diff --git a/core/Makefile b/core/Makefile
index 07d705e..9dfdcd0 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -4173,7 +4173,7 @@
 
 INSTALLED_PVMFWIMAGE_TARGET := $(PRODUCT_OUT)/pvmfw.img
 INSTALLED_PVMFW_EMBEDDED_AVBKEY_TARGET := $(PRODUCT_OUT)/pvmfw_embedded.avbpubkey
-INSTALLED_PVMFW_BINARY_TARGET := $(call module-installed-files,pvmfw_bin)
+INSTALLED_PVMFW_BINARY_TARGET := $(call module-target-built-files,pvmfw_bin)
 INTERNAL_PVMFWIMAGE_FILES := $(call module-target-built-files,pvmfw_img)
 INTERNAL_PVMFW_EMBEDDED_AVBKEY := $(call module-target-built-files,pvmfw_embedded_key)
 INTERNAL_PVMFW_SYMBOL := $(TARGET_OUT_EXECUTABLES_UNSTRIPPED)/pvmfw
@@ -5323,6 +5323,7 @@
   toybox \
   tune2fs \
   unpack_bootimg \
+  update_device \
   update_host_simulator \
   validate_target_files \
   verity_signer \
@@ -6889,6 +6890,14 @@
 ifeq (,$(TARGET_BUILD_UNBUNDLED))
   $(JACOCO_REPORT_CLASSES_ALL): $(INTERNAL_ALLIMAGES_FILES)
 endif
+
+# This is not ideal, but it is difficult to correctly figure out the actual jacoco report
+# jars we need to add here as dependencies, so we add the device-tests as a dependency when
+# the env variable is set and this should guarantee thaat all the jacoco report jars are ready
+# when we package the final report jar here.
+ifeq ($(JACOCO_PACKAGING_INCLUDE_DEVICE_TESTS),true)
+  $(JACOCO_REPORT_CLASSES_ALL): $(COMPATIBILITY.device-tests.FILES)
+endif
 endif # EMMA_INSTRUMENT=true
 
 
@@ -7118,6 +7127,7 @@
 	PATH=$(INTERNAL_USERIMAGES_BINARY_PATHS):$(dir $(ZIP2ZIP)):$$PATH \
 	    $(IMG_FROM_TARGET_FILES) \
 	        --additional IMAGES/VerifiedBootParams.textproto:VerifiedBootParams.textproto \
+	        --build_super_image $(BUILD_SUPER_IMAGE) \
 	        $(BUILT_TARGET_FILES_PACKAGE) $@
 
 $(call declare-1p-container,$(INTERNAL_UPDATE_PACKAGE_TARGET),)
diff --git a/core/config.mk b/core/config.mk
index e919be3..2a30dd9 100644
--- a/core/config.mk
+++ b/core/config.mk
@@ -439,19 +439,14 @@
     ifeq ($(TARGET_ARCH),arm64)
       TARGET_MAX_PAGE_SIZE_SUPPORTED := 65536
     endif
-    ifeq ($(TARGET_ARCH),arm)
-      TARGET_MAX_PAGE_SIZE_SUPPORTED := 65536
-    endif
   endif
 endif
 .KATI_READONLY := TARGET_MAX_PAGE_SIZE_SUPPORTED
 
-# Check that TARGET_MAX_PAGE_SIZE_SUPPORTED is greater than 4096 only for ARM arch.
+# Only arm64 arch supports TARGET_MAX_PAGE_SIZE_SUPPORTED greater than 4096.
 ifneq ($(TARGET_MAX_PAGE_SIZE_SUPPORTED),4096)
   ifneq ($(TARGET_ARCH),arm64)
-    ifneq ($(TARGET_ARCH),arm)
-      $(error TARGET_MAX_PAGE_SIZE_SUPPORTED=$(TARGET_MAX_PAGE_SIZE_SUPPORTED) is greater than 4096. Only supported in ARM arch)
-    endif
+    $(error TARGET_MAX_PAGE_SIZE_SUPPORTED=$(TARGET_MAX_PAGE_SIZE_SUPPORTED) is greater than 4096. Only supported in arm64 arch)
   endif
 endif
 
diff --git a/core/definitions.mk b/core/definitions.mk
index 462c968..8a24f4c 100644
--- a/core/definitions.mk
+++ b/core/definitions.mk
@@ -1547,10 +1547,10 @@
 #
 # You must call this with $(eval).
 define define-aidl-java-rule
-define-aidl-java-rule-src := $(patsubst %.aidl,%.java,$(subst ../,dotdot/,$(addprefix $(2)/,$(1))))
-$$(define-aidl-java-rule-src) : $(call clean-path,$(LOCAL_PATH)/$(1)) $(AIDL)
+define_aidl_java_rule_src := $(patsubst %.aidl,%.java,$(subst ../,dotdot/,$(addprefix $(2)/,$(1))))
+$$(define_aidl_java_rule_src) : $(call clean-path,$(LOCAL_PATH)/$(1)) $(AIDL)
 	$$(transform-aidl-to-java)
-$(3) += $$(define-aidl-java-rule-src)
+$(3) += $$(define_aidl_java_rule_src)
 endef
 
 ## Given a .aidl file path generate the rule to compile it a .cpp file.
@@ -1560,10 +1560,10 @@
 #
 # You must call this with $(eval).
 define define-aidl-cpp-rule
-define-aidl-cpp-rule-src := $(patsubst %.aidl,%$(LOCAL_CPP_EXTENSION),$(subst ../,dotdot/,$(addprefix $(2)/,$(1))))
-$$(define-aidl-cpp-rule-src) : $(call clean-path,$(LOCAL_PATH)/$(1)) $(AIDL_CPP)
+define_aidl_cpp_rule_src := $(patsubst %.aidl,%$(LOCAL_CPP_EXTENSION),$(subst ../,dotdot/,$(addprefix $(2)/,$(1))))
+$$(define_aidl_cpp_rule_src) : $(call clean-path,$(LOCAL_PATH)/$(1)) $(AIDL_CPP)
 	$$(transform-aidl-to-cpp)
-$(3) += $$(define-aidl-cpp-rule-src)
+$(3) += $$(define_aidl_cpp_rule_src)
 endef
 
 ###########################################################
@@ -1585,10 +1585,10 @@
 #
 # You must call this with $(eval).
 define define-vts-cpp-rule
-define-vts-cpp-rule-src := $(patsubst %.vts,%$(LOCAL_CPP_EXTENSION),$(subst ../,dotdot/,$(addprefix $(2)/,$(1))))
-$$(define-vts-cpp-rule-src) : $(LOCAL_PATH)/$(1) $(VTSC)
+define_vts_cpp_rule_src := $(patsubst %.vts,%$(LOCAL_CPP_EXTENSION),$(subst ../,dotdot/,$(addprefix $(2)/,$(1))))
+$$(define_vts_cpp_rule_src) : $(LOCAL_PATH)/$(1) $(VTSC)
 	$$(transform-vts-to-cpp)
-$(3) += $$(define-vts-cpp-rule-src)
+$(3) += $$(define_vts_cpp_rule_src)
 endef
 
 ###########################################################
@@ -3203,8 +3203,9 @@
 define copy-vintf-manifest-checked
 $(2): $(1) $(HOST_OUT_EXECUTABLES)/assemble_vintf
 	@echo "Copy xml: $$@"
-	$(hide) $(HOST_OUT_EXECUTABLES)/assemble_vintf -i $$< >/dev/null  # Don't print the xml file to stdout.
-	$$(copy-file-to-target)
+	$(hide) mkdir -p "$$(dir $$@)"
+	$(hide) VINTF_IGNORE_TARGET_FCM_VERSION=true\
+		$(HOST_OUT_EXECUTABLES)/assemble_vintf -i $$< -o $$@
 endef
 
 # Copies many vintf manifest files checked.
diff --git a/core/main.mk b/core/main.mk
index 48b4b5e..5738cdb 100644
--- a/core/main.mk
+++ b/core/main.mk
@@ -1717,7 +1717,7 @@
     # If they used the magic goal "all" then build all apps in the source tree.
     unbundled_build_modules := $(foreach m,$(sort $(ALL_MODULES)),$(if $(filter APPS,$(ALL_MODULES.$(m).CLASS)),$(m)))
   else
-    unbundled_build_modules := $(TARGET_BUILD_APPS)
+    unbundled_build_modules := $(sort $(TARGET_BUILD_APPS))
   endif
 
   # Dist the installed files if they exist.
@@ -2195,7 +2195,9 @@
 	  $(eval _is_fsverity_build_manifest_apk := $(if $(findstring $f,$(ALL_FSVERITY_BUILD_MANIFEST_APK)),Y)) \
 	  $(eval _is_linker_config := $(if $(findstring $f,$(SYSTEM_LINKER_CONFIG) $(vendor_linker_config_file)),Y)) \
 	  $(eval _is_partition_compat_symlink := $(if $(findstring $f,$(PARTITION_COMPAT_SYMLINKS)),Y)) \
-	  $(eval _is_platform_generated := $(_is_build_prop)$(_is_notice_file)$(_is_dexpreopt_image_profile)$(_is_product_system_other_avbkey)$(_is_event_log_tags_file)$(_is_system_other_odex_marker)$(_is_kernel_modules_blocklist)$(_is_fsverity_build_manifest_apk)$(_is_linker_config)$(_is_partition_compat_symlink)) \
+	  $(eval _is_flags_file := $(if $(findstring $f, $(ALL_FLAGS_FILES)),Y)) \
+	  $(eval _is_rootdir_symlink := $(if $(findstring $f, $(ALL_ROOTDIR_SYMLINKS)),Y)) \
+	  $(eval _is_platform_generated := $(_is_build_prop)$(_is_notice_file)$(_is_dexpreopt_image_profile)$(_is_product_system_other_avbkey)$(_is_event_log_tags_file)$(_is_system_other_odex_marker)$(_is_kernel_modules_blocklist)$(_is_fsverity_build_manifest_apk)$(_is_linker_config)$(_is_partition_compat_symlink)$(_is_flags_file)$(_is_rootdir_symlink)) \
 	  $(eval _static_libs := $(ALL_INSTALLED_FILES.$f.STATIC_LIBRARIES)) \
 	  $(eval _whole_static_libs := $(ALL_INSTALLED_FILES.$f.WHOLE_STATIC_LIBRARIES)) \
 	  $(foreach l,$(_static_libs),$(eval _all_static_libs += $l:$(strip $(sort $(ALL_MODULES.$l.PATH))):$(strip $(sort $(ALL_MODULES.$l.SOONG_MODULE_TYPE))):$(ALL_STATIC_LIBRARIES.$l.BUILT_FILE))) \
diff --git a/core/packaging/flags.mk b/core/packaging/flags.mk
index 4b692be..cb43741 100644
--- a/core/packaging/flags.mk
+++ b/core/packaging/flags.mk
@@ -107,6 +107,7 @@
 		))
 
 ALL_DEFAULT_INSTALLED_MODULES += $(required_flags_files)
+ALL_FLAGS_FILES := $(required_flags_files)
 
 # TODO: Remove
 .PHONY: flag-files
diff --git a/core/proguard_basic_keeps.flags b/core/proguard_basic_keeps.flags
index b59527a..f6b34b8 100644
--- a/core/proguard_basic_keeps.flags
+++ b/core/proguard_basic_keeps.flags
@@ -10,6 +10,12 @@
 # and RuntimeVisibleTypeAnnotations, as well as associated defaults.
 -keepattributes RuntimeVisible*Annotation*,AnnotationDefault
 
+# With R8 full mode, certain attributes are only kept when matched with an
+# explicit keep rule for that target, even with a global -keepattributes rule.
+# As such, we can add the global keep rule here with minimal cost while
+# simplifying incremental development.
+-keepattributes Exceptions
+
 # For enumeration classes, see http://proguard.sourceforge.net/manual/examples.html#enumerations
 -keepclassmembers enum * {
     public static **[] values();
diff --git a/core/release_config.mk b/core/release_config.mk
index b72ee89..4f9daaf 100644
--- a/core/release_config.mk
+++ b/core/release_config.mk
@@ -76,6 +76,12 @@
 ifeq ($(filter $(_all_release_configs), $(TARGET_RELEASE)),)
     $(error No release config found for TARGET_RELEASE: $(TARGET_RELEASE). Available releases are: $(_all_release_configs))
 else
+# TODO(b/294161396): Remove this logic
+ifeq ($(TARGET_RELEASE),next)
+ifndef TESTING_TARGET_RELEASE_NEXT
+   $(error "next" releases are not supported yet.  b/294161396)
+endif
+endif
     # Choose flag files
     # Don't sort this, use it in the order they gave us.
     flag_value_files := $(_all_release_configs.$(TARGET_RELEASE).FILES)
diff --git a/core/rust_device_benchmark_config_template.xml b/core/rust_device_benchmark_config_template.xml
index 2055df2..541630c 100644
--- a/core/rust_device_benchmark_config_template.xml
+++ b/core/rust_device_benchmark_config_template.xml
@@ -16,7 +16,7 @@
 <!-- This test config file is auto-generated. -->
 <configuration description="Config to run {MODULE} rust benchmark tests.">
     <target_preparer class="com.android.tradefed.targetprep.PushFilePreparer">
-        <option name="cleanup" value="false" />
+        <option name="cleanup" value="true" />
         <option name="push" value="{MODULE}->/data/local/tmp/{MODULE}" />
     </target_preparer>
 
diff --git a/core/soong_config.mk b/core/soong_config.mk
index bd6cfbb..26998ed 100644
--- a/core/soong_config.mk
+++ b/core/soong_config.mk
@@ -151,7 +151,7 @@
 $(call add_json_bool, Malloc_pattern_fill_contents,      $(MALLOC_PATTERN_FILL_CONTENTS))
 $(call add_json_str,  Override_rs_driver,                $(OVERRIDE_RS_DRIVER))
 $(call add_json_str,  DeviceMaxPageSizeSupported,        $(TARGET_MAX_PAGE_SIZE_SUPPORTED))
-$(call add_json_bool, Device_page_size_agnostic,         $(filter true,$(TARGET_PAGE_SIZE_AGNOSTIC)))
+$(call add_json_bool, DevicePageSizeAgnostic,            $(filter true,$(TARGET_PAGE_SIZE_AGNOSTIC)))
 
 $(call add_json_bool, UncompressPrivAppDex,              $(call invert_bool,$(filter true,$(DONT_UNCOMPRESS_PRIV_APPS_DEXS))))
 $(call add_json_list, ModulesLoadedByPrivilegedModules,  $(PRODUCT_LOADED_BY_PRIVILEGED_MODULES))
@@ -320,6 +320,7 @@
 
 $(call add_json_str, ReleaseVersion,    $(_RELEASE_VERSION))
 $(call add_json_list, ReleaseAconfigValueSets,    $(RELEASE_ACONFIG_VALUE_SETS))
+$(call add_json_str, ReleaseAconfigFlagDefaultPermission,    $(RELEASE_ACONFIG_FLAG_DEFAULT_PERMISSION))
 
 $(call add_json_bool, KeepVndk, $(filter true,$(KEEP_VNDK)))
 
diff --git a/core/version_defaults.mk b/core/version_defaults.mk
index e288779..99d69d1 100644
--- a/core/version_defaults.mk
+++ b/core/version_defaults.mk
@@ -52,6 +52,8 @@
 
 # These are the current development codenames, if the build is not a final
 # release build.  If this is a final release build, it is simply "REL".
+# Note that this may be overridden by RELEASE_VERSION_CODENAME_REL in
+# version_util.mk.
 PLATFORM_VERSION_CODENAME.UP1A := UpsideDownCake
 PLATFORM_VERSION_CODENAME.VP1A := VanillaIceCream
 
diff --git a/core/version_util.mk b/core/version_util.mk
index d3fcdc2..457f0f7 100644
--- a/core/version_util.mk
+++ b/core/version_util.mk
@@ -56,6 +56,12 @@
 # unreleased API level targetable by this branch, not just those that are valid
 # lunch targets for this branch.
 
+# Release config flag to override the current version to REL.  Note that the
+# codename can also be locked to REL by setting it in versino_defaults.mk.
+ifneq ($(RELEASE_PLATFORM_VERSION_CODENAME_REL),)
+  PLATFORM_VERSION_CODENAME.$(TARGET_PLATFORM_VERSION) := REL
+endif
+
 PLATFORM_VERSION_CODENAME := $(PLATFORM_VERSION_CODENAME.$(TARGET_PLATFORM_VERSION))
 ifndef PLATFORM_VERSION_CODENAME
   # PLATFORM_VERSION_CODENAME falls back to TARGET_PLATFORM_VERSION
diff --git a/tools/aconfig/Android.bp b/tools/aconfig/Android.bp
index a4ea7f4..296091d 100644
--- a/tools/aconfig/Android.bp
+++ b/tools/aconfig/Android.bp
@@ -101,7 +101,7 @@
 android_test {
     name: "aconfig.test.java",
     srcs: [
-        "tests/**/*.java",
+        "tests/AconfigTest.java",
     ],
     manifest: "tests/AndroidManifest.xml",
     certificate: "platform",
@@ -113,6 +113,25 @@
     test_suites: ["device-tests"],
 }
 
+java_aconfig_library {
+    name: "aconfig_host_test_java_library",
+    aconfig_declarations: "aconfig.test.flags",
+    host_supported: true,
+    test: true,
+}
+
+java_test_host {
+    name: "AconfigJavaHostTest",
+    srcs: [
+        "tests/AconfigHostTest.java",
+    ],
+    static_libs: [
+        "aconfig_host_test_java_library",
+        "junit",
+    ],
+    test_suites: ["general-tests"],
+}
+
 // integration tests: C++
 
 cc_aconfig_library {
@@ -133,3 +152,36 @@
         "server_configurable_flags",
     ],
 }
+
+rust_aconfig_library {
+    name: "libaconfig_test_rust_library",
+    crate_name: "aconfig_test_rust_library",
+    aconfig_declarations: "aconfig.test.flags",
+}
+
+rust_test {
+    name: "aconfig.prod_mode.test.rust",
+    srcs: [
+        "tests/aconfig_prod_mode_test.rs"
+    ],
+    rustlibs: [
+        "libaconfig_test_rust_library",
+    ],
+}
+
+rust_aconfig_library {
+    name: "libaconfig_test_rust_library_with_test_mode",
+    crate_name: "aconfig_test_rust_library",
+    aconfig_declarations: "aconfig.test.flags",
+    test: true,
+}
+
+rust_test {
+    name: "aconfig.test_mode.test.rust",
+    srcs: [
+        "tests/aconfig_test_mode_test.rs"
+    ],
+    rustlibs: [
+        "libaconfig_test_rust_library_with_test_mode",
+    ],
+}
\ No newline at end of file
diff --git a/tools/aconfig/src/codegen_cpp.rs b/tools/aconfig/src/codegen_cpp.rs
index 530af49..30e564a 100644
--- a/tools/aconfig/src/codegen_cpp.rs
+++ b/tools/aconfig/src/codegen_cpp.rs
@@ -289,7 +289,7 @@
 
             virtual bool disabled_rw() override {
                 return server_configurable_flags::GetServerConfigurableFlag(
-                    "aconfig_test",
+                    "aconfig_flags.aconfig_test",
                     "com.android.aconfig.test.disabled_rw",
                     "false") == "true";
             }
@@ -300,7 +300,7 @@
 
             virtual bool enabled_rw() override {
                 return server_configurable_flags::GetServerConfigurableFlag(
-                    "aconfig_test",
+                    "aconfig_flags.aconfig_test",
                     "com.android.aconfig.test.enabled_rw",
                     "true") == "true";
             }
@@ -363,7 +363,7 @@
                       return it->second;
                 } else {
                   return server_configurable_flags::GetServerConfigurableFlag(
-                      "aconfig_test",
+                      "aconfig_flags.aconfig_test",
                       "com.android.aconfig.test.disabled_rw",
                       "false") == "true";
                 }
@@ -392,7 +392,7 @@
                       return it->second;
                 } else {
                   return server_configurable_flags::GetServerConfigurableFlag(
-                      "aconfig_test",
+                      "aconfig_flags.aconfig_test",
                       "com.android.aconfig.test.enabled_rw",
                       "true") == "true";
                 }
diff --git a/tools/aconfig/src/codegen_java.rs b/tools/aconfig/src/codegen_java.rs
index 8ab6ffa..2c9dcf5 100644
--- a/tools/aconfig/src/codegen_java.rs
+++ b/tools/aconfig/src/codegen_java.rs
@@ -47,9 +47,13 @@
         "FeatureFlags.java",
         include_str!("../templates/FeatureFlags.java.template"),
     )?;
+    template.add_template(
+        "FakeFeatureFlagsImpl.java",
+        include_str!("../templates/FakeFeatureFlagsImpl.java.template"),
+    )?;
 
     let path: PathBuf = package.split('.').collect();
-    ["Flags.java", "FeatureFlagsImpl.java", "FeatureFlags.java"]
+    ["Flags.java", "FeatureFlags.java", "FeatureFlagsImpl.java", "FakeFeatureFlagsImpl.java"]
         .iter()
         .map(|file| {
             Ok(OutputFile {
@@ -112,14 +116,14 @@
     use super::*;
     use std::collections::HashMap;
 
-    const EXPECTED_FEATUREFLAGS_CONTENT: &str = r#"
+    const EXPECTED_FEATUREFLAGS_COMMON_CONTENT: &str = r#"
     package com.android.aconfig.test;
     public interface FeatureFlags {
         boolean disabledRo();
         boolean disabledRw();
         boolean enabledRo();
         boolean enabledRw();
-    }"#;
+    "#;
 
     const EXPECTED_FLAG_COMMON_CONTENT: &str = r#"
     package com.android.aconfig.test;
@@ -143,6 +147,29 @@
         }
     "#;
 
+    const EXPECTED_METHOD_NOT_IMPL_COMMON_CONTENT: &str = r#"
+        @Override
+        public boolean disabledRo() {
+            throw new UnsupportedOperationException(
+                "Method is not implemented.");
+        }
+        @Override
+        public boolean disabledRw() {
+            throw new UnsupportedOperationException(
+                "Method is not implemented.");
+        }
+        @Override
+        public boolean enabledRo() {
+            throw new UnsupportedOperationException(
+                "Method is not implemented.");
+        }
+        @Override
+        public boolean enabledRw() {
+            throw new UnsupportedOperationException(
+                "Method is not implemented.");
+        }
+    "#;
+
     #[test]
     fn test_generate_java_code_production() {
         let parsed_flags = crate::test::parse_test_flags();
@@ -152,11 +179,22 @@
             CodegenMode::Production,
         )
         .unwrap();
+        let expect_featureflags_content = EXPECTED_FEATUREFLAGS_COMMON_CONTENT.to_string()
+            + r#"
+        }"#;
         let expect_flags_content = EXPECTED_FLAG_COMMON_CONTENT.to_string()
             + r#"
             private static FeatureFlags FEATURE_FLAGS = new FeatureFlagsImpl();
         }"#;
-        let expected_featureflagsimpl_content = r#"
+        let expect_fakefeatureflagsimpl_content = r#"
+        package com.android.aconfig.test;
+        public class FakeFeatureFlagsImpl implements FeatureFlags {"#
+            .to_owned()
+            + EXPECTED_METHOD_NOT_IMPL_COMMON_CONTENT
+            + r#"
+        }
+        "#;
+        let expect_featureflagsimpl_content = r#"
         package com.android.aconfig.test;
         import android.provider.DeviceConfig;
         public final class FeatureFlagsImpl implements FeatureFlags {
@@ -188,8 +226,12 @@
         "#;
         let mut file_set = HashMap::from([
             ("com/android/aconfig/test/Flags.java", expect_flags_content.as_str()),
-            ("com/android/aconfig/test/FeatureFlagsImpl.java", expected_featureflagsimpl_content),
-            ("com/android/aconfig/test/FeatureFlags.java", EXPECTED_FEATUREFLAGS_CONTENT),
+            ("com/android/aconfig/test/FeatureFlagsImpl.java", expect_featureflagsimpl_content),
+            ("com/android/aconfig/test/FeatureFlags.java", expect_featureflags_content.as_str()),
+            (
+                "com/android/aconfig/test/FakeFeatureFlagsImpl.java",
+                expect_fakefeatureflagsimpl_content.as_str(),
+            ),
         ]);
 
         for file in generated_files {
@@ -219,24 +261,47 @@
             CodegenMode::Test,
         )
         .unwrap();
+        let expect_featureflags_content = EXPECTED_FEATUREFLAGS_COMMON_CONTENT.to_string()
+            + r#"
+            public void setFlag(String flagName, boolean value);
+            public void resetAll();
+        }"#;
         let expect_flags_content = EXPECTED_FLAG_COMMON_CONTENT.to_string()
             + r#"
-            public static void setFeatureFlagsImpl(FeatureFlags featureFlags) {
+            public static void setFeatureFlags(FeatureFlags featureFlags) {
                 Flags.FEATURE_FLAGS = featureFlags;
             }
-            public static void unsetFeatureFlagsImpl() {
+            public static void unsetFeatureFlags() {
                 Flags.FEATURE_FLAGS = null;
             }
             private static FeatureFlags FEATURE_FLAGS;
         }
         "#;
-        let expected_featureflagsimpl_content = r#"
+        let expect_featureflagsimpl_content = r#"
+        package com.android.aconfig.test;
+        public final class FeatureFlagsImpl implements FeatureFlags {"#
+            .to_owned()
+            + EXPECTED_METHOD_NOT_IMPL_COMMON_CONTENT
+            + r#"
+            @Override
+            public void setFlag(String flagName, boolean value) {
+                throw new UnsupportedOperationException(
+                    "Method is not implemented.");
+            }
+            @Override
+            public void resetAll() {
+                throw new UnsupportedOperationException(
+                    "Method is not implemented.");
+            }
+        }
+        "#;
+        let expect_fakefeatureflagsimpl_content = r#"
         package com.android.aconfig.test;
         import static java.util.stream.Collectors.toMap;
         import java.util.HashMap;
         import java.util.Map;
         import java.util.stream.Stream;
-        public final class FeatureFlagsImpl implements FeatureFlags {
+        public class FakeFeatureFlagsImpl implements FeatureFlags {
             @Override
             public boolean disabledRo() {
                 return getFlag(Flags.FLAG_DISABLED_RO);
@@ -253,12 +318,14 @@
             public boolean enabledRw() {
                 return getFlag(Flags.FLAG_ENABLED_RW);
             }
+            @Override
             public void setFlag(String flagName, boolean value) {
                 if (!this.mFlagMap.containsKey(flagName)) {
                     throw new IllegalArgumentException("no such flag" + flagName);
                 }
                 this.mFlagMap.put(flagName, value);
             }
+            @Override
             public void resetAll() {
                 for (Map.Entry entry : mFlagMap.entrySet()) {
                     entry.setValue(null);
@@ -284,10 +351,18 @@
                 );
         }
         "#;
+
         let mut file_set = HashMap::from([
             ("com/android/aconfig/test/Flags.java", expect_flags_content.as_str()),
-            ("com/android/aconfig/test/FeatureFlagsImpl.java", expected_featureflagsimpl_content),
-            ("com/android/aconfig/test/FeatureFlags.java", EXPECTED_FEATUREFLAGS_CONTENT),
+            ("com/android/aconfig/test/FeatureFlags.java", expect_featureflags_content.as_str()),
+            (
+                "com/android/aconfig/test/FeatureFlagsImpl.java",
+                expect_featureflagsimpl_content.as_str(),
+            ),
+            (
+                "com/android/aconfig/test/FakeFeatureFlagsImpl.java",
+                expect_fakefeatureflagsimpl_content,
+            ),
         ]);
 
         for file in generated_files {
diff --git a/tools/aconfig/src/codegen_rust.rs b/tools/aconfig/src/codegen_rust.rs
index 053cebc..0234eb2 100644
--- a/tools/aconfig/src/codegen_rust.rs
+++ b/tools/aconfig/src/codegen_rust.rs
@@ -103,7 +103,7 @@
     /// query flag disabled_rw
     pub fn disabled_rw(&self) -> bool {
         flags_rust::GetServerConfigurableFlag(
-            "aconfig_test",
+            "aconfig_flags.aconfig_test",
             "com.android.aconfig.test.disabled_rw",
             "false") == "true"
     }
@@ -116,7 +116,7 @@
     /// query flag enabled_rw
     pub fn enabled_rw(&self) -> bool {
         flags_rust::GetServerConfigurableFlag(
-            "aconfig_test",
+            "aconfig_flags.aconfig_test",
             "com.android.aconfig.test.enabled_rw",
             "true") == "true"
     }
@@ -178,7 +178,7 @@
     pub fn disabled_rw(&self) -> bool {
         self.overrides.get("disabled_rw").copied().unwrap_or(
             flags_rust::GetServerConfigurableFlag(
-                "aconfig_test",
+                "aconfig_flags.aconfig_test",
                 "com.android.aconfig.test.disabled_rw",
                 "false") == "true"
         )
@@ -205,7 +205,7 @@
     pub fn enabled_rw(&self) -> bool {
         self.overrides.get("enabled_rw").copied().unwrap_or(
             flags_rust::GetServerConfigurableFlag(
-                "aconfig_test",
+                "aconfig_flags.aconfig_test",
                 "com.android.aconfig.test.enabled_rw",
                 "true") == "true"
         )
diff --git a/tools/aconfig/src/commands.rs b/tools/aconfig/src/commands.rs
index bd09e24..ab5b0f2 100644
--- a/tools/aconfig/src/commands.rs
+++ b/tools/aconfig/src/commands.rs
@@ -52,10 +52,15 @@
     pub contents: Vec<u8>,
 }
 
-const DEFAULT_FLAG_STATE: ProtoFlagState = ProtoFlagState::DISABLED;
-const DEFAULT_FLAG_PERMISSION: ProtoFlagPermission = ProtoFlagPermission::READ_WRITE;
+pub const DEFAULT_FLAG_STATE: ProtoFlagState = ProtoFlagState::DISABLED;
+pub const DEFAULT_FLAG_PERMISSION: ProtoFlagPermission = ProtoFlagPermission::READ_WRITE;
 
-pub fn parse_flags(package: &str, declarations: Vec<Input>, values: Vec<Input>) -> Result<Vec<u8>> {
+pub fn parse_flags(
+    package: &str,
+    declarations: Vec<Input>,
+    values: Vec<Input>,
+    default_permission: ProtoFlagPermission,
+) -> Result<Vec<u8>> {
     let mut parsed_flags = ProtoParsedFlags::new();
 
     for mut input in declarations {
@@ -86,11 +91,11 @@
             parsed_flag.set_description(flag_declaration.take_description());
             parsed_flag.bug.append(&mut flag_declaration.bug);
             parsed_flag.set_state(DEFAULT_FLAG_STATE);
-            parsed_flag.set_permission(DEFAULT_FLAG_PERMISSION);
+            parsed_flag.set_permission(default_permission);
             let mut tracepoint = ProtoTracepoint::new();
             tracepoint.set_source(input.source.clone());
             tracepoint.set_state(DEFAULT_FLAG_STATE);
-            tracepoint.set_permission(DEFAULT_FLAG_PERMISSION);
+            tracepoint.set_permission(default_permission);
             parsed_flag.trace.push(tracepoint);
 
             // verify ParsedFlag looks reasonable
@@ -328,6 +333,36 @@
     }
 
     #[test]
+    fn test_parse_flags_setting_default() {
+        let first_flag = r#"
+        package: "com.first"
+        flag {
+            name: "first"
+            namespace: "first_ns"
+            description: "This is the description of the first flag."
+            bug: "123"
+        }
+        "#;
+        let declaration =
+            vec![Input { source: "momery".to_string(), reader: Box::new(first_flag.as_bytes()) }];
+        let value: Vec<Input> = vec![];
+
+        let flags_bytes = crate::commands::parse_flags(
+            "com.first",
+            declaration,
+            value,
+            ProtoFlagPermission::READ_ONLY,
+        )
+        .unwrap();
+        let parsed_flags =
+            crate::protos::parsed_flags::try_from_binary_proto(&flags_bytes).unwrap();
+        assert_eq!(1, parsed_flags.parsed_flag.len());
+        let parsed_flag = parsed_flags.parsed_flag.first().unwrap();
+        assert_eq!(ProtoFlagState::DISABLED, parsed_flag.state());
+        assert_eq!(ProtoFlagPermission::READ_ONLY, parsed_flag.permission());
+    }
+
+    #[test]
     fn test_create_device_config_defaults() {
         let input = parse_test_flags_as_input();
         let bytes = create_device_config_defaults(input).unwrap();
diff --git a/tools/aconfig/src/main.rs b/tools/aconfig/src/main.rs
index 920b761..84073f7 100644
--- a/tools/aconfig/src/main.rs
+++ b/tools/aconfig/src/main.rs
@@ -44,6 +44,14 @@
                 .arg(Arg::new("package").long("package").required(true))
                 .arg(Arg::new("declarations").long("declarations").action(ArgAction::Append))
                 .arg(Arg::new("values").long("values").action(ArgAction::Append))
+                .arg(
+                    Arg::new("default-permission")
+                        .long("default-permission")
+                        .value_parser(protos::flag_permission::parse_from_str)
+                        .default_value(protos::flag_permission::to_string(
+                            &commands::DEFAULT_FLAG_PERMISSION,
+                        )),
+                )
                 .arg(Arg::new("cache").long("cache").required(true)),
         )
         .subcommand(
@@ -161,7 +169,9 @@
             let package = get_required_arg::<String>(sub_matches, "package")?;
             let declarations = open_zero_or_more_files(sub_matches, "declarations")?;
             let values = open_zero_or_more_files(sub_matches, "values")?;
-            let output = commands::parse_flags(package, declarations, values)
+            let default_permission =
+                get_required_arg::<protos::ProtoFlagPermission>(sub_matches, "default-permission")?;
+            let output = commands::parse_flags(package, declarations, values, *default_permission)
                 .context("failed to create cache")?;
             let path = get_required_arg::<String>(sub_matches, "cache")?;
             write_output_to_file_or_stdout(path, &output)?;
diff --git a/tools/aconfig/src/protos.rs b/tools/aconfig/src/protos.rs
index 2ab6e05..c3911e5 100644
--- a/tools/aconfig/src/protos.rs
+++ b/tools/aconfig/src/protos.rs
@@ -156,6 +156,26 @@
     }
 }
 
+pub mod flag_permission {
+    use super::*;
+    use anyhow::bail;
+
+    pub fn parse_from_str(permission: &str) -> Result<ProtoFlagPermission> {
+        match permission.to_ascii_lowercase().as_str() {
+            "read_write" => Ok(ProtoFlagPermission::READ_WRITE),
+            "read_only" => Ok(ProtoFlagPermission::READ_ONLY),
+            _ => bail!("Permission needs to be read_only or read_write."),
+        }
+    }
+
+    pub fn to_string(permission: &ProtoFlagPermission) -> &str {
+        match permission {
+            ProtoFlagPermission::READ_WRITE => "read_write",
+            ProtoFlagPermission::READ_ONLY => "read_only",
+        }
+    }
+}
+
 pub mod tracepoint {
     use super::*;
     use anyhow::ensure;
diff --git a/tools/aconfig/src/test.rs b/tools/aconfig/src/test.rs
index 14beb93..6c27885 100644
--- a/tools/aconfig/src/test.rs
+++ b/tools/aconfig/src/test.rs
@@ -118,6 +118,7 @@
                     reader: Box::new(include_bytes!("../tests/second.values").as_slice()),
                 },
             ],
+            crate::commands::DEFAULT_FLAG_PERMISSION,
         )
         .unwrap();
         crate::protos::parsed_flags::try_from_binary_proto(&bytes).unwrap()
diff --git a/tools/aconfig/templates/FakeFeatureFlagsImpl.java.template b/tools/aconfig/templates/FakeFeatureFlagsImpl.java.template
new file mode 100644
index 0000000..dba82ef
--- /dev/null
+++ b/tools/aconfig/templates/FakeFeatureFlagsImpl.java.template
@@ -0,0 +1,61 @@
+package {package_name};
+{{ if is_test_mode }}
+import static java.util.stream.Collectors.toMap;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.stream.Stream;
+
+public class FakeFeatureFlagsImpl implements FeatureFlags \{
+{{ for item in class_elements}}
+    @Override
+    public boolean {item.method_name}() \{
+        return getFlag(Flags.FLAG_{item.flag_name_constant_suffix});
+    }
+{{ endfor}}
+    @Override
+    public void setFlag(String flagName, boolean value) \{
+        if (!this.mFlagMap.containsKey(flagName)) \{
+            throw new IllegalArgumentException("no such flag" + flagName);
+        }
+        this.mFlagMap.put(flagName, value);
+    }
+
+    @Override
+    public void resetAll() \{
+        for (Map.Entry entry : mFlagMap.entrySet()) \{
+            entry.setValue(null);
+        }
+    }
+
+    private boolean getFlag(String flagName) \{
+        Boolean value = this.mFlagMap.get(flagName);
+        if (value == null) \{
+            throw new IllegalArgumentException(flagName + " is not set");
+        }
+        return value;
+    }
+
+    private HashMap<String, Boolean> mFlagMap = Stream.of(
+            {{-for item in class_elements}}
+            Flags.FLAG_{item.flag_name_constant_suffix}{{ if not @last }},{{ endif }}
+            {{ -endfor }}
+        )
+        .collect(
+            HashMap::new,
+            (map, elem) -> map.put(elem, null),
+            HashMap::putAll
+        );
+}
+{{ else }}
+{#- Generate only stub if in prod mode #}
+public class FakeFeatureFlagsImpl implements FeatureFlags \{
+{{ for item in class_elements}}
+    @Override
+    public boolean {item.method_name}() \{
+        throw new UnsupportedOperationException(
+            "Method is not implemented.");
+    }
+{{ endfor}}
+}
+{{ endif }}
diff --git a/tools/aconfig/templates/FeatureFlags.java.template b/tools/aconfig/templates/FeatureFlags.java.template
index e0f201f..c99ccbb 100644
--- a/tools/aconfig/templates/FeatureFlags.java.template
+++ b/tools/aconfig/templates/FeatureFlags.java.template
@@ -4,4 +4,10 @@
 {{ for item in class_elements}}
     boolean {item.method_name}();
 {{ endfor }}
+
+{{ -if is_test_mode }}
+    public void setFlag(String flagName, boolean value);
+
+    public void resetAll();
+{{ -endif }}
 }
diff --git a/tools/aconfig/templates/FeatureFlagsImpl.java.template b/tools/aconfig/templates/FeatureFlagsImpl.java.template
index 082d476..7e1eb15 100644
--- a/tools/aconfig/templates/FeatureFlagsImpl.java.template
+++ b/tools/aconfig/templates/FeatureFlagsImpl.java.template
@@ -1,65 +1,44 @@
 package {package_name};
-{{ -if is_test_mode }}
-import static java.util.stream.Collectors.toMap;
-
-import java.util.HashMap;
-import java.util.Map;
-import java.util.stream.Stream;
-{{ else}}
+{{ if not is_test_mode }}
 {{ if is_read_write- }}
 import android.provider.DeviceConfig;
-{{ -endif- }}
 {{ endif }}
 public final class FeatureFlagsImpl implements FeatureFlags \{
 {{ for item in class_elements}}
     @Override
     public boolean {item.method_name}() \{
-        {{ -if not is_test_mode- }}
-        {{ if item.is_read_write }}
+    {{ -if item.is_read_write }}
         return DeviceConfig.getBoolean(
             "{item.device_config_namespace}",
             "{item.device_config_flag}",
             {item.default_value}
         );
-        {{ -else }}
+    {{ else }}
         return {item.default_value};
-        {{ -endif- }}
-        {{ else }}
-        return getFlag(Flags.FLAG_{item.flag_name_constant_suffix});
-        {{ -endif }}
+    {{ endif- }}
     }
 {{ endfor- }}
-{{ if is_test_mode }}
-    public void setFlag(String flagName, boolean value) \{
-        if (!this.mFlagMap.containsKey(flagName)) \{
-            throw new IllegalArgumentException("no such flag" + flagName);
-        }
-        this.mFlagMap.put(flagName, value);
-    }
-
-    public void resetAll() \{
-        for (Map.Entry entry : mFlagMap.entrySet()) \{
-            entry.setValue(null);
-        }
-    }
-
-    private boolean getFlag(String flagName) \{
-        Boolean value = this.mFlagMap.get(flagName);
-        if (value == null) \{
-            throw new IllegalArgumentException(flagName + " is not set");
-        }
-        return value;
-    }
-
-    private HashMap<String, Boolean> mFlagMap = Stream.of(
-            {{-for item in class_elements}}
-            Flags.FLAG_{item.flag_name_constant_suffix}{{ if not @last }},{{ endif }}
-            {{ -endfor }}
-        )
-        .collect(
-            HashMap::new,
-            (map, elem) -> map.put(elem, null),
-            HashMap::putAll
-        );
-{{ -endif }}
 }
+{{ else }}
+{#- Generate only stub if in test mode #}
+public final class FeatureFlagsImpl implements FeatureFlags \{
+{{ for item in class_elements}}
+    @Override
+    public boolean {item.method_name}() \{
+        throw new UnsupportedOperationException(
+            "Method is not implemented.");
+    }
+{{ endfor- }}
+    @Override
+    public void setFlag(String flagName, boolean value) \{
+        throw new UnsupportedOperationException(
+            "Method is not implemented.");
+    }
+
+    @Override
+    public void resetAll() \{
+        throw new UnsupportedOperationException(
+            "Method is not implemented.");
+    }
+}
+{{ endif }}
diff --git a/tools/aconfig/templates/Flags.java.template b/tools/aconfig/templates/Flags.java.template
index c244b15..012eba6 100644
--- a/tools/aconfig/templates/Flags.java.template
+++ b/tools/aconfig/templates/Flags.java.template
@@ -10,11 +10,11 @@
     }
 {{ endfor }}
 {{ -if is_test_mode }}
-    public static void setFeatureFlagsImpl(FeatureFlags featureFlags) \{
+    public static void setFeatureFlags(FeatureFlags featureFlags) \{
         Flags.FEATURE_FLAGS = featureFlags;
     }
 
-    public static void unsetFeatureFlagsImpl() \{
+    public static void unsetFeatureFlags() \{
         Flags.FEATURE_FLAGS = null;
     }
 {{ endif}}
diff --git a/tools/aconfig/templates/cpp_source_file.template b/tools/aconfig/templates/cpp_source_file.template
index 289e299..f373bc6 100644
--- a/tools/aconfig/templates/cpp_source_file.template
+++ b/tools/aconfig/templates/cpp_source_file.template
@@ -23,7 +23,7 @@
             } else \{
               {{ if item.readwrite- }}
               return server_configurable_flags::GetServerConfigurableFlag(
-                  "{item.device_config_namespace}",
+                  "aconfig_flags.{item.device_config_namespace}",
                   "{item.device_config_flag}",
                   "{item.default_value}") == "true";
               {{ -else- }}
@@ -50,7 +50,7 @@
         virtual bool {item.flag_name}() override \{
             {{ if item.readwrite- }}
             return server_configurable_flags::GetServerConfigurableFlag(
-                "{item.device_config_namespace}",
+                "aconfig_flags.{item.device_config_namespace}",
                 "{item.device_config_flag}",
                 "{item.default_value}") == "true";
             {{ -else- }}
diff --git a/tools/aconfig/templates/rust_prod.template b/tools/aconfig/templates/rust_prod.template
index d518694..e22ad6f 100644
--- a/tools/aconfig/templates/rust_prod.template
+++ b/tools/aconfig/templates/rust_prod.template
@@ -10,7 +10,7 @@
     pub fn {flag.name}(&self) -> bool \{
     {{ if flag.readwrite -}}
         flags_rust::GetServerConfigurableFlag(
-          "{flag.device_config_namespace}",
+          "aconfig_flags.{flag.device_config_namespace}",
           "{flag.device_config_flag}",
           "{flag.default_value}") == "true"
     {{ -else- }}
diff --git a/tools/aconfig/templates/rust_test.template b/tools/aconfig/templates/rust_test.template
index 1e2c28a..fd1229b 100644
--- a/tools/aconfig/templates/rust_test.template
+++ b/tools/aconfig/templates/rust_test.template
@@ -15,7 +15,7 @@
         self.overrides.get("{flag.name}").copied().unwrap_or(
         {{ if flag.readwrite -}}
           flags_rust::GetServerConfigurableFlag(
-            "{flag.device_config_namespace}",
+            "aconfig_flags.{flag.device_config_namespace}",
             "{flag.device_config_flag}",
             "{flag.default_value}") == "true"
         {{ -else- }}
diff --git a/tools/aconfig/tests/AconfigHostTest.java b/tools/aconfig/tests/AconfigHostTest.java
new file mode 100644
index 0000000..29a01e3
--- /dev/null
+++ b/tools/aconfig/tests/AconfigHostTest.java
@@ -0,0 +1,88 @@
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertThrows;
+import static org.junit.Assert.assertTrue;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+
+import com.android.aconfig.test.FakeFeatureFlagsImpl;
+import com.android.aconfig.test.FeatureFlags;
+import com.android.aconfig.test.FeatureFlagsImpl;
+import com.android.aconfig.test.Flags;
+
+@RunWith(JUnit4.class)
+public final class AconfigHostTest {
+    @Test
+    public void testThrowsExceptionIfFlagNotSet() {
+        assertThrows(NullPointerException.class, () -> Flags.disabledRo());
+        FeatureFlags featureFlags = new FakeFeatureFlagsImpl();
+        assertThrows(IllegalArgumentException.class, () -> featureFlags.disabledRo());
+    }
+
+    @Test
+    public void testSetFlagInFakeFeatureFlagsImpl() {
+        FeatureFlags featureFlags = new FakeFeatureFlagsImpl();
+        featureFlags.setFlag(Flags.FLAG_ENABLED_RW, true);
+        assertTrue(featureFlags.enabledRw());
+        featureFlags.setFlag(Flags.FLAG_ENABLED_RW, false);
+        assertFalse(featureFlags.enabledRw());
+
+        //Set Flags
+        assertThrows(NullPointerException.class, () -> Flags.enabledRw());
+        Flags.setFeatureFlags(featureFlags);
+        featureFlags.setFlag(Flags.FLAG_ENABLED_RW, true);
+        assertTrue(Flags.enabledRw());
+        Flags.unsetFeatureFlags();
+    }
+
+    @Test
+    public void testSetFlagWithRandomName() {
+        FeatureFlags featureFlags = new FakeFeatureFlagsImpl();
+        assertThrows(IllegalArgumentException.class,
+            () -> featureFlags.setFlag("Randome_name", true));
+    }
+
+    @Test
+    public void testResetFlagsInFakeFeatureFlagsImpl() {
+        FeatureFlags featureFlags = new FakeFeatureFlagsImpl();
+        featureFlags.setFlag(Flags.FLAG_ENABLED_RO, true);
+        assertTrue(featureFlags.enabledRo());
+        featureFlags.resetAll();
+        assertThrows(IllegalArgumentException.class, () -> featureFlags.enabledRo());
+
+        // Set value after reset
+        featureFlags.setFlag(Flags.FLAG_ENABLED_RO, false);
+        assertFalse(featureFlags.enabledRo());
+    }
+
+    @Test
+    public void testFlagsSetFeatureFlags() {
+        FeatureFlags featureFlags = new FakeFeatureFlagsImpl();
+        featureFlags.setFlag(Flags.FLAG_ENABLED_RW, true);
+        assertThrows(NullPointerException.class, () -> Flags.enabledRw());
+        Flags.setFeatureFlags(featureFlags);
+        assertTrue(Flags.enabledRw());
+        Flags.unsetFeatureFlags();
+    }
+
+    @Test
+    public void testFlagsUnsetFeatureFlags() {
+        FeatureFlags featureFlags = new FakeFeatureFlagsImpl();
+        featureFlags.setFlag(Flags.FLAG_ENABLED_RW, true);
+        assertThrows(NullPointerException.class, () -> Flags.enabledRw());
+        Flags.setFeatureFlags(featureFlags);
+        assertTrue(Flags.enabledRw());
+
+        Flags.unsetFeatureFlags();
+        assertThrows(NullPointerException.class, () -> Flags.enabledRw());
+    }
+
+    @Test
+    public void testFeatureFlagsImplNotImpl() {
+        FeatureFlags featureFlags = new FeatureFlagsImpl();
+        assertThrows(UnsupportedOperationException.class,
+            () -> featureFlags.enabledRw());
+    }
+}
diff --git a/tools/aconfig/tests/AconfigTest.java b/tools/aconfig/tests/AconfigTest.java
index 6681f32..317289d 100644
--- a/tools/aconfig/tests/AconfigTest.java
+++ b/tools/aconfig/tests/AconfigTest.java
@@ -8,12 +8,16 @@
 import static com.android.aconfig.test.Flags.enabledRw;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertThrows;
 import static org.junit.Assert.assertTrue;
 
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.junit.runners.JUnit4;
 
+import com.android.aconfig.test.FakeFeatureFlagsImpl;
+import com.android.aconfig.test.FeatureFlags;
+
 @RunWith(JUnit4.class)
 public final class AconfigTest {
     @Test
@@ -43,4 +47,10 @@
         // (currently all flags are assigned the default READ_ONLY + DISABLED)
         assertFalse(enabledRw());
     }
+
+    @Test
+    public void testFakeFeatureFlagsImplNotImpl() {
+        FeatureFlags featureFlags = new FakeFeatureFlagsImpl();
+        assertThrows(UnsupportedOperationException.class, () -> featureFlags.enabledRw());
+    }
 }
diff --git a/tools/aconfig/tests/aconfig_prod_mode_test.rs b/tools/aconfig/tests/aconfig_prod_mode_test.rs
new file mode 100644
index 0000000..708604b
--- /dev/null
+++ b/tools/aconfig/tests/aconfig_prod_mode_test.rs
@@ -0,0 +1,8 @@
+#[test]
+fn test_flags() {
+    assert!(!aconfig_test_rust_library::disabled_ro());
+    assert!(!aconfig_test_rust_library::disabled_rw());
+    // TODO: Fix template to not default both disabled and enabled to false
+    assert!(!aconfig_test_rust_library::enabled_ro());
+    assert!(!aconfig_test_rust_library::enabled_rw());
+}
diff --git a/tools/aconfig/tests/aconfig_test_mode_test.rs b/tools/aconfig/tests/aconfig_test_mode_test.rs
new file mode 100644
index 0000000..7d40a44
--- /dev/null
+++ b/tools/aconfig/tests/aconfig_test_mode_test.rs
@@ -0,0 +1,23 @@
+#[test]
+fn test_flags() {
+    assert!(!aconfig_test_rust_library::disabled_ro());
+    assert!(!aconfig_test_rust_library::disabled_rw());
+    // TODO: Fix template to not default both disabled and enabled to false
+    assert!(!aconfig_test_rust_library::enabled_ro());
+    assert!(!aconfig_test_rust_library::enabled_rw());
+
+    aconfig_test_rust_library::set_disabled_ro(true);
+    assert!(aconfig_test_rust_library::disabled_ro());
+    aconfig_test_rust_library::set_disabled_rw(true);
+    assert!(aconfig_test_rust_library::disabled_rw());
+    aconfig_test_rust_library::set_enabled_ro(true);
+    assert!(aconfig_test_rust_library::enabled_ro());
+    aconfig_test_rust_library::set_enabled_rw(true);
+    assert!(aconfig_test_rust_library::enabled_rw());
+
+    aconfig_test_rust_library::reset_flags();
+    assert!(!aconfig_test_rust_library::disabled_ro());
+    assert!(!aconfig_test_rust_library::disabled_rw());
+    assert!(!aconfig_test_rust_library::enabled_ro());
+    assert!(!aconfig_test_rust_library::enabled_rw());
+}
diff --git a/tools/releasetools/common.py b/tools/releasetools/common.py
index 826ab1b..ec53a47 100644
--- a/tools/releasetools/common.py
+++ b/tools/releasetools/common.py
@@ -450,6 +450,10 @@
     return system_prop and system_prop.GetProp("ro.build.version.release") == "11"
 
   @property
+  def vabc_compression_param(self):
+    return self.get("virtual_ab_compression_method", "")
+
+  @property
   def vendor_api_level(self):
     vendor_prop = self.info_dict.get("vendor.build.prop")
     if not vendor_prop:
diff --git a/tools/releasetools/img_from_target_files.py b/tools/releasetools/img_from_target_files.py
index fa53ad2..5412b2a 100755
--- a/tools/releasetools/img_from_target_files.py
+++ b/tools/releasetools/img_from_target_files.py
@@ -65,6 +65,7 @@
 OPTIONS.build_super = None
 OPTIONS.sparse_userimages = None
 OPTIONS.use_fastboot_info = False
+OPTIONS.build_super_image = None
 
 def LoadOptions(input_file):
   """Loads information from input_file to OPTIONS.
@@ -174,7 +175,13 @@
   input_tmp = common.UnzipTemp(input_file)
 
   super_file = common.MakeTempFile('super_', '.img')
-  BuildSuperImage(input_tmp, super_file)
+
+  # Allow overriding the BUILD_SUPER_IMAGE binary
+  if OPTIONS.build_super_image:
+    command = [OPTIONS.build_super_image, input_tmp, super_file]
+    common.RunAndCheckOutput(command)
+  else:
+    BuildSuperImage(input_tmp, super_file)
 
   logger.info('Writing super.img to archive...')
   with zipfile.ZipFile(
@@ -231,6 +238,8 @@
       OPTIONS.bootable_only = True
     elif o == '--additional':
       OPTIONS.additional_entries.append(a)
+    elif o == '--build_super_image':
+      OPTIONS.build_super_image = a
     else:
       return False
     return True
@@ -240,6 +249,7 @@
                              extra_long_opts=[
                                  'additional=',
                                  'bootable_zip',
+                                 'build_super_image=',
                              ],
                              extra_option_handler=option_handler)
   if len(args) != 2:
diff --git a/tools/releasetools/ota_from_target_files.py b/tools/releasetools/ota_from_target_files.py
index 28943fc..56ec929 100755
--- a/tools/releasetools/ota_from_target_files.py
+++ b/tools/releasetools/ota_from_target_files.py
@@ -247,7 +247,9 @@
       older SPL.
 
   --vabc_compression_param
-      Compression algorithm to be used for VABC. Available options: gz, lz4, zstd, brotli, none
+      Compression algorithm to be used for VABC. Available options: gz, lz4, zstd, brotli, none. 
+      Compression level can be specified by appending ",$LEVEL" to option. 
+      e.g. --vabc_compression_param=gz,9 specifies level 9 compression with gz algorithm
 
   --security_patch_level
       Override the security patch level in target files
@@ -272,7 +274,7 @@
 import care_map_pb2
 import common
 import ota_utils
-from ota_utils import (UNZIP_PATTERN, FinalizeMetadata, GetPackageMetadata,
+from ota_utils import (VABC_COMPRESSION_PARAM_SUPPORT, FinalizeMetadata, GetPackageMetadata,
                        PayloadGenerator, SECURITY_PATCH_LEVEL_PROP_NAME, ExtractTargetFiles, CopyTargetFilesDir)
 from common import DoesInputFileContain, IsSparseImage
 import target_files_diff
@@ -870,6 +872,10 @@
     if not source_info.is_vabc or not target_info.is_vabc:
       logger.info("Either source or target does not support VABC, disabling.")
       OPTIONS.disable_vabc = True
+    if source_info.vabc_compression_param != target_info.vabc_compression_param:
+      logger.info("Source build and target build use different compression methods {} vs {}, default to source builds parameter {}".format(
+          source_info.vabc_compression_param, target_info.vabc_compression_param, source_info.vabc_compression_param))
+      OPTIONS.vabc_compression_param = source_info.vabc_compression_param
 
     # Virtual AB Compression was introduced in Androd S.
     # Later, we backported VABC to Android R. But verity support was not
@@ -884,6 +890,22 @@
         "META/ab_partitions.txt is required for ab_update."
     target_info = common.BuildInfo(OPTIONS.info_dict, OPTIONS.oem_dicts)
     source_info = None
+    if target_info.vabc_compression_param:
+      minimum_api_level_required = VABC_COMPRESSION_PARAM_SUPPORT[
+          target_info.vabc_compression_param]
+      if target_info.vendor_api_level < minimum_api_level_required:
+        logger.warning(
+            "This full OTA is configured to use VABC compression algorithm"
+            " {}, which is supported since"
+            " Android API level {}, but device is "
+            "launched with {} . If this full OTA is"
+            " served to a device running old build, OTA might fail due to "
+            "unsupported compression parameter. For safety, gz is used because "
+            "it's supported since day 1.".format(
+                target_info.vabc_compression_param,
+                minimum_api_level_required,
+                target_info.vendor_api_level))
+        OPTIONS.vabc_compression_param = "gz"
 
   if OPTIONS.partial == []:
     logger.info(
@@ -1210,7 +1232,13 @@
       assert a.lower() in ["true", "false"]
       OPTIONS.enable_lz4diff = a.lower() != "false"
     elif o == "--vabc_compression_param":
+      words = a.split(",")
+      assert len(words) >= 1 and len(words) <= 2
       OPTIONS.vabc_compression_param = a.lower()
+      if len(words) == 2:
+        if not words[1].isdigit():
+          raise ValueError("Cannot parse value %r for option $COMPRESSION_LEVEL - only "
+                         "integers are allowed." % words[1])
     elif o == "--security_patch_level":
       OPTIONS.security_patch_level = a
     elif o in ("--max_threads"):
diff --git a/tools/releasetools/ota_utils.py b/tools/releasetools/ota_utils.py
index 68c6887..f288a9c 100644
--- a/tools/releasetools/ota_utils.py
+++ b/tools/releasetools/ota_utils.py
@@ -51,6 +51,19 @@
 TARGET_FILES_IMAGES_SUBDIR = ["IMAGES", "PREBUILT_IMAGES", "RADIO"]
 
 
+# Key is the compression algorithm, value is minimum API level required to
+# use this compression algorithm for VABC OTA on device.
+VABC_COMPRESSION_PARAM_SUPPORT = {
+    "gz": 31,
+    "brotli": 31,
+    "none": 31,
+    # lz4 support is added in Android U
+    "lz4": 34,
+    # zstd support is added in Android V
+    "zstd": 35,
+}
+
+
 def FinalizeMetadata(metadata, input_file, output_file, needed_property_files=None, package_key=None, pw=None):
   """Finalizes the metadata and signs an A/B OTA package.
 
@@ -727,6 +740,7 @@
     logger.info("target files %s is already extracted", path)
     return path
   extracted_dir = common.MakeTempDir("target_files")
+  logger.info(f"Extracting target files {path} to {extracted_dir}")
   common.UnzipToDir(path, extracted_dir, UNZIP_PATTERN + [""])
   for subdir in TARGET_FILES_IMAGES_SUBDIR:
     image_dir = os.path.join(extracted_dir, subdir)
@@ -850,7 +864,7 @@
       cmd.extend(["--dynamic_partition_info_file", dynamic_partition_info])
 
     apex_info = os.path.join(
-      target_dir, "META", "apex_info.pb")
+        target_dir, "META", "apex_info.pb")
     if os.path.exists(apex_info):
       cmd.extend(["--apex_info_file", apex_info])