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: head/share/man/man8/uefi.8 295522 2016-02-11 14:45:18Z emaste $ 26.\" 27.Dd March 31, 2017 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 arm64 and ia64. 41.Pp 42The 43.Nm 44boot process loads system bootstrap code located in an EFI System Partition 45(ESP). 46The ESP is a GPT or MBR partition with a specific identifier that contains an 47.Xr msdos 5 48FAT file system with a specified file hierarchy. 49.Bl -column -offset indent ".Sy Partition Scheme" ".Sy ESP Identifier" 50.It Sy "Partition Scheme" Ta Sy "ESP Identifier" 51.It GPT Ta C12A7328-F81F-11D2-BA4B-00A0C93EC93B 52.It MBR Ta 0xEF 53.El 54.Pp 55The 56.Nm 57boot process proceeds as follows: 58.Bl -enum -offset indent -compact 59.It 60.Nm 61firmware runs at power up and searches for an OS loader in the EFI system 62partition. 63The path to the loader may be set by an EFI environment variable. 64If not set, the default is 65.Pa /EFI/BOOT/BOOTX64.EFI . 66The default 67.Nm 68boot configuration for 69.Dx 70installs 71.Pa boot1.efi 72as 73.Pa /EFI/BOOT/BOOTX64.EFI . 74.It 75.Pa boot1.efi 76reads boot configuration from 77.Pa /boot.config 78or 79.Pa /boot/config . 80Unlike other first-stage boot loaders, 81.Pa boot1.efi 82passes the configuration to the next stage boot loader and does not 83itself act on the contents of the file. 84.It 85.Pa boot1.efi 86searches partitions of type 87.Sq DragonFly UFS1 88and the first 89.Xr disklabel64 5 90partition in GPT partitions of type 91.Sq DragonFly Label64 92for 93.Pa loader.efi . 94The search begins with partitions on the device from which 95.Pa boot1.efi 96was loaded, and continues with other available partitions. 97.\"If both 98.\".Li DragonFly UFS1 99.\"and 100.\".Li DragonFly Label64 101.\"partitions exist on the same device 102.\"... 103.Pa boot1.efi 104then loads and executes 105.Pa loader.efi . 106.It 107.Pa loader.efi 108loads and boots the kernel, as described in 109.Xr loader 8 . 110.El 111.Sh FILES 112.Bl -tag -width /boot/loader -compact 113.It Pa /boot/boot1.efi 114First stage 115.Nm 116bootstrap 117.It Pa /boot/loader.efi 118Final stage bootstrap 119.It Pa /boot/kernel/kernel 120default kernel 121.It Pa /boot/kernel.old/kernel 122typical non-default kernel (optional) 123.El 124.Sh SEE ALSO 125.\".Xr boot.config 5 , 126.Xr efivar 3 , 127.Xr disklabel64 5 , 128.Xr msdos 5 , 129.Xr boot 8 , 130.Xr efisetup 8 , 131.Xr efivar 8 , 132.Xr uefisign 8 133.Sh HISTORY 134.Nm 135boot support first appeared in 136.Fx 10.1 137and was brought into 138.Dx 4.5 . 139.Sh AUTHORS 140.An -nosplit 141.Nm 142boot support was developed by 143.An Benno Rice Aq Mt benno@FreeBSD.org , 144.An \&Ed Maste Aq Mt emaste@FreeBSD.org , 145and 146.An Nathan Whitehorn Aq Mt nwhitehorn@FreeBSD.org . 147The 148.Fx 149Foundation sponsored portions of the work. 150.Sh CAVEATS 151EFI environment variables are not supported by 152.Xr loader 8 153or the kernel. 154