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 March 18, 2022 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 riscv architectures. 41.Pp 42The UEFI specification is the successor to the Extensible Firmware Interface 43(EFI) specification. 44The terms UEFI and EFI 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 "Partition Scheme" "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 managed by 68.Xr efibootmgr 8 . 69If not set, an architecture-specific default is used. 70.Bl -column -offset indent "Architecture" "Default Path" 71.It Sy Architecture Ta Sy Default Path 72.It amd64 Ta Pa /EFI/BOOT/BOOTX64.EFI 73.It arm Ta Pa /EFI/BOOT/BOOTARM.EFI 74.It arm64 Ta Pa /EFI/BOOT/BOOTAA64.EFI 75.It i386 Ta Pa /EFI/BOOT/BOOTIA32.EFI 76.It riscv Ta Pa /EFI/BOOT/BOOTRISCV64.EFI 77.El 78.Pp 79The default 80.Nm 81boot configuration for 82.Fx 83installs 84.Pa loader.efi 85in the default path. 86.It 87.Pa loader.efi 88reads boot configuration from 89.Pa /boot.config 90or 91.Pa /boot/config . 92.It 93.Pa loader.efi 94loads and boots the kernel, as described in 95.Xr loader 8 . 96.El 97.Pp 98The 99.Xr vt 4 100system console is automatically selected when booting via 101.Nm . 102.Sh FILES 103.Bl -tag -width /boot/loader -compact 104.Nm 105bootstrap 106.It Pa /boot/loader.efi 107Final stage bootstrap 108.It Pa /boot/kernel/kernel 109Default kernel 110.It Pa /boot/kernel.old/kernel 111Typical non-default kernel (optional) 112.El 113.Sh SEE ALSO 114.Xr vt 4 , 115.Xr boot.config 5 , 116.Xr msdosfs 5 , 117.Xr boot 8 , 118.Xr efibootmgr 8 , 119.Xr efidp 8 , 120.Xr efivar 8 , 121.Xr gpart 8 , 122.Xr uefisign 8 123.Sh HISTORY 124EFI boot support for the ia64 architecture first appeared in 125.Fx 5.0 . 126.Nm 127boot support for amd64 first appeared in 128.Fx 10.1 ; 129for arm64 in 130.Fx 11.0 ; 131for armv6 and armv7 in 132.Fx 12.0 ; 133and for riscv in 134.Fx 13.0 . 135.Sh BUGS 136There is no support for 32-bit i386 booting via UEFI. 137