What is the Bootloader?


Surely most of you have heard about bootloader, especially when you have tried to rotate your device or install a custom ROM.

For all these cases the first step is to unlock the bootloader in order to install a new software that does not come from the manufacturer. Here we explain what the bootloader is and what it’s for.Bootloader

What is the Bootloader?

Bootloader is the English name for the device boot loader. It’s the first program that runs on the processor when you turn on an Android smartphone.

It is in charge of loading the Linux Kernel and the Android operating system. The bootloader is a fundamental part of every machine running an operating system whether it is a smartphone or a computer.

How does the Bootloader work?

The bootloader is a program developed by the manufacturer of the device itself to work with your particular hardware.

When you turn on the smartphone, the bootloader performs tests to check which parts of the memory the kernel is in or the recovery to load one of these parts.

If you press the power button the bootloader understands that you want to load the operating system and therefore chooses the kernel to boot.

If, on the other hand, you press the key combination to enter the recovery (reboot bootloader, restart bootloader), the bootloader will choose to load the memory part where the recovery is stored.

By default the bootloader is locked, this means that it can only boot a partition that has the manufacturer’s or operator’s digital signature, either the original operating system or the manufacturer’s recovery.

In order to install another operating system or another custom recovery we must be able to load a part of the memory that is not signed by the manufacturer, which involves unlocking the bootloader or even replacing it and in most cases this voids the manufacturer’s warranty.

Why do manufacturers block the Bootloader?

The bootloader is locked so that it only reads the Android system that the manufacturer installs. In other words, the bootloader is used to block unofficial ROMs.

Here the controversy is born, since the bootloader works like a kind of customs that the software has to pass to be able to be executed in our devices.

This implies that if we want to install an unofficial ROM, first we have to unlock the famous bootloader, which is not always easy and involves the loss of the warranty.

From here also arises the controversy about losing the warranty by rooting the device. The problem lies in the bootloader because in the vast majority of rooteo cases the bootloader is modified.

In Samsung there is also a security system called knox, which incorporates in the bootloader a function called KNOX Void Warranty, which counts the times that you flash a Samsung software without signature, usually with Odin but also recognizes the flashes from the custom recovery.

Can the Bootloader be unlocked?

Yes, you can effectively unlock the Bootloader in most cases. Some manufacturers make it easy by providing tools to do so or simply through the ADB and Fastboot, but in some cases you have to break security with an exploit.

In any case, the process of releasing the bootloader involves the loss of all device data (it is important to make a backup before unlocking), the loss of warranty and can endanger our terminals.

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