Samsung Galaxy S II : Rooting & Installing insecure kernel and restoring back stock kernel

Posted on May 14, 2011

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These are the steps ( with some edits )  I took based on the guides at forum XDA :

PC prerequisite : Miccrosoft.Net Framework 4 , download at :
http://www.microsoft.com/downloads/en/details.aspx?FamilyID=9cfb2d51-5ff4-4491-b0e5-b386f32c0992&displaylang=en

Samsung KIES : If you do not have Samsung’s KIES 2.0 installed, download and install it. You need it to install the correct USB drivers, so the programs can communicate with the device. Reboot your computer after installation of KIES. Download it at :
http://downloadcenter.samsung.com/content/SW/201105/20110530093235856/Kies_2.0.0.11044_11_3.exe

ROOTING :

Reference : http://forum.xda-developers.com/showthread.php?t=1056334

First is to install an “insecure” modded kernel. This is a kernel that does NOT include the tools you need for Superuser, but it DOES give you root shell access, so you can install these manually.

- Download the attached ODIN file and extract the .zip file
– Download the attached XWKDD, but do NOT extract the .tar file
– Download and extract SuperOneClick  from :  http://forum.xda-developers.com/showthread.php?t=803682

- Make sure your device is in USB debugging mode: Settings -> Applications -> Development -> USB debugging
– Reboot your device into download mode: Turn the device off, then power it on again by pressing and holding VolumeDown + Home + Power simultaneously. Select Volume Up to continue . You will see Downloading on screen
– Start ODIN
– Connect the device to your computer using USB
– Wait a few seconds, the ODIN screen should show you that a device is now connected
– Make sure that in ODIN NOTHING is checked, except the “Auto reboot” and “F. Reset Time” checkboxes. Press the “PDA” button, and select the “XWKDD_insecure.tar” file.
– Press “Start”. ODIN you should now be flashing the kernel, and the device should reboot. This will take about 2-3 minutes
– Wait until the device is rebooted, and while still being connected over USB, start SuperOneClick, and press ROOT.
– Reboot the device

Your phone is now rooted.

Downloads :

Odin 1.85 : http://forum.xda-developers.com/attachment.php?attachmentid=581913&d=1304094576

XWKDD insecure kernel : http://forum.xda-developers.com/attachment.php?attachmentid=581915&d=1304094698

Restore back stock kernel :

You will notice, during the initial bootup before the Galaxy blue splash screen you will see a YELLOW triangle. This is Samsung built in display showing a insecure kernel is used. Get rid of this Yellow display using these steps to flash back stock kernel :

By uskr : http://forum.xda-developers.com/showthread.php?t=1074930

First download the stock kernel:

If you have XWKDD firmware: http://nma.usk.bz/files/I9100XWKDD_StockKernel.tar
If you have XWKE1 firmware: http://nma.usk.bz/files/I9100XWKE1_StockKernel.tar
If you have XWKE2 firmware: http://nma.usk.bz/files/I9100XWKE2_StockKernel.tar

DO NOT UNTAR THE FILE. Leave it as it is.

2. Now open Odin
3. IMPORTANT: Make sure that “Auto Reboot” and “F.Reset Time” are check. And that EVERYTHING else is UNchecked.
4. Load the .tar file on the PDA field. Just click on “PDA” and open the file.
5. Click “Start” . This whole process will take less than a minute

Once you see PASS on Odin window, remove USB cable and restart phone

You are now  back to your stock kernel and the root status remains.

My phone firmware details :

Baseband/PHONE :  I9100XXKDH
Kernel : 2.6.35.7-i9100xwkdd-cl161513root@dell103#2
Build : gingerbread.xwkdd
PDA :  I9100XWKDD
CSC :  I9100XEUKD1