W4118 OPERATING SYSTEMS I

Unlocking your device

To complete the assignments, you need to unlock your device.

With an unlocked device, you can test the kernel you built. You can even flash the kernel to the device, so the device will always boot with your kernel.

You may also flash system images to your device.

To unlock your device, you must first install Android SDK. Please follow link to complete this.

1. Enable USB debugging

1a. Start the Settings application. Click "About tablet".

1b. Click the Build Number multiple times until you see the notification "You are a developer"

1c. Return to Settings. Now you should see a new entry called "Developer options". Enter it.

1d. Enable "USB debugging"

1e. Plug in your device

1f. When a window pops up that asks whether you want to allow debugging on this computer, check "Always ..." and select "OK".

1g. Run

    adb devices

and find a line containing serial number and "device" to ensure that the device is correctly connected. It should look like this:

    List of devices attached 
    704b03fc    device

2. Reboot to fastboot mode

Run

    adb reboot bootloader

and your Nexus 7 should reboot into a screen, with an Android in the center of the screen. This is the fastboot mode. It allows you to write to system partitions. It also allows you to boot custom kernels which we will do in homework 2.

Notice that it says "locked" in the lower left corner now.

3. Unlock

3a. Download unlock.sh from http://www.cs.columbia.edu/~junfeng/13fa-w4118/hw/unlock.sh. Run

    sh unlock.sh

3b. The tablet will ask you whether you really want to unlock. Use volume keys to select "Yes"

3c. Push power button. Now you have answered "Yes" and the device is unlocked.

3d. When returned to fastboot mode, notice that now it says "unlocked" in the lower left corner.

3e. Use volume keys to select "Start" and push power button. The device will boot.

3f. Wait for device to finish booting. Follow step 1 to enable USB debugging again.

Now your device is unlocked and ready for experiments!

In case of failure

Press the power button for ~15 seconds. The device will power off. You may now boot it normally.

Warranty concerns

Most reports say that even if a device is unlocked, it goes through the warranty process just fine.