rom flashing - Is it possible to unlock the bootloader without root access?

Is it possible to unlock the bootloader without root access? If so, is there another way to unlock the bootloader without using the command...

fastboot oem unlock 

Now, for the background stuff that might be helpful to understand my question. My particular device does not seem to support fastboot so I am wondering if there is a way to do it using

adb shell

This is the behavior when I try to use fastboot.

build@build-VirtualBox:~$ lsusb
Bus 001 Device 009: ID 2207:0010  
Bus 002 Device 002: ID 80ee:0021 VirtualBox USB Tablet
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub

build@build-VirtualBox:~$ adb devices
List of devices attached 
OUGRYBWWCM  device


build@build-VirtualBox:~$ adb reboot bootloader   #<--- Tablet enters      bootloader mode

build@build-VirtualBox:~$ fastboot devices        #<--- Empty results, no fastboot commands will work

build@build-VirtualBox:~$ lsusb  
Bus 002 Device 002: ID 80ee:0021 VirtualBox USB Tablet
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub


# Bus 001 Device 009: ID 2207:0010 --> missing from lsusb command

The device is based on Rockchip's RK3066 processor.

Answer

Short answer is yes you can. Long answer is below but basically it depends on your device, your bootloader and if someone has figured out an exploid to unlock the bootloader yet.

More information:

From this link you can see the difference:

What is bootloader and why unlock it?

In literal terms, bootloader is code that is executed before any Operating System starts to run. Bootloaders basically package the instructions to boot operating system kernel and most of them also have their own debugging or modification environment. As the bootloader kicks off before any piece of software on your device, it makes it extremely processor specific and every motherboard has it’s own bootloader. Every Android phone has a bootloader that instructs the operating system kernel to boot normally.

Why is it locked?

A bootloader is usually locked on an Android device because although it’s an open source OS, still the manufacturers want you to stick to their Android OS version specifically designed for the device. In order to apply this concept, manufacturers lock the bootloader. With a locked bootloader on Android devices, it is virtually impossible to flash a Custom ROM and forced attempts void warranty as well as usually end up in bricks.

Why should I unlock?

The explanation to this question is really simple. If you want root, you’d be wanting to flash Custom ROM post-root, and if you want to install a Custom ROM, you’d need to have your stock bootloader unlocked. In simple terms Unlocking the bootloader allows you to install custom Firmware on your Android phone Warning: Unlocking your phone’s bootloader voids its warranty. It also completely wipes (formats) your Android phone’s internal memory including applications, contacts, SMS and MMS messages etc.

Just a quick note…. Root can be achieved without unlocking the bootloader but that requires an exploit that is discovered by a developer.

This quick note is the important part really. It has to be discovered by a developer, so it depends on the device and if someone has figured out the exploit and released tools for you to do it. HTC let you unlock your bootloader through HTC Dev Site but others will not give you an inch on this.