Compile Android Kernel for Goldfish

Goldfish is Google's ARM-based Android emulator.

First, we check out the source:

$ cd ~/Research/android/ginger/
$ git clone git://android.git.kernel.org/kernel/common.git android_kernel

This will clone the source into a directory android_kernel.

$ git checkout --track -b android-goldfish-2.6.27 origin/archive/android-goldfish-2.6.27


[tja@tja-desktop ginger]$ adb shell
# cat /proc/version
Linux version 2.6.29-00261-g0097074-dirty (digit@digit.mtv.corp.google.com) (gcc version 4.4.0 (GCC) ) #20 Wed Mar 31 09:54:02 PDT 2010

[tja@tja-desktop android_kernel]$ ARCH=arm
[tja@tja-desktop android_kernel]$ COSS_COMPILE=/home/tja/Downloads/android-ndk-r5b/toolchains/arm-eabi-4.4.0/prebuilt/linux-x86/bin/arm-eabi-
[tja@tja-desktop android_kernel]$ make

Meeting the natives

Of course I want to tinker with Android to the fullest, so we install the Native Development Kit (NDK).

After downloading the appropriate NDK from Google, simply uncompress it into a suitable directory.

$ bunzip2 ~/Downloads/android-ndk-r5b-linux-x86.tar.bz2
$ tar xvf ~/Downloads/android-ndk-r5b-linux-x86.tar ./

Now the NDK is located is some directory /android-ndk-r5b/.

...and that's it! Now time to have some fun.


NDK Examples

First review the examples included with the NDK. The basic flow (as described by the NDK page):

1. Place your native sources under <project>/jni/...
2. Create <project>/jni/Android.mk to describe your native sources to the NDK build system
3. Optional: Create <project>/jni/Application.mk.
4. Build your native code by running the 'ndk-build' script from your project's directory. It is located in the top-level NDK directory:

   cd <project>
   <ndk>/ndk-build
   

   The build tools copy the stripped, shared libraries needed by your application to the proper location in the application's project directory.
5. Finally, compile your application using the SDK tools in the usual way. The SDK build tools will package the shared libraries in the application's deployable .apk file.

For complete information on all of the steps listed above, please see the documentation included with the NDK package.

Getting to the source...

Getting repo installed

$ mkdir ~/bin
$ export PATH=${PATH}:~/bin
$ curl http://android.git.kernel.org/repo > ~/bin/repo
$ chmod a+x ~/bin/repo

Now initialize the repo

The new stuff, gingerbread...create it in any directory $ANDROID_SOURCE. This clones the entire platform, not just a kernel.

$ mkdir $ANDROID_SOURCE
$ cd $ANDROID_SOURCE
$repo init -u git://android.git.kernel.org/platform/manifest.git -b gingerbread

When prompted, configure for the user.

repo initialized in /home/tja/Research/android/android_latest

Pull down default files specified in the manifest with sync:

$ repo sync

At this point feel free to get a sandwich and a Dogfish Head. This is going to take a while...

Verify GIT tags

$ gpg --import
THEN PASTE THIS IN, TERMINATE WITH CTRL-D (EOF)
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Version: GnuPG v1.4.2.2 (GNU/Linux)

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Building The Source

From Android Open-source:

$ cd ~/directory
$ source build/envsetup.sh
$ lunch
$ make
If your build fails because of a missing run-java-tool, try setting the ANDROID_JAVA_HOME environment variable before making.
$ export ANDROID_JAVA_HOME=$JAVA_HOME