android kernel module building and installation

1. download android source (the platform) with repo

    - checkout the official tutorial

    - the toolchain is in mydroid/prebuilt, we need it

2. download android kernel: common.git (this is out of the platform)

     - a simple git will work

3. compile kernel

    1. refer to this link: stackoverflow.com/questions/1809774/android-kernel-compile-and-test-with-android-emulator

    2. enable loadable modules for the kernel: kerneltrap.org/node/16607

    3. make and get the kernel in arch/arm/boot

4. make your module by setting KDIR to common.git

   - do not forget to set ARCH=arm CROSS_COMPILE=xxxx

   - say your module is foo.ko

5. start the android emulator

   - download the sdk, and make tools in your path

   - create avd (android list targets to make sure which target to choose)

   - emulator -avd youravd -kernel your/path/common.git/arch/arm/boot/zImage -show-kernel 

     - append -show-kernel to know what's going on

   - now, see the window?

6. cd to your kernel module folder, and upload foo.ko to the emulator

   - adb push foo.ko /data

      - do not push to /, it's read-only

7. install the module

    - adb shell

    - cd /data

    - insmod foo.ko

      # check the terminal where you starts the emulator, see something related to foo.ko?