Install platform tools

Ubuntu: sudo apt-get install android-tools-adb

Other: https://developer.android.com/studio/releases/platform-tools#downloads

Install Magisk

• download apk from https://github.com/topjohnwu/Magisk/releases
• Install magisk
  • Enable developer mode
  • Enable usb debugging
  • adb install Magisk-v25.1.apk

Getting stock boot image

• use adb shell to find boot_* on device (/dev/block/by-name)
• show why we can't use this file:

130|crosshatch:/dev/block/by-name $ ls -lZ boot*
lrwxrwxrwx 1 root root u:object_r:block_device:s0  16 1970-04-19 13:31 boot_a -> /dev/block/sda11
lrwxrwxrwx 1 root root u:object_r:block_device:s0  16 1970-04-19 13:31 boot_b -> /dev/block/sda12
crosshatch:/dev/block/by-name $ ls -lZ /dev/block/sda11
brw------- 1 root root u:object_r:boot_block_device:s0  8,  11 1970-04-19 13:31 /dev/block/sda11

• extract boot.img from stock firmware (image-crosshatch-sp1a.210812.016.c1.zip) available at https://developers.google.com/android/images
• T:\MCH\RootingfWorkshop>adb push boot.img /sdcard/Download

Rooting stock boot.img

• Start magisk app and select boot.img from Downloads
• adb pull /sdcard/Download

deponald@host:/mnt/t/MCH/RootingfWorkshop$ ls -l Download/
total 131072
-rwxrwxrwx 1 deponald deponald 67108864 Jun 24 18:52 boot.img
-rwxrwxrwx 1 deponald deponald 67108864 Jun 24 18:52 magisk_patched-25100_VL6BZ.img

• mv Download/magisk_patched-25100_VL6BZ.img boot_magisk.img

Booting from patched boot image

• Try from original stock device
  • adb reboot bootloader
  • fastboot boot boot_magisk.img

Sending 'boot.img' (65536 KB)                      OKAY [  1.606s]
Booting                                            FAILED (remote: 'Fastboot command (boot) is not allowed when locked')
fastboot: error: Command failed 

• Unlock the bootloader
  • fastboot flashing unlock
  • fastboot boot boot_magisk.img

Sending 'boot.img' (65536 KB)                      OKAY [  1.606s]
Booting                                            OKAY [  5.272s]
Finished. Total time: 6.933s

• Enable developer mode and usb debugging again
• Install magisk again
• Get a adb shell and try su (don't forget to grant permissions in the phone GUI)

crosshatch:/ $ id -Z
u:r:shell:s0
crosshatch:/ $ su
127|crosshatch:/ # id -Z
u:r:magisk:s0

Permanent rooting

• boot with patched boot_magisk.img
• Use Magisk app Direct Install function to overwrite stock boot.img with boot_magisk.img