diff --git a/bbootimg/src/main/kotlin/bootimg/v3/BootV3.kt b/bbootimg/src/main/kotlin/bootimg/v3/BootV3.kt
index 241cb25..59e6096 100644
--- a/bbootimg/src/main/kotlin/bootimg/v3/BootV3.kt
+++ b/bbootimg/src/main/kotlin/bootimg/v3/BootV3.kt
@@ -320,6 +320,7 @@ data class BootV3(
                 val alg = Algorithms.get(origSig.header!!.algorithm_type)!!
                 ret.addArgument("--gki_signing_algorithm").addArgument(alg.name)
                 ret.addArgument("--gki_signing_key").addArgument(alg.defaultKey)
+                ret.addArgument("--gki_signing_avbtool_path").addArgument(String.format(Helper.prop("avbtool"), "v1.2"))
             }
             ret.addArgument(" --id ")
             ret.addArgument(" --output ")
diff --git a/doc/additional_tricks.md b/doc/additional_tricks.md
index 35034b3..1396650 100644
--- a/doc/additional_tricks.md
+++ b/doc/additional_tricks.md
@@ -88,5 +88,10 @@ Emulate creating GKI image:
 out/host/linux-x86/bin/mkbootimg --kernel out/target/product/vsoc_arm64/kernel  --ramdisk out/target/product/vsoc_arm64/ramdisk.img --gki_signing_key external/avb/test/data/testkey_rsa4096.pem --gki_signing_algorithm SHA256_RSA4096 --os_version 11 --os_patch_level 2021-03-05 --header_version 4 --output out/target/product/vsoc_arm64/boot.img
 out/host/linux-x86/bin/avbtool add_hash_footer --image out/target/product/vsoc_arm64/boot.img --partition_size   67108864 --partition_name boot --algorithm SHA256_RSA2048 --key external/avb/test/data/testkey_rsa2048.pem --prop com.android.build.boot.fingerprint:nicefinger --prop com.android.build.boot.os_version:11 --rollback_index 1614902400
 ```
-As it's only used for GKI verification, I don't want to spend too much time on any special steps in 'gradle pack' flow, as long as DUT can boot up properly.
 
+## bootconfig in VendorBoot V4
+Depends on kernel 5.6+
+https://cateee.net/lkddb/web-lkddb/BOOT_CONFIG.html
+
+VTS requirement:
+if (S-launched, Kernel 5.10+), no "androidboot." should be placed in kernel commandline.