Sarul in Xiaomi: what is this technology and why it is needed in your device

If you own a Xiaomi TV or smartphone and stumble upon the enigmatic word Sarul in settings, system logs or forum discussions, you are not alone.The term is often questionable, especially among users who are first confronted with deep customization of the brand's devices. Sarul is not the official name of the feature in Xiaomi's documentation, but is mentioned in the context of firmware updates, system recovery, and even service menus.

In practice, Sarul is an internal firmware component that is associated with a secure boot and integrity check mechanism. It works at the kernel level and is responsible for making sure that the device only boots with “trusted” firmware, protecting it from unauthorized changes. In this article, we will look at how Sarul affects the work of your Xiaomi, why it is mentioned when discussing unlocking the bootloader, and what to do if you see an error mentioning this term.

It’s important to understand that Sarul is not a standalone app or feature that you can turn on or off in the settings menu. It’s part of the security architecture that has become especially relevant since the release of Mi TVs based on Android TVs and smartphones with MediaTek processors. If you plan to customize your device (install custom firmware, get root rights), knowing Sarul will help you avoid bricks and other critical errors.

What is Sarul in Xiaomi devices: a technical explanation

Sarul (sometimes spelled SARUL or sarul) is an acronym for Secure Authentication and Recovery Utility Layer, a set of checks that are performed at the boot stage of a device before the operating system starts.

• 🔒 Firmware signature verification: Make sure that the installed software is Xiaomi certified and has not been modified by third-party tools.
• 🛡️ Firmware rollback protection: Prevent installation of an outdated version of software that may contain vulnerabilities.
• 🔄 Recovery Control: Ensure that Fastboot and Recovery modes work properly, even if the main system is damaged.
• 🔧 Integration with bootloader: Interact with bootloader to block unauthorized commands (for example, when trying to unlock).

In Xiaomi Mi TVs (especially PatchWall models), Sarul is closely related to the OTA-updates mechanism. For example, if you try to manually flash a device over USB, the system first turns to Sarul to confirm the legitimacy of the firmware file. In smartphones (such as Redmi Note or POCO), this component can block the installation of informal backups such as TWRP if the bootloader is not unlocked.

The main difference between Sarul and traditional security mechanisms (such as DM-Verity in Android) is its integration with hardware keys that are stored in a secure area of the device’s memory, which means that even with physical access to the device, it is extremely difficult to bypass Sarul checks without special equipment.

Where to find the mention of Sarul: typical scenarios

Users commonly encounter the term Sarul in three situations:

1. Errors when updating firmware (especially on Mi TV 4/5 TVs). For example, a Sarul verification failed message may appear if the firmware file is corrupted or not intended for your model.
2. Logs unlock bootloader. When using the Mi Unlock Tool utility, a string mentioning Sarul may appear in debugging logs if the process is blocked during the device verification phase.
3. Castom firmware and root. Developers of informal software (for example, for the POCO F1 or Redmi K20 Pro) often warn that bypassing Sarul requires additional manipulation of the bootloader.

Sarul can also be mentioned in the service menu of TVs, for example, if you go to Settings → About TV → Software version and click on the MI logo several times, a hidden menu with diagnostic information will open, where, among other parameters, Sarul status can be displayed (for example, Sarul: Enforced).

If you see these messages, it doesn't always mean that you're broken, and most often, you can do it by flashing through official channels or resetting to factory settings, but in some cases, like trying to get root, you may need to go to a service center.

Sarul and unlock the bootloader: what you need to know

One of the most controversial topics surrounding Sarul is its role in the bootloader process on Xiaomi devices, which adds an extra layer of verification that can block standard unlock methods even if you use the official Mi Unlock Tool utility.

Here are the key points to consider:

• 🔓 Unlocking through the Mi Unlock Tool can result in a Couldn't verify device error if Sarul detects a discrepancy in firmware or security key versions.
• ⏳ On some models (for example, Redmi Note 10 Pro) after unlocking the bootloader Sarul requires a time limit (up to 720 hours!) before allowing custom software to flash.
• 🚫 Bypassing Sarul on Mi TVs TV It is almost impossible without physical access to a memory chip (unlike smartphones, where there are workarounds through the memory chip). EDL-regime).

If you plan to unlock the bootloader, be sure to check your model’s compatibility with current Sarul bypass methods. For example, for Qualcomm Snapdragon smartphones (such as the POCO X3), there are tools like XiaomiTool V2 that automate the process. But TV owners should be careful: a failed attempt to unlock can lead to a complete loss of warranty and the need to flash through the service center.

💡

Before unlocking the bootloader on a Xiaomi smartphone, link your Mi Account to the device and wait for confirmation by SMS. This will reduce the risk of blocking Sarul during the verification stage.

How to update the firmware if there is a Sarul error

Sarul-related errors are most common when you try to update your firmware manually (for example, via USB on your TV or Fastboot on your smartphone).

Check the device model and firmware version|Download the official firmware file from the Xiaomi website|Format. USB-storage FAT32|Reset the device to Recovery mode|Follow the instructions on the screen

-->

If there is a mistake on the TV:

1. Download the firmware strictly for your model from the official Xiaomi website. the file name must contain the model code (for example, L43M5-5AIN).
2. Unpack the archive and copy the file update.zip root USB-storage device (not in the folder!).
3. Insert the flash drive into the TV, go to Settings → About TV → Software Update → Update via USB.
4. If you have a Sarul verification failed error, try: Use another one. USB-The storage device (preferably no more) 8 Rename the firmware file to update.zip (register is important!) Reset the TV to factory settings (Settings → Reset).

For smartphones, the process is similar, but instead of USB, you use Fastboot or Recovery mode. If Sarul blocks the installation, try:

• Install firmware through the Mi Flash Tool in clean all mode (erase all data!).
• Use it. EDL-Mode (requires an authorized Xiaomi account).
• Contact the service center if the device stops turning on.

💡

Never interrupt the firmware process if the Sarul check indicator is on the screen (usually a progress bar or the words "Verifying").

Xiaomi models in which Sarul plays a key role

Not all Xiaomi devices have the same strict Sarul mechanism, and here is a table with the models where it is most visible and the features of its operation:

If your model is not in the spreadsheet, it doesn't mean it doesn't have a Sarul. It's just that on some devices (like the Redmi 7A or Mi A3) it's minimal because of the simplified security architecture. To find out exactly if your device has a Sarul, you can use the command in ADB:

adb shell getprop ro.boot.sarul

If the command returns a value of 1 or true, the mechanism is active, and on TVs this information can be found in the service menu (see section above).

Frequent Sarul-related errors and their solutions

Let's look at the typical problems and how to fix them, and it's important that some solutions require technical skills and can lead to a loss of warranty.

⚠️ Note: If your device is warranty-free, contact the official Xiaomi service center before attempting self-repair.Sarul bypass may be regarded as hacking.

If none of the solutions worked, check out the following points:

• 🔌 Make sure your device is at least 50% charged (for smartphones) or connected to the network (for TVs).
• 📥 Download firmware only from official sources (en.miui.com for smartphones, mi.com for TVs).
• 🔧 For Mi TVs, TV use USB-a storage device not exceeding 32 GB formatted in FAT32.

In extreme cases, if the device does not respond to buttons and does not turn on, a hardware reset can help (for TVs, pressing the Power + Menu button for 10 seconds; for smartphones, a Power + Volume Up combination).

FAQ: Answers to popular questions about Sarul