Difference between bootloader and bootstrap loader?

Question

how boot loader is different from bootstrap loader. According to me bootstrap loaders are stored in ROM and boot loaders are in hard disk in MBR (please correct me if I am wrong). bootstrap loader is the first program which get executed after startup. Now I am not getting the meaning of these sentences:- After power on , the bootloader is controlling the board and does not rely on the linux kernel on any way. And The bootstrap loader acts as a glue between the bootloader and the linux kernel. what these mean? And why we require both of them?

Aster

Answer 1

• Bootstrap Loader
  Alternatively referred to as bootstrapping, bootloader, or boot program, a bootstrap loader is a program that resides in the computer's EPROM, ROM, or other non-volatile memory. It is automatically executed by the processor when turning on the computer. (Come from WIKI)
  You can think it will turn on immediately after power on, and it's part of the BIOS(BIOS has many other functions such as providing some diagnostic output, and providing a way for the user to configure the hardware) Pay attention, in some situation Bootstrap Loader can also be called as bootloader or bootstrap...
• Bootloader
  Bootloader is a piece of code that runs before any operating system is running. Bootloader are used to boot other operating systems, usually each operating system has a set of bootloaders specific for it. (Come from google)

HERE IS THE STEP

0 : Power On!
1 : CPU Power On! CPU try to find something in ROM(Or ERROM)
2 : Find BIOS (or other firmware). Run BIOS
3 : BIOS(bootstrap loader and other functions) run
4 : BIOS try to find something in MBR
5 : Find MBR(512 bytes) there is some useful information of the partition
6 : Copy the MBR content into physical disk 0x7c00 where is the location of the Grub.
7 : Grub(a type of bootloader) use the information of the MBR finds a linux! Prepare to run.
8 : Run your linux!

Meave

Answer 2

Many architectures use a bootstrap loader or second-stage loader to load the Linux kernel image into memory. Some bootstrap loaders perform checksum verification of the kernel image, and most perform decompression and relocation of the kernel image.

The difference between a bootloader and a bootstrap loader in this context is simple:

• bootloader
  The bootloader controls the board upon power-up and does not rely on the Linux kernel in any way.
• bootstrap loader
  In contrast, the bootstrap loader's primary purpose in life is to act as the glue between a board-level bootloader and the Linux kernel. It is the bootstrap loader's responsibility to provide a proper context for the kernel to run in, as well as perform the necessary steps to decompress and relocate the kernel binary image.

Alternatively referred to as bootstrapping, boot loader, or boot program, a bootstrap loader is a program that resides in the computers EPROM, ROM, or other non-volatile memory that automatically executed by the processor when turning on the computer. The bootstrap loader reads the hard drives boot sector to continue the process of loading the computers operating system. The term boostrap comes from the old phrase "Pull yourself up by your bootstraps." The boot loader has been replaced in computers that have an Extensible Firmware Interface (EFI). The boot loader is now part of the EFI BIOS.

Fullerton

Answer 3

A bootloader, such as U-Boot or RedBoot, takes control of the hardware immediately after turn on. Boostrap loader, on the other hand, is attached to the kernel image to prepare a proper context for running kernel. For example, when compiling the kernel for an ARM architecture, the kernel file is compiled as the piggy.o file, and the boostrap loader files are misc.o, big_endian.o and head.o.

Bis