150 lines
4.1 KiB
Groff
150 lines
4.1 KiB
Groff
.\" Copyright (c) 2014 The FreeBSD Foundation
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd May 9, 2020
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.Dt UEFI 8
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.Os
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.Sh NAME
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.Nm UEFI
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.Nd Unified Extensible Firmware Interface bootstrapping procedures
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.Sh DESCRIPTION
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The
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.Nm
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Unified Extensible Firmware Interface provides boot- and run-time services
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to operating systems.
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.Nm
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is a replacement for the legacy BIOS on the i386 and amd64 CPU architectures,
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and is also used on arm, arm64 and ia64.
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.Pp
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The UEFI specification is the successor to the Extensible Firmware Interface
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(EFI) specification.
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The terms are often used interchangeably.
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.Pp
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The
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.Nm
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boot process loads system bootstrap code located in an EFI System Partition
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(ESP).
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The ESP is a GPT or MBR partition with a specific identifier that contains an
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.Xr msdosfs 5
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FAT file system with a specified file hierarchy.
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.Bl -column -offset indent ".Sy Partition Scheme" ".Sy ESP Identifier"
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.It Sy "Partition Scheme" Ta Sy "ESP Identifier"
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.It GPT Ta C12A7328-F81F-11D2-BA4B-00A0C93EC93B
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.It MBR Ta 0xEF
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.El
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.Pp
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The
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.Nm
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boot process proceeds as follows:
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.Bl -enum -offset indent -compact
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.It
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.Nm
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firmware runs at power up and searches for an OS loader in the EFI system
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partition.
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The path to the loader may be set by an EFI environment variable.
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If not set, an architecture-specific default is used.
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.Bl -column -offset indent "Architecture" "Default Path"
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.It Sy Architecture Ta Sy Default Path
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.It amd64 Ta Pa /EFI/BOOT/BOOTX64.EFI
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.It arm Ta Pa /EFI/BOOT/BOOTARM.EFI
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.It arm64 Ta Pa /EFI/BOOT/BOOTAA64.EFI
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.El
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.Pp
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The default
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.Nm
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boot configuration for
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.Fx
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installs
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.Pa loader.efi
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in the default path.
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.It
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.Pa loader.efi
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reads boot configuration from
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.Pa /boot.config
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or
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.Pa /boot/config .
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.It
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.Pa loader.efi
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searches partitions of type
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.Li freebsd-ufs
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and
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.Li freebsd-zfs
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for
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.Pa loader.efi .
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The search begins with partitions on the device from which
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.Pa loader.efi
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was loaded, and continues with other available partitions.
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If both
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.Li freebsd-ufs
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and
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.Li freebsd-zfs
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partitions exist on the same device the
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.Li freebsd-zfs
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partition is preferred.
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.It
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.Pa loader.efi
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loads and boots the kernel, as described in
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.Xr loader 8 .
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.El
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.Pp
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The
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.Xr vt 4
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system console is automatically selected when booting via
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.Nm .
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.Sh FILES
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.Bl -tag -width /boot/loader -compact
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.Nm
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bootstrap
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.It Pa /boot/loader.efi
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Final stage bootstrap
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.It Pa /boot/kernel/kernel
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default kernel
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.It Pa /boot/kernel.old/kernel
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typical non-default kernel (optional)
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.El
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.Sh SEE ALSO
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.Xr vt 4 ,
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.Xr boot.config 5 ,
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.Xr msdosfs 5 ,
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.Xr boot 8 ,
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.Xr efibootmgr 8 ,
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.Xr efidp 8 ,
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.Xr efivar 8 ,
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.Xr gpart 8 ,
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.Xr uefisign 8
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.Sh HISTORY
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EFI boot support for the ia64 architecture first appeared in
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.Fx 5.0 .
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.Nm
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boot support for amd64 first appeared in
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.Fx 10.1
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and for arm64 in
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.Fx 11.0 .
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.Sh CAVEATS
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EFI environment variables are not supported by
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.Xr loader 8
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or the kernel.
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