.\" Copyright (c) 2014 The FreeBSD Foundation .\" All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" .\" THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE .\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" .\" $FreeBSD: head/share/man/man8/uefi.8 295522 2016-02-11 14:45:18Z emaste $ .\" .Dd June 13, 2020 .Dt UEFI 8 .Os .Sh NAME .Nm UEFI .Nd Unified Extensible Firmware Interface bootstrapping procedures .Sh DESCRIPTION The .Nm Unified Extensible Firmware Interface provides boot- and run-time services to operating systems. .Nm is a replacement for the legacy BIOS on the i386 and amd64 CPU architectures, and is also used on arm64 and ia64. .Pp The .Nm boot process loads system bootstrap code located in an EFI System Partition (ESP). The ESP is a GPT or MBR partition with a specific identifier that contains an .Xr msdos 5 FAT file system with a specified file hierarchy. .Bl -column -offset indent ".Sy Partition Scheme" ".Sy ESP Identifier" .It Sy "Partition Scheme" Ta Sy "ESP Identifier" .It GPT Ta C12A7328-F81F-11D2-BA4B-00A0C93EC93B .It MBR Ta 0xEF .El .Pp The .Nm boot process proceeds as follows: .Bl -enum -offset indent -compact .It .Nm firmware runs at power up and searches for an OS loader in the EFI system partition. The path to the loader may be set by an EFI environment variable. If not set, the default is .Pa /EFI/BOOT/BOOTX64.EFI . The default .Nm boot configuration for .Dx installs .Pa boot1.efi as .Pa /EFI/BOOT/BOOTX64.EFI . .It .Pa boot1.efi reads boot configuration from .Pa /boot.config or .Pa /boot/config . Unlike other first-stage boot loaders, .Pa boot1.efi passes the configuration to the next stage boot loader and does not itself act on the contents of the file. .It .Pa boot1.efi searches partitions of type .Sq DragonFly UFS1 and the first .Xr disklabel64 5 partition in GPT partitions of type .Sq DragonFly Label64 for .Pa loader.efi . The search begins with partitions on the device from which .Pa boot1.efi was loaded, and continues with other available partitions. .\"If both .\".Li DragonFly UFS1 .\"and .\".Li DragonFly Label64 .\"partitions exist on the same device .\"... .Pa boot1.efi then loads and executes .Pa loader.efi . .It .Pa loader.efi loads and boots the kernel, as described in .Xr loader 8 . .El .Sh FILES .Bl -tag -width /boot/loader -compact .It Pa /boot/boot1.efi First stage .Nm bootstrap .It Pa /boot/loader.efi Final stage bootstrap .It Pa /boot/kernel/kernel default kernel .It Pa /boot/kernel.old/kernel typical non-default kernel (optional) .El .Sh SEE ALSO .\".Xr boot.config 5 , .Xr efivar 3 , .Xr disklabel64 5 , .Xr msdos 5 , .Xr boot 8 , .Xr efibootmgr 8 , .Xr efidp 8 , .Xr efisetup 8 , .Xr efivar 8 , .Xr uefisign 8 .Sh HISTORY .Nm boot support first appeared in .Fx 10.1 and was brought into .Dx 4.5 . .Sh AUTHORS .An -nosplit .Nm boot support was developed by .An Benno Rice Aq Mt benno@FreeBSD.org , .An \&Ed Maste Aq Mt emaste@FreeBSD.org , and .An Nathan Whitehorn Aq Mt nwhitehorn@FreeBSD.org . The .Fx Foundation sponsored portions of the work. .Sh CAVEATS EFI environment variables are not supported by .Xr loader 8 or the kernel.