From c1a8f1a5d7e8bc772ac5694be655a83c3c2d494a Mon Sep 17 00:00:00 2001
From: Bowgo Tsai <bowgotsai@google.com>
Date: Tue, 19 Feb 2019 10:30:50 +0800
Subject: [PATCH] GSI vbmeta.img: set rollback_index to zero

The major purpose of vbmeta.img built on GSI targets (e.g., aosp_arm,
aosp_arm64, etc) is to disable AVB. We should also set the rollback
index to zero, to prevent the device bootloader from updating the
last seen rollback index in the tamper-evident storage.

Bug: 122583908
Test: build aosp_arm64, then `avbtool info_image --image $OUT/vbmeta.img`
Change-Id: I48a49957f8dd3169003b9507fe80e519f301d5b5
---
 target/board/BoardConfigGsiCommon.mk | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/target/board/BoardConfigGsiCommon.mk b/target/board/BoardConfigGsiCommon.mk
index 88bc7daa3..68d29c8af 100644
--- a/target/board/BoardConfigGsiCommon.mk
+++ b/target/board/BoardConfigGsiCommon.mk
@@ -34,11 +34,14 @@ BOARD_USES_METADATA_PARTITION := true
 
 # Android Verified Boot (AVB):
 #   Set AVB_VBMETA_IMAGE_FLAGS_VERIFICATION_DISABLED (--flags 2) in
-#   vbmeta.img to disable AVB verification.
+#   vbmeta.img to disable AVB verification. Also set the rollback index
+#   to zero, to prevent the device bootloader from updating the last seen
+#   rollback index in the tamper-evident storage.
 #
 # To disable AVB for GSI, use the vbmeta.img and the GSI together.
 # To enable AVB for GSI, include the GSI public key into the device-specific
 # vbmeta.img.
+BOARD_AVB_ROLLBACK_INDEX := 0
 BOARD_AVB_MAKE_VBMETA_IMAGE_ARGS += --flags 2
 
 # Enable chain partition for system.