How to Root Galaxy S21 Series

  

Prepare for Root Samsung Galaxy S21

• Battery at least 80%
• Back up data first : How to Backup Full Android Without Root
• Do it with your own risk, the author is not responsible for the damage that occurs
• Install Canary Magisk Manager
• Note : Installing Magisk WILL trip KNOX
• Do Unlocking Bootloader Samsung Galaxy S21 : How to Unlock Bootloader on Samsung Galaxy
• This tutorial assumes you already know how to use adb and fastboot
• If you want to Install Custom Kernels, do after you already Install Magisk

after installing Magisk, see the information in the application, especially in the Ramdisk section.

As you can see in the picture, if the Ramdisk is Yes then you can directly install Magisk. But if the result is No in Ramdisk, then there are several steps that must be done.

Unlocking Bootloader

you can Unlocking your Galaxy S21 series read in this thread How to Unlock Bootloader on Samsung Galaxy

Patching Boot Image

• If your device already has a boot ramdisk, you must have a copy of boot.img
• Use tools Frija or Samloader to download newest firmware zip of your phone from Samsung Server
• Unzip boot.img and copy file to your phone 
• Then tap install in Magisk Card
• Choose "Select and Patch a File" in the methode, and choose stock boot image
• Magisk Manager will do the patch to image [Internal Storage]/Download/magisk_patched.img
• Copy patched image to PC
• Flash the patched boot image to your phone
• Usually, with reboot device you will go to fastboot mode and flash with command: fastboot flash boot/path/to/magisk_patched.img or Rename Magisk_patched.img to boot.img and use 7zip to use for the flash.
• Reboot to download mode. Open Odin on PC and flash boot_patched.tar as AP.
• Reboot dan done

Patching AP

• Use tools Frija or Samloader to download newest firmware zip of your phone from Samsung Server
• Unzip firmware and copy AP tar file to your phone. Usually file will be name AP_[device_model_sw_ver].tar.md5
• Tap and install Magisk Card
• Choose "Select and Patch a File" in methode, and choose AP Tar File
• Magisk Manager will patch image to [Internal Storage]/Download/magisk_patched.tar
• Copy patched tar file to PC with ADB: adb pull/sdcard/download/magisk_patched.tar
• Reboot to download mode. Open Odin on PC and do flash magisk_patched.tar as AP, with  BL, CP, and CSC (Not HOME_CSC because we wann to delete data from original firmware)
• After process on Odin finish, your phone will Reboot and start the initial setup.
• If stuck on bootloop, allow to do factory reset if the message appear
• Even though Magisk is already installed, it still requires some setup, connecting your device to the internet.
• Install the latest Magisk Manager and open the app. There will be some dialogue to do additional setups. Follow the process and your device will reboot.
• Done