diff --git a/TEST_MAPPING b/TEST_MAPPING
index 89bd66a..52cff94 100644
--- a/TEST_MAPPING
+++ b/TEST_MAPPING
@@ -22,12 +22,6 @@
       "name": "CtsInitTestCases"
     },
     {
-      "name": "CtsLiblogTestCases"
-    },
-    {
-      "name": "CtsLogdTestCases"
-    },
-    {
       "name": "debuggerd_test"
     },
     {
diff --git a/debuggerd/debuggerd_test.cpp b/debuggerd/debuggerd_test.cpp
index 5ed9e57..5565e8b 100644
--- a/debuggerd/debuggerd_test.cpp
+++ b/debuggerd/debuggerd_test.cpp
@@ -312,7 +312,7 @@
 
   if (mte_supported()) {
     // Test that the default TAGGED_ADDR_CTRL value is set.
-    ASSERT_MATCH(result, R"(tagged_addr_ctrl: 000000000007fff3)");
+    ASSERT_MATCH(result, R"(tagged_addr_ctrl: 000000000007fff5)");
   }
 }
 
diff --git a/fastboot/device/flashing.cpp b/fastboot/device/flashing.cpp
index 1bf4c9c..333ca50 100644
--- a/fastboot/device/flashing.cpp
+++ b/fastboot/device/flashing.cpp
@@ -67,7 +67,7 @@
 
         if ((partition + device->GetCurrentSlot()) == partition_name) {
             mount_metadata.emplace();
-            fs_mgr_overlayfs_teardown(entry.mount_point.c_str());
+            android::fs_mgr::TeardownAllOverlayForMountPoint(entry.mount_point);
         }
     }
 }
@@ -194,7 +194,7 @@
         if (!FlashPartitionTable(super_name, *new_metadata.get())) {
             return device->WriteFail("Unable to flash new partition table");
         }
-        fs_mgr_overlayfs_teardown();
+        android::fs_mgr::TeardownAllOverlayForMountPoint();
         sync();
         return device->WriteOkay("Successfully flashed partition table");
     }
@@ -234,7 +234,7 @@
     if (!UpdateAllPartitionMetadata(device, super_name, *new_metadata.get())) {
         return device->WriteFail("Unable to write new partition table");
     }
-    fs_mgr_overlayfs_teardown();
+    android::fs_mgr::TeardownAllOverlayForMountPoint();
     sync();
     return device->WriteOkay("Successfully updated partition table");
 }
diff --git a/fs_mgr/fs_mgr.cpp b/fs_mgr/fs_mgr.cpp
index fe72393..6294b3f 100644
--- a/fs_mgr/fs_mgr.cpp
+++ b/fs_mgr/fs_mgr.cpp
@@ -1534,6 +1534,8 @@
                            attempted_entry.mount_point},
                           nullptr)) {
                 ++error_count;
+            } else if (current_entry.mount_point == "/data") {
+                userdata_mounted = true;
             }
             encryptable = FS_MGR_MNTALL_DEV_IS_METADATA_ENCRYPTED;
             continue;
diff --git a/fs_mgr/fs_mgr_fstab.cpp b/fs_mgr/fs_mgr_fstab.cpp
index 616a06f..793a725 100644
--- a/fs_mgr/fs_mgr_fstab.cpp
+++ b/fs_mgr/fs_mgr_fstab.cpp
@@ -591,7 +591,7 @@
     FstabEntry userdata;
     if (FstabEntry* entry = GetEntryForMountPoint(fstab, "/data")) {
         userdata = *entry;
-        userdata.blk_device = "userdata_gsi";
+        userdata.blk_device = android::gsi::kDsuUserdata;
         userdata.fs_mgr_flags.logical = true;
         userdata.fs_mgr_flags.formattable = true;
         if (!userdata.metadata_key_dir.empty()) {
@@ -611,7 +611,11 @@
             continue;
         }
         // userdata has been handled
-        if (StartsWith(partition, "user")) {
+        if (partition == android::gsi::kDsuUserdata) {
+            continue;
+        }
+        // scratch is handled by fs_mgr_overlayfs
+        if (partition == android::gsi::kDsuScratch) {
             continue;
         }
         // dsu_partition_name = corresponding_partition_name + kDsuPostfix
diff --git a/fs_mgr/fs_mgr_overlayfs.cpp b/fs_mgr/fs_mgr_overlayfs.cpp
index a7704de..899978f 100644
--- a/fs_mgr/fs_mgr_overlayfs.cpp
+++ b/fs_mgr/fs_mgr_overlayfs.cpp
@@ -73,6 +73,25 @@
     return ret;
 }
 
+bool fs_mgr_in_recovery() {
+    // Check the existence of recovery binary instead of using the compile time
+    // macro, because first-stage-init is compiled with __ANDROID_RECOVERY__
+    // defined, albeit not in recovery. More details: system/core/init/README.md
+    return fs_mgr_access("/system/bin/recovery");
+}
+
+bool fs_mgr_is_dsu_running() {
+    // Since android::gsi::CanBootIntoGsi() or android::gsi::MarkSystemAsGsi() is
+    // never called in recovery, the return value of android::gsi::IsGsiRunning()
+    // is not well-defined. In this case, just return false as being in recovery
+    // implies not running a DSU system.
+    if (fs_mgr_in_recovery()) return false;
+    auto saved_errno = errno;
+    auto ret = android::gsi::IsGsiRunning();
+    errno = saved_errno;
+    return ret;
+}
+
 // determine if a filesystem is available
 bool fs_mgr_overlayfs_filesystem_available(const std::string& filesystem) {
     std::string filesystems;
@@ -113,8 +132,11 @@
 namespace android {
 namespace fs_mgr {
 
-void MapScratchPartitionIfNeeded(Fstab*,
-                                 const std::function<bool(const std::set<std::string>&)>&) {}
+void MapScratchPartitionIfNeeded(Fstab*, const std::function<bool(const std::set<std::string>&)>&) {
+}
+
+void TeardownAllOverlayForMountPoint(const std::string&) {}
+
 }  // namespace fs_mgr
 }  // namespace android
 
@@ -171,6 +193,10 @@
 
 // Note: this is meant only for recovery/first-stage init.
 bool ScratchIsOnData() {
+    // The scratch partition of DSU is managed by gsid.
+    if (fs_mgr_is_dsu_running()) {
+        return false;
+    }
     return fs_mgr_access(kScratchImageMetadata);
 }
 
@@ -464,6 +490,12 @@
     // umount and delete kScratchMountPoint storage if we have logical partitions
     if (overlay != kScratchMountPoint) return true;
 
+    // Validation check.
+    if (fs_mgr_is_dsu_running()) {
+        LERROR << "Destroying DSU scratch is not allowed.";
+        return false;
+    }
+
     auto save_errno = errno;
     if (fs_mgr_overlayfs_already_mounted(kScratchMountPoint, false)) {
         fs_mgr_overlayfs_umount_scratch();
@@ -512,10 +544,13 @@
 }
 
 bool fs_mgr_overlayfs_teardown_one(const std::string& overlay, const std::string& mount_point,
-                                   bool* change) {
+                                   bool* change, bool* should_destroy_scratch = nullptr) {
     const auto top = overlay + kOverlayTopDir;
 
-    if (!fs_mgr_access(top)) return fs_mgr_overlayfs_teardown_scratch(overlay, change);
+    if (!fs_mgr_access(top)) {
+        if (should_destroy_scratch) *should_destroy_scratch = true;
+        return true;
+    }
 
     auto cleanup_all = mount_point.empty();
     const auto partition_name = android::base::Basename(mount_point);
@@ -571,7 +606,7 @@
             PERROR << "rmdir " << top;
         }
     }
-    if (cleanup_all) ret &= fs_mgr_overlayfs_teardown_scratch(overlay, change);
+    if (should_destroy_scratch) *should_destroy_scratch = cleanup_all;
     return ret;
 }
 
@@ -881,12 +916,29 @@
     return "";
 }
 
+// Note: The scratch partition of DSU is managed by gsid, and should be initialized during
+// first-stage-mount. Just check if the DM device for DSU scratch partition is created or not.
+static std::string GetDsuScratchDevice() {
+    auto& dm = DeviceMapper::Instance();
+    std::string device;
+    if (dm.GetState(android::gsi::kDsuScratch) != DmDeviceState::INVALID &&
+        dm.GetDmDevicePathByName(android::gsi::kDsuScratch, &device)) {
+        return device;
+    }
+    return "";
+}
+
 // This returns the scratch device that was detected during early boot (first-
 // stage init). If the device was created later, for example during setup for
 // the adb remount command, it can return an empty string since it does not
 // query ImageManager. (Note that ImageManager in first-stage init will always
 // use device-mapper, since /data is not available to use loop devices.)
 static std::string GetBootScratchDevice() {
+    // Note: fs_mgr_is_dsu_running() always returns false in recovery or fastbootd.
+    if (fs_mgr_is_dsu_running()) {
+        return GetDsuScratchDevice();
+    }
+
     auto& dm = DeviceMapper::Instance();
 
     // If there is a scratch partition allocated in /data or on super, we
@@ -1108,6 +1160,14 @@
 
 bool fs_mgr_overlayfs_create_scratch(const Fstab& fstab, std::string* scratch_device,
                                      bool* partition_exists, bool* change) {
+    // Use the DSU scratch device managed by gsid if within a DSU system.
+    if (fs_mgr_is_dsu_running()) {
+        *scratch_device = GetDsuScratchDevice();
+        *partition_exists = !scratch_device->empty();
+        *change = false;
+        return *partition_exists;
+    }
+
     // Try a physical partition first.
     *scratch_device = GetPhysicalScratchDevice();
     if (!scratch_device->empty() && fs_mgr_rw_access(*scratch_device)) {
@@ -1166,12 +1226,8 @@
 bool fs_mgr_overlayfs_invalid() {
     if (fs_mgr_overlayfs_valid() == OverlayfsValidResult::kNotSupported) return true;
 
-    // in recovery, fastbootd, or gsi mode, not allowed!
-    if (fs_mgr_access("/system/bin/recovery")) return true;
-    auto save_errno = errno;
-    auto ret = android::gsi::IsGsiRunning();
-    errno = save_errno;
-    return ret;
+    // in recovery or fastbootd, not allowed!
+    return fs_mgr_in_recovery();
 }
 
 }  // namespace
@@ -1314,6 +1370,8 @@
     return ret;
 }
 
+// Note: This function never returns the DSU scratch device in recovery or fastbootd,
+// because the DSU scratch is created in the first-stage-mount, which is not run in recovery.
 static bool EnsureScratchMapped(std::string* device, bool* mapped) {
     *mapped = false;
     *device = GetBootScratchDevice();
@@ -1321,6 +1379,11 @@
         return true;
     }
 
+    if (!fs_mgr_in_recovery()) {
+        errno = EINVAL;
+        return false;
+    }
+
     auto partition_name = android::base::Basename(kScratchMountPoint);
 
     // Check for scratch on /data first, before looking for a modified super
@@ -1362,10 +1425,27 @@
     return true;
 }
 
-static void UnmapScratchDevice() {
-    // This should only be reachable in recovery, where scratch is not
-    // automatically mapped and therefore can be unmapped.
-    DestroyLogicalPartition(android::base::Basename(kScratchMountPoint));
+// This should only be reachable in recovery, where DSU scratch is not
+// automatically mapped.
+static bool MapDsuScratchDevice(std::string* device) {
+    std::string dsu_slot;
+    if (!android::gsi::IsGsiInstalled() || !android::gsi::GetActiveDsu(&dsu_slot) ||
+        dsu_slot.empty()) {
+        // Nothing to do if no DSU installation present.
+        return false;
+    }
+
+    auto images = IImageManager::Open("dsu/" + dsu_slot, 10s);
+    if (!images || !images->BackingImageExists(android::gsi::kDsuScratch)) {
+        // Nothing to do if DSU scratch device doesn't exist.
+        return false;
+    }
+
+    images->UnmapImageDevice(android::gsi::kDsuScratch);
+    if (!images->MapImageDevice(android::gsi::kDsuScratch, 10s, device)) {
+        return false;
+    }
+    return true;
 }
 
 // Returns false if teardown not permitted, errno set to last error.
@@ -1377,21 +1457,27 @@
     // If scratch exists, but is not mounted, lets gain access to clean
     // specific override entries.
     auto mount_scratch = false;
-    bool unmap = false;
     if ((mount_point != nullptr) && !fs_mgr_overlayfs_already_mounted(kScratchMountPoint, false)) {
-        std::string scratch_device;
-        if (EnsureScratchMapped(&scratch_device, &unmap)) {
+        std::string scratch_device = GetBootScratchDevice();
+        if (!scratch_device.empty()) {
             mount_scratch = fs_mgr_overlayfs_mount_scratch(scratch_device,
                                                            fs_mgr_overlayfs_scratch_mount_type());
         }
     }
+    bool should_destroy_scratch = false;
     for (const auto& overlay_mount_point : kOverlayMountPoints) {
         ret &= fs_mgr_overlayfs_teardown_one(
-                overlay_mount_point, mount_point ? fs_mgr_mount_point(mount_point) : "", change);
+                overlay_mount_point, mount_point ? fs_mgr_mount_point(mount_point) : "", change,
+                overlay_mount_point == kScratchMountPoint ? &should_destroy_scratch : nullptr);
+    }
+    // Do not attempt to destroy DSU scratch if within a DSU system,
+    // because DSU scratch partition is managed by gsid.
+    if (should_destroy_scratch && !fs_mgr_is_dsu_running()) {
+        ret &= fs_mgr_overlayfs_teardown_scratch(kScratchMountPoint, change);
     }
     if (fs_mgr_overlayfs_valid() == OverlayfsValidResult::kNotSupported) {
         // After obligatory teardown to make sure everything is clean, but if
-        // we didn't want overlayfs in the the first place, we do not want to
+        // we didn't want overlayfs in the first place, we do not want to
         // waste time on a reboot (or reboot request message).
         if (change) *change = false;
     }
@@ -1405,9 +1491,6 @@
     if (mount_scratch) {
         fs_mgr_overlayfs_umount_scratch();
     }
-    if (unmap) {
-        UnmapScratchDevice();
-    }
     return ret;
 }
 
@@ -1475,6 +1558,54 @@
     }
 }
 
+void TeardownAllOverlayForMountPoint(const std::string& mount_point) {
+    if (!fs_mgr_in_recovery()) {
+        LERROR << __FUNCTION__ << "(): must be called within recovery.";
+        return;
+    }
+
+    // Empty string means teardown everything.
+    const std::string teardown_dir = mount_point.empty() ? "" : fs_mgr_mount_point(mount_point);
+    constexpr bool* ignore_change = nullptr;
+
+    // Teardown legacy overlay mount points that's not backed by a scratch device.
+    for (const auto& overlay_mount_point : kOverlayMountPoints) {
+        if (overlay_mount_point == kScratchMountPoint) {
+            continue;
+        }
+        fs_mgr_overlayfs_teardown_one(overlay_mount_point, teardown_dir, ignore_change);
+    }
+
+    // Map scratch device, mount kScratchMountPoint and teardown kScratchMountPoint.
+    bool mapped = false;
+    std::string scratch_device;
+    if (EnsureScratchMapped(&scratch_device, &mapped)) {
+        fs_mgr_overlayfs_umount_scratch();
+        if (fs_mgr_overlayfs_mount_scratch(scratch_device, fs_mgr_overlayfs_scratch_mount_type())) {
+            bool should_destroy_scratch = false;
+            fs_mgr_overlayfs_teardown_one(kScratchMountPoint, teardown_dir, ignore_change,
+                                          &should_destroy_scratch);
+            if (should_destroy_scratch) {
+                fs_mgr_overlayfs_teardown_scratch(kScratchMountPoint, nullptr);
+            }
+            fs_mgr_overlayfs_umount_scratch();
+        }
+        if (mapped) {
+            DestroyLogicalPartition(android::base::Basename(kScratchMountPoint));
+        }
+    }
+
+    // Teardown DSU overlay if present.
+    if (MapDsuScratchDevice(&scratch_device)) {
+        fs_mgr_overlayfs_umount_scratch();
+        if (fs_mgr_overlayfs_mount_scratch(scratch_device, fs_mgr_overlayfs_scratch_mount_type())) {
+            fs_mgr_overlayfs_teardown_one(kScratchMountPoint, teardown_dir, ignore_change);
+            fs_mgr_overlayfs_umount_scratch();
+        }
+        DestroyLogicalPartition(android::gsi::kDsuScratch);
+    }
+}
+
 }  // namespace fs_mgr
 }  // namespace android
 
diff --git a/fs_mgr/include/fs_mgr_overlayfs.h b/fs_mgr/include/fs_mgr_overlayfs.h
index 34aded9..d45e2de 100644
--- a/fs_mgr/include/fs_mgr_overlayfs.h
+++ b/fs_mgr/include/fs_mgr_overlayfs.h
@@ -49,5 +49,12 @@
                                  const std::function<bool(const std::set<std::string>&)>& init);
 void CleanupOldScratchFiles();
 
+// Teardown overlays of all sources (cache dir, scratch device, DSU) for |mount_point|.
+// Teardown all overlays if |mount_point| is empty.
+//
+// Note: This should be called if and only if in recovery or fastbootd to teardown
+// overlays if any partition is flashed or updated.
+void TeardownAllOverlayForMountPoint(const std::string& mount_point = {});
+
 }  // namespace fs_mgr
 }  // namespace android
diff --git a/fs_mgr/libsnapshot/Android.bp b/fs_mgr/libsnapshot/Android.bp
index 059a469..f1b0031 100644
--- a/fs_mgr/libsnapshot/Android.bp
+++ b/fs_mgr/libsnapshot/Android.bp
@@ -31,15 +31,17 @@
         "libbrotli",
         "libdm",
         "libfstab",
-        "libsnapshot_cow",
         "update_metadata-protos",
     ],
     whole_static_libs: [
+        "libbrotli",
         "libcutils",
         "libext2_uuid",
         "libext4_utils",
         "libfstab",
+        "libsnapshot_cow",
         "libsnapshot_snapuserd",
+        "libz",
     ],
     header_libs: [
         "libchrome",
@@ -432,6 +434,7 @@
     init_rc: [
         "snapuserd.rc",
     ],
+    static_executable: true,
 }
 
 cc_binary {
diff --git a/fs_mgr/libsnapshot/include/libsnapshot/snapshot.h b/fs_mgr/libsnapshot/include/libsnapshot/snapshot.h
index 35ed04a..8bed1b9 100644
--- a/fs_mgr/libsnapshot/include/libsnapshot/snapshot.h
+++ b/fs_mgr/libsnapshot/include/libsnapshot/snapshot.h
@@ -15,6 +15,7 @@
 #pragma once
 
 #include <stdint.h>
+#include <unistd.h>
 
 #include <chrono>
 #include <map>
@@ -77,6 +78,7 @@
 class SnapshotStatus;
 
 static constexpr const std::string_view kCowGroupName = "cow";
+static constexpr char kVirtualAbCompressionProp[] = "ro.virtual_ab.compression.enabled";
 
 bool OptimizeSourceCopyOperation(const chromeos_update_engine::InstallOperation& operation,
                                  chromeos_update_engine::InstallOperation* optimized);
@@ -104,6 +106,7 @@
                 android::hardware::boot::V1_1::MergeStatus status) = 0;
         virtual bool SetSlotAsUnbootable(unsigned int slot) = 0;
         virtual bool IsRecovery() const = 0;
+        virtual bool IsTestDevice() const { return false; }
     };
     virtual ~ISnapshotManager() = default;
 
@@ -303,6 +306,14 @@
     // Helper function for second stage init to restorecon on the rollback indicator.
     static std::string GetGlobalRollbackIndicatorPath();
 
+    // Initiate the transition from first-stage to second-stage snapuserd. This
+    // process involves re-creating the dm-user table entries for each device,
+    // so that they connect to the new daemon. Once all new tables have been
+    // activated, we ask the first-stage daemon to cleanly exit.
+    //
+    // The caller must pass a function which starts snapuserd.
+    bool PerformSecondStageTransition();
+
     // ISnapshotManager overrides.
     bool BeginUpdate() override;
     bool CancelUpdate() override;
@@ -345,6 +356,7 @@
     FRIEND_TEST(SnapshotTest, Merge);
     FRIEND_TEST(SnapshotTest, NoMergeBeforeReboot);
     FRIEND_TEST(SnapshotTest, UpdateBootControlHal);
+    FRIEND_TEST(SnapshotUpdateTest, DaemonTransition);
     FRIEND_TEST(SnapshotUpdateTest, DataWipeAfterRollback);
     FRIEND_TEST(SnapshotUpdateTest, DataWipeRollbackInRecovery);
     FRIEND_TEST(SnapshotUpdateTest, FullUpdateFlow);
@@ -372,11 +384,13 @@
     // Ensure we're connected to snapuserd.
     bool EnsureSnapuserdConnected();
 
-    // Helper for first-stage init.
+    // Helpers for first-stage init.
     bool ForceLocalImageManager();
+    const std::unique_ptr<IDeviceInfo>& device() const { return device_; }
 
-    // Helper function for tests.
+    // Helper functions for tests.
     IImageManager* image_manager() const { return images_.get(); }
+    void set_use_first_stage_snapuserd(bool value) { use_first_stage_snapuserd_ = value; }
 
     // Since libsnapshot is included into multiple processes, we flock() our
     // files for simple synchronization. LockedFile is a helper to assist with
@@ -545,6 +559,9 @@
     std::string GetSnapshotDeviceName(const std::string& snapshot_name,
                                       const SnapshotStatus& status);
 
+    bool MapAllPartitions(LockedFile* lock, const std::string& super_device, uint32_t slot,
+                          const std::chrono::milliseconds& timeout_ms);
+
     // Reason for calling MapPartitionWithSnapshot.
     enum class SnapshotContext {
         // For writing or verification (during update_engine).
@@ -618,9 +635,12 @@
             const LpMetadata* exported_target_metadata, const std::string& target_suffix,
             const std::map<std::string, SnapshotStatus>& all_snapshot_status);
 
+    // Implementation of UnmapAllSnapshots(), with the lock provided.
+    bool UnmapAllSnapshots(LockedFile* lock);
+
     // Unmap all partitions that were mapped by CreateLogicalAndSnapshotPartitions.
     // This should only be called in recovery.
-    bool UnmapAllPartitions();
+    bool UnmapAllPartitionsInRecovery();
 
     // Check no snapshot overflows. Note that this returns false negatives if the snapshot
     // overflows, then is remapped and not written afterwards.
@@ -660,6 +680,7 @@
     std::unique_ptr<IDeviceInfo> device_;
     std::unique_ptr<IImageManager> images_;
     bool has_local_image_manager_ = false;
+    bool use_first_stage_snapuserd_ = false;
     bool in_factory_data_reset_ = false;
     std::unique_ptr<SnapuserdClient> snapuserd_client_;
 };
diff --git a/fs_mgr/libsnapshot/include/libsnapshot/snapuserd_client.h b/fs_mgr/libsnapshot/include/libsnapshot/snapuserd_client.h
index 0bbdaa5..aaec229 100644
--- a/fs_mgr/libsnapshot/include/libsnapshot/snapuserd_client.h
+++ b/fs_mgr/libsnapshot/include/libsnapshot/snapuserd_client.h
@@ -14,6 +14,8 @@
 
 #pragma once
 
+#include <unistd.h>
+
 #include <chrono>
 #include <cstring>
 #include <iostream>
@@ -31,9 +33,15 @@
 static constexpr char kSnapuserdSocketFirstStage[] = "snapuserd_first_stage";
 static constexpr char kSnapuserdSocket[] = "snapuserd";
 
+static constexpr char kSnapuserdFirstStagePidVar[] = "FIRST_STAGE_SNAPUSERD_PID";
+
 // Ensure that the second-stage daemon for snapuserd is running.
 bool EnsureSnapuserdStarted();
 
+// Start the first-stage version of snapuserd, returning its pid. This is used
+// by first-stage init, as well as vts_libsnapshot_test. On failure, -1 is returned.
+pid_t StartFirstStageSnapuserd();
+
 class SnapuserdClient {
   private:
     android::base::unique_fd sockfd_;
diff --git a/fs_mgr/libsnapshot/include_test/libsnapshot/test_helpers.h b/fs_mgr/libsnapshot/include_test/libsnapshot/test_helpers.h
index 197aeaa..7aef086 100644
--- a/fs_mgr/libsnapshot/include_test/libsnapshot/test_helpers.h
+++ b/fs_mgr/libsnapshot/include_test/libsnapshot/test_helpers.h
@@ -95,6 +95,7 @@
         unbootable_slots_.insert(slot);
         return true;
     }
+    bool IsTestDevice() const override { return true; }
 
     bool IsSlotUnbootable(uint32_t slot) { return unbootable_slots_.count(slot) != 0; }
 
diff --git a/fs_mgr/libsnapshot/snapshot.cpp b/fs_mgr/libsnapshot/snapshot.cpp
index 7061d56..f9bb0dd 100644
--- a/fs_mgr/libsnapshot/snapshot.cpp
+++ b/fs_mgr/libsnapshot/snapshot.cpp
@@ -31,8 +31,10 @@
 #include <android-base/properties.h>
 #include <android-base/strings.h>
 #include <android-base/unique_fd.h>
+#include <cutils/sockets.h>
 #include <ext4_utils/ext4_utils.h>
 #include <fs_mgr.h>
+#include <fs_mgr/file_wait.h>
 #include <fs_mgr_dm_linear.h>
 #include <fstab/fstab.h>
 #include <libdm/dm.h>
@@ -100,6 +102,12 @@
     if (!sm || !sm->ForceLocalImageManager()) {
         return nullptr;
     }
+
+    // The first-stage version of snapuserd is explicitly started by init. Do
+    // not attempt to using it during tests (which run in normal AOSP).
+    if (!sm->device()->IsTestDevice()) {
+        sm->use_first_stage_snapuserd_ = true;
+    }
     return sm;
 }
 
@@ -400,8 +408,15 @@
         base_sectors = dev_size / kSectorSize;
     }
 
+    // Use an extra decoration for first-stage init, so we can transition
+    // to a new table entry in second-stage.
+    std::string misc_name = name;
+    if (use_first_stage_snapuserd_) {
+        misc_name += "-init";
+    }
+
     DmTable table;
-    table.Emplace<DmTargetUser>(0, base_sectors, name);
+    table.Emplace<DmTargetUser>(0, base_sectors, misc_name);
     if (!dm.CreateDevice(name, table, path, timeout_ms)) {
         return false;
     }
@@ -410,7 +425,7 @@
         return false;
     }
 
-    auto control_device = "/dev/dm-user/" + name;
+    auto control_device = "/dev/dm-user/" + misc_name;
     return snapuserd_client_->InitializeSnapuserd(cow_file, base_device, control_device);
 }
 
@@ -1284,6 +1299,107 @@
     return RemoveAllUpdateState(lock, before_cancel);
 }
 
+bool SnapshotManager::PerformSecondStageTransition() {
+    LOG(INFO) << "Performing second-stage transition for snapuserd.";
+
+    // Don't use EnsuerSnapuserdConnected() because this is called from init,
+    // and attempting to do so will deadlock.
+    if (!snapuserd_client_) {
+        snapuserd_client_ = SnapuserdClient::Connect(kSnapuserdSocket, 10s);
+        if (!snapuserd_client_) {
+            LOG(ERROR) << "Unable to connect to snapuserd";
+            return false;
+        }
+    }
+
+    auto& dm = DeviceMapper::Instance();
+
+    auto lock = LockExclusive();
+    if (!lock) return false;
+
+    std::vector<std::string> snapshots;
+    if (!ListSnapshots(lock.get(), &snapshots)) {
+        LOG(ERROR) << "Failed to list snapshots.";
+        return false;
+    }
+
+    size_t num_cows = 0;
+    size_t ok_cows = 0;
+    for (const auto& snapshot : snapshots) {
+        std::string cow_name = GetDmUserCowName(snapshot);
+        if (dm.GetState(cow_name) == DmDeviceState::INVALID) {
+            continue;
+        }
+
+        DeviceMapper::TargetInfo target;
+        if (!GetSingleTarget(cow_name, TableQuery::Table, &target)) {
+            continue;
+        }
+
+        auto target_type = DeviceMapper::GetTargetType(target.spec);
+        if (target_type != "user") {
+            LOG(ERROR) << "Unexpected target type for " << cow_name << ": " << target_type;
+            continue;
+        }
+
+        num_cows++;
+
+        DmTable table;
+        table.Emplace<DmTargetUser>(0, target.spec.length, cow_name);
+        if (!dm.LoadTableAndActivate(cow_name, table)) {
+            LOG(ERROR) << "Unable to swap tables for " << cow_name;
+            continue;
+        }
+
+        std::string backing_device;
+        if (!dm.GetDmDevicePathByName(GetBaseDeviceName(snapshot), &backing_device)) {
+            LOG(ERROR) << "Could not get device path for " << GetBaseDeviceName(snapshot);
+            continue;
+        }
+
+        std::string cow_device;
+        if (!dm.GetDmDevicePathByName(GetCowName(snapshot), &cow_device)) {
+            LOG(ERROR) << "Could not get device path for " << GetCowName(snapshot);
+            continue;
+        }
+
+        // Wait for ueventd to acknowledge and create the control device node.
+        std::string control_device = "/dev/dm-user/" + cow_name;
+        if (!android::fs_mgr::WaitForFile(control_device, 10s)) {
+            LOG(ERROR) << "Could not find control device: " << control_device;
+            continue;
+        }
+
+        if (!snapuserd_client_->InitializeSnapuserd(cow_device, backing_device, control_device)) {
+            // This error is unrecoverable. We cannot proceed because reads to
+            // the underlying device will fail.
+            LOG(FATAL) << "Could not initialize snapuserd for " << cow_name;
+            return false;
+        }
+
+        ok_cows++;
+    }
+
+    if (ok_cows != num_cows) {
+        LOG(ERROR) << "Could not transition all snapuserd consumers.";
+        return false;
+    }
+
+    int pid;
+    const char* pid_str = getenv(kSnapuserdFirstStagePidVar);
+    if (pid_str && android::base::ParseInt(pid_str, &pid)) {
+        if (kill(pid, SIGTERM) < 0 && errno != ESRCH) {
+            LOG(ERROR) << "kill snapuserd failed";
+            return false;
+        }
+    } else {
+        LOG(ERROR) << "Could not find or parse " << kSnapuserdFirstStagePidVar
+                   << " for snapuserd pid";
+        return false;
+    }
+    return true;
+}
+
 std::unique_ptr<LpMetadata> SnapshotManager::ReadCurrentMetadata() {
     const auto& opener = device_->GetPartitionOpener();
     uint32_t slot = SlotNumberForSlotSuffix(device_->GetSlotSuffix());
@@ -1593,8 +1709,13 @@
     auto lock = LockExclusive();
     if (!lock) return false;
 
-    const auto& opener = device_->GetPartitionOpener();
     uint32_t slot = SlotNumberForSlotSuffix(device_->GetSlotSuffix());
+    return MapAllPartitions(lock.get(), super_device, slot, timeout_ms);
+}
+
+bool SnapshotManager::MapAllPartitions(LockedFile* lock, const std::string& super_device,
+                                       uint32_t slot, const std::chrono::milliseconds& timeout_ms) {
+    const auto& opener = device_->GetPartitionOpener();
     auto metadata = android::fs_mgr::ReadMetadata(opener, super_device, slot);
     if (!metadata) {
         LOG(ERROR) << "Could not read dynamic partition metadata for device: " << super_device;
@@ -1615,12 +1736,20 @@
                 .partition_opener = &opener,
                 .timeout_ms = timeout_ms,
         };
-        if (!MapPartitionWithSnapshot(lock.get(), std::move(params), SnapshotContext::Mount,
-                                      nullptr)) {
+        if (!MapPartitionWithSnapshot(lock, std::move(params), SnapshotContext::Mount, nullptr)) {
             return false;
         }
     }
 
+    if (use_first_stage_snapuserd_) {
+        // Remove the first-stage socket as a precaution, there is no need to
+        // access the daemon anymore and we'll be killing it once second-stage
+        // is running.
+        auto socket = ANDROID_SOCKET_DIR + "/"s + kSnapuserdSocketFirstStage;
+        snapuserd_client_ = nullptr;
+        unlink(socket.c_str());
+    }
+
     LOG(INFO) << "Created logical partitions with snapshot.";
     return true;
 }
@@ -1925,10 +2054,18 @@
             LOG(ERROR) << "Cannot unmap " << dm_user_name;
             return false;
         }
-        if (!snapuserd_client_->WaitForDeviceDelete("/dev/dm-user/" + dm_user_name)) {
+
+        auto control_device = "/dev/dm-user/" + dm_user_name;
+        if (!snapuserd_client_->WaitForDeviceDelete(control_device)) {
             LOG(ERROR) << "Failed to wait for " << dm_user_name << " control device to delete";
             return false;
         }
+
+        // Ensure the control device is gone so we don't run into ABA problems.
+        if (!android::fs_mgr::WaitForFileDeleted(control_device, 10s)) {
+            LOG(ERROR) << "Timed out waiting for " << control_device << " to unlink";
+            return false;
+        }
     }
 
     auto cow_name = GetCowName(name);
@@ -1945,14 +2082,49 @@
     return true;
 }
 
-bool SnapshotManager::MapAllSnapshots(const std::chrono::milliseconds&) {
-    LOG(ERROR) << "Not yet implemented.";
-    return false;
+bool SnapshotManager::MapAllSnapshots(const std::chrono::milliseconds& timeout_ms) {
+    auto lock = LockExclusive();
+    if (!lock) return false;
+
+    auto state = ReadUpdateState(lock.get());
+    if (state == UpdateState::Unverified) {
+        if (GetCurrentSlot() == Slot::Target) {
+            LOG(ERROR) << "Cannot call MapAllSnapshots when booting from the target slot.";
+            return false;
+        }
+    } else if (state != UpdateState::Initiated) {
+        LOG(ERROR) << "Cannot call MapAllSnapshots from update state: " << state;
+        return false;
+    }
+
+    if (!UnmapAllSnapshots(lock.get())) {
+        return false;
+    }
+
+    uint32_t slot = SlotNumberForSlotSuffix(device_->GetOtherSlotSuffix());
+    return MapAllPartitions(lock.get(), device_->GetSuperDevice(slot), slot, timeout_ms);
 }
 
 bool SnapshotManager::UnmapAllSnapshots() {
-    LOG(ERROR) << "Not yet implemented.";
-    return false;
+    auto lock = LockExclusive();
+    if (!lock) return false;
+
+    return UnmapAllSnapshots(lock.get());
+}
+
+bool SnapshotManager::UnmapAllSnapshots(LockedFile* lock) {
+    std::vector<std::string> snapshots;
+    if (!ListSnapshots(lock, &snapshots)) {
+        return false;
+    }
+
+    for (const auto& snapshot : snapshots) {
+        if (!UnmapPartitionWithSnapshot(lock, snapshot)) {
+            LOG(ERROR) << "Failed to unmap snapshot: " << snapshot;
+            return false;
+        }
+    }
+    return true;
 }
 
 auto SnapshotManager::OpenFile(const std::string& file, int lock_flags)
@@ -2212,15 +2384,35 @@
 }
 
 bool SnapshotManager::EnsureSnapuserdConnected() {
-    if (!snapuserd_client_) {
+    if (snapuserd_client_) {
+        return true;
+    }
+
+    std::string socket;
+    if (use_first_stage_snapuserd_) {
+        auto pid = StartFirstStageSnapuserd();
+        if (pid < 0) {
+            LOG(ERROR) << "Failed to start snapuserd";
+            return false;
+        }
+
+        auto pid_str = std::to_string(static_cast<int>(pid));
+        if (setenv(kSnapuserdFirstStagePidVar, pid_str.c_str(), 1) < 0) {
+            PLOG(ERROR) << "setenv failed storing the snapuserd pid";
+        }
+
+        socket = kSnapuserdSocketFirstStage;
+    } else {
         if (!EnsureSnapuserdStarted()) {
             return false;
         }
-        snapuserd_client_ = SnapuserdClient::Connect(kSnapuserdSocket, 10s);
-        if (!snapuserd_client_) {
-            LOG(ERROR) << "Unable to connect to snapuserd";
-            return false;
-        }
+        socket = kSnapuserdSocket;
+    }
+
+    snapuserd_client_ = SnapuserdClient::Connect(socket, 10s);
+    if (!snapuserd_client_) {
+        LOG(ERROR) << "Unable to connect to snapuserd";
+        return false;
     }
     return true;
 }
@@ -2538,11 +2730,26 @@
             return Return::Error();
         }
 
-        auto ret = InitializeCow(cow_path);
-        if (!ret.is_ok()) {
-            LOG(ERROR) << "Can't zero-fill COW device for " << target_partition->name() << ": "
-                       << cow_path;
-            return AddRequiredSpace(ret, all_snapshot_status);
+        if (IsCompressionEnabled()) {
+            unique_fd fd(open(cow_path.c_str(), O_RDWR | O_CLOEXEC));
+            if (fd < 0) {
+                PLOG(ERROR) << "open " << cow_path << " failed for snapshot "
+                            << cow_params.partition_name;
+                return Return::Error();
+            }
+
+            CowWriter writer(CowOptions{});
+            if (!writer.Initialize(fd) || !writer.Finalize()) {
+                LOG(ERROR) << "Could not initialize COW device for " << target_partition->name();
+                return Return::Error();
+            }
+        } else {
+            auto ret = InitializeKernelCow(cow_path);
+            if (!ret.is_ok()) {
+                LOG(ERROR) << "Can't zero-fill COW device for " << target_partition->name() << ": "
+                           << cow_path;
+                return AddRequiredSpace(ret, all_snapshot_status);
+            }
         }
         // Let destructor of created_devices_for_cow to unmap the COW devices.
     };
@@ -2700,7 +2907,7 @@
     return UnmapPartitionWithSnapshot(lock.get(), target_partition_name);
 }
 
-bool SnapshotManager::UnmapAllPartitions() {
+bool SnapshotManager::UnmapAllPartitionsInRecovery() {
     auto lock = LockExclusive();
     if (!lock) return false;
 
@@ -2844,7 +3051,7 @@
     }
 
     // Nothing should be depending on partitions now, so unmap them all.
-    if (!UnmapAllPartitions()) {
+    if (!UnmapAllPartitionsInRecovery()) {
         LOG(ERROR) << "Unable to unmap all partitions; fastboot may fail to flash.";
     }
     return true;
@@ -2875,7 +3082,7 @@
     }
 
     // Nothing should be depending on partitions now, so unmap them all.
-    if (!UnmapAllPartitions()) {
+    if (!UnmapAllPartitionsInRecovery()) {
         LOG(ERROR) << "Unable to unmap all partitions; fastboot may fail to flash.";
     }
     return true;
diff --git a/fs_mgr/libsnapshot/snapshot_test.cpp b/fs_mgr/libsnapshot/snapshot_test.cpp
index 9660357..7fc64e5 100644
--- a/fs_mgr/libsnapshot/snapshot_test.cpp
+++ b/fs_mgr/libsnapshot/snapshot_test.cpp
@@ -15,6 +15,7 @@
 #include <libsnapshot/snapshot.h>
 
 #include <fcntl.h>
+#include <signal.h>
 #include <sys/file.h>
 #include <sys/stat.h>
 #include <sys/types.h>
@@ -29,6 +30,7 @@
 #include <android-base/properties.h>
 #include <android-base/strings.h>
 #include <android-base/unique_fd.h>
+#include <fs_mgr/file_wait.h>
 #include <fs_mgr/roots.h>
 #include <fs_mgr_dm_linear.h>
 #include <gtest/gtest.h>
@@ -118,6 +120,8 @@
         image_manager_ = sm->image_manager();
 
         test_device->set_slot_suffix("_a");
+
+        sm->set_use_first_stage_snapuserd(false);
     }
 
     void CleanupTestArtifacts() {
@@ -265,7 +269,7 @@
         if (!map_res) {
             return map_res;
         }
-        if (!InitializeCow(cow_device)) {
+        if (!InitializeKernelCow(cow_device)) {
             return AssertionFailure() << "Cannot zero fill " << cow_device;
         }
         if (!sm->UnmapCowImage(name)) {
@@ -1736,6 +1740,74 @@
     ASSERT_LT(res.required_size(), 15_MiB);
 }
 
+class AutoKill final {
+  public:
+    explicit AutoKill(pid_t pid) : pid_(pid) {}
+    ~AutoKill() {
+        if (pid_ > 0) kill(pid_, SIGKILL);
+    }
+
+    bool valid() const { return pid_ > 0; }
+
+  private:
+    pid_t pid_;
+};
+
+TEST_F(SnapshotUpdateTest, DaemonTransition) {
+    if (!IsCompressionEnabled()) {
+        GTEST_SKIP() << "Skipping Virtual A/B Compression test";
+    }
+
+    AutoKill auto_kill(StartFirstStageSnapuserd());
+    ASSERT_TRUE(auto_kill.valid());
+
+    // Ensure a connection to the second-stage daemon, but use the first-stage
+    // code paths thereafter.
+    ASSERT_TRUE(sm->EnsureSnapuserdConnected());
+    sm->set_use_first_stage_snapuserd(true);
+
+    AddOperationForPartitions();
+    // Execute the update.
+    ASSERT_TRUE(sm->BeginUpdate());
+    ASSERT_TRUE(sm->CreateUpdateSnapshots(manifest_));
+    ASSERT_TRUE(MapUpdateSnapshots());
+    ASSERT_TRUE(sm->FinishedSnapshotWrites(false));
+    ASSERT_TRUE(UnmapAll());
+
+    auto init = SnapshotManager::NewForFirstStageMount(new TestDeviceInfo(fake_super, "_b"));
+    ASSERT_NE(init, nullptr);
+
+    ASSERT_TRUE(init->EnsureSnapuserdConnected());
+    init->set_use_first_stage_snapuserd(true);
+
+    ASSERT_TRUE(init->NeedSnapshotsInFirstStageMount());
+    ASSERT_TRUE(init->CreateLogicalAndSnapshotPartitions("super", snapshot_timeout_));
+
+    ASSERT_EQ(access("/dev/dm-user/sys_b-user-cow-init", F_OK), 0);
+    ASSERT_EQ(access("/dev/dm-user/sys_b-user-cow", F_OK), -1);
+
+    ASSERT_TRUE(init->PerformSecondStageTransition());
+
+    // The control device should have been renamed.
+    ASSERT_TRUE(android::fs_mgr::WaitForFileDeleted("/dev/dm-user/sys_b-user-cow-init", 10s));
+    ASSERT_EQ(access("/dev/dm-user/sys_b-user-cow", F_OK), 0);
+}
+
+TEST_F(SnapshotUpdateTest, MapAllSnapshots) {
+    AddOperationForPartitions();
+    // Execute the update.
+    ASSERT_TRUE(sm->BeginUpdate());
+    ASSERT_TRUE(sm->CreateUpdateSnapshots(manifest_));
+    for (const auto& name : {"sys_b", "vnd_b", "prd_b"}) {
+        ASSERT_TRUE(WriteSnapshotAndHash(name));
+    }
+    ASSERT_TRUE(sm->FinishedSnapshotWrites(false));
+    ASSERT_TRUE(sm->MapAllSnapshots(10s));
+
+    // Read bytes back and verify they match the cache.
+    ASSERT_TRUE(IsPartitionUnchanged("sys_b"));
+}
+
 class FlashAfterUpdateTest : public SnapshotUpdateTest,
                              public WithParamInterface<std::tuple<uint32_t, bool>> {
   public:
diff --git a/fs_mgr/libsnapshot/snapuserd_client.cpp b/fs_mgr/libsnapshot/snapuserd_client.cpp
index 35bb29b..5650139 100644
--- a/fs_mgr/libsnapshot/snapuserd_client.cpp
+++ b/fs_mgr/libsnapshot/snapuserd_client.cpp
@@ -51,6 +51,25 @@
     return true;
 }
 
+pid_t StartFirstStageSnapuserd() {
+    pid_t pid = fork();
+    if (pid < 0) {
+        PLOG(ERROR) << "fork failed";
+        return pid;
+    }
+    if (pid != 0) {
+        return pid;
+    }
+
+    std::string arg0 = "/system/bin/snapuserd";
+    std::string arg1 = kSnapuserdSocketFirstStage;
+    char* const argv[] = {arg0.data(), arg1.data(), nullptr};
+    if (execv(arg0.c_str(), argv) < 0) {
+        PLOG(FATAL) << "execv failed";
+    }
+    return pid;
+}
+
 SnapuserdClient::SnapuserdClient(android::base::unique_fd&& sockfd) : sockfd_(std::move(sockfd)) {}
 
 static inline bool IsRetryErrno() {
diff --git a/fs_mgr/libsnapshot/snapuserd_server.cpp b/fs_mgr/libsnapshot/snapuserd_server.cpp
index 6b8cdd9..6a89218 100644
--- a/fs_mgr/libsnapshot/snapuserd_server.cpp
+++ b/fs_mgr/libsnapshot/snapuserd_server.cpp
@@ -191,6 +191,8 @@
 }
 
 void SnapuserdServer::RunThread(DmUserHandler* handler) {
+    LOG(INFO) << "Entering thread for handler: " << handler->GetControlDevice();
+
     while (!StopRequested()) {
         if (handler->snapuserd()->Run() < 0) {
             LOG(INFO) << "Snapuserd: Thread terminating as control device is de-registered";
@@ -198,6 +200,8 @@
         }
     }
 
+    LOG(INFO) << "Exiting thread for handler: " << handler->GetControlDevice();
+
     if (auto client = RemoveHandler(handler->GetControlDevice())) {
         // The main thread did not receive a WaitForDelete request for this
         // control device. Since we transferred ownership within the lock,
diff --git a/fs_mgr/libsnapshot/utility.cpp b/fs_mgr/libsnapshot/utility.cpp
index d32b61e..4cae83a 100644
--- a/fs_mgr/libsnapshot/utility.cpp
+++ b/fs_mgr/libsnapshot/utility.cpp
@@ -91,7 +91,7 @@
     }
 }
 
-Return InitializeCow(const std::string& device) {
+Return InitializeKernelCow(const std::string& device) {
     // When the kernel creates a persistent dm-snapshot, it requires a CoW file
     // to store the modifications. The kernel interface does not specify how
     // the CoW is used, and there is no standard associated.
diff --git a/fs_mgr/libsnapshot/utility.h b/fs_mgr/libsnapshot/utility.h
index e69bdad..482888a 100644
--- a/fs_mgr/libsnapshot/utility.h
+++ b/fs_mgr/libsnapshot/utility.h
@@ -112,7 +112,7 @@
         android::fs_mgr::MetadataBuilder* builder, const std::string& suffix);
 
 // Initialize a device before using it as the COW device for a dm-snapshot device.
-Return InitializeCow(const std::string& device);
+Return InitializeKernelCow(const std::string& device);
 
 // "Atomically" write string to file. This is done by a series of actions:
 // 1. Write to path + ".tmp"
diff --git a/fs_mgr/tests/adb-remount-test.sh b/fs_mgr/tests/adb-remount-test.sh
index e995888..f5bbe35 100755
--- a/fs_mgr/tests/adb-remount-test.sh
+++ b/fs_mgr/tests/adb-remount-test.sh
@@ -1380,9 +1380,9 @@
 check_eq "${VENDOR_DEVT}" "`adb_sh stat --format=%D /vendor/hello </dev/null`" vendor devt after reboot
 check_eq "${SYSTEM_INO}" "`adb_sh stat --format=%i /system/hello </dev/null`" system inode after reboot
 check_eq "${VENDOR_INO}" "`adb_sh stat --format=%i /vendor/hello </dev/null`" vendor inode after reboot
-check_eq "${BASE_SYSTEM_DEVT}" "`adb_sh stat --format=%D /system/bin/stat </dev/null`" base system devt after reboot
-check_eq "${BASE_VENDOR_DEVT}" "`adb_sh stat --format=%D /vendor/bin/stat </dev/null`" base system devt after reboot
-check_eq "${BASE_SYSTEM_DEVT}" "`adb_sh stat --format=%D /system/xbin/su </dev/null`" devt for su after reboot
+check_eq "${BASE_SYSTEM_DEVT}" "`adb_sh stat --format=%D /system/bin/stat </dev/null`" --warning base system devt after reboot
+check_eq "${BASE_VENDOR_DEVT}" "`adb_sh stat --format=%D /vendor/bin/stat </dev/null`" --warning base vendor devt after reboot
+check_eq "${BASE_SYSTEM_DEVT}" "`adb_sh stat --format=%D /system/xbin/su </dev/null`" --warning devt for su after reboot
 
 # Feed log with selinux denials as a result of overlays
 adb_sh find ${MOUNTS} </dev/null >/dev/null 2>/dev/null
@@ -1509,8 +1509,8 @@
 
   check_eq "${SYSTEM_DEVT}" "`adb_sh stat --format=%D /system/hello </dev/null`" system devt after reboot
   check_eq "${SYSTEM_INO}" "`adb_sh stat --format=%i /system/hello </dev/null`" system inode after reboot
-  check_eq "${BASE_SYSTEM_DEVT}" "`adb_sh stat --format=%D /system/bin/stat </dev/null`" base system devt after reboot
-  check_eq "${BASE_SYSTEM_DEVT}" "`adb_sh stat --format=%D /system/xbin/su </dev/null`" devt for su after reboot
+  check_eq "${BASE_SYSTEM_DEVT}" "`adb_sh stat --format=%D /system/bin/stat </dev/null`" --warning base system devt after reboot
+  check_eq "${BASE_SYSTEM_DEVT}" "`adb_sh stat --format=%D /system/xbin/su </dev/null`" --warning devt for su after reboot
 
 fi
 
diff --git a/init/first_stage_init.cpp b/init/first_stage_init.cpp
index 554f301..d2a952f 100644
--- a/init/first_stage_init.cpp
+++ b/init/first_stage_init.cpp
@@ -99,6 +99,34 @@
     return cmdline.find("androidboot.force_normal_boot=1") != std::string::npos;
 }
 
+// Move e2fsck before switching root, so that it is available at the same path
+// after switching root.
+void PrepareSwitchRoot() {
+    constexpr const char* src = "/system/bin/e2fsck";
+    constexpr const char* dst = "/first_stage_ramdisk/system/bin/e2fsck";
+
+    if (access(dst, X_OK) == 0) {
+        LOG(INFO) << dst << " already exists and it can be executed";
+        return;
+    }
+
+    if (access(src, F_OK) != 0) {
+        PLOG(INFO) << "Not moving " << src << " because it cannot be accessed";
+        return;
+    }
+
+    auto dst_dir = android::base::Dirname(dst);
+    std::error_code ec;
+    if (!fs::create_directories(dst_dir, ec)) {
+        LOG(FATAL) << "Cannot create " << dst_dir << ": " << ec.message();
+    }
+    if (rename(src, dst) != 0) {
+        PLOG(FATAL) << "Cannot move " << src << " to " << dst
+                    << ". Either install e2fsck.ramdisk so that it is at the correct place (" << dst
+                    << "), or make ramdisk writable";
+    }
+}
+
 }  // namespace
 
 std::string GetModuleLoadList(bool recovery, const std::string& dir_path) {
@@ -298,6 +326,7 @@
 
     if (ForceNormalBoot(cmdline)) {
         mkdir("/first_stage_ramdisk", 0755);
+        PrepareSwitchRoot();
         // SwitchRoot() must be called with a mount point as the target, so we bind mount the
         // target directory to itself here.
         if (mount("/first_stage_ramdisk", "/first_stage_ramdisk", nullptr, MS_BIND, nullptr) != 0) {
diff --git a/init/init.cpp b/init/init.cpp
index ea04494..c6f2066 100644
--- a/init/init.cpp
+++ b/init/init.cpp
@@ -53,6 +53,7 @@
 #include <keyutils.h>
 #include <libavb/libavb.h>
 #include <libgsi/libgsi.h>
+#include <libsnapshot/snapshot.h>
 #include <processgroup/processgroup.h>
 #include <processgroup/setup.h>
 #include <selinux/android.h>
@@ -94,6 +95,7 @@
 using android::base::Timer;
 using android::base::Trim;
 using android::fs_mgr::AvbHandle;
+using android::snapshot::SnapshotManager;
 
 namespace android {
 namespace init {
@@ -722,6 +724,32 @@
     }
 }
 
+static Result<void> TransitionSnapuserdAction(const BuiltinArguments&) {
+    if (!SnapshotManager::IsSnapshotManagerNeeded() ||
+        !android::base::GetBoolProperty(android::snapshot::kVirtualAbCompressionProp, false)) {
+        return {};
+    }
+
+    auto sm = SnapshotManager::New();
+    if (!sm) {
+        LOG(FATAL) << "Failed to create SnapshotManager, will not transition snapuserd";
+        return {};
+    }
+
+    ServiceList& service_list = ServiceList::GetInstance();
+    auto svc = service_list.FindService("snapuserd");
+    if (!svc) {
+        LOG(FATAL) << "Failed to find snapuserd service, aborting transition";
+        return {};
+    }
+    svc->Start();
+
+    if (!sm->PerformSecondStageTransition()) {
+        LOG(FATAL) << "Failed to transition snapuserd to second-stage";
+    }
+    return {};
+}
+
 int SecondStageMain(int argc, char** argv) {
     if (REBOOT_BOOTLOADER_ON_PANIC) {
         InstallRebootSignalHandlers();
@@ -847,6 +875,7 @@
     SetProperty(gsi::kGsiInstalledProp, is_installed);
 
     am.QueueBuiltinAction(SetupCgroupsAction, "SetupCgroups");
+    am.QueueBuiltinAction(TransitionSnapuserdAction, "TransitionSnapuserd");
     am.QueueBuiltinAction(SetKptrRestrictAction, "SetKptrRestrict");
     am.QueueBuiltinAction(TestPerfEventSelinuxAction, "TestPerfEventSelinux");
     am.QueueEventTrigger("early-init");
diff --git a/init/security.cpp b/init/security.cpp
index 2450d65..ac784a3 100644
--- a/init/security.cpp
+++ b/init/security.cpp
@@ -19,6 +19,7 @@
 #include <errno.h>
 #include <fcntl.h>
 #include <linux/perf_event.h>
+#include <selinux/selinux.h>
 #include <sys/ioctl.h>
 #include <sys/syscall.h>
 #include <unistd.h>
@@ -222,6 +223,19 @@
 // supporting kernels that precede the perf_event_open hooks (Android common
 // kernels 4.4 and 4.9).
 Result<void> TestPerfEventSelinuxAction(const BuiltinArguments&) {
+    // Special case: for *development devices* that boot with permissive
+    // SELinux, treat the LSM hooks as present for the effect of lowering the
+    // perf_event_paranoid sysctl. The sysprop is reused for pragmatic reasons,
+    // as there no existing way for init rules to check for permissive boot at
+    // the time of writing.
+    if (ALLOW_PERMISSIVE_SELINUX) {
+        if (!security_getenforce()) {
+            LOG(INFO) << "Permissive SELinux boot, forcing sys.init.perf_lsm_hooks to 1.";
+            SetProperty("sys.init.perf_lsm_hooks", "1");
+            return {};
+        }
+    }
+
     // Use a trivial event that will be configured, but not started.
     struct perf_event_attr pe = {
             .type = PERF_TYPE_SOFTWARE,
diff --git a/libbacktrace b/libbacktrace
deleted file mode 120000
index 571194c..0000000
--- a/libbacktrace
+++ /dev/null
@@ -1 +0,0 @@
-../unwinding/libbacktrace
\ No newline at end of file
diff --git a/liblog b/liblog
deleted file mode 120000
index 71443ae..0000000
--- a/liblog
+++ /dev/null
@@ -1 +0,0 @@
-../logging/liblog
\ No newline at end of file
diff --git a/libpackagelistparser/Android.bp b/libpackagelistparser/Android.bp
index b56dcdb..c3f8692 100644
--- a/libpackagelistparser/Android.bp
+++ b/libpackagelistparser/Android.bp
@@ -1,5 +1,7 @@
 cc_library {
     name: "libpackagelistparser",
+    ramdisk_available: true,
+    vendor_ramdisk_available: true,
     recovery_available: true,
     srcs: ["packagelistparser.cpp"],
     shared_libs: ["liblog"],
diff --git a/libprocessgroup/Android.bp b/libprocessgroup/Android.bp
index d101774..71e2b91 100644
--- a/libprocessgroup/Android.bp
+++ b/libprocessgroup/Android.bp
@@ -32,6 +32,8 @@
     name: "libprocessgroup",
     host_supported: true,
     native_bridge_supported: true,
+    ramdisk_available: true,
+    vendor_ramdisk_available: true,
     recovery_available: true,
     vendor_available: true,
     vndk: {
diff --git a/libprocessgroup/cgrouprc/Android.bp b/libprocessgroup/cgrouprc/Android.bp
index a107baa..bb59942 100644
--- a/libprocessgroup/cgrouprc/Android.bp
+++ b/libprocessgroup/cgrouprc/Android.bp
@@ -15,6 +15,8 @@
 cc_library {
     name: "libcgrouprc",
     host_supported: true,
+    ramdisk_available: true,
+    vendor_ramdisk_available: true,
     recovery_available: true,
     // Do not ever mark this as vendor_available; otherwise, vendor modules
     // that links to the static library will behave unexpectedly. All on-device
diff --git a/libprocessgroup/cgrouprc_format/Android.bp b/libprocessgroup/cgrouprc_format/Android.bp
index 559a869..6428930 100644
--- a/libprocessgroup/cgrouprc_format/Android.bp
+++ b/libprocessgroup/cgrouprc_format/Android.bp
@@ -15,6 +15,8 @@
 cc_library_static {
     name: "libcgrouprc_format",
     host_supported: true,
+    ramdisk_available: true,
+    vendor_ramdisk_available: true,
     recovery_available: true,
     native_bridge_supported: true,
     srcs: [
diff --git a/libprocessgroup/profiles/cgroups.json b/libprocessgroup/profiles/cgroups.json
index 4518487..5b7a28a 100644
--- a/libprocessgroup/profiles/cgroups.json
+++ b/libprocessgroup/profiles/cgroups.json
@@ -32,13 +32,6 @@
       "Mode": "0700",
       "UID": "root",
       "GID": "system"
-    },
-    {
-      "Controller": "schedtune",
-      "Path": "/dev/stune",
-      "Mode": "0755",
-      "UID": "system",
-      "GID": "system"
     }
   ],
   "Cgroups2": {
diff --git a/libprocessgroup/profiles/task_profiles.json b/libprocessgroup/profiles/task_profiles.json
index c4dbf8e..ea0064f 100644
--- a/libprocessgroup/profiles/task_profiles.json
+++ b/libprocessgroup/profiles/task_profiles.json
@@ -31,16 +31,6 @@
       "File": "memory.swappiness"
     },
     {
-      "Name": "STuneBoost",
-      "Controller": "schedtune",
-      "File": "schedtune.boost"
-    },
-    {
-      "Name": "STunePreferIdle",
-      "Controller": "schedtune",
-      "File": "schedtune.prefer_idle"
-    },
-    {
       "Name": "UClampMin",
       "Controller": "cpu",
       "File": "cpu.uclamp.min"
@@ -51,6 +41,11 @@
       "File": "cpu.uclamp.max"
     },
     {
+      "Name": "UClampLatencySensitive",
+      "Controller": "cpu",
+      "File": "cpu.uclamp.latency_sensitive"
+    },
+    {
       "Name": "FreezerState",
       "Controller": "freezer",
       "File": "cgroup.freeze"
@@ -65,7 +60,7 @@
           "Name": "JoinCgroup",
           "Params":
           {
-            "Controller": "schedtune",
+            "Controller": "cpu",
             "Path": "background"
           }
         }
@@ -104,7 +99,7 @@
           "Name": "JoinCgroup",
           "Params":
           {
-            "Controller": "schedtune",
+            "Controller": "cpu",
             "Path": ""
           }
         }
@@ -117,7 +112,7 @@
           "Name": "JoinCgroup",
           "Params":
           {
-            "Controller": "schedtune",
+            "Controller": "cpu",
             "Path": "foreground"
           }
         }
@@ -130,7 +125,7 @@
           "Name": "JoinCgroup",
           "Params":
           {
-            "Controller": "schedtune",
+            "Controller": "cpu",
             "Path": "top-app"
           }
         }
@@ -143,7 +138,7 @@
           "Name": "JoinCgroup",
           "Params":
           {
-            "Controller": "schedtune",
+            "Controller": "cpu",
             "Path": "rt"
           }
         }
@@ -156,12 +151,25 @@
           "Name": "JoinCgroup",
           "Params":
           {
-            "Controller": "schedtune",
+            "Controller": "cpu",
             "Path": "camera-daemon"
           }
         }
       ]
     },
+    {
+      "Name": "NNApiHALPerformance",
+      "Actions": [
+        {
+          "Name": "JoinCgroup",
+          "Params":
+          {
+            "Controller": "cpu",
+            "Path": "nnapi-hal"
+          }
+        }
+      ]
+    },
 
     {
       "Name": "CpuPolicySpread",
@@ -170,7 +178,7 @@
           "Name": "SetAttribute",
           "Params":
           {
-            "Name": "STunePreferIdle",
+            "Name": "UClampLatencySensitive",
             "Value": "1"
           }
         }
@@ -183,7 +191,7 @@
           "Name": "SetAttribute",
           "Params":
           {
-            "Name": "STunePreferIdle",
+            "Name": "UClampLatencySensitive",
             "Value": "0"
           }
         }
diff --git a/libprocinfo b/libprocinfo
deleted file mode 120000
index dec8cf8..0000000
--- a/libprocinfo
+++ /dev/null
@@ -1 +0,0 @@
-../libprocinfo
\ No newline at end of file
diff --git a/libunwindstack b/libunwindstack
deleted file mode 120000
index 9a12403..0000000
--- a/libunwindstack
+++ /dev/null
@@ -1 +0,0 @@
-../unwinding/libunwindstack
\ No newline at end of file
diff --git a/rootdir/init.rc b/rootdir/init.rc
index 900edb4..746fc61 100644
--- a/rootdir/init.rc
+++ b/rootdir/init.rc
@@ -148,6 +148,27 @@
     chmod 0664 /dev/stune/top-app/tasks
     chmod 0664 /dev/stune/rt/tasks
 
+    # cpuctl hierarchy for devices using utilclamp
+    mkdir /dev/cpuctl/foreground
+    mkdir /dev/cpuctl/background
+    mkdir /dev/cpuctl/top-app
+    mkdir /dev/cpuctl/rt
+    chown system system /dev/cpuctl
+    chown system system /dev/cpuctl/foreground
+    chown system system /dev/cpuctl/background
+    chown system system /dev/cpuctl/top-app
+    chown system system /dev/cpuctl/rt
+    chown system system /dev/cpuctl/tasks
+    chown system system /dev/cpuctl/foreground/tasks
+    chown system system /dev/cpuctl/background/tasks
+    chown system system /dev/cpuctl/top-app/tasks
+    chown system system /dev/cpuctl/rt/tasks
+    chmod 0664 /dev/cpuctl/tasks
+    chmod 0664 /dev/cpuctl/foreground/tasks
+    chmod 0664 /dev/cpuctl/background/tasks
+    chmod 0664 /dev/cpuctl/top-app/tasks
+    chmod 0664 /dev/cpuctl/rt/tasks
+
     # Create an stune group for NNAPI HAL processes
     mkdir /dev/stune/nnapi-hal
     chown system system /dev/stune/nnapi-hal
@@ -156,6 +177,14 @@
     write /dev/stune/nnapi-hal/schedtune.boost 1
     write /dev/stune/nnapi-hal/schedtune.prefer_idle 1
 
+    # cpuctl hierarchy for devices using utilclamp
+    mkdir /dev/cpuctl/nnapi-hal
+    chown system system /dev/cpuctl/nnapi-hal
+    chown system system /dev/cpuctl/nnapi-hal/tasks
+    chmod 0664 /dev/cpuctl/nnapi-hal/tasks
+    write /dev/cpuctl/nnapi-hal/cpu.uclamp.min 1
+    write /dev/cpuctl/nnapi-hal/cpu.uclamp.latency_sensitive 1
+
     # Create blkio group and apply initial settings.
     # This feature needs kernel to support it, and the
     # device's init.rc must actually set the correct values.
diff --git a/shell_and_utilities/Android.bp b/shell_and_utilities/Android.bp
index f83c43e..5e013fe 100644
--- a/shell_and_utilities/Android.bp
+++ b/shell_and_utilities/Android.bp
@@ -51,3 +51,13 @@
         "toybox_vendor",
     ],
 }
+
+// shell and utilities for first stage console. The list of binaries are
+// enough for debugging purposes.
+phony {
+    name: "shell_and_utilities_vendor_ramdisk",
+    required: [
+        "sh.vendor_ramdisk",
+        "toybox.vendor_ramdisk",
+    ],
+}
diff --git a/trusty/fuzz/Android.bp b/trusty/fuzz/Android.bp
new file mode 100644
index 0000000..969431c
--- /dev/null
+++ b/trusty/fuzz/Android.bp
@@ -0,0 +1,42 @@
+// 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.
+
+cc_defaults {
+    name: "trusty_fuzzer_defaults",
+    static_libs: [
+        "libtrusty_fuzz_utils",
+    ],
+    shared_libs: [
+        "libbase",
+        "liblog",
+    ],
+    cflags: [
+        "-Wall",
+        "-Werror",
+    ],
+    fuzz_config: {
+        fuzz_on_haiku_device: false,
+        fuzz_on_haiku_host: false,
+    },
+}
+
+cc_library {
+    name: "libtrusty_fuzz_utils",
+    srcs: ["utils.cpp"],
+    export_include_dirs: ["include"],
+    shared_libs: [
+        "libbase",
+        "liblog",
+    ],
+}
diff --git a/trusty/fuzz/include/trusty/fuzz/utils.h b/trusty/fuzz/include/trusty/fuzz/utils.h
new file mode 100644
index 0000000..bca84e9
--- /dev/null
+++ b/trusty/fuzz/include/trusty/fuzz/utils.h
@@ -0,0 +1,50 @@
+/*
+ * 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.
+ */
+
+#pragma once
+
+#include <string>
+
+#include <android-base/result.h>
+#include <android-base/unique_fd.h>
+
+#define TIPC_MAX_MSG_SIZE PAGE_SIZE
+
+namespace android {
+namespace trusty {
+namespace fuzz {
+
+class TrustyApp {
+  public:
+    TrustyApp(std::string tipc_dev, std::string ta_port);
+
+    android::base::Result<void> Connect();
+    android::base::Result<void> Read(void* buf, size_t len);
+    android::base::Result<void> Write(const void* buf, size_t len);
+
+    android::base::Result<int> GetRawFd();
+
+  private:
+    std::string tipc_dev_;
+    std::string ta_port_;
+    android::base::unique_fd ta_fd_;
+};
+
+void Abort();
+
+}  // namespace fuzz
+}  // namespace trusty
+}  // namespace android
diff --git a/trusty/fuzz/utils.cpp b/trusty/fuzz/utils.cpp
new file mode 100644
index 0000000..240afe7
--- /dev/null
+++ b/trusty/fuzz/utils.cpp
@@ -0,0 +1,152 @@
+/*
+ * Copyright (C) 2020 The Android Open Sourete 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.
+ */
+
+#define LOG_TAG "trusty-fuzz-utils"
+
+#include <trusty/fuzz/utils.h>
+
+#include <android-base/logging.h>
+#include <android-base/unique_fd.h>
+#include <linux/ioctl.h>
+#include <linux/types.h>
+#include <linux/uio.h>
+#include <log/log_read.h>
+#include <time.h>
+#include <iostream>
+
+using android::base::ErrnoError;
+using android::base::Error;
+using android::base::Result;
+using android::base::unique_fd;
+
+#define TIPC_IOC_MAGIC 'r'
+#define TIPC_IOC_CONNECT _IOW(TIPC_IOC_MAGIC, 0x80, char*)
+
+namespace {
+
+const size_t kTimeoutSeconds = 5;
+const std::string kTrustyLogTag = "trusty-log";
+
+const time_t kInitialTime = time(nullptr);
+
+void PrintTrustyLog() {
+    auto logger_list = android_logger_list_open(LOG_ID_KERNEL, ANDROID_LOG_NONBLOCK, 1000, 0);
+    if (logger_list == nullptr) {
+        std::cerr << "Could not open android kernel log\n";
+        return;
+    }
+
+    while (true) {
+        log_msg log_msg;
+        int rc = android_logger_list_read(logger_list, &log_msg);
+        if (rc < 0) {
+            break;
+        }
+        if (log_msg.entry.sec < kInitialTime) {
+            continue;
+        }
+        char* msg = log_msg.msg();
+        if (msg) {
+            std::string line(msg, log_msg.entry.len);
+            if (line.find(kTrustyLogTag) != std::string::npos) {
+                std::cerr << line.substr(kTrustyLogTag.length() + 2) << std::endl;
+            }
+        }
+    }
+
+    android_logger_list_free(logger_list);
+}
+
+}  // namespace
+
+namespace android {
+namespace trusty {
+namespace fuzz {
+
+TrustyApp::TrustyApp(std::string tipc_dev, std::string ta_port)
+    : tipc_dev_(tipc_dev), ta_port_(ta_port), ta_fd_(-1) {}
+
+Result<void> TrustyApp::Connect() {
+    /*
+     * TODO: We can't use libtrusty because (yet)
+     * (1) cc_fuzz can't deal with vendor components (b/170753563)
+     * (2) We need non-blocking behavior to detect Trusty going down.
+     * (we could implement the timeout in the fuzzing code though, as
+     * it needs to be around the call to read())
+     */
+    alarm(kTimeoutSeconds);
+    int fd = open(tipc_dev_.c_str(), O_RDWR);
+    alarm(0);
+    if (fd < 0) {
+        return ErrnoError() << "failed to open TIPC device: ";
+    }
+    ta_fd_.reset(fd);
+
+    // This ioctl will time out in the kernel if it can't connect.
+    int rc = TEMP_FAILURE_RETRY(ioctl(ta_fd_, TIPC_IOC_CONNECT, ta_port_.c_str()));
+    if (rc < 0) {
+        return ErrnoError() << "failed to connect to TIPC service: ";
+    }
+
+    return {};
+}
+
+Result<void> TrustyApp::Read(void* buf, size_t len) {
+    if (ta_fd_ == -1) {
+        return Error() << "TA is not connected to yet: ";
+    }
+
+    alarm(kTimeoutSeconds);
+    int rc = read(ta_fd_, buf, len);
+    alarm(0);
+    if (rc < 0) {
+        return Error() << "failed to read TIPC message from TA: ";
+    }
+
+    return {};
+}
+
+Result<void> TrustyApp::Write(const void* buf, size_t len) {
+    if (ta_fd_ == -1) {
+        return Error() << "TA is not connected to yet: ";
+    }
+
+    alarm(kTimeoutSeconds);
+    int rc = write(ta_fd_, buf, len);
+    alarm(0);
+    if (rc < 0) {
+        return Error() << "failed to read TIPC message from TA: ";
+    }
+
+    return {};
+}
+
+Result<int> TrustyApp::GetRawFd() {
+    if (ta_fd_ == -1) {
+        return Error() << "TA is not connected to yet: ";
+    }
+
+    return ta_fd_;
+}
+
+void Abort() {
+    PrintTrustyLog();
+    exit(-1);
+}
+
+}  // namespace fuzz
+}  // namespace trusty
+}  // namespace android
diff --git a/trusty/gatekeeper/fuzz/Android.bp b/trusty/gatekeeper/fuzz/Android.bp
new file mode 100644
index 0000000..7ffa776
--- /dev/null
+++ b/trusty/gatekeeper/fuzz/Android.bp
@@ -0,0 +1,24 @@
+// 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.
+
+cc_fuzz {
+    name: "trusty_gatekeeper_fuzzer",
+    defaults: ["trusty_fuzzer_defaults"],
+    srcs: ["fuzz.cpp"],
+
+    // The initial corpus for this fuzzer was derived by dumping messages from
+    // the `secure_env` emulator interface for cuttlefish while enrolling a new
+    // password in the emulator.
+    corpus: ["corpus/*"],
+}
diff --git a/trusty/gatekeeper/fuzz/corpus/gatekeeper-recv-2MMzSr b/trusty/gatekeeper/fuzz/corpus/gatekeeper-recv-2MMzSr
new file mode 100644
index 0000000..f3c1f79
--- /dev/null
+++ b/trusty/gatekeeper/fuzz/corpus/gatekeeper-recv-2MMzSr
Binary files differ
diff --git a/trusty/gatekeeper/fuzz/corpus/gatekeeper-recv-Et63W0 b/trusty/gatekeeper/fuzz/corpus/gatekeeper-recv-Et63W0
new file mode 100644
index 0000000..b3e6585
--- /dev/null
+++ b/trusty/gatekeeper/fuzz/corpus/gatekeeper-recv-Et63W0
Binary files differ
diff --git a/trusty/gatekeeper/fuzz/corpus/gatekeeper-recv-G41Iz8 b/trusty/gatekeeper/fuzz/corpus/gatekeeper-recv-G41Iz8
new file mode 100644
index 0000000..1cec413
--- /dev/null
+++ b/trusty/gatekeeper/fuzz/corpus/gatekeeper-recv-G41Iz8
Binary files differ
diff --git a/trusty/gatekeeper/fuzz/corpus/gatekeeper-recv-ItEoqJ b/trusty/gatekeeper/fuzz/corpus/gatekeeper-recv-ItEoqJ
new file mode 100644
index 0000000..85d38c7
--- /dev/null
+++ b/trusty/gatekeeper/fuzz/corpus/gatekeeper-recv-ItEoqJ
Binary files differ
diff --git a/trusty/gatekeeper/fuzz/corpus/gatekeeper-recv-MGXdfu b/trusty/gatekeeper/fuzz/corpus/gatekeeper-recv-MGXdfu
new file mode 100644
index 0000000..f8e1467
--- /dev/null
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diff --git a/trusty/gatekeeper/fuzz/fuzz.cpp b/trusty/gatekeeper/fuzz/fuzz.cpp
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@@ -0,0 +1,55 @@
+/*
+ * 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.
+ */
+
+#undef NDEBUG
+
+#include <assert.h>
+#include <log/log.h>
+#include <stdlib.h>
+#include <trusty/fuzz/utils.h>
+#include <unistd.h>
+
+#define TIPC_DEV "/dev/trusty-ipc-dev0"
+#define GATEKEEPER_PORT "com.android.trusty.gatekeeper"
+
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
+    static uint8_t buf[TIPC_MAX_MSG_SIZE];
+
+    android::trusty::fuzz::TrustyApp ta(TIPC_DEV, GATEKEEPER_PORT);
+
+    auto ret = ta.Connect();
+    /*
+     * If we can't connect, then assume TA crashed.
+     * TODO: Get some more info, e.g. stacks, to help Haiku dedup crashes.
+     */
+    if (!ret.ok()) {
+        android::trusty::fuzz::Abort();
+    }
+
+    /* Send message to test server */
+    ret = ta.Write(data, size);
+    if (!ret.ok()) {
+        return -1;
+    }
+
+    /* Read message from test server */
+    ret = ta.Read(&buf, sizeof(buf));
+    if (!ret.ok()) {
+        return -1;
+    }
+
+    return 0;
+}