diff --git a/CleanSpec.mk b/CleanSpec.mk
index 6c5ecd9..42bcb3c 100644
--- a/CleanSpec.mk
+++ b/CleanSpec.mk
@@ -699,6 +699,9 @@
 # again, as the original change removing them was reverted.
 $(call add-clean-step, rm -rf $(PRODUCT_OUT)/system/framework/*.jar)
 
+# The core image variant has been renamed to ""
+$(call add-clean-step, find $(SOONG_OUT_DIR)/.intermediates -type d -name "android_*_core*" -print0 | xargs -0 rm -rf)
+
 # ************************************************
 # NEWER CLEAN STEPS MUST BE AT THE END OF THE LIST
 # ************************************************
diff --git a/core/Makefile b/core/Makefile
index 9946d42..5fdca13 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -94,6 +94,8 @@
   $(error duplicate header copies are no longer allowed. For more information about headers, see: https://android.googlesource.com/platform/build/soong/+/master/docs/best_practices.md#headers)
 endif
 
+$(file >$(PRODUCT_OUT)/.copied_headers_list,$(TARGET_OUT_HEADERS) $(ALL_COPIED_HEADERS))
+
 # -----------------------------------------------------------------
 # docs/index.html
 ifeq (,$(TARGET_BUILD_APPS))
@@ -3625,6 +3627,8 @@
 	$(build-vbmetaimage-target)
 
 .PHONY: vbmetaimage-nodeps
+vbmetaimage-nodeps: PRIVATE_AVB_VBMETA_SIGNING_ARGS := \
+    --algorithm $(BOARD_AVB_ALGORITHM) --key $(BOARD_AVB_KEY_PATH)
 vbmetaimage-nodeps:
 	$(build-vbmetaimage-target)
 endif # BUILDING_VBMETA_IMAGE
diff --git a/core/build_id.mk b/core/build_id.mk
index cefc4b2..ba5ca42 100644
--- a/core/build_id.mk
+++ b/core/build_id.mk
@@ -18,4 +18,4 @@
 # (like "CRB01").  It must be a single word, and is
 # capitalized by convention.
 
-BUILD_ID=QQ1A.191205.011
+BUILD_ID=AOSP.MASTER
diff --git a/core/java.mk b/core/java.mk
index 907f2dc..a041321 100644
--- a/core/java.mk
+++ b/core/java.mk
@@ -413,6 +413,7 @@
 legacy_proguard_flags += -printmapping $(proguard_dictionary)
 legacy_proguard_flags += -printconfiguration $(proguard_configuration)
 
+common_proguard_flags :=
 common_proguard_flag_files := $(BUILD_SYSTEM)/proguard.flags
 ifneq ($(LOCAL_INSTRUMENTATION_FOR)$(filter tests,$(LOCAL_MODULE_TAGS)),)
 common_proguard_flags += -dontshrink # don't shrink tests by default
diff --git a/core/product_config.mk b/core/product_config.mk
index 4fc7bf6..afe91d4 100644
--- a/core/product_config.mk
+++ b/core/product_config.mk
@@ -264,6 +264,13 @@
   endif
 endif
 
+$(foreach pair,$(PRODUCT_UPDATABLE_BOOT_JARS), \
+  $(if $(findstring $(call word-colon,2,$(pair)),$(PRODUCT_BOOT_JARS)),, \
+    $(error Every jar in PRODUCT_UPDATABLE_BOOT_JARS must also be in PRODUCT_BOOT_JARS, \
+      $(call word-colon,2,$(pair)) is not) \
+  ) \
+)
+
 ENFORCE_SYSTEM_CERTIFICATE := $(PRODUCT_ENFORCE_ARTIFACT_SYSTEM_CERTIFICATE_REQUIREMENT)
 ENFORCE_SYSTEM_CERTIFICATE_WHITELIST := $(PRODUCT_ARTIFACT_SYSTEM_CERTIFICATE_REQUIREMENT_WHITELIST)
 
diff --git a/target/product/base_system.mk b/target/product/base_system.mk
index 42e0f5d..95e6fb0 100644
--- a/target/product/base_system.mk
+++ b/target/product/base_system.mk
@@ -50,6 +50,7 @@
     com.android.adbd \
     com.android.apex.cts.shim.v1_prebuilt \
     com.android.conscrypt \
+    com.android.cronet \
     com.android.i18n \
     com.android.ipsec \
     com.android.location.provider \
diff --git a/target/product/gsi_release.mk b/target/product/gsi_release.mk
index a6dd418..ee644f6 100644
--- a/target/product/gsi_release.mk
+++ b/target/product/gsi_release.mk
@@ -29,6 +29,12 @@
     system/product/% \
     system/system_ext/%
 
+
+# GSI doesn't support apex for now.
+# Properties set in product take precedence over those in vendor.
+PRODUCT_PRODUCT_PROPERTIES += \
+    ro.apex.updatable=false
+
 # Split selinux policy
 PRODUCT_FULL_TREBLE_OVERRIDE := true
 
diff --git a/tools/releasetools/sign_target_files_apks.py b/tools/releasetools/sign_target_files_apks.py
index 0f4f1da..35b11c1 100755
--- a/tools/releasetools/sign_target_files_apks.py
+++ b/tools/releasetools/sign_target_files_apks.py
@@ -972,6 +972,7 @@
           devkeydir + "/media":    d + "/media",
           devkeydir + "/shared":   d + "/shared",
           devkeydir + "/platform": d + "/platform",
+          devkeydir + "/networkstack": d + "/networkstack",
           })
     else:
       OPTIONS.key_map[s] = d