diff --git a/bootloader_message/bootloader_message.cpp b/bootloader_message/bootloader_message.cpp
index e684abb..b15a9b9 100644
--- a/bootloader_message/bootloader_message.cpp
+++ b/bootloader_message/bootloader_message.cpp
@@ -20,6 +20,7 @@
 #include <fcntl.h>
 #include <string.h>
 
+#include <optional>
 #include <string>
 #include <string_view>
 #include <vector>
@@ -37,7 +38,7 @@
 using android::fs_mgr::Fstab;
 using android::fs_mgr::ReadDefaultFstab;
 
-static std::string g_misc_device_for_test;
+static std::optional<std::string> g_misc_device_for_test;
 
 // Exposed for test purpose.
 void SetMiscBlockDeviceForTest(std::string_view misc_device) {
@@ -45,8 +46,8 @@
 }
 
 static std::string get_misc_blk_device(std::string* err) {
-  if (!g_misc_device_for_test.empty()) {
-    return g_misc_device_for_test;
+  if (g_misc_device_for_test.has_value() && !g_misc_device_for_test->empty()) {
+    return *g_misc_device_for_test;
   }
   Fstab fstab;
   if (!ReadDefaultFstab(&fstab)) {
diff --git a/common.h b/common.h
deleted file mode 100644
index 128a69d..0000000
--- a/common.h
+++ /dev/null
@@ -1,25 +0,0 @@
-/*
- * Copyright (C) 2007 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>
-
-// The current stage, e.g. "1/2".
-extern std::string stage;
-
-// The reason argument provided in "--reason=".
-extern const char* reason;
diff --git a/minui/events.cpp b/minui/events.cpp
index 7d0250e..f331ed6 100644
--- a/minui/events.cpp
+++ b/minui/events.cpp
@@ -22,6 +22,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <sys/epoll.h>
+#include <sys/inotify.h>
 #include <sys/ioctl.h>
 #include <sys/types.h>
 #include <unistd.h>
@@ -33,6 +34,8 @@
 
 #include "minui/minui.h"
 
+constexpr const char* INPUT_DEV_DIR = "/dev/input";
+
 constexpr size_t MAX_DEVICES = 16;
 constexpr size_t MAX_MISC_FDS = 16;
 
@@ -46,6 +49,8 @@
   ev_callback cb;
 };
 
+static bool g_allow_touch_inputs = true;
+static ev_callback g_saved_input_cb;
 static android::base::unique_fd g_epoll_fd;
 static epoll_event g_polled_events[MAX_DEVICES + MAX_MISC_FDS];
 static int g_polled_events_count;
@@ -60,6 +65,78 @@
   return (array[bit / BITS_PER_LONG] & (1UL << (bit % BITS_PER_LONG))) != 0;
 }
 
+static bool should_add_input_device(int fd, bool allow_touch_inputs) {
+  // Use unsigned long to match ioctl's parameter type.
+  unsigned long ev_bits[BITS_TO_LONGS(EV_MAX)];  // NOLINT
+
+  // Read the evbits of the input device.
+  if (ioctl(fd, EVIOCGBIT(0, sizeof(ev_bits)), ev_bits) == -1) {
+    return false;
+  }
+
+  // We assume that only EV_KEY, EV_REL, and EV_SW event types are ever needed. EV_ABS is also
+  // allowed if allow_touch_inputs is set.
+  if (!test_bit(EV_KEY, ev_bits) && !test_bit(EV_REL, ev_bits) && !test_bit(EV_SW, ev_bits)) {
+    if (!allow_touch_inputs || !test_bit(EV_ABS, ev_bits)) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
+static int inotify_cb(int fd, __unused uint32_t epevents) {
+  if (g_saved_input_cb == nullptr) return -1;
+
+  // The inotify will put one or several complete events.
+  // Should not read part of one event.
+  size_t event_len;
+  int ret = ioctl(fd, FIONREAD, &event_len);
+  if (ret != 0) return -1;
+
+  std::unique_ptr<DIR, decltype(&closedir)> dir(opendir(INPUT_DEV_DIR), closedir);
+  if (!dir) {
+    return -1;
+  }
+
+  std::vector<int8_t> buf(event_len);
+
+  ssize_t r = TEMP_FAILURE_RETRY(read(fd, buf.data(), event_len));
+  if (r != event_len) {
+    return -1;
+  }
+
+  size_t offset = 0;
+  while (offset < event_len) {
+    struct inotify_event* pevent = reinterpret_cast<struct inotify_event*>(buf.data() + offset);
+    if (offset + sizeof(inotify_event) + pevent->len > event_len) {
+      // The pevent->len is too large and buffer will over flow.
+      // In general, should not happen, just make more stable.
+      return -1;
+    }
+    offset += sizeof(inotify_event) + pevent->len;
+
+    pevent->name[pevent->len] = '\0';
+    if (strncmp(pevent->name, "event", 5)) {
+      continue;
+    }
+
+    android::base::unique_fd dfd(openat(dirfd(dir.get()), pevent->name, O_RDONLY));
+    if (dfd == -1) {
+      break;
+    }
+
+    if (!should_add_input_device(dfd, g_allow_touch_inputs)) {
+      continue;
+    }
+
+    // Only add, we assume the user will not plug out and plug in USB device again and again :)
+    ev_add_fd(std::move(dfd), g_saved_input_cb);
+  }
+
+  return 0;
+}
+
 int ev_init(ev_callback input_cb, bool allow_touch_inputs) {
   g_epoll_fd.reset();
 
@@ -68,7 +145,16 @@
     return -1;
   }
 
-  std::unique_ptr<DIR, decltype(&closedir)> dir(opendir("/dev/input"), closedir);
+  android::base::unique_fd inotify_fd(inotify_init1(IN_CLOEXEC));
+  if (inotify_fd.get() == -1) {
+    return -1;
+  }
+
+  if (inotify_add_watch(inotify_fd, INPUT_DEV_DIR, IN_CREATE) < 0) {
+    return -1;
+  }
+
+  std::unique_ptr<DIR, decltype(&closedir)> dir(opendir(INPUT_DEV_DIR), closedir);
   if (!dir) {
     return -1;
   }
@@ -80,22 +166,10 @@
     android::base::unique_fd fd(openat(dirfd(dir.get()), de->d_name, O_RDONLY | O_CLOEXEC));
     if (fd == -1) continue;
 
-    // Use unsigned long to match ioctl's parameter type.
-    unsigned long ev_bits[BITS_TO_LONGS(EV_MAX)];  // NOLINT
-
-    // Read the evbits of the input device.
-    if (ioctl(fd, EVIOCGBIT(0, sizeof(ev_bits)), ev_bits) == -1) {
+    if (!should_add_input_device(fd, allow_touch_inputs)) {
       continue;
     }
 
-    // We assume that only EV_KEY, EV_REL, and EV_SW event types are ever needed. EV_ABS is also
-    // allowed if allow_touch_inputs is set.
-    if (!test_bit(EV_KEY, ev_bits) && !test_bit(EV_REL, ev_bits) && !test_bit(EV_SW, ev_bits)) {
-      if (!allow_touch_inputs || !test_bit(EV_ABS, ev_bits)) {
-        continue;
-      }
-    }
-
     epoll_event ev;
     ev.events = EPOLLIN | EPOLLWAKEUP;
     ev.data.ptr = &ev_fdinfo[g_ev_count];
@@ -116,6 +190,11 @@
   }
 
   g_epoll_fd.reset(epoll_fd.release());
+
+  g_saved_input_cb = input_cb;
+  g_allow_touch_inputs = allow_touch_inputs;
+  ev_add_fd(std::move(inotify_fd), inotify_cb);
+
   return 0;
 }
 
@@ -148,6 +227,7 @@
   }
   g_ev_misc_count = 0;
   g_ev_dev_count = 0;
+  g_saved_input_cb = nullptr;
   g_epoll_fd.reset();
 }
 
@@ -170,13 +250,17 @@
 }
 
 int ev_get_input(int fd, uint32_t epevents, input_event* ev) {
-    if (epevents & EPOLLIN) {
-        ssize_t r = TEMP_FAILURE_RETRY(read(fd, ev, sizeof(*ev)));
-        if (r == sizeof(*ev)) {
-            return 0;
-        }
+  if (epevents & EPOLLIN) {
+    ssize_t r = TEMP_FAILURE_RETRY(read(fd, ev, sizeof(*ev)));
+    if (r == sizeof(*ev)) {
+      return 0;
     }
-    return -1;
+  }
+  if (epevents & EPOLLHUP) {
+    // Delete this watch
+    epoll_ctl(g_epoll_fd, EPOLL_CTL_DEL, fd, nullptr);
+  }
+  return -1;
 }
 
 int ev_sync_key_state(const ev_set_key_callback& set_key_cb) {
diff --git a/otautil/include/otautil/boot_state.h b/otautil/include/otautil/boot_state.h
new file mode 100644
index 0000000..6c877ba
--- /dev/null
+++ b/otautil/include/otautil/boot_state.h
@@ -0,0 +1,36 @@
+/*
+ * Copyright (C) 2019 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 <string_view>
+
+class BootState {
+ public:
+  BootState(std::string_view reason, std::string_view stage) : reason_(reason), stage_(stage) {}
+
+  std::string reason() const {
+    return reason_;
+  }
+  std::string stage() const {
+    return stage_;
+  }
+
+ private:
+  std::string reason_;  // The reason argument provided in "--reason=".
+  std::string stage_;   // The current stage, e.g. "1/2".
+};
diff --git a/recovery.cpp b/recovery.cpp
index b989b24..4862dfc 100644
--- a/recovery.cpp
+++ b/recovery.cpp
@@ -46,7 +46,6 @@
 #include <ziparchive/zip_archive.h>
 
 #include "bootloader_message/bootloader_message.h"
-#include "common.h"
 #include "fsck_unshare_blocks.h"
 #include "install/adb_install.h"
 #include "install/fuse_install.h"
@@ -54,6 +53,7 @@
 #include "install/package.h"
 #include "install/wipe_data.h"
 #include "install/wipe_device.h"
+#include "otautil/boot_state.h"
 #include "otautil/error_code.h"
 #include "otautil/logging.h"
 #include "otautil/paths.h"
@@ -70,8 +70,6 @@
 static constexpr const char* CACHE_ROOT = "/cache";
 
 static bool save_current_log = false;
-std::string stage;
-const char* reason = nullptr;
 
 /*
  * The recovery tool communicates with the main system through /cache files.
@@ -208,7 +206,8 @@
     }
 
     if (ask_to_wipe_data(device)) {
-      bool convert_fbe = reason && strcmp(reason, "convert_fbe") == 0;
+      CHECK(device->GetReason().has_value());
+      bool convert_fbe = device->GetReason().value() == "convert_fbe";
       if (WipeData(device, convert_fbe)) {
         return INSTALL_SUCCESS;
       } else {
@@ -635,12 +634,10 @@
           fsck_unshare_blocks = true;
         } else if (option == "install_with_fuse") {
           install_with_fuse = true;
-        } else if (option == "locale" || option == "fastboot") {
+        } else if (option == "locale" || option == "fastboot" || option == "reason") {
           // Handled in recovery_main.cpp
         } else if (option == "prompt_and_wipe_data") {
           should_prompt_and_wipe_data = true;
-        } else if (option == "reason") {
-          reason = optarg;
         } else if (option == "rescue") {
           rescue = true;
         } else if (option == "retry_count") {
@@ -674,8 +671,8 @@
   }
   optind = 1;
 
-  printf("stage is [%s]\n", stage.c_str());
-  printf("reason is [%s]\n", reason);
+  printf("stage is [%s]\n", device->GetStage().value_or("").c_str());
+  printf("reason is [%s]\n", device->GetReason().value_or("").c_str());
 
   auto ui = device->GetUI();
 
@@ -684,7 +681,8 @@
   ui->SetSystemUpdateText(security_update);
 
   int st_cur, st_max;
-  if (!stage.empty() && sscanf(stage.c_str(), "%d/%d", &st_cur, &st_max) == 2) {
+  if (!device->GetStage().has_value() &&
+      sscanf(device->GetStage().value().c_str(), "%d/%d", &st_cur, &st_max) == 2) {
     ui->SetStage(st_cur, st_max);
   }
 
@@ -790,7 +788,8 @@
     }
   } else if (should_wipe_data) {
     save_current_log = true;
-    bool convert_fbe = reason && strcmp(reason, "convert_fbe") == 0;
+    CHECK(device->GetReason().has_value());
+    bool convert_fbe = device->GetReason().value() == "convert_fbe";
     if (!WipeData(device, convert_fbe)) {
       status = INSTALL_ERROR;
     }
diff --git a/recovery_main.cpp b/recovery_main.cpp
index f0d75ee..28197bf 100644
--- a/recovery_main.cpp
+++ b/recovery_main.cpp
@@ -48,9 +48,9 @@
 #include <selinux/label.h>
 #include <selinux/selinux.h>
 
-#include "common.h"
 #include "fastboot/fastboot.h"
 #include "install/wipe_data.h"
+#include "otautil/boot_state.h"
 #include "otautil/logging.h"
 #include "otautil/paths.h"
 #include "otautil/roots.h"
@@ -80,11 +80,12 @@
   }
 }
 
+// Parses the command line argument from various sources; and reads the stage field from BCB.
 // command line args come from, in decreasing precedence:
 //   - the actual command line
 //   - the bootloader control block (one per line, after "recovery")
 //   - the contents of COMMAND_FILE (one per line)
-static std::vector<std::string> get_args(const int argc, char** const argv) {
+static std::vector<std::string> get_args(const int argc, char** const argv, std::string* stage) {
   CHECK_GT(argc, 0);
 
   bootloader_message boot = {};
@@ -94,7 +95,9 @@
     // If fails, leave a zeroed bootloader_message.
     boot = {};
   }
-  stage = std::string(boot.stage);
+  if (stage) {
+    *stage = std::string(boot.stage);
+  }
 
   std::string boot_command;
   if (boot.command[0] != 0) {
@@ -331,12 +334,14 @@
 
   load_volume_table();
 
-  std::vector<std::string> args = get_args(argc, argv);
+  std::string stage;
+  std::vector<std::string> args = get_args(argc, argv, &stage);
   auto args_to_parse = StringVectorToNullTerminatedArray(args);
 
   static constexpr struct option OPTIONS[] = {
     { "fastboot", no_argument, nullptr, 0 },
     { "locale", required_argument, nullptr, 0 },
+    { "reason", required_argument, nullptr, 0 },
     { "show_text", no_argument, nullptr, 't' },
     { nullptr, 0, nullptr, 0 },
   };
@@ -344,6 +349,7 @@
   bool show_text = false;
   bool fastboot = false;
   std::string locale;
+  std::string reason;
 
   int arg;
   int option_index;
@@ -357,6 +363,8 @@
         std::string option = OPTIONS[option_index].name;
         if (option == "locale") {
           locale = optarg;
+        } else if (option == "reason") {
+          reason = optarg;
         } else if (option == "fastboot" &&
                    android::base::GetBoolProperty("ro.boot.dynamic_partitions", false)) {
           fastboot = true;
@@ -412,6 +420,9 @@
       device->ResetUI(new StubRecoveryUI());
     }
   }
+
+  BootState boot_state(reason, stage);  // recovery_main owns the state of boot.
+  device->SetBootState(&boot_state);
   ui = device->GetUI();
 
   if (!HasCache()) {
diff --git a/recovery_ui/device.cpp b/recovery_ui/device.cpp
index e7ae1a3..d46df92 100644
--- a/recovery_ui/device.cpp
+++ b/recovery_ui/device.cpp
@@ -23,6 +23,7 @@
 
 #include <android-base/logging.h>
 
+#include "otautil/boot_state.h"
 #include "recovery_ui/ui.h"
 
 static std::vector<std::pair<std::string, Device::BuiltinAction>> g_menu_actions{
@@ -95,3 +96,15 @@
       return ui_->HasThreeButtons() ? kNoAction : kHighlightDown;
   }
 }
+
+void Device::SetBootState(const BootState* state) {
+  boot_state_ = state;
+}
+
+std::optional<std::string> Device::GetReason() const {
+  return boot_state_ ? std::make_optional(boot_state_->reason()) : std::nullopt;
+}
+
+std::optional<std::string> Device::GetStage() const {
+  return boot_state_ ? std::make_optional(boot_state_->stage()) : std::nullopt;
+}
diff --git a/recovery_ui/include/recovery_ui/device.h b/recovery_ui/include/recovery_ui/device.h
index 9a4edf2..f4f9936 100644
--- a/recovery_ui/include/recovery_ui/device.h
+++ b/recovery_ui/include/recovery_ui/device.h
@@ -20,12 +20,15 @@
 #include <stddef.h>
 
 #include <memory>
+#include <optional>
 #include <string>
 #include <vector>
 
 // Forward declaration to avoid including "ui.h".
 class RecoveryUI;
 
+class BootState;
+
 class Device {
  public:
   static constexpr const int kNoAction = -1;
@@ -126,9 +129,16 @@
     return true;
   }
 
+  void SetBootState(const BootState* state);
+  // The getters for reason and stage may return std::nullopt until StartRecovery() is called. It's
+  // the caller's responsibility to perform the check and handle the exception.
+  std::optional<std::string> GetReason() const;
+  std::optional<std::string> GetStage() const;
+
  private:
   // The RecoveryUI object that should be used to display the user interface for this device.
   std::unique_ptr<RecoveryUI> ui_;
+  const BootState* boot_state_{ nullptr };
 };
 
 // Disable name mangling, as this function will be loaded via dlsym(3).