Install OkcarOS on
Samsung Galaxy S II

Preparing for installation

Samsung devices come with a unique boot mode called “Download mode”, which is very similar to “Fastboot mode” on some devices with unlocked bootloaders. Heimdall is a cross-platform, open-source tool for interfacing with Download mode on Samsung devices. The preferred method of installing a custom recovery is through Download Mode – rooting the stock firmware is neither necessary nor required.

1. Download and install the appropriate version of the Heimdall suite for your machine’s OS
   • Windows: Extract the Heimdall suite zip and take note of the new directory containing heimdall.exe. You can verify Heimdall is functioning by opening a Command Prompt or PowerShell in that directory and running heimdall version.
     • If you receive an error, install the Microsoft Visual C++ 2015-2019 Redistributable Package (x86) on your computer.
   • Linux: Extract the Heimdall suite zip and take note of the new directory containing heimdall. Now copy heimdall into a directory in $PATH, a common one on most distros will be /usr/local/bin. For example cp heimdall /usr/local/bin. You can verify Heimdall is functioning by opening a Terminal and running heimdall version.
   • macOS: Mount the Heimdall suite DMG. Now drag heimdall down into the /usr/local/bin symlink provided in the DMG. You can verify Heimdall is functioning by opening a Terminal and running heimdall version.
   info_outline

   NOTE: These Heimdall suite distributions were built by OkcarOS Developers Nolen Johnson (npjohnson) and Jan Altensen (Stricted), as the Heimdall suite executables distributed on the official Heimdall website were outdated and the repo mostly abandoned. Modifications were made to make it build and function on modern OSes.
2. Power off the device, and boot it into download mode:
   • With the device powered off, hold Volume Down + Home + Power.
   • Now, click the button that the on screen instructions correlate to “Continue”, and insert the USB cable into the device.
3. For Windows users only: install the necessary drivers. A more complete set of instructions can be found in the Zadig user guide.
   1. If nothing relevant appears, try uninstalling any Samsung related Windows software, like Samsung Windows drivers and/or Samsung Kies.
   2. Run zadig.exe found in your extracted Heimdall directory.
      info_outline

      NOTE: For the interested, source and documentation for zadig.exe can be found here.
   3. Choose Options » List all devices from the menu.
   4. Select Samsung USB Composite Device or MSM8x60 or Gadget Serial or Device Name from the drop down menu.
   5. Click Replace Driver, then selecting Install Driver from the drop down list built into the button.
   6. If you are prompted with a warning that the installer is unable to verify the publisher of the driver, select Install this driver anyway. You may receive two more prompts about security. Select the options that accept the warnings and allow you to carry on.
4. On your machine, open a Command Prompt or PowerShell (Windows) window, or Terminal (Linux or macOS) window, and type:

   heimdall print-pit
   

5. If the device reboots that indicates that Heimdall is installed and working properly. If it does not, please refollow these instructions to verify steps weren’t missed, try a different USB cable, and a different USB port.

Installing a custom recovery using heimdall

1. Download a custom recovery - you can download TWRP. Simply download the latest recovery file, named something like twrp-x.x.x-x-i9100.img and rename it to recovery.img.
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   Tip: Ensure you download the .img file and not the .tar or .tar.md5 versions.
   warning

   Important: Other recoveries may not work for installation or updates. We strongly recommend to use the one linked above!
2. Power off the device, and boot it into download mode:
   • With the device powered off, hold Volume Down + Home + Power.
   • Now, click the button that the on screen instructions correlate to “Continue”, and insert the USB cable into the device.
3. On your machine, open a Command Prompt or PowerShell (Windows) window, or Terminal (Linux or macOS) window, and type:

   heimdall flash --RECOVERY recovery.img --no-reboot
   

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   Tip: The file may not be named identically to what stands in this command, so adjust accordingly. If the file is wrapped in a zip or tar file, extract the file first, because Heimdall is not going to do it for you.
4. A transfer bar will appear on the device showing the recovery image being flashed.
   info_outline

   NOTE: The device will continue to display Downloading... Do not turn off target!! even after the process is complete.
5. Unplug the USB cable from your device.
6. Manually reboot into recovery, this may require pulling the device’s battery out and putting it back in, or if you have a non-removable battery, press the Volume Down + Power buttons for 8~10 seconds until the screen turns black & release the buttons immediately when it does, then boot to recovery:
   • With the device powered off, hold Volume Up + Home + Power.
   info_outline

   NOTE: Be sure to reboot into recovery immediately after installing the custom recovery. If you don’t the stock ROM will overwrite the custom recovery with the stock recovery, and you’ll need to flash it again.

Installing OkcarOS from recovery

1. Build a OkcarOS installation package.
   • (Optionally): If you want to install Google Apps add-on package (use the arm architecture), you can download it from here.
2. If you are not in recovery, reboot into recovery:
   • With the device powered off, hold Volume Up + Home + Power.
3. Now tap Wipe.
4. Now tap Format Data and continue with the formatting process. This will remove encryption and delete all files stored in the internal storage.
5. Return to the previous menu and tap Advanced Wipe, then select the Cache and System partitions and then Swipe to Wipe.
6. Sideload the OkcarOS .zip package:
   • On the device, select “Advanced”, “ADB Sideload”, then swipe to begin sideload.
   • On the host machine, sideload the package using: adb -d sideload filename.zip.
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     Tip: Normally, adb will report Total xfer: 1.00x, but in some cases, even if the process succeeds the output will stop at 47% and report adb: failed to read command: Success. In some cases it will report adb: failed to read command: No error or adb: failed to read command: Undefined error: 0 which is also fine.

Installing Add-Ons

1. Repeat the sideload steps above for all desired packages in sequence.

All set!

Once you have installed everything successfully, you can now reboot your device into the OS for the first time!

• Run adb -d reboot.

Get assistance

After you’ve double checked that you followed the steps precisely, didn’t skip any and still have questions or got stuck, feel free to ask on our subreddit or in #OkcarOS on Libera.Chat.