Build android source code 3 -- 编译

The basic sequence of build commands is as follows:

Initialize

Initialize the environment with theenvsetup.shscript. 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 withlunch. 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 argumentslunchwill 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	fullbuild running on Galaxy Nexus GSM/HSPA+ ("maguro")
full_panda	panda	fullbuild 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, seeBuilding for devices

Build the Code

Build everything withmake. GNU make can handle parallel tasks with a-jNargument, 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 betweenmake -j16andmake -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 withlunch, 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 usefastboot, 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-woption wipes the/datapartition 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, seeBuilding 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 replacelinux-x86withdarwin-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,makewill 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 theInitializingpage. 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 inmakeversion 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 theInitializingpage 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 theInitializingpage 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 theInitializingpage 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 withadb kill-server. That will cause adb to restart with the new configuration.