1.\" Copyright (c) 2014 The FreeBSD Foundation 2.\" All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 13.\" THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND 14.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 15.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 16.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE 17.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 18.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 19.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 20.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 21.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 22.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 23.\" SUCH DAMAGE. 24.\" 25.\" $FreeBSD$ 26.\" 27.Dd February 22, 2021 28.Dt UEFI 8 29.Os 30.Sh NAME 31.Nm UEFI 32.Nd Unified Extensible Firmware Interface bootstrapping procedures 33.Sh DESCRIPTION 34The 35.Nm 36Unified Extensible Firmware Interface provides boot- and run-time services 37to operating systems. 38.Nm 39is a replacement for the legacy BIOS on the i386 and amd64 CPU architectures, 40and is also used on arm, arm64 and ia64. 41.Pp 42The UEFI specification is the successor to the Extensible Firmware Interface 43(EFI) specification. 44The terms are often used interchangeably. 45.Pp 46The 47.Nm 48boot process loads system bootstrap code located in an EFI System Partition 49(ESP). 50The ESP is a GPT or MBR partition with a specific identifier that contains an 51.Xr msdosfs 5 52FAT file system with a specified file hierarchy. 53.Bl -column -offset indent ".Sy Partition Scheme" ".Sy ESP Identifier" 54.It Sy "Partition Scheme" Ta Sy "ESP Identifier" 55.It GPT Ta C12A7328-F81F-11D2-BA4B-00A0C93EC93B 56.It MBR Ta 0xEF 57.El 58.Pp 59The 60.Nm 61boot process proceeds as follows: 62.Bl -enum -offset indent -compact 63.It 64.Nm 65firmware runs at power up and searches for an OS loader in the EFI system 66partition. 67The path to the loader may be set by an EFI environment variable. 68If not set, an architecture-specific default is used. 69.Bl -column -offset indent "Architecture" "Default Path" 70.It Sy Architecture Ta Sy Default Path 71.It amd64 Ta Pa /EFI/BOOT/BOOTX64.EFI 72.It arm Ta Pa /EFI/BOOT/BOOTARM.EFI 73.It arm64 Ta Pa /EFI/BOOT/BOOTAA64.EFI 74.El 75.Pp 76The default 77.Nm 78boot configuration for 79.Fx 80installs 81.Pa loader.efi 82in the default path. 83.It 84.Pa loader.efi 85reads boot configuration from 86.Pa /boot.config 87or 88.Pa /boot/config . 89.It 90.Pa loader.efi 91loads and boots the kernel, as described in 92.Xr loader 8 . 93.El 94.Pp 95The 96.Xr vt 4 97system console is automatically selected when booting via 98.Nm . 99.Sh FILES 100.Bl -tag -width /boot/loader -compact 101.Nm 102bootstrap 103.It Pa /boot/loader.efi 104Final stage bootstrap 105.It Pa /boot/kernel/kernel 106default kernel 107.It Pa /boot/kernel.old/kernel 108typical non-default kernel (optional) 109.El 110.Sh SEE ALSO 111.Xr vt 4 , 112.Xr boot.config 5 , 113.Xr msdosfs 5 , 114.Xr boot 8 , 115.Xr efibootmgr 8 , 116.Xr efidp 8 , 117.Xr efivar 8 , 118.Xr gpart 8 , 119.Xr uefisign 8 120.Sh HISTORY 121EFI boot support for the ia64 architecture first appeared in 122.Fx 5.0 . 123.Nm 124boot support for amd64 first appeared in 125.Fx 10.1 ; 126for arm64 in 127.Fx 11.0 ; 128for armv6 and armv7 in 129.Fx 12.0 ; 130and for riscv in 131.Fx 13.0 . 132