Compile the Android JB 4.1,need 64 bit linux,so use VirtualBox to install Ubuntu 12.04.

1. https://source.android.com/source/initializing.html
2. https://developers.google.com/android/nexus/drivers#magurojro03c
3. http://source.android.com/source/building-devices.html

http://download.oracle.com/otn-pub/java/jdk/6u31-b04/jdk-6u31-linux-x64.bin

Download it and move to /opt:

chmod +x jdk-6u31-linux-x64.bin
./jdk-6u31-linux-x64.bin

After install,append folloing config to /etc/profile:

export JAVA_HOME=/opt/jdk1.6.0_31
export JRE_HOME=/opt/jdk1.6.0_31/jre
export CLASSPATH=.:$JAVA_HOME/lib:$JRE_HOME/lib:$CLASSPATH
export PATH=$JAVA_HOME/bin:$JRE_HOME/bin:$PATH

Use java -version to check it is correct:

java version "1.6.0_31"
Java(TM) SE Runtime Environment (build 1.6.0_31-b04)
Java HotSpot(TM) 64-Bit Server VM (build 20.6-b01, mixed mode)

1. Fist add file share in VirtualBox setting.The share file name:Android 2.Then mount it in the Ubuntu:

mount -t vboxfs Android /mnt/Android

Or add to /etc/fstab:

Android /mnt/Android vboxsf rw,gid=100,uid=1000,auto 0 0

Resize to 40G

VBoxManage modifyhd android_vhdd.vdi --resize 40000

Then use gparted to resize the origin extend partitoin.

Download recovery here:

http://www.clockworkmod.com/rommanager/

http://download2.clockworkmod.com/recoveries/recovery-clockwork-6.0.1.0-maguro.img

fastboot flash recovery recovery-clockwork-6.0.1.0-maguro.img

  adb root
  adb remount
  adb push su /system/bin
  adb push Superuser.apk /system/app
  adb shell chmod 06755 /system/bin/su
  adb shell chmod 06755 /system/app/Superuser.apk

Volume UP+DOWN+Power

http://goo.im/gapps/

jb:http://goo.im/gapps/gapps-jb-20120726-signed.zip

USAGE:http://wiki.cyanogenmod.com/wiki/Fastboot

1. fastboot flash system system.img 
2. fastboot flash boot boot.img
3. fastboot -w

NOTICE:it will format the sdcard,so need backup the data on sdcard first.

fastboot flash recovery recovery-clockwork-6.0.1.0-maguro.img

Root step:
1.boot to fastboot mode.
2.flash the recovery
3.push su&Superuser.apk,add execute permission.
4.reboot.

Now use SuperSU to manager the root list:

http://forum.xda-developers.com/showthread.php?t=1538053