diff --git a/init/README.md b/init/README.md
index 6439393..ab6a885 100644
--- a/init/README.md
+++ b/init/README.md
@@ -172,9 +172,12 @@
   This option connects stdin, stdout, and stderr to the console. It is mutually exclusive with the
   stdio_to_kmsg option, which only connects stdout and stderr to kmsg.
 
-`critical`
+`critical [window=<fatal crash window mins>] [target=<fatal reboot target>]`
 > This is a device-critical service. If it exits more than four times in
-  four minutes or before boot completes, the device will reboot into bootloader.
+  _fatal crash window mins_ minutes or before boot completes, the device
+  will reboot into _fatal reboot target_.
+  The default value of _fatal crash window mins_ is 4, and default value
+  of _fatal reboot target_ is 'bootloader'.
 
 `disabled`
 > This service will not automatically start with its class.
diff --git a/init/host_init_stubs.h b/init/host_init_stubs.h
index caa8f8d..2a8bf6c 100644
--- a/init/host_init_stubs.h
+++ b/init/host_init_stubs.h
@@ -20,6 +20,7 @@
 #include <sys/socket.h>
 #include <sys/types.h>
 
+#include <optional>
 #include <string>
 
 #include <android-base/properties.h>
@@ -41,7 +42,7 @@
 }
 
 // reboot_utils.h
-inline void SetFatalRebootTarget() {}
+inline void SetFatalRebootTarget(const std::optional<std::string>& = std::nullopt) {}
 inline void __attribute__((noreturn)) InitFatalReboot(int signal_number) {
     abort();
 }
diff --git a/init/reboot_utils.cpp b/init/reboot_utils.cpp
index 76460a5..98f6857 100644
--- a/init/reboot_utils.cpp
+++ b/init/reboot_utils.cpp
@@ -19,6 +19,7 @@
 #include <sys/syscall.h>
 #include <unistd.h>
 
+#include <optional>
 #include <string>
 
 #include <android-base/file.h>
@@ -37,7 +38,7 @@
 static std::string init_fatal_reboot_target = "bootloader";
 static bool init_fatal_panic = false;
 
-void SetFatalRebootTarget() {
+void SetFatalRebootTarget(const std::optional<std::string>& reboot_target) {
     std::string cmdline;
     android::base::ReadFileToString("/proc/cmdline", &cmdline);
     cmdline = android::base::Trim(cmdline);
@@ -45,6 +46,11 @@
     const char kInitFatalPanicString[] = "androidboot.init_fatal_panic=true";
     init_fatal_panic = cmdline.find(kInitFatalPanicString) != std::string::npos;
 
+    if (reboot_target) {
+        init_fatal_reboot_target = *reboot_target;
+        return;
+    }
+
     const char kRebootTargetString[] = "androidboot.init_fatal_reboot_target=";
     auto start_pos = cmdline.find(kRebootTargetString);
     if (start_pos == std::string::npos) {
diff --git a/init/reboot_utils.h b/init/reboot_utils.h
index 05bb9ae..a0023b9 100644
--- a/init/reboot_utils.h
+++ b/init/reboot_utils.h
@@ -16,6 +16,7 @@
 
 #pragma once
 
+#include <optional>
 #include <string>
 
 #define PROC_SYSRQ "/proc/sysrq-trigger"
@@ -23,7 +24,7 @@
 namespace android {
 namespace init {
 
-void SetFatalRebootTarget();
+void SetFatalRebootTarget(const std::optional<std::string>& reboot_target = std::nullopt);
 // Determines whether the system is capable of rebooting. This is conservative,
 // so if any of the attempts to determine this fail, it will still return true.
 bool IsRebootCapable();
diff --git a/init/service.cpp b/init/service.cpp
index 68365b3..ecc86d9 100644
--- a/init/service.cpp
+++ b/init/service.cpp
@@ -45,6 +45,7 @@
 #include <android/api-level.h>
 
 #include "mount_namespace.h"
+#include "reboot_utils.h"
 #include "selinux.h"
 #else
 #include "host_init_stubs.h"
@@ -312,20 +313,24 @@
 #endif
     const bool is_process_updatable = !pre_apexd_ && is_apex_updatable;
 
-    // If we crash > 4 times in 4 minutes or before boot_completed,
+    // If we crash > 4 times in 'fatal_crash_window_' minutes or before boot_completed,
     // reboot into bootloader or set crashing property
     boot_clock::time_point now = boot_clock::now();
     if (((flags_ & SVC_CRITICAL) || is_process_updatable) && !(flags_ & SVC_RESTART)) {
         bool boot_completed = android::base::GetBoolProperty("sys.boot_completed", false);
-        if (now < time_crashed_ + 4min || !boot_completed) {
+        if (now < time_crashed_ + fatal_crash_window_ || !boot_completed) {
             if (++crash_count_ > 4) {
+                auto exit_reason = boot_completed ?
+                    "in " + std::to_string(fatal_crash_window_.count()) + " minutes" :
+                    "before boot completed";
                 if (flags_ & SVC_CRITICAL) {
-                    // Aborts into bootloader
+                    // Aborts into `fatal_reboot_target_'.
+                    SetFatalRebootTarget(fatal_reboot_target_);
                     LOG(FATAL) << "critical process '" << name_ << "' exited 4 times "
-                               << (boot_completed ? "in 4 minutes" : "before boot completed");
+                               << exit_reason;
                 } else {
                     LOG(ERROR) << "updatable process '" << name_ << "' exited 4 times "
-                               << (boot_completed ? "in 4 minutes" : "before boot completed");
+                               << exit_reason;
                     // Notifies update_verifier and apexd
                     SetProperty("sys.init.updatable_crashing_process_name", name_);
                     SetProperty("sys.init.updatable_crashing", "1");
diff --git a/init/service.h b/init/service.h
index 34ed5ef..bc5c90f 100644
--- a/init/service.h
+++ b/init/service.h
@@ -155,6 +155,8 @@
     android::base::boot_clock::time_point time_started_;  // time of last start
     android::base::boot_clock::time_point time_crashed_;  // first crash within inspection window
     int crash_count_;                     // number of times crashed within window
+    std::chrono::minutes fatal_crash_window_ = 4min;  // fatal() when more than 4 crashes in it
+    std::optional<std::string> fatal_reboot_target_;  // reboot target of fatal handler
 
     std::optional<CapSet> capabilities_;
     ProcessAttributes proc_attr_;
diff --git a/init/service_parser.cpp b/init/service_parser.cpp
index bdac077..97621da 100644
--- a/init/service_parser.cpp
+++ b/init/service_parser.cpp
@@ -93,6 +93,39 @@
 }
 
 Result<void> ServiceParser::ParseCritical(std::vector<std::string>&& args) {
+    std::optional<std::string> fatal_reboot_target;
+    std::optional<std::chrono::minutes> fatal_crash_window;
+
+    for (auto it = args.begin() + 1; it != args.end(); ++it) {
+        auto arg = android::base::Split(*it, "=");
+        if (arg.size() != 2) {
+            return Error() << "critical: Argument '" << *it << "' is not supported";
+        } else if (arg[0] == "target") {
+            fatal_reboot_target = arg[1];
+        } else if (arg[0] == "window") {
+            int minutes;
+            auto window = ExpandProps(arg[1]);
+            if (!window.ok()) {
+                return Error() << "critical: Could not expand argument ': " << arg[1];
+            }
+            if (*window == "off") {
+                return {};
+            }
+            if (!ParseInt(*window, &minutes, 0)) {
+                return Error() << "critical: 'fatal_crash_window' must be an integer > 0";
+            }
+            fatal_crash_window = std::chrono::minutes(minutes);
+        } else {
+            return Error() << "critical: Argument '" << *it << "' is not supported";
+        }
+    }
+
+    if (fatal_reboot_target) {
+        service_->fatal_reboot_target_ = *fatal_reboot_target;
+    }
+    if (fatal_crash_window) {
+        service_->fatal_crash_window_ = *fatal_crash_window;
+    }
     service_->flags_ |= SVC_CRITICAL;
     return {};
 }
@@ -506,7 +539,7 @@
         {"capabilities",            {0,     kMax, &ServiceParser::ParseCapabilities}},
         {"class",                   {1,     kMax, &ServiceParser::ParseClass}},
         {"console",                 {0,     1,    &ServiceParser::ParseConsole}},
-        {"critical",                {0,     0,    &ServiceParser::ParseCritical}},
+        {"critical",                {0,     2,    &ServiceParser::ParseCritical}},
         {"disabled",                {0,     0,    &ServiceParser::ParseDisabled}},
         {"enter_namespace",         {2,     2,    &ServiceParser::ParseEnterNamespace}},
         {"file",                    {2,     2,    &ServiceParser::ParseFile}},
diff --git a/libutils/Unicode.cpp b/libutils/Unicode.cpp
index b6e457b..843a81a 100644
--- a/libutils/Unicode.cpp
+++ b/libutils/Unicode.cpp
@@ -359,49 +359,6 @@
 // UTF-8
 // --------------------------------------------------------------------------
 
-ssize_t utf8_length(const char *src)
-{
-    const char *cur = src;
-    size_t ret = 0;
-    while (*cur != '\0') {
-        const char first_char = *cur++;
-        if ((first_char & 0x80) == 0) { // ASCII
-            ret += 1;
-            continue;
-        }
-        // (UTF-8's character must not be like 10xxxxxx,
-        //  but 110xxxxx, 1110xxxx, ... or 1111110x)
-        if ((first_char & 0x40) == 0) {
-            return -1;
-        }
-
-        int32_t mask, to_ignore_mask;
-        size_t num_to_read = 0;
-        char32_t utf32 = 0;
-        for (num_to_read = 1, mask = 0x40, to_ignore_mask = 0x80;
-             num_to_read < 5 && (first_char & mask);
-             num_to_read++, to_ignore_mask |= mask, mask >>= 1) {
-            if ((*cur & 0xC0) != 0x80) { // must be 10xxxxxx
-                return -1;
-            }
-            // 0x3F == 00111111
-            utf32 = (utf32 << 6) + (*cur++ & 0x3F);
-        }
-        // "first_char" must be (110xxxxx - 11110xxx)
-        if (num_to_read == 5) {
-            return -1;
-        }
-        to_ignore_mask |= mask;
-        utf32 |= ((~to_ignore_mask) & first_char) << (6 * (num_to_read - 1));
-        if (utf32 > kUnicodeMaxCodepoint) {
-            return -1;
-        }
-
-        ret += num_to_read;
-    }
-    return ret;
-}
-
 ssize_t utf16_to_utf8_length(const char16_t *src, size_t src_len)
 {
     if (src == nullptr || src_len == 0) {
diff --git a/libutils/include/utils/Unicode.h b/libutils/include/utils/Unicode.h
index fc6712d..0087383 100644
--- a/libutils/include/utils/Unicode.h
+++ b/libutils/include/utils/Unicode.h
@@ -111,24 +111,6 @@
 void utf16_to_utf8(const char16_t* src, size_t src_len, char* dst, size_t dst_len);
 
 /**
- * Returns the length of "src" when "src" is valid UTF-8 string.
- * Returns 0 if src is NULL or 0-length string. Returns -1 when the source
- * is an invalid string.
- *
- * This function should be used to determine whether "src" is valid UTF-8
- * characters with valid unicode codepoints. "src" must be nul-terminated.
- *
- * If you are going to use other utf8_to_... functions defined in this header
- * with string which may not be valid UTF-8 with valid codepoint (form 0 to
- * 0x10FFFF), you should use this function before calling others, since the
- * other functions do not check whether the string is valid UTF-8 or not.
- *
- * If you do not care whether "src" is valid UTF-8 or not, you should use
- * strlen() as usual, which should be much faster.
- */
-ssize_t utf8_length(const char *src);
-
-/**
  * Returns the UTF-16 length of UTF-8 string "src". Returns -1 in case
  * it's invalid utf8. No buffer over-read occurs because of bound checks. Using overreadIsFatal you
  * can ask to log a message and fail in case the invalid utf8 could have caused an override if no
diff --git a/rootdir/init.zygote32.rc b/rootdir/init.zygote32.rc
index e827cf5..9469a48 100644
--- a/rootdir/init.zygote32.rc
+++ b/rootdir/init.zygote32.rc
@@ -13,3 +13,4 @@
     onrestart restart netd
     onrestart restart wificond
     writepid /dev/cpuset/foreground/tasks
+    critical window=${zygote.critical_window.minute:-off} target=zygote-fatal
diff --git a/rootdir/init.zygote64.rc b/rootdir/init.zygote64.rc
index adc7031..98dc088 100644
--- a/rootdir/init.zygote64.rc
+++ b/rootdir/init.zygote64.rc
@@ -13,3 +13,4 @@
     onrestart restart netd
     onrestart restart wificond
     writepid /dev/cpuset/foreground/tasks
+    critical window=${zygote.critical_window.minute:-off} target=zygote-fatal
diff --git a/rootdir/init.zygote64_32.rc b/rootdir/init.zygote64_32.rc
index fb9e99b..3eee180 100644
--- a/rootdir/init.zygote64_32.rc
+++ b/rootdir/init.zygote64_32.rc
@@ -13,6 +13,7 @@
     onrestart restart netd
     onrestart restart wificond
     task_profiles ProcessCapacityHigh MaxPerformance
+    critical window=${zygote.critical_window.minute:-off} target=zygote-fatal
 
 service zygote_secondary /system/bin/app_process32 -Xzygote /system/bin --zygote --socket-name=zygote_secondary --enable-lazy-preload
     class main