No flashable zip for that software release is publicly available, meaning its stock boot.img cannot be extracted.
You then need to update to a newer build first. You can do so from my OxygenOS builds repo thread.
Once done, enable developers options and enable OEM unlock.
Reboot to fastboot (enable USB debugging in dev options and use adb reboot bootloader)
Type fastboot oem unlock and accept to unlock bootloader (warning: as a safety measure Android will wipe your userdata)
Go through OxygenOS setup
Install Magisk Manager from https://github.com/topjohnwu/Magisk/...ger-v7.5.1.apk
Move stock boot.img to your phone internal storage (please open spoiler)
EU download: https://drive.google.com/file/d/18aP...ew?usp=sharing
India download: https://drive.google.com/file/d/1ZIE...ew?usp=sharing
For future builds, you can use payload dumper (Windows) , (Linux ) to extract stock boot.img
Click on Install
Choose "Select and patch a file"
Select your stock boot.img
Wait until Magisk patches your boot.img, and once patched it can be found in the Downloads folder
Copy that patched boot.img (which should be named magisk_patched.img) to your computer
Boot into fastboot again
Type fastboot getvar current-slot into your terminal window and press Enter.
If the output is a , type fastboot flash boot_a magisk_patched.img into your terminal window and press Enter.
If the output is b , type fastboot flash boot_b magisk_patched.img into your terminal window and press Enter.
Reboot to OxygenOS
Open Magisk Manager and your device should now be rooted.
- Ensure you got latest platform tools installed from https://developer.android.com/studio...platform-tools
- Backup your /persist once rooted (dd if=/dev/block/bootdevice/by-name/persist of=/sdcard/persist.img) and save it somewhere on your cloud/computer, this might save you from a broken fingerprint sensor and an RMA in the future if it turns out this device has same issue as 8-series when it comes to crossflash regional builds of OOS.
@topjohnwu for making Magisk
/u/Jisifus for testing on his device and for screenshots