diff --git a/adb/client/adb_install.cpp b/adb/client/adb_install.cpp
index fe9182e..092a866 100644
--- a/adb/client/adb_install.cpp
+++ b/adb/client/adb_install.cpp
@@ -22,11 +22,12 @@
 #include <stdlib.h>
 #include <unistd.h>
 #include <algorithm>
-#include <iostream>
 #include <string>
+#include <string_view>
 #include <vector>
 
 #include <android-base/file.h>
+#include <android-base/parsebool.h>
 #include <android-base/stringprintf.h>
 #include <android-base/strings.h>
 
@@ -39,8 +40,9 @@
 #include "fastdeploy.h"
 #include "incremental.h"
 
+using namespace std::literals;
+
 static constexpr int kFastDeployMinApi = 24;
-static constexpr int kIncrementalMinApi = 29;
 
 namespace {
 
@@ -50,6 +52,8 @@
     INSTALL_STREAM,
     INSTALL_INCREMENTAL,
 };
+
+enum class CmdlineOption { None, Enable, Disable };
 }
 
 static bool can_use_feature(const char* feature) {
@@ -299,45 +303,52 @@
     return std::chrono::duration_cast<std::chrono::milliseconds>(end - start).count();
 }
 
-static int install_app_incremental(int argc, const char** argv) {
-    printf("Performing Incremental Install\n");
+static int install_app_incremental(int argc, const char** argv, bool wait, bool silent) {
     using clock = std::chrono::high_resolution_clock;
     const auto start = clock::now();
     int first_apk = -1;
     int last_apk = -1;
-    std::string cert_path;
-    bool wait = false;
-    std::vector<std::string_view> args = {"package"};
+    std::vector<std::string_view> args = {"package"sv};
     for (int i = 0; i < argc; ++i) {
         const auto arg = std::string_view(argv[i]);
-        if (android::base::EndsWithIgnoreCase(arg, ".apk")) {
+        if (android::base::EndsWithIgnoreCase(arg, ".apk"sv)) {
             last_apk = i;
             if (first_apk == -1) {
                 first_apk = i;
             }
-        } else if (arg == "--wait") {
-            wait = true;
-        } else if (arg.starts_with("install-")) {
+        } else if (arg.starts_with("install-"sv)) {
             // incremental installation command on the device is the same for all its variations in
             // the adb, e.g. install-multiple or install-multi-package
-            args.push_back("install");
+            args.push_back("install"sv);
         } else {
             args.push_back(arg);
         }
     }
 
-    if (first_apk == -1) error_exit("Need at least one APK file on command line");
+    if (first_apk == -1) {
+        if (!silent) {
+            fprintf(stderr, "error: need at least one APK file on command line\n");
+        }
+        return -1;
+    }
 
-    const auto afterApk = clock::now();
+    auto files = incremental::Files{argv + first_apk, argv + last_apk + 1};
+    if (silent) {
+        // For a silent installation we want to do the lightweight check first and bail early and
+        // quietly if it fails.
+        if (!incremental::can_install(files)) {
+            return -1;
+        }
+    }
 
-    auto server_process = incremental::install({argv + first_apk, argv + last_apk + 1});
+    printf("Performing Incremental Install\n");
+    auto server_process = incremental::install(files, silent);
     if (!server_process) {
         return -1;
     }
 
     const auto end = clock::now();
-    printf("Install command complete (ms: %d total, %d apk prep, %d install)\n",
-           msBetween(start, end), msBetween(start, afterApk), msBetween(afterApk, end));
+    printf("Install command complete in %d ms\n", msBetween(start, end));
 
     if (wait) {
         (*server_process).wait();
@@ -346,66 +357,134 @@
     return 0;
 }
 
+static std::pair<InstallMode, std::optional<InstallMode>> calculateInstallMode(
+        InstallMode modeFromArgs, bool fastdeploy, CmdlineOption incrementalRequest) {
+    if (incrementalRequest == CmdlineOption::Enable) {
+        if (fastdeploy) {
+            error_exit(
+                    "--incremental and --fast-deploy options are incompatible. "
+                    "Please choose one");
+        }
+    }
+
+    if (modeFromArgs != INSTALL_DEFAULT) {
+        if (incrementalRequest == CmdlineOption::Enable) {
+            error_exit("--incremental is not compatible with other installation modes");
+        }
+        return {modeFromArgs, std::nullopt};
+    }
+
+    if (incrementalRequest != CmdlineOption::Disable && !is_abb_exec_supported()) {
+        if (incrementalRequest == CmdlineOption::None) {
+            incrementalRequest = CmdlineOption::Disable;
+        } else {
+            error_exit("Device doesn't support incremental installations");
+        }
+    }
+    if (incrementalRequest == CmdlineOption::None) {
+        // check if the host is ok with incremental by default
+        if (const char* incrementalFromEnv = getenv("ADB_INSTALL_DEFAULT_INCREMENTAL")) {
+            using namespace android::base;
+            auto val = ParseBool(incrementalFromEnv);
+            if (val == ParseBoolResult::kFalse) {
+                incrementalRequest = CmdlineOption::Disable;
+            }
+        }
+    }
+    if (incrementalRequest == CmdlineOption::None) {
+        // still ok: let's see if the device allows using incremental by default
+        // it starts feeling like we're looking for an excuse to not to use incremental...
+        std::string error;
+        std::vector<std::string> args = {"settings", "get",
+                                         "enable_adb_incremental_install_default"};
+        auto fd = send_abb_exec_command(args, &error);
+        if (!fd.ok()) {
+            fprintf(stderr, "adb: retrieving the default device installation mode failed: %s",
+                    error.c_str());
+        } else {
+            char buf[BUFSIZ] = {};
+            read_status_line(fd.get(), buf, sizeof(buf));
+            using namespace android::base;
+            auto val = ParseBool(buf);
+            if (val == ParseBoolResult::kFalse) {
+                incrementalRequest = CmdlineOption::Disable;
+            }
+        }
+    }
+
+    if (incrementalRequest == CmdlineOption::Enable) {
+        // explicitly requested - no fallback
+        return {INSTALL_INCREMENTAL, std::nullopt};
+    }
+    const auto bestMode = best_install_mode();
+    if (incrementalRequest == CmdlineOption::None) {
+        // no opinion - use incremental, fallback to regular on a failure.
+        return {INSTALL_INCREMENTAL, bestMode};
+    }
+    // incremental turned off - use the regular best mode without a fallback.
+    return {bestMode, std::nullopt};
+}
+
 int install_app(int argc, const char** argv) {
     std::vector<int> processedArgIndices;
     InstallMode installMode = INSTALL_DEFAULT;
     bool use_fastdeploy = false;
     bool is_reinstall = false;
+    bool wait = false;
+    auto incremental_request = CmdlineOption::None;
     FastDeploy_AgentUpdateStrategy agent_update_strategy = FastDeploy_AgentUpdateDifferentVersion;
 
     for (int i = 1; i < argc; i++) {
-        if (!strcmp(argv[i], "--streaming")) {
+        if (argv[i] == "--streaming"sv) {
             processedArgIndices.push_back(i);
             installMode = INSTALL_STREAM;
-        } else if (!strcmp(argv[i], "--no-streaming")) {
+        } else if (argv[i] == "--no-streaming"sv) {
             processedArgIndices.push_back(i);
             installMode = INSTALL_PUSH;
-        } else if (!strcmp(argv[i], "-r")) {
+        } else if (argv[i] == "-r"sv) {
             // Note that this argument is not added to processedArgIndices because it
             // must be passed through to pm
             is_reinstall = true;
-        } else if (!strcmp(argv[i], "--fastdeploy")) {
+        } else if (argv[i] == "--fastdeploy"sv) {
             processedArgIndices.push_back(i);
             use_fastdeploy = true;
-        } else if (!strcmp(argv[i], "--no-fastdeploy")) {
+        } else if (argv[i] == "--no-fastdeploy"sv) {
             processedArgIndices.push_back(i);
             use_fastdeploy = false;
-        } else if (!strcmp(argv[i], "--force-agent")) {
+        } else if (argv[i] == "--force-agent"sv) {
             processedArgIndices.push_back(i);
             agent_update_strategy = FastDeploy_AgentUpdateAlways;
-        } else if (!strcmp(argv[i], "--date-check-agent")) {
+        } else if (argv[i] == "--date-check-agent"sv) {
             processedArgIndices.push_back(i);
             agent_update_strategy = FastDeploy_AgentUpdateNewerTimeStamp;
-        } else if (!strcmp(argv[i], "--version-check-agent")) {
+        } else if (argv[i] == "--version-check-agent"sv) {
             processedArgIndices.push_back(i);
             agent_update_strategy = FastDeploy_AgentUpdateDifferentVersion;
-        } else if (!strcmp(argv[i], "--incremental")) {
+        } else if (strlen(argv[i]) >= "--incr"sv.size() && "--incremental"sv.starts_with(argv[i])) {
             processedArgIndices.push_back(i);
-            installMode = INSTALL_INCREMENTAL;
-        } else if (!strcmp(argv[i], "--no-incremental")) {
+            incremental_request = CmdlineOption::Enable;
+        } else if (strlen(argv[i]) >= "--no-incr"sv.size() &&
+                   "--no-incremental"sv.starts_with(argv[i])) {
             processedArgIndices.push_back(i);
-            installMode = INSTALL_DEFAULT;
+            incremental_request = CmdlineOption::Disable;
+        } else if (argv[i] == "--wait"sv) {
+            processedArgIndices.push_back(i);
+            wait = true;
         }
     }
 
-    if (installMode == INSTALL_INCREMENTAL) {
-        if (get_device_api_level() < kIncrementalMinApi || !is_abb_exec_supported()) {
-            error_exit("Attempting to use incremental install on unsupported device");
-        }
-    }
-
-    if (installMode == INSTALL_DEFAULT) {
-        installMode = best_install_mode();
-    }
-
-    if (installMode == INSTALL_STREAM && best_install_mode() == INSTALL_PUSH) {
+    auto [primaryMode, fallbackMode] =
+            calculateInstallMode(installMode, use_fastdeploy, incremental_request);
+    if ((primaryMode == INSTALL_STREAM || fallbackMode.value_or(INSTALL_PUSH) == INSTALL_STREAM) &&
+        best_install_mode() == INSTALL_PUSH) {
         error_exit("Attempting to use streaming install on unsupported device");
     }
 
     if (use_fastdeploy && get_device_api_level() < kFastDeployMinApi) {
-        printf("Fast Deploy is only compatible with devices of API version %d or higher, "
-               "ignoring.\n",
-               kFastDeployMinApi);
+        fprintf(stderr,
+                "Fast Deploy is only compatible with devices of API version %d or higher, "
+                "ignoring.\n",
+                kFastDeployMinApi);
         use_fastdeploy = false;
     }
     fastdeploy_set_agent_update_strategy(agent_update_strategy);
@@ -421,19 +500,27 @@
         error_exit("install requires an apk argument");
     }
 
-    switch (installMode) {
-        case INSTALL_PUSH:
-            return install_app_legacy(passthrough_argv.size(), passthrough_argv.data(),
-                                      use_fastdeploy);
-        case INSTALL_STREAM:
-            return install_app_streamed(passthrough_argv.size(), passthrough_argv.data(),
-                                        use_fastdeploy);
-        case INSTALL_INCREMENTAL:
-            return install_app_incremental(passthrough_argv.size(), passthrough_argv.data());
-        case INSTALL_DEFAULT:
-        default:
-            return 1;
+    auto runInstallMode = [&](InstallMode installMode, bool silent) {
+        switch (installMode) {
+            case INSTALL_PUSH:
+                return install_app_legacy(passthrough_argv.size(), passthrough_argv.data(),
+                                          use_fastdeploy);
+            case INSTALL_STREAM:
+                return install_app_streamed(passthrough_argv.size(), passthrough_argv.data(),
+                                            use_fastdeploy);
+            case INSTALL_INCREMENTAL:
+                return install_app_incremental(passthrough_argv.size(), passthrough_argv.data(),
+                                               wait, silent);
+            case INSTALL_DEFAULT:
+            default:
+                return 1;
+        }
+    };
+    auto res = runInstallMode(primaryMode, fallbackMode.has_value());
+    if (res && fallbackMode.value_or(primaryMode) != primaryMode) {
+        res = runInstallMode(*fallbackMode, false);
     }
+    return res;
 }
 
 int install_multiple_app(int argc, const char** argv) {
diff --git a/adb/client/incremental.cpp b/adb/client/incremental.cpp
index a9e65dc..b56df44 100644
--- a/adb/client/incremental.cpp
+++ b/adb/client/incremental.cpp
@@ -90,38 +90,58 @@
     return total_tree_block_count * INCFS_DATA_FILE_BLOCK_SIZE;
 }
 
-// Base64-encode signature bytes. Keeping fd at the position of start of verity tree.
-static std::pair<unique_fd, std::string> read_and_encode_signature(Size file_size,
-                                                                   std::string signature_file) {
+// Read, verify and return the signature bytes. Keeping fd at the position of start of verity tree.
+static std::pair<unique_fd, std::vector<char>> read_signature(Size file_size,
+                                                              std::string signature_file,
+                                                              bool silent) {
     signature_file += IDSIG;
 
     struct stat st;
     if (stat(signature_file.c_str(), &st)) {
-        fprintf(stderr, "Failed to stat signature file %s. Abort.\n", signature_file.c_str());
+        if (!silent) {
+            fprintf(stderr, "Failed to stat signature file %s. Abort.\n", signature_file.c_str());
+        }
         return {};
     }
 
     unique_fd fd(adb_open(signature_file.c_str(), O_RDONLY | O_CLOEXEC));
     if (fd < 0) {
-        fprintf(stderr, "Failed to open signature file: %s. Abort.\n", signature_file.c_str());
+        if (!silent) {
+            fprintf(stderr, "Failed to open signature file: %s. Abort.\n", signature_file.c_str());
+        }
         return {};
     }
 
     auto [signature, tree_size] = read_id_sig_headers(fd);
     if (auto expected = verity_tree_size_for_file(file_size); tree_size != expected) {
-        fprintf(stderr,
-                "Verity tree size mismatch in signature file: %s [was %lld, expected %lld].\n",
-                signature_file.c_str(), (long long)tree_size, (long long)expected);
+        if (!silent) {
+            fprintf(stderr,
+                    "Verity tree size mismatch in signature file: %s [was %lld, expected %lld].\n",
+                    signature_file.c_str(), (long long)tree_size, (long long)expected);
+        }
+        return {};
+    }
+
+    return {std::move(fd), std::move(signature)};
+}
+
+// Base64-encode signature bytes. Keeping fd at the position of start of verity tree.
+static std::pair<unique_fd, std::string> read_and_encode_signature(Size file_size,
+                                                                   std::string signature_file,
+                                                                   bool silent) {
+    auto [fd, signature] = read_signature(file_size, std::move(signature_file), silent);
+    if (!fd.ok()) {
         return {};
     }
 
     size_t base64_len = 0;
     if (!EVP_EncodedLength(&base64_len, signature.size())) {
-        fprintf(stderr, "Fail to estimate base64 encoded length. Abort.\n");
+        if (!silent) {
+            fprintf(stderr, "Fail to estimate base64 encoded length. Abort.\n");
+        }
         return {};
     }
-    std::string encoded_signature;
-    encoded_signature.resize(base64_len);
+    std::string encoded_signature(base64_len, '\0');
     encoded_signature.resize(EVP_EncodeBlock((uint8_t*)encoded_signature.data(),
                                              (const uint8_t*)signature.data(), signature.size()));
 
@@ -130,7 +150,7 @@
 
 // Send install-incremental to the device along with properly configured file descriptors in
 // streaming format. Once connection established, send all fs-verity tree bytes.
-static unique_fd start_install(const std::vector<std::string>& files) {
+static unique_fd start_install(const Files& files, bool silent) {
     std::vector<std::string> command_args{"package", "install-incremental"};
 
     // fd's with positions at the beginning of fs-verity
@@ -141,11 +161,13 @@
 
         struct stat st;
         if (stat(file.c_str(), &st)) {
-            fprintf(stderr, "Failed to stat input file %s. Abort.\n", file.c_str());
+            if (!silent) {
+                fprintf(stderr, "Failed to stat input file %s. Abort.\n", file.c_str());
+            }
             return {};
         }
 
-        auto [signature_fd, signature] = read_and_encode_signature(st.st_size, file);
+        auto [signature_fd, signature] = read_and_encode_signature(st.st_size, file, silent);
         if (!signature_fd.ok()) {
             return {};
         }
@@ -161,15 +183,19 @@
     std::string error;
     auto connection_fd = unique_fd(send_abb_exec_command(command_args, &error));
     if (connection_fd < 0) {
-        fprintf(stderr, "Failed to run: %s, error: %s\n",
-                android::base::Join(command_args, " ").c_str(), error.c_str());
+        if (!silent) {
+            fprintf(stderr, "Failed to run: %s, error: %s\n",
+                    android::base::Join(command_args, " ").c_str(), error.c_str());
+        }
         return {};
     }
 
     // Pushing verity trees for all installation files.
     for (auto&& local_fd : signature_fds) {
         if (!copy_to_file(local_fd.get(), connection_fd.get())) {
-            fprintf(stderr, "Failed to stream tree bytes: %s. Abort.\n", strerror(errno));
+            if (!silent) {
+                fprintf(stderr, "Failed to stream tree bytes: %s. Abort.\n", strerror(errno));
+            }
             return {};
         }
     }
@@ -179,10 +205,27 @@
 
 }  // namespace
 
-std::optional<Process> install(std::vector<std::string> files) {
-    auto connection_fd = start_install(files);
+bool can_install(const Files& files) {
+    for (const auto& file : files) {
+        struct stat st;
+        if (stat(file.c_str(), &st)) {
+            return false;
+        }
+
+        auto [fd, _] = read_signature(st.st_size, file, true);
+        if (!fd.ok()) {
+            return false;
+        }
+    }
+    return true;
+}
+
+std::optional<Process> install(const Files& files, bool silent) {
+    auto connection_fd = start_install(files, silent);
     if (connection_fd < 0) {
-        fprintf(stderr, "adb: failed to initiate installation on device.\n");
+        if (!silent) {
+            fprintf(stderr, "adb: failed to initiate installation on device.\n");
+        }
         return {};
     }
 
@@ -198,7 +241,9 @@
     // pipe for child process to write output
     int print_fds[2];
     if (adb_socketpair(print_fds) != 0) {
-        fprintf(stderr, "Failed to create socket pair for child to print to parent\n");
+        if (!silent) {
+            fprintf(stderr, "Failed to create socket pair for child to print to parent\n");
+        }
         return {};
     }
     auto [pipe_read_fd, pipe_write_fd] = print_fds;
@@ -210,7 +255,9 @@
     auto child =
             adb_launch_process(adb_path, std::move(args), {connection_fd.get(), pipe_write_fd});
     if (!child) {
-        fprintf(stderr, "adb: failed to fork: %s\n", strerror(errno));
+        if (!silent) {
+            fprintf(stderr, "adb: failed to fork: %s\n", strerror(errno));
+        }
         return {};
     }
 
diff --git a/adb/client/incremental.h b/adb/client/incremental.h
index 731e6fb..1fb1e0b 100644
--- a/adb/client/incremental.h
+++ b/adb/client/incremental.h
@@ -25,7 +25,10 @@
 
 namespace incremental {
 
-std::optional<Process> install(std::vector<std::string> files);
+using Files = std::vector<std::string>;
+
+bool can_install(const Files& files);
+std::optional<Process> install(const Files& files, bool silent);
 
 enum class Result { Success, Failure, None };
 Result wait_for_installation(int read_fd);
diff --git a/init/oneshot_on_test.cpp b/init/oneshot_on_test.cpp
index 7e7cc36..650f065 100644
--- a/init/oneshot_on_test.cpp
+++ b/init/oneshot_on_test.cpp
@@ -26,6 +26,11 @@
 using namespace std::literals;
 
 TEST(init, oneshot_on) {
+    if (getuid() != 0) {
+        GTEST_SKIP() << "Skipping test, must be run as root.";
+        return;
+    }
+
     // Bootanim shouldn't be running once the device has booted.
     ASSERT_EQ("stopped", GetProperty("init.svc.bootanim", ""));
 
diff --git a/libstats/pull/include/stats_pull_atom_callback.h b/libstats/pull/include/stats_pull_atom_callback.h
index c976c68..17df584 100644
--- a/libstats/pull/include/stats_pull_atom_callback.h
+++ b/libstats/pull/include/stats_pull_atom_callback.h
@@ -46,7 +46,8 @@
 
 /**
  * Set the cool down time of the pull in milliseconds. If two successive pulls are issued
- * within the cool down, a cached version of the first will be used for the second.
+ * within the cool down, a cached version of the first will be used for the second. The minimum
+ * allowed cool down is one second.
  */
 void AStatsManager_PullAtomMetadata_setCoolDownMillis(AStatsManager_PullAtomMetadata* metadata,
                                                       int64_t cool_down_millis);
@@ -58,6 +59,7 @@
 
 /**
  * Set the maximum time the pull can take in milliseconds.
+ * The maximum allowed timeout is 10 seconds.
  */
 void AStatsManager_PullAtomMetadata_setTimeoutMillis(AStatsManager_PullAtomMetadata* metadata,
                                                      int64_t timeout_millis);