  $ sudo port install gmake-3.81

  1	$ 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:

在下载Android源码时老是断断续续，很是烦人！不过有人写了一个shell脚本很好的解决了这个问题，其内容如下：

放到Android路径，执行./文件名 就可以了，又是需要更改权限chmod 777 文件

这段脚本很简单，首先先执行repo sync，如果失败了，就会发出错误退出信号1，由while捕获，判断如果是错误退出就继续，否则完成。主要就是“$?”这个变量，是由上一个执行完的命令返回的退出状态。

这部分脚本仅仅用来同步文件，其他步骤严格按照Google的说明来操作即可。

本来以为要下载安装程序，结果发现是通过配置KVM来实现的，废话少说，附上原文，由于国内经常被和谐，因此复制原文还是有必要的。

原文地址 http://software.intel.com/en-us/blogs/2012/03/12/how-to-start-intel-hardware-assisted-virtualization-hypervisor-on-linux-to-speed-up-intel-android-x86-gingerbread-emulator

How to Start Intel Hardware-assisted Virtualization (hypervisor) on Linux to Speed-up Intel Android x86 Gingerbread Emulator

      The Intel Hardware Accelerated Execution Manager (Intel® HAXM) is a hardware-assisted virtualization engine (hypervisor) that uses Intel Virtualization Technology (VT) to speed up Android app emulation on a host machine. In combination with Android x86 emulator images provided by Intel and the official Android SDK Manager, HAXM allows for faster Android emulation on Intel VT enabled systems. HAXM for both Windows and IOS are available now.

Since Google mainly support Android build on Linux platform (with Ubuntu 64-bit OS as top Linux platform, and IOS as 2nd), and a lot of Android Developers are using AVD on Eclipse hosted by a Linux system, it is very critical that Android developers take advantage of Intel hardware-assisted KVM virtualization for Linux just like HAXM for Windows and IOS.

Below are the quick step-by-step's on how to install, enable KVM  on Ubuntu host platform and  start Intel Android x86 Gingerbread emulator with Intel hardware-assisted virtualization (hypervisor). The result is very pleasing and AVD runs significantly faster and smoother than without hypervisor

KVM Installation

I referred the instructions from Ubuntu community documentation page. to get KVM installed.To see if your processor supports hardware virtualization, you can review the output from this command:

I got 64. If 0 it means that your CPU doesn't support hardware virtualization.

Next is to install CPU checker:

Now you can check if your cpu supports kvm:

It means you can  run your virtual machine faster with the KVM extensions.

If you see:
"INFO: KVM is disabled by your BIOS
HINT: Enter your BIOS setup and enable Virtualization Technology (VT),
and then hard poweroff/poweron your system
KVM acceleration can NOT be used"

You need to go to BIOS setup and enable the VT.

Use a 64 bit kernel

Running a 64 bit kernel on the host operating system is recommended but not required.
To serve more than 2GB of RAM for your VMs, you must use a 64-bit kernel (see 32bit_and_64bit). On a 32-bit kernel install, you'll be limited to 2GB RAM at maximum for a given VM.
Also, a 64-bit system can host both 32-bit and 64-bit guests. A 32-bit system can only host 32-bit guests.
To see if your processor is 64-bit, you can run this command:

If 0 is printed, it means that your CPU is not 64-bit.

If 1 or higher, it is. Note: lm stands for Long Mode which equates to a 64-bit CPU.
Now see if your running kernel is 64-bit, just issue the following command:

x86_64 indicates a running 64-bit kernel. If you see i386, i486, i586 or i686, you're running a 32-bit kernel.

Install KVM

For Ubuntu Lucid (10.04) or later:

You may ignore the Postfix Configuration below by selecting "No Configuration"

Next is to add your <username> account to the group kvm and libvirtd

After the installation, you need to relogin so that your user account becomes an effective member of kvm and libvirtd user groups. The members of this group can run virtual machines.

Verify Installation
You can test if your install has been successful with the following command:

Start the AVD from Android SDK Directly from Terminal

Now start the Android for x86 Intel Emulator using  the following command:

Only a 64-bits Ubuntu can allow you to run allocated Memory of 2G or more. My 64-bit Ubuntu has 6G of Memory, so I used 1/3 of it for Android AVD. My AVD name is Intel_Atom_gingerbread_2.3 . '-qemu' provides the options to qemu, and '-m' specifies the amount of memory for the emulated Android (i.e. guest). If you use too small value for that, it's possible that performance is bad because of frequent swapping activities. Add '-show-kernel' to see the message from the kernel.

Start the AVD by AVD Manager in Eclipse

Below is procedures recommended by Google. If you are running the emulator from Eclipse, run your Android application with an x86-based AVD and include the KVM options:

• • In Eclipse, click your Android project folder and then select Run > Run Configurations...

• • In the left panel of the Run Configurations dialog, select your Android project run configuration or create a new configuration.

• • Click the Target tab.

• • Select the x86-based AVD you created previously.

• • In the Additional Emulator Command Line Options field, enter:
    -qemu -m 2047 -enable-kvm

    1	-qemu -m 2047 -enable-kvm

• Run your Android project using this run configuration.