diff --git a/tools/releasetools/Android.bp b/tools/releasetools/Android.bp
index 21134b6..7f727fb 100644
--- a/tools/releasetools/Android.bp
+++ b/tools/releasetools/Android.bp
@@ -89,16 +89,35 @@
     ],
 }
 
+python_library_host {
+    name: "ota_metadata_proto",
+    version: {
+        py2: {
+            enabled: true,
+        },
+        py3: {
+            enabled: true,
+        },
+    },
+    srcs: [
+       "ota_metadata.proto",
+    ],
+    proto: {
+        canonical_path_from_root: false,
+    },
+}
+
 python_defaults {
     name: "releasetools_ota_from_target_files_defaults",
     srcs: [
         "edify_generator.py",
-        "ota_from_target_files.py",
         "non_ab_ota.py",
-        "target_files_diff.py",
+        "ota_from_target_files.py",
         "ota_utils.py",
+        "target_files_diff.py",
     ],
     libs: [
+        "ota_metadata_proto",
         "releasetools_check_target_files_vintf",
         "releasetools_common",
         "releasetools_verity_utils",
diff --git a/tools/releasetools/non_ab_ota.py b/tools/releasetools/non_ab_ota.py
index 3a87957..471ef25 100644
--- a/tools/releasetools/non_ab_ota.py
+++ b/tools/releasetools/non_ab_ota.py
@@ -276,7 +276,7 @@
 
   script.SetProgress(1)
   script.AddToZip(input_zip, output_zip, input_path=OPTIONS.updater_binary)
-  metadata["ota-required-cache"] = str(script.required_cache)
+  metadata.required_cache = script.required_cache
 
   # We haven't written the metadata entry, which will be done in
   # FinalizeMetadata.
@@ -530,7 +530,7 @@
     script.AddToZip(source_zip, output_zip, input_path=OPTIONS.updater_binary)
   else:
     script.AddToZip(target_zip, output_zip, input_path=OPTIONS.updater_binary)
-  metadata["ota-required-cache"] = str(script.required_cache)
+  metadata.required_cache = script.required_cache
 
   # We haven't written the metadata entry yet, which will be handled in
   # FinalizeMetadata().
diff --git a/tools/releasetools/ota_from_target_files.py b/tools/releasetools/ota_from_target_files.py
index 962adc1..93a3e0e 100755
--- a/tools/releasetools/ota_from_target_files.py
+++ b/tools/releasetools/ota_from_target_files.py
@@ -848,7 +848,7 @@
   if OPTIONS.downgrade:
     max_timestamp = source_info.GetBuildProp("ro.build.date.utc")
   else:
-    max_timestamp = metadata["post-timestamp"]
+    max_timestamp = str(metadata.postcondition.timestamp)
   additional_args = ["--max_timestamp", max_timestamp]
 
   payload.Generate(target_file, source_file, additional_args)
diff --git a/tools/releasetools/ota_metadata.proto b/tools/releasetools/ota_metadata.proto
new file mode 100644
index 0000000..4d87619
--- /dev/null
+++ b/tools/releasetools/ota_metadata.proto
@@ -0,0 +1,88 @@
+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+syntax = "proto3";
+
+package build.tools.releasetools;
+option optimize_for = LITE_RUNTIME;
+
+// The build information of a particular partition on the device.
+message PartitionState {
+  string partition_name = 1;
+  repeated string device = 2;
+  repeated string build = 3;
+  // The version string of the partition. It's usually timestamp if present.
+  // One known exception is the boot image, who uses the kmi version, e.g.
+  // 5.4.42-android12-0
+  string version = 4;
+
+  // TODO(xunchang), revisit other necessary fields, e.g. security_patch_level.
+}
+
+// The build information on the device. The bytes of the running images are thus
+// inferred from the device state. For more information of the meaning of each
+// subfield, check
+// https://source.android.com/compatibility/android-cdd#3_2_2_build_parameters
+message DeviceState {
+  // device name. i.e. ro.product.device; if the field has multiple values, it
+  // means the ota package supports multiple devices. This usually happens when
+  // we use the same image to support multiple skus.
+  repeated string device = 1;
+  // device fingerprint. Up to R build, the value reads from
+  // ro.build.fingerprint.
+  repeated string build = 2;
+  // A value that specify a version of the android build.
+  string build_incremental = 3;
+  // The timestamp when the build is generated.
+  int64 timestamp = 4;
+  // The version of the currently-executing Android system.
+  string sdk_level = 5;
+  // A value indicating the security patch level of a build.
+  string security_patch_level = 6;
+
+  // The detailed state of each partition. For partial updates or devices with
+  // mixed build of partitions, some of the above fields may left empty. And the
+  // client will rely on the information of specific partitions to target the
+  // update.
+  repeated PartitionState partition_state = 7;
+}
+
+// The metadata of an OTA package. It contains the information of the package
+// and prerequisite to install the update correctly.
+message OtaMetadata {
+  enum OtaType {
+    AB = 0;
+    BLOCK = 1;
+  };
+  OtaType type = 1;
+  // True if we need to wipe after the update.
+  bool wipe = 2;
+  // True if the timestamp of the post build is older than the pre build.
+  bool downgrade = 3;
+  // A map of name:content of property files, e.g. ota-property-files.
+  map<string, string> property_files = 4;
+
+  // The required device state in order to install the package.
+  DeviceState precondition = 5;
+  // The expected device state after the update.
+  DeviceState postcondition = 6;
+
+  // True if the ota that updates a device to support dynamic partitions, where
+  // the source build doesn't support it.
+  bool retrofit_dynamic_partitions = 7;
+  // The required size of the cache partition, only valid for non-A/B update.
+  int64 required_cache = 8;
+}
diff --git a/tools/releasetools/ota_utils.py b/tools/releasetools/ota_utils.py
index 4bb2b61..97a6280 100644
--- a/tools/releasetools/ota_utils.py
+++ b/tools/releasetools/ota_utils.py
@@ -17,6 +17,7 @@
 import os
 import zipfile
 
+import ota_metadata_pb2
 from common import (ZipDelete, ZipClose, OPTIONS, MakeTempFile,
                     ZipWriteStr, BuildInfo, LoadDictionaryFromFile,
                     SignFile, PARTITIONS_WITH_CARE_MAP, PartitionBuildProps)
@@ -34,6 +35,7 @@
 OPTIONS.boot_variable_file = None
 
 METADATA_NAME = 'META-INF/com/android/metadata'
+METADATA_PROTO_NAME = 'META-INF/com/android/metadata.pb'
 UNZIP_PATTERN = ['IMAGES/*', 'META/*', 'OTA/*', 'RADIO/*']
 
 
@@ -62,11 +64,12 @@
     # Write the current metadata entry with placeholders.
     with zipfile.ZipFile(input_file) as input_zip:
       for property_files in needed_property_files:
-        metadata[property_files.name] = property_files.Compute(input_zip)
+        metadata.property_files[property_files.name] = property_files.Compute(
+            input_zip)
       namelist = input_zip.namelist()
 
-    if METADATA_NAME in namelist:
-      ZipDelete(input_file, METADATA_NAME)
+    if METADATA_NAME in namelist or METADATA_PROTO_NAME in namelist:
+      ZipDelete(input_file, [METADATA_NAME, METADATA_PROTO_NAME])
     output_zip = zipfile.ZipFile(input_file, 'a')
     WriteMetadata(metadata, output_zip)
     ZipClose(output_zip)
@@ -81,8 +84,9 @@
   def FinalizeAllPropertyFiles(prelim_signing, needed_property_files):
     with zipfile.ZipFile(prelim_signing) as prelim_signing_zip:
       for property_files in needed_property_files:
-        metadata[property_files.name] = property_files.Finalize(
-            prelim_signing_zip, len(metadata[property_files.name]))
+        metadata.property_files[property_files.name] = property_files.Finalize(
+            prelim_signing_zip,
+            len(metadata.property_files[property_files.name]))
 
   # SignOutput(), which in turn calls signapk.jar, will possibly reorder the ZIP
   # entries, as well as padding the entry headers. We do a preliminary signing
@@ -103,7 +107,7 @@
     FinalizeAllPropertyFiles(prelim_signing, needed_property_files)
 
   # Replace the METADATA entry.
-  ZipDelete(prelim_signing, METADATA_NAME)
+  ZipDelete(prelim_signing, [METADATA_NAME, METADATA_PROTO_NAME])
   output_zip = zipfile.ZipFile(prelim_signing, 'a')
   WriteMetadata(metadata, output_zip)
   ZipClose(output_zip)
@@ -117,7 +121,8 @@
   # Reopen the final signed zip to double check the streaming metadata.
   with zipfile.ZipFile(output_file) as output_zip:
     for property_files in needed_property_files:
-      property_files.Verify(output_zip, metadata[property_files.name].strip())
+      property_files.Verify(
+          output_zip, metadata.property_files[property_files.name].strip())
 
   # If requested, dump the metadata to a separate file.
   output_metadata_path = OPTIONS.output_metadata_path
@@ -125,30 +130,60 @@
     WriteMetadata(metadata, output_metadata_path)
 
 
-def WriteMetadata(metadata, output):
+def WriteMetadata(metadata_proto, output):
   """Writes the metadata to the zip archive or a file.
 
   Args:
-    metadata: The metadata dict for the package.
-    output: A ZipFile object or a string of the output file path.
+    metadata_proto: The metadata protobuf for the package.
+    output: A ZipFile object or a string of the output file path. If a string
+      path is given, the metadata in the protobuf format will be written to
+      {output}.pb, e.g. ota_metadata.pb
   """
 
-  value = "".join(["%s=%s\n" % kv for kv in sorted(metadata.items())])
+  metadata_dict = BuildLegacyOtaMetadata(metadata_proto)
+  legacy_metadata = "".join(["%s=%s\n" % kv for kv in
+                             sorted(metadata_dict.items())])
   if isinstance(output, zipfile.ZipFile):
-    ZipWriteStr(output, METADATA_NAME, value,
+    ZipWriteStr(output, METADATA_PROTO_NAME, metadata_proto.SerializeToString(),
+                compress_type=zipfile.ZIP_STORED)
+    ZipWriteStr(output, METADATA_NAME, legacy_metadata,
                 compress_type=zipfile.ZIP_STORED)
     return
 
+  with open('{}.pb'.format(output), 'w') as f:
+    f.write(metadata_proto.SerializeToString())
   with open(output, 'w') as f:
-    f.write(value)
+    f.write(legacy_metadata)
+
+
+def UpdateDeviceState(device_state, build_info, boot_variable_values,
+                      is_post_build):
+  """Update the fields of the DeviceState proto with build info."""
+
+  build_devices, build_fingerprints = \
+      CalculateRuntimeDevicesAndFingerprints(build_info, boot_variable_values)
+  device_state.device.extend(sorted(build_devices))
+  device_state.build.extend(sorted(build_fingerprints))
+  device_state.build_incremental = build_info.GetBuildProp(
+      'ro.build.version.incremental')
+
+  # TODO(xunchang) update the partition state
+
+  if is_post_build:
+    device_state.sdk_level = build_info.GetBuildProp(
+        'ro.build.version.sdk')
+    device_state.security_patch_level = build_info.GetBuildProp(
+        'ro.build.version.security_patch')
+    # Use the actual post-timestamp, even for a downgrade case.
+    device_state.timestamp = int(build_info.GetBuildProp('ro.build.date.utc'))
 
 
 def GetPackageMetadata(target_info, source_info=None):
-  """Generates and returns the metadata dict.
+  """Generates and returns the metadata proto.
 
-  It generates a dict() that contains the info to be written into an OTA
-  package (META-INF/com/android/metadata). It also handles the detection of
-  downgrade / data wipe based on the global options.
+  It generates a ota_metadata protobuf that contains the info to be written
+  into an OTA package (META-INF/com/android/metadata.pb). It also handles the
+  detection of downgrade / data wipe based on the global options.
 
   Args:
     target_info: The BuildInfo instance that holds the target build info.
@@ -156,66 +191,96 @@
         None if generating full OTA.
 
   Returns:
-    A dict to be written into package metadata entry.
+    A protobuf to be written into package metadata entry.
   """
   assert isinstance(target_info, BuildInfo)
   assert source_info is None or isinstance(source_info, BuildInfo)
 
-  separator = '|'
-
   boot_variable_values = {}
   if OPTIONS.boot_variable_file:
     d = LoadDictionaryFromFile(OPTIONS.boot_variable_file)
     for key, values in d.items():
       boot_variable_values[key] = [val.strip() for val in values.split(',')]
 
-  post_build_devices, post_build_fingerprints = \
-      CalculateRuntimeDevicesAndFingerprints(target_info, boot_variable_values)
-  metadata = {
-      'post-build': separator.join(sorted(post_build_fingerprints)),
-      'post-build-incremental': target_info.GetBuildProp(
-          'ro.build.version.incremental'),
-      'post-sdk-level': target_info.GetBuildProp(
-          'ro.build.version.sdk'),
-      'post-security-patch-level': target_info.GetBuildProp(
-          'ro.build.version.security_patch'),
-  }
+  metadata_proto = ota_metadata_pb2.OtaMetadata()
+  # TODO(xunchang) some fields, e.g. post-device isn't necessary. We can
+  # consider skipping them if they aren't used by clients.
+  UpdateDeviceState(metadata_proto.postcondition, target_info,
+                    boot_variable_values, True)
 
   if target_info.is_ab and not OPTIONS.force_non_ab:
-    metadata['ota-type'] = 'AB'
-    metadata['ota-required-cache'] = '0'
+    metadata_proto.type = ota_metadata_pb2.OtaMetadata.AB
+    metadata_proto.required_cache = 0
   else:
-    metadata['ota-type'] = 'BLOCK'
+    metadata_proto.type = ota_metadata_pb2.OtaMetadata.BLOCK
+    # cache requirement will be updated by the non-A/B codes.
 
   if OPTIONS.wipe_user_data:
-    metadata['ota-wipe'] = 'yes'
+    metadata_proto.wipe = True
 
   if OPTIONS.retrofit_dynamic_partitions:
-    metadata['ota-retrofit-dynamic-partitions'] = 'yes'
+    metadata_proto.retrofit_dynamic_partitions = True
 
   is_incremental = source_info is not None
   if is_incremental:
-    pre_build_devices, pre_build_fingerprints = \
-        CalculateRuntimeDevicesAndFingerprints(source_info,
-                                               boot_variable_values)
-    metadata['pre-build'] = separator.join(sorted(pre_build_fingerprints))
-    metadata['pre-build-incremental'] = source_info.GetBuildProp(
-        'ro.build.version.incremental')
-    metadata['pre-device'] = separator.join(sorted(pre_build_devices))
+    UpdateDeviceState(metadata_proto.precondition, source_info,
+                      boot_variable_values, False)
   else:
-    metadata['pre-device'] = separator.join(sorted(post_build_devices))
-
-  # Use the actual post-timestamp, even for a downgrade case.
-  metadata['post-timestamp'] = target_info.GetBuildProp('ro.build.date.utc')
+    metadata_proto.precondition.device.extend(
+        metadata_proto.postcondition.device)
 
   # Detect downgrades and set up downgrade flags accordingly.
   if is_incremental:
-    HandleDowngradeMetadata(metadata, target_info, source_info)
+    HandleDowngradeMetadata(metadata_proto, target_info, source_info)
 
-  return metadata
+  return metadata_proto
 
 
-def HandleDowngradeMetadata(metadata, target_info, source_info):
+def BuildLegacyOtaMetadata(metadata_proto):
+  """Converts the metadata proto to a legacy metadata dict.
+
+  This metadata dict is used to build the legacy metadata text file for
+  backward compatibility. We won't add new keys to the legacy metadata format.
+  If new information is needed, we should add it as a new field in OtaMetadata
+  proto definition.
+  """
+
+  separator = '|'
+
+  metadata_dict = {}
+  if metadata_proto.type == ota_metadata_pb2.OtaMetadata.AB:
+    metadata_dict['ota-type'] = 'AB'
+  elif metadata_proto.type == ota_metadata_pb2.OtaMetadata.BLOCK:
+    metadata_dict['ota-type'] = 'BLOCK'
+  if metadata_proto.wipe:
+    metadata_dict['ota-wipe'] = 'yes'
+  if metadata_proto.retrofit_dynamic_partitions:
+    metadata_dict['ota-retrofit-dynamic-partitions'] = 'yes'
+  if metadata_proto.downgrade:
+    metadata_dict['ota-downgrade'] = 'yes'
+
+  metadata_dict['ota-required-cache'] = str(metadata_proto.required_cache)
+
+  post_build = metadata_proto.postcondition
+  metadata_dict['post-build'] = separator.join(post_build.build)
+  metadata_dict['post-build-incremental'] = post_build.build_incremental
+  metadata_dict['post-sdk-level'] = post_build.sdk_level
+  metadata_dict['post-security-patch-level'] = post_build.security_patch_level
+  metadata_dict['post-timestamp'] = str(post_build.timestamp)
+
+  pre_build = metadata_proto.precondition
+  metadata_dict['pre-device'] = separator.join(pre_build.device)
+  # incremental updates
+  if len(pre_build.build) != 0:
+    metadata_dict['pre-build'] = separator.join(pre_build.build)
+    metadata_dict['pre-build-incremental'] = pre_build.build_incremental
+
+  metadata_dict.update(metadata_proto.property_files)
+
+  return metadata_dict
+
+
+def HandleDowngradeMetadata(metadata_proto, target_info, source_info):
   # Only incremental OTAs are allowed to reach here.
   assert OPTIONS.incremental_source is not None
 
@@ -228,7 +293,7 @@
       raise RuntimeError(
           "--downgrade or --override_timestamp specified but no downgrade "
           "detected: pre: %s, post: %s" % (pre_timestamp, post_timestamp))
-    metadata["ota-downgrade"] = "yes"
+    metadata_proto.downgrade = True
   else:
     if is_downgrade:
       raise RuntimeError(
@@ -415,8 +480,10 @@
     # reserved space serves the metadata entry only.
     if reserve_space:
       tokens.append('metadata:' + ' ' * 15)
+      tokens.append('metadata.pb:' + ' ' * 15)
     else:
       tokens.append(ComputeEntryOffsetSize(METADATA_NAME))
+      tokens.append(ComputeEntryOffsetSize(METADATA_PROTO_NAME))
 
     return ','.join(tokens)
 
diff --git a/tools/releasetools/test_non_ab_ota.py b/tools/releasetools/test_non_ab_ota.py
index ee1b411..5207e2f 100644
--- a/tools/releasetools/test_non_ab_ota.py
+++ b/tools/releasetools/test_non_ab_ota.py
@@ -42,12 +42,13 @@
       property_files_string = property_files.Compute(zip_fp)
 
     tokens = self._parse_property_files_string(property_files_string)
-    self.assertEqual(1, len(tokens))
+    self.assertEqual(2, len(tokens))
     self._verify_entries(zip_file, tokens, entries)
 
   def test_Finalize(self):
     entries = [
         'META-INF/com/android/metadata',
+        'META-INF/com/android/metadata.pb',
     ]
     zip_file = self.construct_zip_package(entries)
     property_files = NonAbOtaPropertyFiles()
@@ -57,14 +58,16 @@
       property_files_string = property_files.Finalize(zip_fp, len(raw_metadata))
     tokens = self._parse_property_files_string(property_files_string)
 
-    self.assertEqual(1, len(tokens))
+    self.assertEqual(2, len(tokens))
     # 'META-INF/com/android/metadata' will be key'd as 'metadata'.
     entries[0] = 'metadata'
+    entries[1] = 'metadata.pb'
     self._verify_entries(zip_file, tokens, entries)
 
   def test_Verify(self):
     entries = (
         'META-INF/com/android/metadata',
+        'META-INF/com/android/metadata.pb',
     )
     zip_file = self.construct_zip_package(entries)
     property_files = NonAbOtaPropertyFiles()
diff --git a/tools/releasetools/test_ota_from_target_files.py b/tools/releasetools/test_ota_from_target_files.py
index 52aa487..045191c 100644
--- a/tools/releasetools/test_ota_from_target_files.py
+++ b/tools/releasetools/test_ota_from_target_files.py
@@ -20,17 +20,20 @@
 import zipfile
 
 import common
+import ota_metadata_pb2
 import test_utils
-from ota_utils import CalculateRuntimeDevicesAndFingerprints
+from ota_utils import (
+    BuildLegacyOtaMetadata, CalculateRuntimeDevicesAndFingerprints,
+    FinalizeMetadata, GetPackageMetadata, PropertyFiles)
 from ota_from_target_files import (
-    _LoadOemDicts, AbOtaPropertyFiles, FinalizeMetadata,
-    GetPackageMetadata, GetTargetFilesZipForSecondaryImages,
+    _LoadOemDicts, AbOtaPropertyFiles,
+    GetTargetFilesZipForSecondaryImages,
     GetTargetFilesZipWithoutPostinstallConfig,
-    Payload, PayloadSigner, POSTINSTALL_CONFIG, PropertyFiles,
+    Payload, PayloadSigner, POSTINSTALL_CONFIG,
     StreamingPropertyFiles)
-from non_ab_ota import NonAbOtaPropertyFiles
 from test_utils import PropertyFilesTestCase
 
+
 def construct_target_files(secondary=False):
   """Returns a target-files.zip file for generating OTA packages."""
   target_files = common.MakeTempFile(prefix='target_files-', suffix='.zip')
@@ -150,7 +153,6 @@
       'oem_fingerprint_properties': 'ro.product.device ro.product.brand',
   }
 
-
   def setUp(self):
     self.testdata_dir = test_utils.get_testdata_dir()
     self.assertTrue(os.path.exists(self.testdata_dir))
@@ -169,11 +171,16 @@
 
     common.OPTIONS.search_path = test_utils.get_search_path()
 
+  @staticmethod
+  def GetLegacyOtaMetadata(target_info, source_info=None):
+    metadata_proto = GetPackageMetadata(target_info, source_info)
+    return BuildLegacyOtaMetadata(metadata_proto)
+
   def test_GetPackageMetadata_abOta_full(self):
     target_info_dict = copy.deepcopy(self.TEST_TARGET_INFO_DICT)
     target_info_dict['ab_update'] = 'true'
     target_info = common.BuildInfo(target_info_dict, None)
-    metadata = GetPackageMetadata(target_info)
+    metadata = self.GetLegacyOtaMetadata(target_info)
     self.assertDictEqual(
         {
             'ota-type' : 'AB',
@@ -193,7 +200,7 @@
     target_info = common.BuildInfo(target_info_dict, None)
     source_info = common.BuildInfo(self.TEST_SOURCE_INFO_DICT, None)
     common.OPTIONS.incremental_source = ''
-    metadata = GetPackageMetadata(target_info, source_info)
+    metadata = self.GetLegacyOtaMetadata(target_info, source_info)
     self.assertDictEqual(
         {
             'ota-type' : 'AB',
@@ -211,10 +218,11 @@
 
   def test_GetPackageMetadata_nonAbOta_full(self):
     target_info = common.BuildInfo(self.TEST_TARGET_INFO_DICT, None)
-    metadata = GetPackageMetadata(target_info)
+    metadata = self.GetLegacyOtaMetadata(target_info)
     self.assertDictEqual(
         {
             'ota-type' : 'BLOCK',
+            'ota-required-cache' : '0',
             'post-build' : 'build-fingerprint-target',
             'post-build-incremental' : 'build-version-incremental-target',
             'post-sdk-level' : '27',
@@ -228,10 +236,11 @@
     target_info = common.BuildInfo(self.TEST_TARGET_INFO_DICT, None)
     source_info = common.BuildInfo(self.TEST_SOURCE_INFO_DICT, None)
     common.OPTIONS.incremental_source = ''
-    metadata = GetPackageMetadata(target_info, source_info)
+    metadata = self.GetLegacyOtaMetadata(target_info, source_info)
     self.assertDictEqual(
         {
             'ota-type' : 'BLOCK',
+            'ota-required-cache' : '0',
             'post-build' : 'build-fingerprint-target',
             'post-build-incremental' : 'build-version-incremental-target',
             'post-sdk-level' : '27',
@@ -246,10 +255,11 @@
   def test_GetPackageMetadata_wipe(self):
     target_info = common.BuildInfo(self.TEST_TARGET_INFO_DICT, None)
     common.OPTIONS.wipe_user_data = True
-    metadata = GetPackageMetadata(target_info)
+    metadata = self.GetLegacyOtaMetadata(target_info)
     self.assertDictEqual(
         {
             'ota-type' : 'BLOCK',
+            'ota-required-cache' : '0',
             'ota-wipe' : 'yes',
             'post-build' : 'build-fingerprint-target',
             'post-build-incremental' : 'build-version-incremental-target',
@@ -263,11 +273,12 @@
   def test_GetPackageMetadata_retrofitDynamicPartitions(self):
     target_info = common.BuildInfo(self.TEST_TARGET_INFO_DICT, None)
     common.OPTIONS.retrofit_dynamic_partitions = True
-    metadata = GetPackageMetadata(target_info)
+    metadata = self.GetLegacyOtaMetadata(target_info)
     self.assertDictEqual(
         {
             'ota-retrofit-dynamic-partitions' : 'yes',
             'ota-type' : 'BLOCK',
+            'ota-required-cache' : '0',
             'post-build' : 'build-fingerprint-target',
             'post-build-incremental' : 'build-version-incremental-target',
             'post-sdk-level' : '27',
@@ -293,7 +304,7 @@
     target_info = common.BuildInfo(target_info_dict, None)
     source_info = common.BuildInfo(source_info_dict, None)
     common.OPTIONS.incremental_source = ''
-    self.assertRaises(RuntimeError, GetPackageMetadata, target_info,
+    self.assertRaises(RuntimeError, self.GetLegacyOtaMetadata, target_info,
                       source_info)
 
   def test_GetPackageMetadata_downgrade(self):
@@ -307,11 +318,13 @@
     common.OPTIONS.incremental_source = ''
     common.OPTIONS.downgrade = True
     common.OPTIONS.wipe_user_data = True
-    metadata = GetPackageMetadata(target_info, source_info)
+    metadata = self.GetLegacyOtaMetadata(target_info, source_info)
+
     self.assertDictEqual(
         {
             'ota-downgrade' : 'yes',
             'ota-type' : 'BLOCK',
+            'ota-required-cache' : '0',
             'ota-wipe' : 'yes',
             'post-build' : 'build-fingerprint-target',
             'post-build-incremental' : 'build-version-incremental-target',
@@ -464,13 +477,13 @@
             'A' * 1024 * 1024 * 1024,
             zipfile.ZIP_STORED)
 
-    metadata = {}
+    metadata = ota_metadata_pb2.OtaMetadata()
     output_file = common.MakeTempFile(suffix='.zip')
     needed_property_files = (
         TestPropertyFiles(),
     )
     FinalizeMetadata(metadata, zip_file, output_file, needed_property_files)
-    self.assertIn('ota-test-property-files', metadata)
+    self.assertIn('ota-test-property-files', metadata.property_files)
 
   @test_utils.SkipIfExternalToolsUnavailable()
   def test_FinalizeMetadata(self):
@@ -508,13 +521,13 @@
           'A' * 1024 * 1024,
           zipfile.ZIP_STORED)
 
-    metadata = {}
+    metadata = ota_metadata_pb2.OtaMetadata()
     needed_property_files = (
         TestPropertyFiles(),
     )
     output_file = common.MakeTempFile(suffix='.zip')
     FinalizeMetadata(metadata, zip_file, output_file, needed_property_files)
-    self.assertIn('ota-test-property-files', metadata)
+    self.assertIn('ota-test-property-files', metadata.property_files)
 
 
 class TestPropertyFiles(PropertyFiles):
@@ -532,8 +545,8 @@
         'optional-entry2',
     )
 
-class PropertyFilesTest(PropertyFilesTestCase):
 
+class PropertyFilesTest(PropertyFilesTestCase):
 
   @test_utils.SkipIfExternalToolsUnavailable()
   def test_Compute(self):
@@ -547,7 +560,7 @@
       property_files_string = property_files.Compute(zip_fp)
 
     tokens = self._parse_property_files_string(property_files_string)
-    self.assertEqual(3, len(tokens))
+    self.assertEqual(4, len(tokens))
     self._verify_entries(zip_file, tokens, entries)
 
   def test_Compute_withOptionalEntries(self):
@@ -563,7 +576,7 @@
       property_files_string = property_files.Compute(zip_fp)
 
     tokens = self._parse_property_files_string(property_files_string)
-    self.assertEqual(5, len(tokens))
+    self.assertEqual(6, len(tokens))
     self._verify_entries(zip_file, tokens, entries)
 
   def test_Compute_missingRequiredEntry(self):
@@ -581,6 +594,7 @@
         'required-entry1',
         'required-entry2',
         'META-INF/com/android/metadata',
+        'META-INF/com/android/metadata.pb',
     ]
     zip_file = self.construct_zip_package(entries)
     property_files = TestPropertyFiles()
@@ -590,10 +604,11 @@
       streaming_metadata = property_files.Finalize(zip_fp, len(raw_metadata))
     tokens = self._parse_property_files_string(streaming_metadata)
 
-    self.assertEqual(3, len(tokens))
+    self.assertEqual(4, len(tokens))
     # 'META-INF/com/android/metadata' will be key'd as 'metadata' in the
     # streaming metadata.
     entries[2] = 'metadata'
+    entries[3] = 'metadata.pb'
     self._verify_entries(zip_file, tokens, entries)
 
   @test_utils.SkipIfExternalToolsUnavailable()
@@ -604,6 +619,7 @@
         'optional-entry1',
         'optional-entry2',
         'META-INF/com/android/metadata',
+        'META-INF/com/android/metadata.pb',
     )
     zip_file = self.construct_zip_package(entries)
     property_files = TestPropertyFiles()
@@ -638,6 +654,7 @@
         'optional-entry1',
         'optional-entry2',
         'META-INF/com/android/metadata',
+        'META-INF/com/android/metadata.pb',
     )
     zip_file = self.construct_zip_package(entries)
     property_files = TestPropertyFiles()
@@ -687,7 +704,7 @@
       property_files_string = property_files.Compute(zip_fp)
 
     tokens = self._parse_property_files_string(property_files_string)
-    self.assertEqual(5, len(tokens))
+    self.assertEqual(6, len(tokens))
     self._verify_entries(zip_file, tokens, entries)
 
   def test_Finalize(self):
@@ -697,6 +714,7 @@
         'care_map.txt',
         'compatibility.zip',
         'META-INF/com/android/metadata',
+        'META-INF/com/android/metadata.pb',
     ]
     zip_file = self.construct_zip_package(entries)
     property_files = StreamingPropertyFiles()
@@ -706,10 +724,11 @@
       streaming_metadata = property_files.Finalize(zip_fp, len(raw_metadata))
     tokens = self._parse_property_files_string(streaming_metadata)
 
-    self.assertEqual(5, len(tokens))
+    self.assertEqual(6, len(tokens))
     # 'META-INF/com/android/metadata' will be key'd as 'metadata' in the
     # streaming metadata.
     entries[4] = 'metadata'
+    entries[5] = 'metadata.pb'
     self._verify_entries(zip_file, tokens, entries)
 
   def test_Verify(self):
@@ -719,6 +738,7 @@
         'care_map.txt',
         'compatibility.zip',
         'META-INF/com/android/metadata',
+        'META-INF/com/android/metadata.pb',
     )
     zip_file = self.construct_zip_package(entries)
     property_files = StreamingPropertyFiles()
@@ -855,6 +875,7 @@
       # Put META-INF/com/android/metadata if needed.
       if with_metadata:
         entries.append('META-INF/com/android/metadata')
+        entries.append('META-INF/com/android/metadata.pb')
 
       for entry in entries:
         zip_fp.writestr(
@@ -870,9 +891,9 @@
       property_files_string = property_files.Compute(zip_fp)
 
     tokens = self._parse_property_files_string(property_files_string)
-    # "6" indcludes the four entries above, one metadata entry, and one entry
+    # "7" indcludes the four entries above, two metadata entries, and one entry
     # for payload-metadata.bin.
-    self.assertEqual(6, len(tokens))
+    self.assertEqual(7, len(tokens))
     self._verify_entries(
         zip_file, tokens, ('care_map.txt', 'compatibility.zip'))
 
@@ -886,9 +907,9 @@
       property_files_string = property_files.Finalize(zip_fp, len(raw_metadata))
 
     tokens = self._parse_property_files_string(property_files_string)
-    # "6" indcludes the four entries above, one metadata entry, and one entry
+    # "7" includes the four entries above, two metadata entries, and one entry
     # for payload-metadata.bin.
-    self.assertEqual(6, len(tokens))
+    self.assertEqual(7, len(tokens))
     self._verify_entries(
         zip_file, tokens, ('care_map.txt', 'compatibility.zip'))
 
@@ -1187,10 +1208,29 @@
       'ro.build.tags=build-tags',
       'ro.build.version.sdk=30',
       'ro.build.version.security_patch=2020',
-      'ro.build.date.utc=12345678'
+      'ro.build.date.utc=12345678',
+      'ro.system.build.version.release=version-release',
+      'ro.system.build.id=build-id',
+      'ro.system.build.version.incremental=version-incremental',
+      'ro.system.build.type=build-type',
+      'ro.system.build.tags=build-tags',
+      'ro.system.build.version.sdk=30',
+      'ro.system.build.version.security_patch=2020',
+      'ro.system.build.date.utc=12345678',
+      'ro.product.system.brand=generic',
+      'ro.product.system.name=generic',
+      'ro.product.system.device=generic',
   ]
 
   VENDOR_BUILD_PROP = [
+      'ro.vendor.build.version.release=version-release',
+      'ro.vendor.build.id=build-id',
+      'ro.vendor.build.version.incremental=version-incremental',
+      'ro.vendor.build.type=build-type',
+      'ro.vendor.build.tags=build-tags',
+      'ro.vendor.build.version.sdk=30',
+      'ro.vendor.build.version.security_patch=2020',
+      'ro.vendor.build.date.utc=12345678',
       'ro.product.vendor.brand=vendor-product-brand',
       'ro.product.vendor.name=vendor-product-name',
       'ro.product.vendor.device=vendor-product-device'
@@ -1326,8 +1366,8 @@
       f.write('ro.boot.sku_name=std,pro')
 
     build_info = common.BuildInfo(common.LoadInfoDict(self.test_dir))
-    metadata = GetPackageMetadata(build_info)
-    self.assertEqual('vendor-product-device', metadata['pre-device'])
+    metadata_dict = BuildLegacyOtaMetadata(GetPackageMetadata(build_info))
+    self.assertEqual('vendor-product-device', metadata_dict['pre-device'])
     fingerprints = [
         self.constructFingerprint(
             'vendor-product-brand/vendor-product-name/vendor-product-device'),
@@ -1336,7 +1376,33 @@
         self.constructFingerprint(
             'vendor-product-brand/vendor-product-std/vendor-product-device'),
     ]
-    self.assertEqual('|'.join(fingerprints), metadata['post-build'])
+    self.assertEqual('|'.join(fingerprints), metadata_dict['post-build'])
+
+  def CheckMetadataEqual(self, metadata_dict, metadata_proto):
+    post_build = metadata_proto.postcondition
+    self.assertEqual('|'.join(post_build.build),
+                     metadata_dict['post-build'])
+    self.assertEqual(post_build.build_incremental,
+                     metadata_dict['post-build-incremental'])
+    self.assertEqual(post_build.sdk_level,
+                     metadata_dict['post-sdk-level'])
+    self.assertEqual(post_build.security_patch_level,
+                     metadata_dict['post-security-patch-level'])
+
+    if metadata_proto.type == ota_metadata_pb2.OtaMetadata.AB:
+      ota_type = 'AB'
+    elif metadata_proto.type == ota_metadata_pb2.OtaMetadata.BLOCK:
+      ota_type = 'BLOCK'
+    else:
+      ota_type = ''
+    self.assertEqual(ota_type, metadata_dict['ota-type'])
+    self.assertEqual(metadata_proto.wipe,
+                     metadata_dict.get('ota-wipe') == 'yes')
+    self.assertEqual(metadata_proto.required_cache,
+                     int(metadata_dict.get('ota-required-cache', 0)))
+    self.assertEqual(metadata_proto.retrofit_dynamic_partitions,
+                     metadata_dict.get(
+                        'ota-retrofit-dynamic-partitions') == 'yes')
 
   def test_GetPackageMetadata_incremental_package(self):
     vendor_build_prop = copy.deepcopy(self.VENDOR_BUILD_PROP)
@@ -1365,7 +1431,18 @@
         'ro.build.tags=build-tags',
         'ro.build.version.sdk=29',
         'ro.build.version.security_patch=2020',
-        'ro.build.date.utc=12340000'
+        'ro.build.date.utc=12340000',
+        'ro.system.build.version.release=source-version-release',
+        'ro.system.build.id=source-build-id',
+        'ro.system.build.version.incremental=source-version-incremental',
+        'ro.system.build.type=build-type',
+        'ro.system.build.tags=build-tags',
+        'ro.system.build.version.sdk=29',
+        'ro.system.build.version.security_patch=2020',
+        'ro.system.build.date.utc=12340000',
+        'ro.product.system.brand=generic',
+        'ro.product.system.name=generic',
+        'ro.product.system.device=generic',
     ]
     self.writeFiles({
         'META/misc_info.txt': '\n'.join(self.MISC_INFO),
@@ -1381,10 +1458,11 @@
     target_info = common.BuildInfo(common.LoadInfoDict(self.test_dir))
     source_info = common.BuildInfo(common.LoadInfoDict(source_dir))
 
-    metadata = GetPackageMetadata(target_info, source_info)
+    metadata_proto = GetPackageMetadata(target_info, source_info)
+    metadata_dict = BuildLegacyOtaMetadata(metadata_proto)
     self.assertEqual(
         'vendor-device-pro|vendor-device-std|vendor-product-device',
-        metadata['pre-device'])
+        metadata_dict['pre-device'])
     suffix = ':source-version-release/source-build-id/' \
              'source-version-incremental:build-type/build-tags'
     pre_fingerprints = [
@@ -1395,7 +1473,7 @@
         'vendor-product-brand/vendor-product-name/vendor-product-device'
         '{}'.format(suffix),
     ]
-    self.assertEqual('|'.join(pre_fingerprints), metadata['pre-build'])
+    self.assertEqual('|'.join(pre_fingerprints), metadata_dict['pre-build'])
 
     post_fingerprints = [
         self.constructFingerprint(
@@ -1405,4 +1483,6 @@
         self.constructFingerprint(
             'vendor-product-brand/vendor-product-name/vendor-product-device'),
     ]
-    self.assertEqual('|'.join(post_fingerprints), metadata['post-build'])
+    self.assertEqual('|'.join(post_fingerprints), metadata_dict['post-build'])
+
+    self.CheckMetadataEqual(metadata_dict, metadata_proto)
diff --git a/tools/releasetools/test_utils.py b/tools/releasetools/test_utils.py
index 65092d8..7b7f22a 100755
--- a/tools/releasetools/test_utils.py
+++ b/tools/releasetools/test_utils.py
@@ -22,6 +22,7 @@
 import logging
 import os
 import os.path
+import re
 import struct
 import sys
 import unittest
@@ -224,13 +225,26 @@
         input_fp.seek(offset)
         if entry == 'metadata':
           expected = b'META-INF/COM/ANDROID/METADATA'
+        elif entry == 'metadata.pb':
+          expected = b'META-INF/COM/ANDROID/METADATA-PB'
         else:
           expected = entry.replace('.', '-').upper().encode()
         self.assertEqual(expected, input_fp.read(size))
 
 
 if __name__ == '__main__':
-  testsuite = unittest.TestLoader().discover(
-      os.path.dirname(os.path.realpath(__file__)))
+  # We only want to run tests from the top level directory. Unfortunately the
+  # pattern option of unittest.discover, internally using fnmatch, doesn't
+  # provide a good API to filter the test files based on directory. So we do an
+  # os walk and load them manually.
+  test_modules = []
+  base_path = os.path.dirname(os.path.realpath(__file__))
+  for dirpath, _, files in os.walk(base_path):
+    for fn in files:
+      if dirpath == base_path and re.match('test_.*\\.py$', fn):
+        test_modules.append(fn[:-3])
+
+  test_suite = unittest.TestLoader().loadTestsFromNames(test_modules)
+
   # atest needs a verbosity level of >= 2 to correctly parse the result.
-  unittest.TextTestRunner(verbosity=2).run(testsuite)
+  unittest.TextTestRunner(verbosity=2).run(test_suite)