Android 8.0.0 creates an appended images to system.img when we build it in user mode
(system.img+verity.img+fec_verity.img)
To stop dm-verity feature need to change following filles
1. file device/fsl/imx6/sabresd_6dq.mk comment out the lines
# setup dm-verity configs.
#PRODUCT_SYSTEM_VERITY_PARTITION := /dev/block/by-name/system
#$(call inherit-product, build/target/product/verity.mk)
2. device/fsl/sabresd_6dq/fstab.freescale
change the line
/dev/block/by-name/system /system ext4 ro,barrier=1 wait,verify=/dev/block/by-name/metadata
to
/dev/block/by-name/system /system ext4 ro,barrier=1 wait
