DB-hub Technology Linux What is difference between BIOS, UEFI, bootloader and firmware?

What is difference between BIOS, UEFI, bootloader and firmware?

转:https://www.quora.com/What-is-difference-between-BIOS-UEFI-bootloader-and-firmware

Firmware: Firmware is programming that’s written to the read-only memory ROM, of a computing device. Firmware, which is added at the time of manufacturing, is used to run user programs on the device.

Boot Loader: Boot loader is code that is executed before any Operating System starts to run. The concept of boot loaders is universal to virtually all Operating systems that inculcates operating systems on your PC, laptop, smartphones, and other such devices. Boot loaders basically package the instructions to boot operating system kernel and most of them also have their own debugging or modification environment.

UEFI: Unified Extensible Firmware Interface (hereafter known as UEFI) Specification describes an interface between the operating system (OS) and the platform firmware.

BIOS: BIOS (basic input/output system) is the program a personal computer’s microprocessor uses to get the computer system started after you turn it on. It also manages data flow between the computer’s operating system and attached devices such as the hard disk, video adapter,keyboard, mouse and printer.

BIOS is an integral part of your computer and comes with it when you bring it home. (In contrast, the operating system can either be pre-installed by the manufacturer or vendor or installed by the user.) BIOS is a program that is made accessible to the microprocessor on an erasable programmable read-only memory (EPROM) chip. When you turn on your computer POST is executed, the microprocessor passes control to the BIOS program, which is always located at the same place on EPROM.

So after reading all four of above we can conclude, following points,

  • BIOS is something that is permanent and stored in non volatile memory.
  • Boot Loader may change with particular OS type
  • UEFI is a specification that allows a firmware to access the hardware in different manner than conventional way.
  • BIOS is firmware and Boot Loader is software
  • BIOS and UEFI sounds similar, where UEFI seems like a successor of BIOS.
    Now according to third point and definitions, BIOS and UEFI sound somewhat similar, yes they are UEFI is a specification introduced by processor vendors to make it easier and efficient for coding as well as execution purpose.

That leads us to another term UEFI BIOS, the BIOS which uses UEFI implementation, there are two kind of BIOS images Legacy and UEFI.

UEFI BIOS supports UEFI enabled OS, following are the advantages of UEFI enabled OS,

  • Legacy uses MBR (Master Boot Record) partition for booting , UEFI uses GPT (GUID partition system) partitioning system,
  • Maximium partition size changes for Legacy aprrox 2TB to UEFI 9 zetabytes.
  • MBR can have only 4 partitions, GPT can have 128.
  • Also UEFI BIOS gives Secure Boot Functionality which secures the bios from getting trifled by external intrusions.
    Now a days most of the BIOSes are UEFI BIOS, but to make sure that if someone uses legacy OS and hardware it comes with the support for Legacy hardware also.

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