Bootloader is the first command that load an operating system when a computer is turned on. Every PC, Laptop and phone has a bootloader that instructs the operating system kernel to boot normally. It is first command when the operating system is turned on. It checks that all the files of operating system and working properly, then it gives permission to run the Operating System. If any file is missing or corrupted, it will not allow to load Operating System on your device. The Android OS is an open source OS and is available on a variety of hardware, every manufacturer has their own version of bootloader specifically for the hardware present in its environment.
Types of Bootloader
- Locked Bootloader: Bootloader is usually locked in Android device because mobile manufacturer doesn’t want to flash custom ROM. With a locked bootloader on Android devices, it is impossible to flash a Custom ROM and forced attempts void warranty as well as usually end up with bricks.
- Unlock Bootloader: It is necessary to unlock your bootloader if you want to flash custom ROM such as Kitkat, Lollipop, Marshmallow etc.
Warning: Unlocking your phone’s bootloader voids its warranty. It also completely wipes/reset (formats) your Android phone’s internal memory.
Recovery, in Android, refers to the bootable partition, in which the recovery console is installed. Recovery is the tool to help repair your installations as well as installing official OS updates by using a combination of key presses or instructions from a command line sometimes. Android is open, meaning the recovery source code is available, so that building a customized ROM is relatively easy.
Types of recovery
- Stock Recovery is the recovery, which is already installed on your mobile by manufacturer, like factory reset, recovery is what boots up and erases the files and data. It has useful features and functions, but limited.
- Custom Recovery is the recovery, which is flash by the user. The most common and useful recovery is ClockworkMod (CWM) and Team Win Recovery Project (TWRP). It offers many more features than stock recovery.
ROM (Read Only Memory) file containing the executable instructions which only readable. It is a software flash on mobile. Android is the Operating System and versions of Android such as Kitkat, Lollipop or Marshmallow are ROM.
Types of ROM
- Stock ROM is the ROM which is already installed on your mobile by manufacturer
- Custom ROM is the ROM which flashes by the user. CyanogenMod is one of the most well-supported ROMs for Android, with a huge community, and frequent updates.
The kernel is the central module (part of a program) of an operating system (OS). The Kernel is the bridge between application software and system software, it works like a middle man.
Every operating system has a kernel and play a very important role. It’s responsible for enabling multiple applications to effectively share the hardware by controlling access to CPU, memory, disk I/O, and networking.