[SOLUTION]
- Android P + kernel-4.4 or kernel-3.18
– download preloader with verified boot disabled which location is the same as scatter file //preloader__SBOOT_DIS.bin
– adb root
– adb disable-verity
– adb reboot
– adb root
– adb remount - Android P + kernel-4.9 or after
– download preloader with verified boot disabled which location is the same as scatter file. //preloader__SBOOT_DIS.bin
– boot to Home Screen
– go to setting -> system -> Developer options -> OEM unlocking
– adb reboot bootloader
– fastboot flashing unlock
– press volume up key
– fastboot reboot
– adb root
– adb disable-verity
– adb reboot
– adb root
– adb remount
After Android P, preloader__SBOOT_DIS.bin will be generated automatically after building preloader.