Bootloader unlocking

Bootloader unlocking is the process of disabling the bootloader security that makes secure boot possible. It can make advanced customizations possible, such as installing a custom firmware. On smartphones this can be a custom Android distribution or another mobile operating system. Some bootloaders are not locked at all, others can be unlocked using a standard command, others need assistance from the manufacturer. Some do not include an unlocking method and can only be unlocked through a software exploit.
Bootloader unlocking is also done for mobile forensics purposes, to extract digital evidence from mobile devices, using tools such as Cellebrite UFED.
== Background ==
Unlocking the bootloader usually voids any warranties and may make the device susceptible to data theft. On Chromebooks, enabling developer mode makes the system less secure than a standard laptop running Linux. Unlocking the bootloader may lead to data loss on Android and ChromeOS devices, as some data is impossible to back up without root permission.
Sascha Segan from PCMag considered a locked bootloader a mistake on the Qualcomm Snapdragon Insiders phone, which is targeted at advanced users.
== Platformsb ==
=== Android ===
Unlocking the bootloader is typically done during the process to obtain root access.
Android bootloader unlocking as of 2023
Manufacturer	Difficulty level 	Method
Google 	Easy (non-Verizon)
Impossible (Verizon) 	Command-line (unlocked variant, not restricted to carrier, and non-Verizon carrier variants when paid off fully)
Samsung 	Easy (outside North America)
Impossible (North America) 	Development settings (except North America variants)
OnePlus 	Easy (non-T-Mobile)
Medium (T-Mobile) 	Command-line, except on T-Mobile US variants where an unlock code is needed
Xiaomi 	Hard 	Add Mi account, request code via Windows-only software, wait up to a month (limited to one device per month).
On devices with Mediatek system on a chip it is easy with a third-party tool called MTKClient
Asus 	Impossible 	Unlocking was performed via a first-party unlocking tool, but servers and app were removed.
Sony 	Medium 	Command-line, request code at Sony website
Fairphone 	Medium 	Command-line, request code at Fairphone website
Motorola 	Medium 	Command-line, request code at Motorola website
Realme 	Medium-Hard 	Command-line, after installation of the in-depth test app and submitting a application for in-depth testing.
Nothing 	Easy 	Command-line
Huawei 	Impossible, due to unlocking services being shut down 	N/A
OPPO 	Impossible (Fastboot binaries are removed) 	N/A
HMD-Nokia 	Impossible 	N/A
vivo 	Impossible 	N/A
LG 	Impossible, due to unlocking services being shut down, only G and V series models from 2015 onwards were affected, including Velvet	N/A
Tecno 	Easy 	Command-line
Infinix 	Easy 	Command-line
TCL 	Impossible 	N/A
==== History[edit] ====
The bootloaders of Nexus and Pixel devices can be unlocked by using the fastboot command fastboot oem unlock or if it doesn't recognize the command fastboot flashing unlock.
When Motorola released a bootloader unlocking tool for the Droid Razr, Verizon removed the tool from their models.
In 2011, Sony Ericsson released an online bootloader unlocking tool. Sony requires the IMEI number to be filled in on their website. For the Asus Transformer Prime TF201, Asus has released a special bootloader unlock tool.
In 2012, Motorola released a limited tool for unlocking bootloaders. They require accepting terms and conditions and creating an account before the bootloader can be unlocked for a Moto G.
HTC phones have an additional layer of lock called "S-OFF/S-ON".
Bootloaders can be unlocked using an exploit or using a way that the vendor supplied. The latter method usually requires wiping all data on the device. In addition, some manufacturers prohibit unlocking on carrier locked phones. Samsung phones and cellular tablets sold in the US and Canada do not allow bootloader unlocks regardless of carrier status.
In 2018, a developer from XDA Developers launched a service which allowed users to unlock the bootloader of some Nokia smartphone models. Similarly, another developer from XDA Developers launched a service to allow users to unlock the bootloaders of Samsung Galaxy S20 and Samsung Galaxy S21 Phones.
Huawei announced plans to allow users to unlock the bootloader of the Mate 30 series, but later retracted that. Huawei has stopped providing bootloader unlock codes since 2018. A bootloader exploit named checkm30 has been developed for HiSilicon based Huawei phones.[non-primary source needed]
When the bootloader of the Samsung Galaxy Z Fold 3 was unlocked, the camera became less functional. This could be restored by re-locking the bootloader. This issue was later fixed by Samsung. For the Samsung Galaxy S22 series, unlocking the bootloader has no effect on the camera.
=== Others ===