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Unified Extensible Firmware Interface

통일 확장 펌웨어 인터페이스(영어: Unified Extensible Firmware Interface, UEFI)는 운영 체제와 플랫폼 펌웨어 사이의 소프트웨어 인터페이스를 정의하는 규격이다. IBM PC 호환기종에서 사용되는 바이오스 인터페이스를 대체할 목적으로 개발되었다. 인텔이 개발한 EFI(Extensible Firmware Interface) 규격에서 출발하였으며, 현재는 통일 EFI 포럼이 UEFI 규격을 관리하고 있다.

GPT

Note

UEFI에서 GPT (GUID Partition Table)를 쓴다면, BIOS에서는 MBR (Master Boot Record)을 사용한다.

Format the partition

The UEFI specification mandates support for the FAT12, FAT16, and FAT32 file systems. To prevent potential issues with other operating systems and also since the UEFI specification only mandates supporting FAT16 and FAT12 on removable media, it is recommended to use FAT32.

After creating the partition, format it as FAT32. To use the mkfs.fat utility, install dosfstools. 

$ mkfs.fat -F32 /dev/sdxY

If you get the message WARNING: Not enough clusters for a 32 bit FAT!, reduce cluster size with mkfs.fat -s2 -F32 ... or -s1; otherwise the partition may be unreadable by UEFI. See mkfs.fat(8) for supported cluster sizes.

Mount the partition

The kernels, initramfs files, and, in most cases, the processor's microcode, need to be accessible by the boot loader or UEFI itself to successfully boot the system. Thus if you want to keep the setup simple, your boot loader choice limits the available mount points for EFI system partition.

Typical mount points

The simplest scenarios for mounting EFI system partition are:

  • mount ESP to /efi and use a boot loader which is capable of accessing the kernel(s) and initramfs image(s) that are stored elsewhere (typically /boot). See Boot loader for more information on boot loader requirements and capabilities.
  • mount ESP to /boot. This is the preferred method when directly booting an EFISTUB kernel from UEFI.

Tip:

  • /efi is a replacement for the previously popular (and possibly still used by other Linux distributions) ESP mountpoint /boot/efi.
  • The /efi directory is not available by default, you will need to first create it with mkdir(1) before mounting the ESP to it.

See also

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References

  1. WEBDIR_-_Understanding_the_hard_disk.pdf ↩