[DESCRIPTION]

     android P上面默认会打开security boot。客户在研发初期，如果想关闭security boot，可以参考以下内容

Enable/Disable Verified Boot

• Verified boot is a chain starting from boot ROM.
• Whether boot ROM verifies preloader is determined by efuse SBC_EN. (SW default on from Android P)
• Security boot starting from preloader can be enabled/disabled with preloader feature option.
• Modify preloader custom file. vendor/mediatek/proprietary/bootable/bootloader/preloader/custom/[project]/[project].mk
• Disable verified boot:
  • MTK_SEC_USBDL=ATTR_SUSBDL_DISABLE
  • MTK_SEC_BOOT=ATTR_SBOOT_DISABLE
• Enable verified boot:
  • MTK_SEC_USBDL=ATTR_SUSBDL_ENABLE
  • MTK_SEC_BOOT=ATTR_SBOOT_ENABLE
  • After this preloader has been flashed into device:
  • • You can only flash signed image (package_name-verified.img) and can only boot device with signed image.
    • Preloader will reject MTK_AllInOne_DA.bin. You must press USBDL key in order to use MTK_AllInOne_DA.bin.

How to Disable Verified Boot from Android P 

Download preloader with verified boot disabled (preloader_[project_name]_SBOOT_DIS.bin), which is in out folder.

After that, image which is not signed can be downloaded and booted.