diff --git a/core/Makefile b/core/Makefile
index a97890e..26ed864 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -2310,7 +2310,7 @@
                  $(INTERNAL_MKBOOTIMG_VERSION_ARGS) $(BOARD_RECOVERY_MKBOOTIMG_ARGS) \
                  --output $(1).unsigned, \
     $(MKBOOTIMG) $(if $(strip $(2)),--kernel $(strip $(2))) $(INTERNAL_RECOVERYIMAGE_ARGS) \
-                 $(INTERNAL_MKBOOTIMG_VERSION_ARGS) $(INTERNAL_MKBOOTIMG_GKI_SINGING_ARGS) \
+                 $(INTERNAL_MKBOOTIMG_VERSION_ARGS) \
                  $(BOARD_RECOVERY_MKBOOTIMG_ARGS) --output $(1))
   $(if $(filter true,$(PRODUCT_SUPPORTS_BOOT_SIGNER)),\
     $(if $(filter true,$(BOARD_USES_RECOVERY_AS_BOOT)),\
@@ -2339,9 +2339,6 @@
 ifeq (true,$(BOARD_AVB_ENABLE))
   recoveryimage-deps += $(AVBTOOL) $(BOARD_AVB_BOOT_KEY_PATH)
 endif
-ifdef BOARD_GKI_SIGNING_KEY_PATH
-  recoveryimage-deps += $(BOARD_GKI_SIGNING_KEY_PATH) $(AVBTOOL)
-endif
 ifdef BOARD_INCLUDE_RECOVERY_DTBO
   ifdef BOARD_PREBUILT_RECOVERY_DTBOIMAGE
     recoveryimage-deps += $(BOARD_PREBUILT_RECOVERY_DTBOIMAGE)
@@ -2505,17 +2502,17 @@
 define build-debug-bootimage-target
   $(MKBOOTIMG) --kernel $(PRODUCT_OUT)/$(subst .img,,$(subst boot-debug,kernel,$(notdir $(1)))) \
     $(INTERNAL_DEBUG_BOOTIMAGE_ARGS) $(INTERNAL_MKBOOTIMG_VERSION_ARGS) \
-    $(INTERNAL_MKBOOTIMG_GKI_SINGING_ARGS) $(BOARD_MKBOOTIMG_ARGS) --output $1
+    $(BOARD_MKBOOTIMG_ARGS) --output $1
   $(if $(BOARD_AVB_BOOT_KEY_PATH),$(call test-key-sign-bootimage,$1,boot-debug))
 endef
 
 # Depends on original boot.img and ramdisk-debug.img, to build the new boot-debug.img
-$(INSTALLED_DEBUG_BOOTIMAGE_TARGET): $(MKBOOTIMG) $(INSTALLED_BOOTIMAGE_TARGET) $(BOARD_GKI_SIGNING_KEY_PATH) $(AVBTOOL)
+$(INSTALLED_DEBUG_BOOTIMAGE_TARGET): $(MKBOOTIMG) $(INSTALLED_BOOTIMAGE_TARGET) $(AVBTOOL)
 	$(call pretty,"Target boot debug image: $@")
 	$(call build-debug-bootimage-target, $@)
 
 .PHONY: bootimage_debug-nodeps
-bootimage_debug-nodeps: $(MKBOOTIMG) $(BOARD_GKI_SIGNING_KEY_PATH) $(AVBTOOL)
+bootimage_debug-nodeps: $(MKBOOTIMG) $(AVBTOOL)
 	echo "make $@: ignoring dependencies"
 	$(foreach b,$(INSTALLED_DEBUG_BOOTIMAGE_TARGET),$(call build-debug-bootimage-target,$b))
 
@@ -2682,17 +2679,17 @@
 define build-boot-test-harness-target
   $(MKBOOTIMG) --kernel $(PRODUCT_OUT)/$(subst .img,,$(subst boot-test-harness,kernel,$(notdir $(1)))) \
     $(INTERNAL_TEST_HARNESS_BOOTIMAGE_ARGS) $(INTERNAL_MKBOOTIMG_VERSION_ARGS) \
-    $(INTERNAL_MKBOOTIMG_GKI_SINGING_ARGS) $(BOARD_MKBOOTIMG_ARGS) --output $@
+    $(BOARD_MKBOOTIMG_ARGS) --output $@
   $(if $(BOARD_AVB_BOOT_KEY_PATH),$(call test-key-sign-bootimage,$@,boot-test-harness))
 endef
 
 # Build the new boot-test-harness.img, based on boot-debug.img and ramdisk-test-harness.img.
-$(INSTALLED_TEST_HARNESS_BOOTIMAGE_TARGET): $(MKBOOTIMG) $(INSTALLED_DEBUG_BOOTIMAGE_TARGET) $(BOARD_GKI_SIGNING_KEY_PATH) $(AVBTOOL)
+$(INSTALLED_TEST_HARNESS_BOOTIMAGE_TARGET): $(MKBOOTIMG) $(INSTALLED_DEBUG_BOOTIMAGE_TARGET) $(AVBTOOL)
 	$(call pretty,"Target boot test harness image: $@")
 	$(call build-boot-test-harness-target,$@)
 
 .PHONY: bootimage_test_harness-nodeps
-bootimage_test_harness-nodeps: $(MKBOOTIMG) $(BOARD_GKI_SIGNING_KEY_PATH) $(AVBTOOL)
+bootimage_test_harness-nodeps: $(MKBOOTIMG) $(AVBTOOL)
 	echo "make $@: ignoring dependencies"
 	$(foreach b,$(INSTALLED_TEST_HARNESS_BOOTIMAGE_TARGET),$(call build-boot-test-harness-target,$b))
 
@@ -3547,7 +3544,10 @@
 # $(INSTALLED_VENDORIMAGE_TARGET)" for "system vendor".
 # (1): list of partitions like "system", "vendor" or "system product system_ext".
 define images-for-partitions
-$(strip $(foreach item,$(1),$(if $(filter $(item),system_other),$(INSTALLED_SYSTEMOTHERIMAGE_TARGET),$(INSTALLED_$(call to-upper,$(item))IMAGE_TARGET))))
+$(strip $(foreach item,$(1),\
+  $(if $(filter $(item),system_other),$(INSTALLED_SYSTEMOTHERIMAGE_TARGET),\
+    $(if $(filter $(item),init_boot),$(INSTALLED_INIT_BOOT_IMAGE_TARGET),\
+      $(INSTALLED_$(call to-upper,$(item))IMAGE_TARGET)))))
 endef
 
 # -----------------------------------------------------------------
@@ -3820,7 +3820,9 @@
 $(eval $(call check-and-set-avb-args,vendor_boot))
 endif
 
+ifdef INSTALLED_SYSTEMIMAGE_TARGET
 $(eval $(call check-and-set-avb-args,system))
+endif
 
 ifdef INSTALLED_VENDORIMAGE_TARGET
 $(eval $(call check-and-set-avb-args,vendor))
@@ -4621,6 +4623,9 @@
 endif
 	$(hide) echo "tool_extensions=$(tool_extensions)" >> $@
 	$(hide) echo "default_system_dev_certificate=$(DEFAULT_SYSTEM_DEV_CERTIFICATE)" >> $@
+ifdef PRODUCT_EXTRA_OTA_KEYS
+	$(hide) echo "extra_ota_keys=$(PRODUCT_EXTRA_OTA_KEYS)" >> $@
+endif
 ifdef PRODUCT_EXTRA_RECOVERY_KEYS
 	$(hide) echo "extra_recovery_keys=$(PRODUCT_EXTRA_RECOVERY_KEYS)" >> $@
 endif
@@ -4631,8 +4636,6 @@
 ifdef BOARD_GKI_SIGNING_KEY_PATH
 	$(hide) echo 'gki_signing_key_path=$(BOARD_GKI_SIGNING_KEY_PATH)' >> $@
 	$(hide) echo 'gki_signing_algorithm=$(BOARD_GKI_SIGNING_ALGORITHM)' >> $@
-endif
-ifdef BOARD_GKI_SIGNING_SIGNATURE_ARGS
 	$(hide) echo 'gki_signing_signature_args=$(BOARD_GKI_SIGNING_SIGNATURE_ARGS)' >> $@
 endif
 	$(hide) echo "multistage_support=1" >> $@
@@ -5331,8 +5334,8 @@
 	$(hide) cp $(INSTALLED_SYSTEM_EXTIMAGE_TARGET) $(zip_root)/IMAGES/
 endif
 ifdef BOARD_PREBUILT_INIT_BOOT_IMAGE
-	$(hide) mkdir -p $(zip_root)/IMAGES
-	$(hide) cp $(INSTALLED_INIT_BOOT_IMAGE_TARGET) $(zip_root)/IMAGES/
+	$(hide) mkdir -p $(zip_root)/PREBUILT_IMAGES
+	$(hide) cp $(INSTALLED_INIT_BOOT_IMAGE_TARGET) $(zip_root)/PREBUILT_IMAGES/
 endif
 ifndef BOARD_PREBUILT_BOOTIMAGE
 ifneq (,$(INTERNAL_PREBUILT_BOOTIMAGE) $(filter true,$(BOARD_COPY_BOOT_IMAGE_TO_TARGET_FILES)))
diff --git a/core/android_soong_config_vars.mk b/core/android_soong_config_vars.mk
index d4bdbbd..0befbfa 100644
--- a/core/android_soong_config_vars.mk
+++ b/core/android_soong_config_vars.mk
@@ -104,6 +104,9 @@
 $(call add_soong_config_var_value,ANDROID,module_build_from_source,true)
 endif
 
+# TODO(b/203088572): Remove when Java optimizations enabled by default for
+# SystemUI.
+$(call add_soong_config_var,ANDROID,SYSTEMUI_OPTIMIZE_JAVA)
 # TODO(b/196084106): Remove when Java optimizations enabled by default for
 # system packages.
 $(call add_soong_config_var,ANDROID,SYSTEM_OPTIMIZE_JAVA)
diff --git a/core/product-graph.mk b/core/product-graph.mk
index f28ea3d..d425b22 100644
--- a/core/product-graph.mk
+++ b/core/product-graph.mk
@@ -126,6 +126,7 @@
 	$(hide) echo 'PRODUCT_CHARACTERISTICS=$(call get-product-var,$(1),PRODUCT_CHARACTERISTICS)' >> $$@
 	$(hide) echo 'PRODUCT_COPY_FILES=$(call get-product-var,$(1),PRODUCT_COPY_FILES)' >> $$@
 	$(hide) echo 'PRODUCT_OTA_PUBLIC_KEYS=$(call get-product-var,$(1),PRODUCT_OTA_PUBLIC_KEYS)' >> $$@
+	$(hide) echo 'PRODUCT_EXTRA_OTA_KEYS=$(call get-product-var,$(1),PRODUCT_EXTRA_OTA_KEYS)' >> $$@
 	$(hide) echo 'PRODUCT_EXTRA_RECOVERY_KEYS=$(call get-product-var,$(1),PRODUCT_EXTRA_RECOVERY_KEYS)' >> $$@
 	$(hide) echo 'PRODUCT_PACKAGE_OVERLAYS=$(call get-product-var,$(1),PRODUCT_PACKAGE_OVERLAYS)' >> $$@
 	$(hide) echo 'DEVICE_PACKAGE_OVERLAYS=$(call get-product-var,$(1),DEVICE_PACKAGE_OVERLAYS)' >> $$@
diff --git a/core/product.mk b/core/product.mk
index 04c59ff..b069dda 100644
--- a/core/product.mk
+++ b/core/product.mk
@@ -183,6 +183,7 @@
 # signing tools can substitute them for the test key embedded by
 # default.
 _product_list_vars += PRODUCT_OTA_PUBLIC_KEYS
+_product_list_vars += PRODUCT_EXTRA_OTA_KEYS
 _product_list_vars += PRODUCT_EXTRA_RECOVERY_KEYS
 
 # Should we use the default resources or add any product specific overlays
diff --git a/core/product_config.mk b/core/product_config.mk
index a376f74..57b7724 100644
--- a/core/product_config.mk
+++ b/core/product_config.mk
@@ -381,6 +381,7 @@
 ENFORCE_SYSTEM_CERTIFICATE_ALLOW_LIST := $(PRODUCT_ARTIFACT_SYSTEM_CERTIFICATE_REQUIREMENT_ALLOW_LIST)
 
 PRODUCT_OTA_PUBLIC_KEYS := $(sort $(PRODUCT_OTA_PUBLIC_KEYS))
+PRODUCT_EXTRA_OTA_KEYS := $(sort $(PRODUCT_EXTRA_OTA_KEYS))
 PRODUCT_EXTRA_RECOVERY_KEYS := $(sort $(PRODUCT_EXTRA_RECOVERY_KEYS))
 
 # Resolve and setup per-module dex-preopt configs.
diff --git a/target/board/BoardConfigGkiCommon.mk b/target/board/BoardConfigGkiCommon.mk
index c0f5db9..63ef2b4 100644
--- a/target/board/BoardConfigGkiCommon.mk
+++ b/target/board/BoardConfigGkiCommon.mk
@@ -16,11 +16,7 @@
 # Enable GKI 2.0 signing.
 BOARD_GKI_SIGNING_KEY_PATH := build/make/target/product/gsi/testkey_rsa2048.pem
 BOARD_GKI_SIGNING_ALGORITHM := SHA256_RSA2048
-
-# The following is needed to allow release signing process appends more extra
-# args, e.g., passing --signing_helper_with_files from mkbootimg to avbtool.
-# See b/178559811 for more details.
-BOARD_GKI_SIGNING_SIGNATURE_ARGS := --prop foo:bar
+BOARD_GKI_SIGNING_SIGNATURE_ARGS :=
 
 # Sets boot SPL.
 BOOT_SECURITY_PATCH = $(PLATFORM_SECURITY_PATCH)
diff --git a/target/product/gsi/Android.mk b/target/product/gsi/Android.mk
index 0d788fa..167ffcf 100644
--- a/target/product/gsi/Android.mk
+++ b/target/product/gsi/Android.mk
@@ -60,11 +60,11 @@
 endif
 
 $(check-vndk-list-timestamp): $(INTERNAL_VNDK_LIB_LIST) $(LATEST_VNDK_LIB_LIST) $(HOST_OUT_EXECUTABLES)/update-vndk-list.sh
-	$(hide) ($(_READ_INTERNAL_VNDK_LIB_LIST) | \
+	$(hide) ($(_READ_INTERNAL_VNDK_LIB_LIST) | sort | \
 	diff --old-line-format="Removed %L" \
 	  --new-line-format="Added %L" \
 	  --unchanged-line-format="" \
-	  $(LATEST_VNDK_LIB_LIST) - \
+	  <(cat $(LATEST_VNDK_LIB_LIST) | sort) - \
 	  || ( echo -e $(_vndk_check_failure_message); exit 1 ))
 	$(hide) mkdir -p $(dir $@)
 	$(hide) touch $@
diff --git a/target/product/gsi/current.txt b/target/product/gsi/current.txt
index e618226..94aaea0 100644
--- a/target/product/gsi/current.txt
+++ b/target/product/gsi/current.txt
@@ -29,10 +29,10 @@
 VNDK-SP: android.hardware.graphics.mapper@3.0.so
 VNDK-SP: android.hardware.graphics.mapper@4.0.so
 VNDK-SP: android.hardware.renderscript@1.0.so
+VNDK-SP: android.hidl.safe_union@1.0.so
 VNDK-SP: android.hidl.memory.token@1.0.so
 VNDK-SP: android.hidl.memory@1.0-impl.so
 VNDK-SP: android.hidl.memory@1.0.so
-VNDK-SP: android.hidl.safe_union@1.0.so
 VNDK-SP: libRSCpuRef.so
 VNDK-SP: libRSDriver.so
 VNDK-SP: libRS_internal.so
diff --git a/target/product/security/Android.mk b/target/product/security/Android.mk
index cedad5b..9daa3bf 100644
--- a/target/product/security/Android.mk
+++ b/target/product/security/Android.mk
@@ -63,9 +63,17 @@
 LOCAL_MODULE_STEM := otacerts.zip
 LOCAL_MODULE_PATH := $(TARGET_OUT_ETC)/security
 include $(BUILD_SYSTEM)/base_rules.mk
+
+extra_ota_keys := $(addsuffix .x509.pem,$(PRODUCT_EXTRA_OTA_KEYS))
+
 $(LOCAL_BUILT_MODULE): PRIVATE_CERT := $(DEFAULT_SYSTEM_DEV_CERTIFICATE).x509.pem
-$(LOCAL_BUILT_MODULE): $(SOONG_ZIP) $(DEFAULT_SYSTEM_DEV_CERTIFICATE).x509.pem
-	$(SOONG_ZIP) -o $@ -j -symlinks=false -f $(PRIVATE_CERT)
+$(LOCAL_BUILT_MODULE): PRIVATE_EXTRA_OTA_KEYS := $(extra_ota_keys)
+$(LOCAL_BUILT_MODULE): \
+	    $(SOONG_ZIP) \
+	    $(DEFAULT_SYSTEM_DEV_CERTIFICATE).x509.pem \
+	    $(extra_ota_keys)
+	$(SOONG_ZIP) -o $@ -j -symlinks=false \
+	    $(addprefix -f ,$(PRIVATE_CERT) $(PRIVATE_EXTRA_OTA_KEYS))
 
 
 #######################################
@@ -80,7 +88,7 @@
 LOCAL_MODULE_PATH := $(TARGET_RECOVERY_ROOT_OUT)/system/etc/security
 include $(BUILD_SYSTEM)/base_rules.mk
 
-extra_recovery_keys := $(patsubst %,%.x509.pem,$(PRODUCT_EXTRA_RECOVERY_KEYS))
+extra_recovery_keys := $(addsuffix .x509.pem,$(PRODUCT_EXTRA_RECOVERY_KEYS))
 
 $(LOCAL_BUILT_MODULE): PRIVATE_CERT := $(DEFAULT_SYSTEM_DEV_CERTIFICATE).x509.pem
 $(LOCAL_BUILT_MODULE): PRIVATE_EXTRA_RECOVERY_KEYS := $(extra_recovery_keys)
@@ -89,4 +97,4 @@
 	    $(DEFAULT_SYSTEM_DEV_CERTIFICATE).x509.pem \
 	    $(extra_recovery_keys)
 	$(SOONG_ZIP) -o $@ -j -symlinks=false \
-	    $(foreach key_file, $(PRIVATE_CERT) $(PRIVATE_EXTRA_RECOVERY_KEYS), -f $(key_file))
+	    $(addprefix -f ,$(PRIVATE_CERT) $(PRIVATE_EXTRA_RECOVERY_KEYS))
diff --git a/tools/Android.bp b/tools/Android.bp
index 269e610..2f3b393 100644
--- a/tools/Android.bp
+++ b/tools/Android.bp
@@ -28,27 +28,11 @@
 python_binary_host {
   name: "generate-self-extracting-archive",
   srcs: ["generate-self-extracting-archive.py"],
-  version: {
-    py2: {
-      enabled: true,
-    },
-    py3: {
-      enabled: false,
-    },
-  },
 }
 
 python_binary_host {
   name: "post_process_props",
   srcs: ["post_process_props.py"],
-  version: {
-    py2: {
-      enabled: false,
-    },
-    py3: {
-      enabled: true,
-    },
-  },
 }
 
 python_test_host {
@@ -58,14 +42,6 @@
     "post_process_props.py",
     "test_post_process_props.py",
   ],
-  version: {
-    py2: {
-      enabled: false,
-    },
-    py3: {
-      enabled: true,
-    },
-  },
   test_config: "post_process_props_unittest.xml",
   test_suites: ["general-tests"],
 }
@@ -73,14 +49,6 @@
 python_binary_host {
   name: "extract_kernel",
   srcs: ["extract_kernel.py"],
-  version: {
-    py2: {
-      enabled: false,
-    },
-    py3: {
-      enabled: true,
-    },
-  },
 }
 
 genrule_defaults {
diff --git a/tools/generate-self-extracting-archive.py b/tools/generate-self-extracting-archive.py
index 5b0628d..c9f56cb 100755
--- a/tools/generate-self-extracting-archive.py
+++ b/tools/generate-self-extracting-archive.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 #
 # Copyright (C) 2019 The Android Open Source Project
 #
@@ -120,7 +120,7 @@
 
 def main(argv):
   if len(argv) != 5:
-    print 'generate-self-extracting-archive.py expects exactly 4 arguments'
+    print('generate-self-extracting-archive.py expects exactly 4 arguments')
     sys.exit(1)
 
   output_filename = argv[1]
@@ -134,11 +134,11 @@
     license = license_file.read()
 
   if not license:
-    print 'License file was empty'
+    print('License file was empty')
     sys.exit(1)
 
   if 'SOFTWARE LICENSE AGREEMENT' not in license:
-    print 'License does not look like a license'
+    print('License does not look like a license')
     sys.exit(1)
 
   comment_line = '# %s\n' % comment
diff --git a/tools/releasetools/sign_target_files_apks.py b/tools/releasetools/sign_target_files_apks.py
index 3f65df1..c615b84 100755
--- a/tools/releasetools/sign_target_files_apks.py
+++ b/tools/releasetools/sign_target_files_apks.py
@@ -520,9 +520,14 @@
                        compressed_extension):
   # maxsize measures the maximum filename length, including the ones to be
   # skipped.
-  maxsize = max(
-      [len(os.path.basename(i.filename)) for i in input_tf_zip.infolist()
-       if GetApkFileInfo(i.filename, compressed_extension, [])[0]])
+  try:
+    maxsize = max(
+        [len(os.path.basename(i.filename)) for i in input_tf_zip.infolist()
+         if GetApkFileInfo(i.filename, compressed_extension, [])[0]])
+  except ValueError:
+    # Sets this to zero for targets without APK files, e.g., gki_arm64.
+    maxsize = 0
+
   system_root_image = misc_info.get("system_root_image") == "true"
 
   for info in input_tf_zip.infolist():
@@ -883,14 +888,27 @@
   except KeyError:
     raise common.ExternalError("can't read META/otakeys.txt from input")
 
-  extra_recovery_keys = misc_info.get("extra_recovery_keys")
-  if extra_recovery_keys:
+  extra_ota_keys_info = misc_info.get("extra_ota_keys")
+  if extra_ota_keys_info:
+    extra_ota_keys = [OPTIONS.key_map.get(k, k) + ".x509.pem"
+                      for k in extra_ota_keys_info.split()]
+    print("extra ota key(s): " + ", ".join(extra_ota_keys))
+  else:
+    extra_ota_keys = []
+  for k in extra_ota_keys:
+    if not os.path.isfile(k):
+      raise common.ExternalError(k + " does not exist or is not a file")
+
+  extra_recovery_keys_info = misc_info.get("extra_recovery_keys")
+  if extra_recovery_keys_info:
     extra_recovery_keys = [OPTIONS.key_map.get(k, k) + ".x509.pem"
-                           for k in extra_recovery_keys.split()]
-    if extra_recovery_keys:
-      print("extra recovery-only key(s): " + ", ".join(extra_recovery_keys))
+                           for k in extra_recovery_keys_info.split()]
+    print("extra recovery-only key(s): " + ", ".join(extra_recovery_keys))
   else:
     extra_recovery_keys = []
+  for k in extra_recovery_keys:
+    if not os.path.isfile(k):
+      raise common.ExternalError(k + " does not exist or is not a file")
 
   mapped_keys = []
   for k in keylist:
@@ -913,13 +931,20 @@
     mapped_keys.append(mapped_devkey + ".x509.pem")
     print("META/otakeys.txt has no keys; using %s for OTA package"
           " verification." % (mapped_keys[0],))
+  for k in mapped_keys:
+    if not os.path.isfile(k):
+      raise common.ExternalError(k + " does not exist or is not a file")
 
   otacerts = [info
               for info in input_tf_zip.infolist()
               if info.filename.endswith("/otacerts.zip")]
   for info in otacerts:
-    print("Rewriting OTA key:", info.filename, mapped_keys)
-    WriteOtacerts(output_tf_zip, info.filename, mapped_keys)
+    if info.filename.startswith(("BOOT/", "RECOVERY/", "VENDOR_BOOT/")):
+      extra_keys = extra_recovery_keys
+    else:
+      extra_keys = extra_ota_keys
+    print("Rewriting OTA key:", info.filename, mapped_keys + extra_keys)
+    WriteOtacerts(output_tf_zip, info.filename, mapped_keys + extra_keys)
 
 
 def ReplaceVerityPublicKey(output_zip, filename, key_path):
diff --git a/tools/warn/html_writer.py b/tools/warn/html_writer.py
index ef173bc..3fa822a 100644
--- a/tools/warn/html_writer.py
+++ b/tools/warn/html_writer.py
@@ -63,6 +63,11 @@
 from .severity import Severity
 
 
+# Report files with this number of warnings or more.
+LIMIT_WARNINGS_PER_FILE = 100
+# Report files/directories with this percentage of total warnings or more.
+LIMIT_PERCENT_WARNINGS = 1
+
 HTML_HEAD_SCRIPTS = """\
   <script type="text/javascript">
   function expand(id) {
@@ -89,12 +94,13 @@
   </script>
   <style type="text/css">
   th,td{border-collapse:collapse; border:1px solid black;}
-  .button{color:blue;font-size:110%;font-weight:bolder;}
+  .button{color:blue;font-size:100%;font-weight:bolder;}
   .bt{color:black;background-color:transparent;border:none;outline:none;
       font-size:140%;font-weight:bolder;}
   .c0{background-color:#e0e0e0;}
   .c1{background-color:#d0d0d0;}
   .t1{border-collapse:collapse; width:100%; border:1px solid black;}
+  .box{margin:5pt; padding:5pt; border:1px solid;}
   </style>
   <script src="https://www.gstatic.com/charts/loader.js"></script>
 """
@@ -287,14 +293,14 @@
 #     sort by project, severity, warn_id, warning_message
 def emit_buttons(writer):
   """Write the button elements in HTML."""
-  writer('<button class="button" onclick="expandCollapse(1);">'
+  writer('<p><button class="button" onclick="expandCollapse(1);">'
          'Expand all warnings</button>\n'
          '<button class="button" onclick="expandCollapse(0);">'
          'Collapse all warnings</button>\n'
-         '<button class="button" onclick="groupBySeverity();">'
+         '<p><button class="button" onclick="groupBySeverity();">'
          'Group warnings by severity</button>\n'
          '<button class="button" onclick="groupByProject();">'
-         'Group warnings by project</button><br>')
+         'Group warnings by project</button>')
 
 
 def all_patterns(category):
@@ -559,6 +565,11 @@
 """
 
 
+# Emit a JavaScript const number
+def emit_const_number(name, value, writer):
+  writer('const ' + name + ' = ' + str(value) + ';')
+
+
 # Emit a JavaScript const string
 def emit_const_string(name, value, writer):
   writer('const ' + name + ' = "' + escape_string(value) + '";')
@@ -602,6 +613,8 @@
   emit_const_string('FlagPlatform', flags.platform, writer)
   emit_const_string('FlagURL', flags.url, writer)
   emit_const_string('FlagSeparator', flags.separator, writer)
+  emit_const_number('LimitWarningsPerFile', LIMIT_WARNINGS_PER_FILE, writer)
+  emit_const_number('LimitPercentWarnings', LIMIT_PERCENT_WARNINGS, writer)
   emit_const_string_array('SeverityColors', [s.color for s in Severity.levels],
                           writer)
   emit_const_string_array('SeverityHeaders',
@@ -624,8 +637,8 @@
 
 DRAW_TABLE_JAVASCRIPT = """
 google.charts.load('current', {'packages':['table']});
-google.charts.setOnLoadCallback(drawTable);
-function drawTable() {
+google.charts.setOnLoadCallback(genTables);
+function genSelectedProjectsTable() {
   var data = new google.visualization.DataTable();
   data.addColumn('string', StatsHeader[0]);
   for (var i=1; i<StatsHeader.length; i++) {
@@ -638,12 +651,167 @@
     }
   }
   var table = new google.visualization.Table(
-      document.getElementById('stats_table'));
+      document.getElementById('selected_projects_section'));
   table.draw(data, {allowHtml: true, alternatingRowStyle: true});
 }
+// Global TopDirs and TopFiles are computed later by genTables.
+window.TopDirs = [];
+window.TopFiles = [];
+function computeTopDirsFiles() {
+  var numWarnings = WarningMessages.length;
+  var warningsOfFiles = {};
+  var warningsOfDirs = {};
+  var subDirs = {};
+  function addOneWarning(map, key) {
+    map[key] = 1 + ((key in map) ? map[key] : 0);
+  }
+  for (var i = 0; i < numWarnings; i++) {
+    var file = WarningMessages[i].replace(/:.*/, "");
+    addOneWarning(warningsOfFiles, file);
+    var dirs = file.split("/");
+    var dir = dirs[0];
+    addOneWarning(warningsOfDirs, dir);
+    for (var d = 1; d < dirs.length - 1; d++) {
+      var subDir = dir + "/" + dirs[d];
+      if (!(dir in subDirs)) {
+        subDirs[dir] = {};
+      }
+      subDirs[dir][subDir] = 1;
+      dir = subDir;
+      addOneWarning(warningsOfDirs, dir);
+    }
+  }
+  var minDirWarnings = numWarnings*(LimitPercentWarnings/100);
+  var minFileWarnings = Math.min(LimitWarningsPerFile, minDirWarnings);
+  // Each row in TopDirs and TopFiles has
+  // [index, {v:<num_of_warnings>, f:<percent>}, file_or_dir_name]
+  function countWarnings(minWarnings, warningsOf, isDir) {
+    var rows = [];
+    for (var name in warningsOf) {
+      if (isDir && name in subDirs && Object.keys(subDirs[name]).length < 2) {
+        continue; // skip a directory if it has only one subdir
+      }
+      var count = warningsOf[name];
+      if (count >= minWarnings) {
+        name = isDir ? (name + "/...") : name;
+        var percent = (100*count/numWarnings).toFixed(1);
+        var countFormat = count + ' (' + percent + '%)';
+        rows.push([0, {v:count, f:countFormat}, name]);
+      }
+    }
+    rows.sort((a,b) => b[1].v - a[1].v);
+    for (var i=0; i<rows.length; i++) {
+      rows[i][0] = i;
+    }
+    return rows;
+  }
+  TopDirs = countWarnings(minDirWarnings, warningsOfDirs, true);
+  TopFiles = countWarnings(minFileWarnings, warningsOfFiles, false);
+}
+function genTopDirsFilesTables() {
+  computeTopDirsFiles();
+  function addTable(name, divName, rows, clickFunction) {
+    var data = new google.visualization.DataTable();
+    data.addColumn("number", "index"); // not shown in view
+    data.addColumn("number", "# of warnings");
+    data.addColumn("string", name);
+    data.addRows(rows);
+    var formatter = new google.visualization.PatternFormat(
+      '<p onclick="' + clickFunction + '({0})">{2}</p>');
+    formatter.format(data, [0, 1, 2], 2);
+    var view = new google.visualization.DataView(data);
+    view.setColumns([1,2]); // hide the index column
+    var table = new google.visualization.Table(
+        document.getElementById(divName));
+    table.draw(view, {allowHtml: true, alternatingRowStyle: true});
+  }
+  addTable("Directory", "top_dirs_table", TopDirs, "selectDir");
+  addTable("File", "top_files_table", TopFiles, "selectFile");
+}
+function selectDirFile(idx, rows, dirFile) {
+  if (rows.length <= idx) {
+    return;
+  }
+  var name = rows[idx][2];
+  var spanName = "selected_" + dirFile + "_name";
+  document.getElementById(spanName).innerHTML = name;
+  var divName = "selected_" + dirFile + "_warnings";
+  var numWarnings = rows[idx][1].v;
+  var prefix = name.replace(/\\.\\.\\.$/, "");
+  var data = new google.visualization.DataTable();
+  data.addColumn('string', numWarnings + ' warnings in ' + name);
+  var getWarningMessage = (FlagPlatform == "chrome")
+        ? ((x) => addURLToLine(WarningMessages[Warnings[x][2]],
+                               WarningLinks[Warnings[x][3]]))
+        : ((x) => addURL(WarningMessages[Warnings[x][2]]));
+  for (var i = 0; i < Warnings.length; i++) {
+    if (WarningMessages[Warnings[i][2]].startsWith(prefix)) {
+      data.addRow([getWarningMessage(i)]);
+    }
+  }
+  var table = new google.visualization.Table(
+      document.getElementById(divName));
+  table.draw(data, {allowHtml: true, alternatingRowStyle: true});
+}
+function selectDir(idx) {
+  selectDirFile(idx, TopDirs, "directory")
+}
+function selectFile(idx) {
+  selectDirFile(idx, TopFiles, "file");
+}
+function genTables() {
+  genSelectedProjectsTable();
+  if (WarningMessages.length > 1) {
+    genTopDirsFilesTables();
+  }
+}
 """
 
 
+def dump_boxed_section(writer, func):
+  writer('<div class="box">')
+  func()
+  writer('</div>')
+
+
+def dump_section_header(writer, table_name, section_title):
+  writer('<h3><b><button id="' + table_name + '_mark" class="bt"\n' +
+         ' onclick="expand(\'' + table_name + '\');">&#x2295</button></b>\n' +
+         section_title + '</h3>')
+
+
+def dump_table_section(writer, table_name, section_title):
+  dump_section_header(writer, table_name, section_title)
+  writer('<div id="' + table_name + '" style="display:none;"></div>')
+
+
+def dump_dir_file_section(writer, dir_file, table_name, section_title):
+  section_name = 'top_' + dir_file + '_section'
+  dump_section_header(writer, section_name, section_title)
+  writer('<div id="' + section_name + '" style="display:none;">')
+  writer('<div id="' + table_name + '"></div>')
+  def subsection():
+    subsection_name = 'selected_' + dir_file + '_warnings'
+    subsection_title = ('Warnings in <span id="selected_' + dir_file +
+                        '_name">(click a ' + dir_file +
+                        ' in the above table)</span>')
+    dump_section_header(writer, subsection_name, subsection_title)
+    writer('<div id="' + subsection_name + '" style="display:none;"></div>')
+  dump_boxed_section(writer, subsection)
+  writer('</div>')
+
+
+# HTML output has the following major div elements:
+#  selected_projects_section
+#  top_directory_section
+#    top_dirs_table
+#    selected_directory_warnings
+#  top_file_section
+#    top_files_table
+#    selected_file_warnings
+#  all_warnings_section
+#    warning_groups
+#    fixed_warnings
 def dump_html(flags, output_stream, warning_messages, warning_links,
               warning_records, header_str, warn_patterns, project_names):
   """Dump the flags output to output_stream."""
@@ -651,20 +819,44 @@
   dump_html_prologue('Warnings for ' + header_str, writer, warn_patterns,
                      project_names)
   dump_stats(writer, warn_patterns)
-  writer('<br><div id="stats_table"></div><br>')
-  writer('\n<script>')
-  emit_js_data(writer, flags, warning_messages, warning_links, warning_records,
-               warn_patterns, project_names)
-  writer(SCRIPTS_FOR_WARNING_GROUPS)
-  writer('</script>')
-  emit_buttons(writer)
-  # Warning messages are grouped by severities or project names.
-  writer('<br><div id="warning_groups"></div>')
-  if flags.byproject:
-    writer('<script>groupByProject();</script>')
-  else:
-    writer('<script>groupBySeverity();</script>')
-  dump_fixed(writer, warn_patterns)
+  writer('<br><br>Press &#x2295 to show section content,'
+         ' and &#x2296 to hide the content.')
+  def section1():
+    dump_table_section(writer, 'selected_projects_section',
+                       'Number of warnings in preselected project directories')
+  def section2():
+    dump_dir_file_section(
+        writer, 'directory', 'top_dirs_table',
+        'Directories with at least ' +
+        str(LIMIT_PERCENT_WARNINGS) + '% warnings')
+  def section3():
+    dump_dir_file_section(
+        writer, 'file', 'top_files_table',
+        'Files with at least ' +
+        str(LIMIT_PERCENT_WARNINGS) + '% or ' +
+        str(LIMIT_WARNINGS_PER_FILE) + ' warnings')
+  def section4():
+    writer('<script>')
+    emit_js_data(writer, flags, warning_messages, warning_links,
+                 warning_records, warn_patterns, project_names)
+    writer(SCRIPTS_FOR_WARNING_GROUPS)
+    writer('</script>')
+    dump_section_header(writer, 'all_warnings_section',
+                        'All warnings grouped by severities or projects')
+    writer('<div id="all_warnings_section" style="display:none;">')
+    emit_buttons(writer)
+    # Warning messages are grouped by severities or project names.
+    writer('<br><div id="warning_groups"></div>')
+    if flags.byproject:
+      writer('<script>groupByProject();</script>')
+    else:
+      writer('<script>groupBySeverity();</script>')
+    dump_fixed(writer, warn_patterns)
+    writer('</div>')
+  dump_boxed_section(writer, section1)
+  dump_boxed_section(writer, section2)
+  dump_boxed_section(writer, section3)
+  dump_boxed_section(writer, section4)
   dump_html_epilogue(writer)
 
 
diff --git a/tools/zipalign/tests/src/align_test.cpp b/tools/zipalign/tests/src/align_test.cpp
index 96d4f73..ff45187 100644
--- a/tools/zipalign/tests/src/align_test.cpp
+++ b/tools/zipalign/tests/src/align_test.cpp
@@ -3,6 +3,7 @@
 
 #include "ZipAlign.h"
 
+#include <filesystem>
 #include <stdio.h>
 #include <string>
 
@@ -16,9 +17,15 @@
   return test_data_dir + filename;
 }
 
+static std::string GetTempPath(const std::string& filename) {
+  std::filesystem::path temp_path = std::filesystem::path(testing::TempDir());
+  temp_path += filename;
+  return temp_path.string();
+}
+
 TEST(Align, Unaligned) {
   const std::string src = GetTestPath("unaligned.zip");
-  const std::string dst = GetTestPath("unaligned_out.zip");
+  const std::string dst = GetTempPath("unaligned_out.zip");
 
   int processed = process(src.c_str(), dst.c_str(), 4, true, false, 4096);
   ASSERT_EQ(0, processed);
@@ -29,8 +36,8 @@
 
 TEST(Align, DoubleAligment) {
   const std::string src = GetTestPath("unaligned.zip");
-  const std::string tmp = GetTestPath("da_aligned.zip");
-  const std::string dst = GetTestPath("da_d_aligner.zip");
+  const std::string tmp = GetTempPath("da_aligned.zip");
+  const std::string dst = GetTempPath("da_d_aligner.zip");
 
   int processed = process(src.c_str(), tmp.c_str(), 4, true, false, 4096);
   ASSERT_EQ(0, processed);
@@ -60,7 +67,7 @@
 // Directory.
 TEST(Align, Holes) {
   const std::string src = GetTestPath("holes.zip");
-  const std::string dst = GetTestPath("holes_out.zip");
+  const std::string dst = GetTempPath("holes_out.zip");
 
   int processed = process(src.c_str(), dst.c_str(), 4, true, false, 4096);
   ASSERT_EQ(0, processed);
@@ -72,7 +79,7 @@
 // Align a zip where LFH order and CD entries differ.
 TEST(Align, DifferenteOrders) {
   const std::string src = GetTestPath("diffOrders.zip");
-  const std::string dst = GetTestPath("diffOrders_out.zip");
+  const std::string dst = GetTempPath("diffOrders_out.zip");
 
   int processed = process(src.c_str(), dst.c_str(), 4, true, false, 4096);
   ASSERT_EQ(0, processed);