Difference between revisions of "Unified Extensible Firmware Interface"

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(→‎Troubleshooting: add →‎Boot entries created with efibootmgr fail to show up in UEFI: https://github.com/rhboot/efibootmgr/issues/86 & https://bbs.archlinux.org/viewtopic.php?id=248031)
 
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[[zh-hans:Unified Extensible Firmware Interface]]
 
[[zh-hans:Unified Extensible Firmware Interface]]
 
{{Related articles start}}
 
{{Related articles start}}
 +
{{Related|EFI system partition}}
 
{{Related|Arch boot process}}
 
{{Related|Arch boot process}}
{{Related|Master Boot Record}}
 
{{Related|EFI System Partition}}
 
 
{{Related|GUID Partition Table}}
 
{{Related|GUID Partition Table}}
 
{{Related|Secure Boot}}
 
{{Related|Secure Boot}}
{{Related|UEFI/Hardware}}
 
 
{{Related articles end}}
 
{{Related articles end}}
{{Warning|While the choice to install in UEFI mode is forward looking, early vendor UEFI implementations ''may'' carry more bugs than their BIOS counterparts. It is advised to do a search relating to your particular mainboard model before proceeding.}}
+
{{Warning|While the choice to install in UEFI mode is forward looking, early vendor UEFI implementations ''may'' carry more bugs than their BIOS counterparts. It is advised to do a search relating to your particular motherboard model before proceeding.}}
  
The [http://www.uefi.org/ Unified Extensible Firmware Interface] (EFI or UEFI for short) is a new model for the interface between operating systems and firmware. It provides a standard environment for booting an operating system and running pre-boot applications.
+
The [https://www.uefi.org/ Unified Extensible Firmware Interface] (UEFI or EFI for short) is a new model for the interface between operating systems and firmware. It provides a standard environment for booting an operating system and running pre-boot applications.
  
It is distinct from the commonly used "[[MBR]] boot code" method followed for [[Wikipedia:BIOS|BIOS]] systems. See [[Arch boot process]] for their differences and the boot process using UEFI. To set up UEFI Boot Loaders, see [[Boot loaders]].
+
It is distinct from the commonly used "[[Partitioning#Master Boot Record (bootstrap code)|MBR boot code]]" method followed for [[Wikipedia:BIOS|BIOS]] systems. See [[Arch boot process]] for their differences and the boot process using UEFI. To set up UEFI boot loaders, see [[Arch boot process#Boot loader]].
  
 
== UEFI versions ==
 
== UEFI versions ==
 +
 
* UEFI started as Intel's EFI in versions 1.x.
 
* UEFI started as Intel's EFI in versions 1.x.
 
* Later, a group of companies called the UEFI Forum took over its development, which renamed it as Unified EFI starting with version 2.0.
 
* Later, a group of companies called the UEFI Forum took over its development, which renamed it as Unified EFI starting with version 2.0.
Line 25: Line 24:
 
* Apple's EFI implementation is neither a EFI 1.x version nor UEFI 2.x version but mixes up both. This kind of firmware does not fall under any one (U)EFI specification and therefore is not a standard UEFI firmware. Unless stated explicitly, these instructions are general and some of them may not work or may be different in [[MacBook|Apple Macs]].
 
* Apple's EFI implementation is neither a EFI 1.x version nor UEFI 2.x version but mixes up both. This kind of firmware does not fall under any one (U)EFI specification and therefore is not a standard UEFI firmware. Unless stated explicitly, these instructions are general and some of them may not work or may be different in [[MacBook|Apple Macs]].
  
The latest UEFI Specification can be found at http://uefi.org/specifications.
+
The latest UEFI specification can be found at https://uefi.org/specifications.
 +
 
 +
== UEFI firmware bitness ==
 +
 
 +
Under UEFI, every program whether it is an OS loader or a utility (e.g. a memory testing app or recovery tool), should be a EFI application corresponding to the UEFI firmware bitness/architecture.
 +
 
 +
The vast majority of UEFI firmwares, including recent Apple Macs, use x86_64 UEFI firmware. The only known devices that use IA32 (32-bit) UEFI are older (pre 2008) Apple Macs, Intel Atom System-on-Chip systems (as on 2 November 2013)[https://software.intel.com/en-us/blogs/2015/07/22/why-cheap-systems-run-32-bit-uefi-on-x64-systems] and some older Intel server boards that are known to operate on Intel EFI 1.10 firmware.
 +
 
 +
An x86_64 UEFI firmware does not include support for launching 32-bit EFI applications (unlike x86_64 Linux and Windows versions which include such support). Therefore the EFI application must be compiled for that specific firmware processor bitness/architecture.
  
== UEFI Firmware bitness ==
+
{{Note|The official ISO does not support booting on 32-bit (IA32) UEFI systems, see [[#Booting 64-bit kernel on 32-bit UEFI]] for available workarounds. The installed system will require using a boot loader that supports IA32 UEFI, for example, [[GRUB]] with the {{ic|i386-efi}} target.}}
  
Under UEFI, every program whether it is an OS loader or a utility (e.g. a memory testing app or recovery tool), should be a UEFI Application corresponding to the EFI firmware bitness/architecture.
+
=== Checking the firmware bitness ===
  
The vast majority of UEFI firmwares, including recent Apple Macs, use x86_64 EFI firmware. The only known devices that use IA32 (32-bit) EFI are older (pre 2008) Apple Macs, some Intel Cloverfield ultrabooks and some older Intel Server boards that are known to operate on Intel EFI 1.10 firmware.
+
The firmware bitness can be checked from a booted operating system.
  
An x86_64 EFI firmware does not include support for launching 32-bit EFI apps (unlike x86_64 Linux and Windows versions which include such support). Therefore the UEFI application must be compiled for that specific firmware processor bitness/architecture.
+
==== From Linux ====
  
=== Non Macs ===
+
On distributions running Linux kernel 4.0 or newer, the UEFI firmware bitness can be found via the sysfs interface. Run:
  
Check whether the dir {{ic|/sys/firmware/efi}} exists, if it exists it means the kernel has booted in EFI mode. In that case the UEFI bitness is same as kernel bitness. (ie. i686 or x86_64)
+
$ cat /sys/firmware/efi/fw_platform_size
  
{{Note|Intel Atom System-on-Chip systems ship with 32-bit UEFI (as on 2 November 2013). See [[#Booting 64-bit kernel on 32-bit UEFI]] for more info. Also see [https://blogs.intel.com/evangelists/2015/07/22/why-cheap-systems-run-32-bit-uefi-on-x64-systems/ this Intel blog post].}}
+
It will return {{ic|64}} for a 64-bit (x86_64) UEFI or {{ic|32}} for a 32-bit (IA32) UEFI. If the file does not exist, then you have not booted in UEFI mode.
  
=== Apple Macs ===
+
==== From macOS ====
  
Pre-2008 Macs mostly have i386-efi firmware while >=2008 Macs have mostly x86_64-efi. All Macs capable of running Mac OS X Snow Leopard 64-bit Kernel have x86_64 EFI 1.x firmware.
+
Pre-2008 [[Mac]]s mostly have IA32 EFI firmware while >=2008 Macs have mostly x86_64 EFI. All Macs capable of running Mac OS X Snow Leopard 64-bit Kernel have x86_64 EFI 1.x firmware.
  
To find out the arch of the efi firmware in a Mac, type the following into the Mac OS X terminal:
+
To find out the arch of the EFI firmware in a Mac, type the following into the Mac OS X terminal:
  
 
  $ ioreg -l -p IODeviceTree | grep firmware-abi
 
  $ ioreg -l -p IODeviceTree | grep firmware-abi
  
If the command returns EFI32 then it is IA32 (32-bit) EFI firmware. If it returns EFI64 then it is x86_64 EFI firmware. Most of the Macs do not have UEFI 2.x firmware as Apple's EFI implementation is not fully compliant with UEFI 2.x Specification.
+
If the command returns {{ic|EFI32}} then it is IA32 (32-bit) EFI firmware. If it returns {{ic|EFI64}} then it is x86_64 EFI firmware. Most of the Macs do not have UEFI 2.x firmware as Apple's EFI implementation is not fully compliant with UEFI 2.x specification.
 +
 
 +
==== From Microsoft Windows ====
 +
 
 +
64-bit versions of Windows do not support booting on a 32-bit UEFI. So, if you have a 32-bit version of Windows booted in UEFI mode, you have a 32-bit UEFI.
  
== Linux Kernel Config options for UEFI ==
+
To check the bitness run {{ic|msinfo32.exe}}. In the ''System Summary'' section look at the values of "System Type" and "BIOS mode".
  
The required Linux Kernel configuration options for UEFI systems are :
+
For a 64-bit Windows on a 64-bit UEFI it will be {{ic|System Type: x64-based PC}} and {{ic|BIOS mode: UEFI}}, for a 32-bit Windows on a 32-bit UEFI - {{ic|System Type: x86-based PC}} and {{ic|BIOS mode: UEFI}}. If the "BIOS mode" is not {{ic|UEFI}}, then Windows is not installed in UEFI mode.
 +
 
 +
== Linux kernel config options for UEFI ==
 +
 
 +
The required Linux Kernel configuration options[https://www.kernel.org/doc/Documentation/x86/x86_64/uefi.txt] for UEFI systems are:
  
 
  CONFIG_RELOCATABLE=y
 
  CONFIG_RELOCATABLE=y
 
  CONFIG_EFI=y
 
  CONFIG_EFI=y
 
  CONFIG_EFI_STUB=y
 
  CONFIG_EFI_STUB=y
  CONFIG_FB_EFI=y
+
  CONFIG_X86_SYSFB=y
 +
CONFIG_FB_SIMPLE=y
 
  CONFIG_FRAMEBUFFER_CONSOLE=y
 
  CONFIG_FRAMEBUFFER_CONSOLE=y
  
UEFI Runtime Variables Support ('''efivarfs''' filesystem - {{ic|/sys/firmware/efi/efivars}}). This option is important as this is required to manipulate UEFI Runtime Variables using tools like {{ic|/usr/bin/efibootmgr}}. The below config option has been added in kernel 3.10 and above.
+
UEFI Runtime Variables Support ('''efivarfs''' filesystem - {{ic|/sys/firmware/efi/efivars}}). This option is important as this is required to manipulate UEFI runtime variables using tools like {{ic|/usr/bin/efibootmgr}}. The below config option has been added in kernel 3.10 and above.
  
 
  CONFIG_EFIVAR_FS=y
 
  CONFIG_EFIVAR_FS=y
Line 69: Line 85:
 
  CONFIG_EFI_VARS=n
 
  CONFIG_EFI_VARS=n
  
GUID Partition Table [[GPT]] config option - mandatory for UEFI support
+
[[GUID Partition Table]] (GPT) config option - mandatory for UEFI support
  
 
  CONFIG_EFI_PARTITION=y
 
  CONFIG_EFI_PARTITION=y
  
{{Note|All of the above options are required to boot Linux via UEFI, and are enabled in Archlinux kernels in official repos.}}
+
EFI mixed-mode support - to boot a x64_64 kernel on a IA32 UEFI.
 +
 
 +
CONFIG_EFI_MIXED=y
 +
 
 +
{{Note|All of the above options are enabled in Arch Linux [[kernels]] in the official repositories.}}
  
Retrieved from https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/plain/Documentation/x86/x86_64/uefi.txt .
+
== UEFI variables ==
  
== UEFI Variables ==
+
UEFI defines variables through which an operating system can interact with the firmware. UEFI boot variables are used by the boot loader and used by the OS only for early system start-up. UEFI runtime variables allow an OS to manage certain settings of the firmware like the UEFI boot manager or managing the keys for UEFI Secure Boot protocol etc. You can get the list using:
  
UEFI defines variables through which an operating system can interact with the firmware. UEFI Boot Variables are used by the boot-loader and used by the OS only for early system start-up. UEFI Runtime Variables allow an OS to manage certain settings of the firmware like the UEFI Boot Manager or managing the keys for UEFI Secure Boot Protocol etc. You can get the list using
+
  $ efivar --list
  $ efivar -l
 
  
=== UEFI Variables Support in Linux Kernel ===
+
=== UEFI variables support in Linux kernel ===
  
Linux kernel exposes EFI variables data to userspace via '''efivarfs''' ('''EFI''' '''VAR'''iable '''F'''ile'''S'''ystem) interface ({{ic|CONFIG_EFIVAR_FS}}) - mounted using {{ic|efivarfs}} kernel module at {{ic|/sys/firmware/efi/efivars}} - it has no maximum per-variable size limitation and supports UEFI Secure Boot variables. Introduced in kernel 3.8.
+
Linux kernel exposes UEFI variables data to userspace via '''efivarfs''' ('''EFI''' '''VAR'''iable '''F'''ile'''S'''ystem) interface ({{ic|CONFIG_EFIVAR_FS}}) - mounted using {{ic|efivarfs}} kernel module at {{ic|/sys/firmware/efi/efivars}} - it has no maximum per-variable size limitation and supports UEFI Secure Boot variables. Introduced in kernel 3.8.
  
 
=== Requirements for UEFI variable support ===
 
=== Requirements for UEFI variable support ===
  
# Kernel processor [[#UEFI Firmware bitness|bitness]] and EFI processor bitness should match.
+
# Kernel should be booted in UEFI mode via [[EFISTUB]] (optionally using a [[boot manager]]) or by a UEFI [[boot loader]] (using either the EFI handover protocol or the UEFI LoadImage function), not via BIOS or CSM, or Apple's Boot Camp which is also a CSM.
# Kernel should be booted in EFI mode (via [[EFISTUB]] or any [[Boot loaders|EFI boot loader]], not via BIOS/CSM or Apple's "bootcamp" which is also BIOS/CSM).
 
 
# EFI Runtime Services support should be present in the kernel ({{ic|1=CONFIG_EFI=y}}, check if present with {{ic|zgrep CONFIG_EFI /proc/config.gz}}).
 
# EFI Runtime Services support should be present in the kernel ({{ic|1=CONFIG_EFI=y}}, check if present with {{ic|zgrep CONFIG_EFI /proc/config.gz}}).
 
# EFI Runtime Services in the kernel SHOULD NOT be disabled via kernel cmdline, i.e. {{ic|noefi}} kernel parameter SHOULD NOT be used.
 
# EFI Runtime Services in the kernel SHOULD NOT be disabled via kernel cmdline, i.e. {{ic|noefi}} kernel parameter SHOULD NOT be used.
 
# {{ic|efivarfs}} filesystem should be mounted at {{ic|/sys/firmware/efi/efivars}}, otherwise follow [[#Mount efivarfs]] section below.
 
# {{ic|efivarfs}} filesystem should be mounted at {{ic|/sys/firmware/efi/efivars}}, otherwise follow [[#Mount efivarfs]] section below.
# {{ic|efivar}} should list (option {{ic|-l}}) the EFI Variables without any error.
+
# {{ic|efivar}} should list (option {{ic|-l}}/{{ic|--list}}) the UEFI variables without any error.
  
If EFI Variables support does not work even after the above conditions are satisfied, try the below workarounds:
+
If UEFI Variables support does not work even after the above conditions are satisfied, try the below workarounds:
  
# If any userspace tool is unable to modify efi variables data, check for existence of {{ic|/sys/firmware/efi/efivars/dump-*}} files. If they exist, delete them, reboot and retry again.
+
# If any userspace tool is unable to modify UEFI variable data, check for existence of {{ic|/sys/firmware/efi/efivars/dump-*}} files. If they exist, delete them, reboot and retry again.
# If the above step does not fix the issue, try booting with {{ic|efi_no_storage_paranoia}} kernel parameter to disable kernel efi variable storage space check that may prevent writing/modification of efi variables.
+
# If the above step does not fix the issue, try booting with {{ic|efi_no_storage_paranoia}} kernel parameter to disable kernel UEFI variable storage space check that may prevent writing/modification of UEFI variables.
  
{{Note|{{ic|efi_no_storage_paranoia}} should only be used when needed and should not be left as a normal boot option. The effect of this kernel command line parameter turns off a safeguard that was put in place to help avoid the bricking of machines when the NVRAM gets too full.}}
+
{{Warning|{{ic|efi_no_storage_paranoia}} should only be used when needed and should not be left as a normal boot option. The effect of this kernel command line parameter turns off a safeguard that was put in place to help avoid the bricking of machines when the NVRAM gets too full. See {{Bug|34641}} for more information.}}
  
 
==== Mount efivarfs ====
 
==== Mount efivarfs ====
  
{{Warning|1=''efivars'' is mounted writeable by default [https://github.com/systemd/systemd/issues/2402], which may cause permanent damage to the system. [https://bbs.archlinux.org/viewtopic.php?id=207549]{{Dead link|2016|08|21}} As such, consider mounting ''efivars'' read-only ({{ic|-o ro}}) as described below. Note that when it is mounted read-only, tools such as ''efibootmgr'' and bootloaders will not be able to change boot settings, nor will commands like {{ic|systemctl reboot --firmware-setup}} work.}}
+
If {{ic|efivarfs}} is not automatically mounted at {{ic|/sys/firmware/efi/efivars}} by [[systemd]] during boot, then you need to manually mount it to expose UEFI variables to [[#Userspace tools|userspace tools]] like ''efibootmgr'':
 
 
If {{ic|efivarfs}} is not automatically mounted at {{ic|/sys/firmware/efi/efivars}} by [[systemd]] during boot, then you need to manually mount it to expose UEFI variables to [[#Userspace tools]] like {{ic|efibootmgr}}:
 
  
 
  # mount -t efivarfs efivarfs /sys/firmware/efi/efivars
 
  # mount -t efivarfs efivarfs /sys/firmware/efi/efivars
Line 112: Line 128:
 
{{Note|The above command should be run both '''outside''' ('''before''') and '''inside''' the [[chroot]], if any.}}
 
{{Note|The above command should be run both '''outside''' ('''before''') and '''inside''' the [[chroot]], if any.}}
  
To mount {{ic|efivarfs}} read-only during boot, add to {{ic|/etc/fstab}}:
+
See [https://www.kernel.org/doc/Documentation/filesystems/efivarfs.txt efivarfs.txt] for kernel documentation.
 
 
{{hc|/etc/fstab|2=
 
efivarfs    /sys/firmware/efi/efivars    efivarfs   '''ro''',nosuid,nodev,noexec,noatime 0 0
 
}}
 
 
 
To remount with write support, run:
 
 
 
# mount -o remount /sys/firmware/efi/efivars -o '''rw''',nosuid,nodev,noexec,noatime
 
  
 
=== Userspace tools ===
 
=== Userspace tools ===
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There are few tools that can access/modify the UEFI variables, namely
 
There are few tools that can access/modify the UEFI variables, namely
  
* {{App|efivar|Library and Tool to manipulate UEFI Variables (used by efibootmgr)|https://github.com/vathpela/efivar|{{Pkg|efivar}}, {{AUR|efivar-git}}}}
+
* {{App|efivar|Library and Tool to manipulate UEFI variables (used by efibootmgr)|https://github.com/rhboot/efivar|{{Pkg|efivar}}, {{AUR|efivar-git}}}}
* {{App|efibootmgr|Tool to manipulate UEFI Firmware Boot Manager Settings|https://github.com/vathpela/efibootmgr|{{Pkg|efibootmgr}}, {{AUR|efibootmgr-git}}{{Broken package link|package not found}}}}
+
* {{App|efibootmgr|Tool to manipulate UEFI Firmware Boot Manager Settings|https://github.com/rhboot/efibootmgr|{{Pkg|efibootmgr}}}}
* {{App|uefivars|Dumps list of EFI variables with some additional PCI related info (uses efibootmgr code internally)|https://github.com/fpmurphy/Various/tree/master/uefivars-2.0|{{AUR|uefivars-git}}}}
+
* {{App|uefivars|Dumps list of UEFI variables with some additional PCI related info (uses efibootmgr code internally)|https://github.com/fpmurphy/Various/tree/master/uefivars-2.0|{{AUR|uefivars-git}}}}
* {{App|efitools|Tools for manipulating UEFI secure boot platforms|http://git.kernel.org/cgit/linux/kernel/git/jejb/efitools.git|{{Pkg|efitools}}, {{AUR|efitools-git}}}}
+
* {{App|efitools|Tools for manipulating UEFI secure boot platforms|https://git.kernel.org/pub/scm/linux/kernel/git/jejb/efitools.git|{{Pkg|efitools}}}}
 
* {{App|Ubuntu's Firmware Test Suite|Test suite that performs sanity checks on Intel/AMD PC firmware|https://wiki.ubuntu.com/FirmwareTestSuite/|{{AUR|fwts-git}}}}
 
* {{App|Ubuntu's Firmware Test Suite|Test suite that performs sanity checks on Intel/AMD PC firmware|https://wiki.ubuntu.com/FirmwareTestSuite/|{{AUR|fwts-git}}}}
  
 
==== efibootmgr ====
 
==== efibootmgr ====
 +
 +
You will have to [[install]] the {{Pkg|efibootmgr}} package.
  
 
{{Note|
 
{{Note|
 
* If ''efibootmgr'' does not work on your system, you can reboot into [[#UEFI Shell]] and use {{ic|bcfg}} to create a boot entry for the bootloader.
 
* If ''efibootmgr'' does not work on your system, you can reboot into [[#UEFI Shell]] and use {{ic|bcfg}} to create a boot entry for the bootloader.
* If you are unable to use {{ic|efibootmgr}}, some UEFI firmwares allow users to directly manage uefi boot entries from within its boot-time interface.  For example, some ASUS firmwares have an "Add New Boot Option" choice which enables you to select a local EFI System Partition and manually enter the EFI application location e.g. {{ic|\EFI\refind\refind_x64.efi}}.
+
* If you are unable to use {{ic|efibootmgr}}, some UEFI firmwares allow users to directly manage UEFI boot entries from within its boot-time interface.  For example, some firmwares have an "Add New Boot Option" choice which enables you to select a local EFI system partition and manually enter the EFI application location e.g. {{ic|\EFI\refind\refind_x64.efi}}.
* The below commands use [[rEFInd]] boot-loader as example.
+
* The below commands use [[rEFInd]] boot manager as example.
 
}}
 
}}
  
 
To add a new boot option using ''efibootmgr'' you need to know three things:
 
To add a new boot option using ''efibootmgr'' you need to know three things:
  
# The disk containing the ESP: {{ic|/dev/sd''X''}}
+
# The disk containing the [[EFI system partition]] (ESP). E.g.: {{ic|/dev/sda}}, {{ic|/dev/nvme0n1}}.
# The partition number of the ESP on that disk: the {{ic|''Y''}} in {{ic|/dev/sdX''Y''}}
+
# The partition number of the ESP on that disk. The {{ic|''Y''}} in {{ic|/dev/sda''Y''}} or {{ic|/dev/nvme0n1p''Y''}}.
# The path to the UEFI application (relative to the root of the ESP)
+
# The path to the EFI application (relative to the root of the ESP)
  
For example, if you want to add a boot option for {{ic|/boot/efi/EFI/refind/refind_x64.efi}} where {{ic|/boot/efi}} is the mount point of the ESP, run
+
For example, if you want to add a boot option for {{ic|/efi/EFI/refind/refind_x64.efi}} where {{ic|/efi}} is the mount point of the ESP, run
  
{{hc|$ findmnt /boot/efi|2=
+
{{hc|$ findmnt /efi|2=
TARGET    SOURCE    FSTYPE OPTIONS
+
TARGET SOURCE   FSTYPE OPTIONS
/boot/efi /dev/sda1 vfat  rw,flush,tz=UTC
+
/efi   /dev/sda1 vfat  rw,flush,tz=UTC
 
}}
 
}}
  
In this example, this indicates that the ESP is on disk {{ic|/dev/sda}} and has partition number 1. The path to the UEFI application relative to the root of the ESP is {{ic|/EFI/refind/refind_x64.efi}}. So you would create the boot entry as follows:
+
In this example, this indicates that the ESP is on disk {{ic|/dev/sda}} and has partition number 1. The path to the EFI application relative to the root of the ESP is {{ic|/EFI/refind/refind_x64.efi}}. So you would create the boot entry as follows:
 +
 
 +
# efibootmgr --create --disk /dev/sda --part 1 --loader /EFI/refind/refind_x64.efi --label "rEFInd Boot Manager" --verbose
  
# efibootmgr --create --disk /dev/sda --part 1 --loader /EFI/refind/refind_x64.efi --label "rEFInd Boot Manager"
+
{{Accuracy|{{ic|/dev/nvme0n1p1}} is a partition not a disk, the partition number should be specified using the {{ic|--part}} option.}}
  
See {{man|8|efibootmgr|url=}} or [https://raw.githubusercontent.com/rhinstaller/efibootmgr/master/README efibootmgr README] for more info.
+
# efibootmgr --create --disk /dev/nvme0n1p1 --loader /EFI/refind/refind_x64.efi --label "rEFINd Boot Manager" --verbose
  
{{Note|1=UEFI uses backward slash {{ic|\}} as path separator but ''efibootmgr'' automatically converts UNIX-style {{ic|/}} path separators.}}
+
See {{man|8|efibootmgr}} or [https://raw.githubusercontent.com/rhinstaller/efibootmgr/master/README efibootmgr README] for more info.
 +
 
 +
{{Note|UEFI uses backward slash {{ic|\}} as path separator but ''efibootmgr'' automatically converts UNIX-style {{ic|/}} path separators.}}
  
 
== UEFI Shell ==
 
== UEFI Shell ==
  
The UEFI Shell is a shell/terminal for the firmware which allows launching uefi applications which include uefi bootloaders. Apart from that, the shell can also be used to obtain various other information about the system or the firmware like memory map (memmap), modifying boot manager variables (bcfg), running partitioning programs (diskpart), loading uefi drivers, editing text files (edit), hexedit etc.
+
The UEFI Shell is a shell/terminal for the firmware which allows launching EFI applications which include UEFI bootloaders. Apart from that, the shell can also be used to obtain various other information about the system or the firmware like memory map (memmap), modifying boot manager variables (bcfg), running partitioning programs (diskpart), loading UEFI drivers, editing text files (edit), hexedit etc.
  
 
=== Obtaining UEFI Shell ===
 
=== Obtaining UEFI Shell ===
  
You can download a BSD licensed UEFI Shell from Intel's Tianocore UDK/EDK2 Sourceforge.net project:
+
You can download a BSD licensed UEFI Shell from Intel's TianoCore UDK/EDK2 project:
* [[AUR]] package {{AUR|uefi-shell-git}} (recommended) - provides x86_64 Shell in x86_64 system and IA32 Shell in i686 system - compiled directly from latest Tianocore EDK2 SVN source
+
 
 +
* [[AUR]] package {{AUR|uefi-shell-git}} (recommended) - provides x86_64 Shell for x86_64 (64-bit) UEFI and IA32 Shell for IA32 (32-bit) UEFI - compiled directly from latest TianoCore EDK2 source.
 
* There are copies of Shell v1 and Shell v2 in the EFI directory on the Arch install media image.
 
* There are copies of Shell v1 and Shell v2 in the EFI directory on the Arch install media image.
* [https://github.com/tianocore/edk2/tree/master/ShellBinPkg Precompiled UEFI Shell v2 binaries] (may not be up-to-date)
+
* [https://github.com/tianocore/edk2/releases/latest/download/ShellBinPkg.zip Precompiled UEFI Shell v2 binaries] (the binary package was moved from its original location in the source tree to the GitHub release assets, as laid out [https://lists.01.org/pipermail/edk2-devel/2019-April/thread.html#38524 here]).
* [https://github.com/tianocore/edk2/tree/master/EdkShellBinPkg Precompiled UEFI Shell v1 binaries] (not updated anymore upstream)
+
* [https://github.com/tianocore/edk2/tree/UDK2018/EdkShellBinPkg Precompiled UEFI Shell v1 binaries] (not updated anymore upstream as of Jan 10, 2014).
* [http://dl.dropbox.com/u/17629062/Shell2.zip Precompiled UEFI Shell v2 binary with bcfg modified to work with UEFI pre-2.3 firmware] - from Clover EFI bootloader
+
* [https://drive.google.com/uc?export=download&id=1OBXYj6MEs7VAZbYnjD9FxOYcZYIQoq36 Precompiled UEFI Shell v2 binary with bcfg modified to work with UEFI pre-2.3 firmware] - from Clover EFI bootloader.
  
Shell v2 works best in UEFI 2.3+ systems and is recommended over Shell v1 in those systems. Shell v1 should work in all UEFI systems irrespective of the spec. version the firmware follows. More info at [http://sourceforge.net/apps/mediawiki/tianocore/index.php?title=ShellPkg ShellPkg] and [http://sourceforge.net/mailarchive/message.php?msg_id=28690732 this mail]{{Dead link|2016|08|21}}
+
Shell v2 works best in UEFI 2.3+ systems and is recommended over Shell v1 in those systems. Shell v1 should work in all UEFI systems irrespective of the spec. version the firmware follows. More info at [https://github.com/tianocore/tianocore.github.io/wiki/ShellPkg ShellPkg] and [https://edk2-devel.narkive.com/zCN4CEnb/inclusion-of-uefi-shell-in-linux-distro-iso this mail].
  
 
=== Launching UEFI Shell ===
 
=== Launching UEFI Shell ===
  
Few Asus and other AMI Aptio x86_64 UEFI firmware based motherboards (from Sandy Bridge onwards) provide an option called {{ic|"Launch EFI Shell from filesystem device"}} . For those motherboards, download the x86_64 UEFI Shell and copy it to your EFI System Partition as {{ic|<EFI_SYSTEM_PARTITION>/shellx64.efi}} (mostly {{ic|/boot/efi/shellx64.efi}}) .
+
Few Asus and other AMI Aptio x86_64 UEFI firmware based motherboards (from Sandy Bridge onwards) provide an option called {{ic|"Launch EFI Shell from filesystem device"}} . For those motherboards, download the x86_64 UEFI Shell and copy it to your EFI system partition as {{ic|<EFI_SYSTEM_PARTITION>/shellx64.efi}}.
  
 
Systems with Phoenix SecureCore Tiano UEFI firmware are known to have embedded UEFI Shell which can be launched using either {{ic|F6}}, {{ic|F11}} or {{ic|F12}} key.
 
Systems with Phoenix SecureCore Tiano UEFI firmware are known to have embedded UEFI Shell which can be launched using either {{ic|F6}}, {{ic|F11}} or {{ic|F12}} key.
  
{{Note|If you are unable to launch UEFI Shell from the firmware directly using any of the above mentioned methods, create a FAT32 USB pen drive with {{ic|Shell.efi}} copied as {{ic|(USB)/efi/boot/bootx64.efi}}. This USB should come up in the firmware boot menu. Launching this option will launch the UEFI Shell for you.}}
+
{{Note|If you are unable to launch UEFI Shell from the firmware directly using any of the above mentioned methods, create a [[FAT32]] USB pen drive with {{ic|Shell.efi}} copied as {{ic|(USB)/EFI/BOOT/BOOTx64.EFI}}. This USB should come up in the firmware boot menu. Launching this option will launch the UEFI Shell for you.}}
  
=== Important UEFI Shell Commands ===
+
=== Important UEFI Shell commands ===
  
UEFI Shell commands usually support {{ic|-b}} option which makes output pause after each page. Run {{ic|help -b}} to list available commands.
+
UEFI Shell commands usually support {{ic|-b}} option which makes output pause after each page. Run {{ic|help -b}} to list available internal commands. Available commands are either built into the shell or discrete EFI applications.
  
More info at http://software.intel.com/en-us/articles/efi-shells-and-scripting/
+
For more info see [https://software.intel.com/en-us/articles/efi-shells-and-scripting/ Intel Scripting Guide 2008] and [https://software.intel.com/en-us/articles/uefi-shell Intel "Course" 2011].
  
 
==== bcfg ====
 
==== bcfg ====
  
{{ic|bcfg}} modifies the UEFI NVRAM entries which allows the user to change the boot entries or driver options. This command is described in detail in page 83 (Section 5.3) of the [http://www.uefi.org/sites/default/files/resources/UEFI_Shell_Spec_2_0.pdf UEFI Shell Specification 2.0] document.
+
{{ic|bcfg}} modifies the UEFI NVRAM entries which allows the user to change the boot entries or driver options. This command is described in detail in page 96 (Section 5.3) of the [https://uefi.org/sites/default/files/resources/UEFI_Shell_2_2.pdf UEFI Shell Specification 2.2] document.
  
 
{{Note|
 
{{Note|
Line 205: Line 220:
 
To add a boot menu entry for rEFInd (for example) as 4th (numbering starts from zero) option in the boot menu:
 
To add a boot menu entry for rEFInd (for example) as 4th (numbering starts from zero) option in the boot menu:
  
  Shell> bcfg boot add 3 fs0:\EFI\refind\refind_x64.efi "rEFInd"
+
  Shell> bcfg boot add 3 FS0:\EFI\refind\refind_x64.efi "rEFInd"
  
where {{ic|fs0:}} is the mapping corresponding to the EFI System Partition and {{ic|fs0:\EFI\refind\refind_x64.efi}} is the file to be launched.
+
where {{ic|FS0:}} is the mapping corresponding to the EFI system partition and {{ic|FS0:\EFI\refind\refind_x64.efi}} is the file to be launched.
  
 
To add an entry to boot directly into your system without a bootloader, configure a boot option using your kernel as an [[EFISTUB#UEFI_Shell|EFISTUB]]:
 
To add an entry to boot directly into your system without a bootloader, configure a boot option using your kernel as an [[EFISTUB#UEFI_Shell|EFISTUB]]:
Line 214: Line 229:
 
  Shell> bcfg boot -opt '''N''' "root='''/dev/sdX#''' initrd=\initramfs-linux.img"
 
  Shell> bcfg boot -opt '''N''' "root='''/dev/sdX#''' initrd=\initramfs-linux.img"
  
where {{ic|N}} is the priority, {{ic|V}} is the volume number of your EFI partition, and {{ic|/dev/sdX#}} is your root partition.
+
where {{ic|N}} is the priority, {{ic|V}} is the volume number of your EFI system partition, and {{ic|/dev/sdX#}} is your root partition.
  
 
To remove the 4th boot option:
 
To remove the 4th boot option:
Line 234: Line 249:
 
==== map ====
 
==== map ====
  
{{ic|map}} displays a list of device mappings i.e. the names of available file systems ({{ic|fs0}}) and storage devices ({{ic|blk0}}).
+
{{ic|map}} displays a list of device mappings i.e. the names of available file systems ({{ic|FS0}}) and storage devices ({{ic|blk0}}).
  
 
Before running file system commands such as {{ic|cd}} or {{ic|ls}}, you need to change the shell to the appropriate file system by typing its name:
 
Before running file system commands such as {{ic|cd}} or {{ic|ls}}, you need to change the shell to the appropriate file system by typing its name:
  
  Shell> fs0:
+
  Shell> FS0:
  fs0:\> cd EFI/
+
  FS0:\> cd EFI/
  
 
==== edit ====
 
==== edit ====
Line 245: Line 260:
 
{{ic|edit}} provides a basic text editor with an interface similar to nano, but slightly less functional. It handles UTF-8 encoding and takes care or LF vs CRLF line endings.
 
{{ic|edit}} provides a basic text editor with an interface similar to nano, but slightly less functional. It handles UTF-8 encoding and takes care or LF vs CRLF line endings.
  
For example, to edit rEFInd's {{ic|refind.conf}} in the EFI System Partition ({{ic|fs0:}} in the firmware),
+
For example, to edit rEFInd's {{ic|refind.conf}} in the EFI system partition ({{ic|FS0:}} in the firmware),
  
 
  Shell> edit FS0:\EFI\refind\refind.conf
 
  Shell> edit FS0:\EFI\refind\refind.conf
Line 251: Line 266:
 
Type {{ic|Ctrl-E}} for help.
 
Type {{ic|Ctrl-E}} for help.
  
== UEFI Linux Hardware Compatibility ==
+
== UEFI drivers ==
  
See [[Unified Extensible Firmware Interface/Hardware]] for more information.
+
{{Expansion|Explain what are and how to use UEFI drivers.}}
  
== UEFI Bootable Media ==
+
== UEFI bootable media ==
  
 
=== Create UEFI bootable USB from ISO ===
 
=== Create UEFI bootable USB from ISO ===
  
Follow [[USB flash installation media#BIOS and UEFI bootable USB]]
+
Follow [[USB flash installation media#BIOS and UEFI bootable USB]].
  
=== Remove UEFI boot support from Optical Media ===
+
=== Remove UEFI boot support from optical media ===
  
{{Note|This section mentions removing UEFI boot support from a '''CD/DVD only''' (Optical Media), not from a USB flash drive.}}
+
{{Note|
 +
* This section mentions removing UEFI boot support from a '''CD/DVD only''' (Optical Media booting via  EL Torito), not from a USB flash drive.
 +
* In order to hide the UEFI equipment on USB stick, use a partition editor after having copied the ISO to the flash drive. Remove the partition of type {{ic|EF}}. '''Do not''' accept offers to convert to GPT.
 +
}}
  
 
Most of the 32-bit EFI Macs and some 64-bit EFI Macs refuse to boot from a UEFI(X64)+BIOS bootable CD/DVD. If one wishes to proceed with the installation using optical media, it might be necessary to remove UEFI support first.
 
Most of the 32-bit EFI Macs and some 64-bit EFI Macs refuse to boot from a UEFI(X64)+BIOS bootable CD/DVD. If one wishes to proceed with the installation using optical media, it might be necessary to remove UEFI support first.
Line 271: Line 289:
 
  # mount -o loop ''input.iso'' /mnt/iso
 
  # mount -o loop ''input.iso'' /mnt/iso
  
* Then rebuild the ISO, excluding the UEFI Optical Media booting support, using {{ic|xorriso}} from {{pkg|libisoburn}}. Be sure to set the correct archisolabel, e.g. "ARCH_201411" or similar:
+
* Then rebuild the ISO, excluding the UEFI optical media booting support, using {{ic|xorriso}} from {{pkg|libisoburn}}. Be sure to set the correct archisolabel, e.g. "ARCH_201411" or similar:
 +
 
 
{{bc|1=
 
{{bc|1=
 
$ xorriso -as mkisofs -iso-level 3 \
 
$ xorriso -as mkisofs -iso-level 3 \
Line 287: Line 306:
  
 
* Burn {{ic|''output.iso''}} to optical media and proceed with installation normally.
 
* Burn {{ic|''output.iso''}} to optical media and proceed with installation normally.
 +
 +
=== Booting 64-bit kernel on 32-bit UEFI ===
 +
 +
Official ISO ([[Archiso]]) does not support booting on 32-bit (IA32) UEFI systems ({{Bug|53182}}) since it uses EFISTUB (via [[systemd-boot]] boot manager for menu) for booting the kernel in UEFI mode. To boot a 64-bit kernel with 32-bit UEFI you have to use a boot loader that does not rely on EFI boot stub for launching kernels.
 +
 +
{{Tip|[[Archboot]] iso supports booting on 32-bit (IA32) UEFI systems.}}
 +
 +
==== Using GRUB ====
 +
 +
This section describes how to setup [[GRUB]] as the USB's UEFI bootloader.
 +
 +
* [[USB flash installation media#Using_manual_formatting|Create an editable USB Flash Installation]]. Since we are going to use GRUB, you only need to follow the steps up until the {{ic|syslinux}} part
 +
 +
* [[GRUB/Tips and tricks#GRUB standalone|Create a GRUB standalone image]] for 32-bit UEFI systems:
 +
 +
# echo 'configfile ${cmdpath}/grub.cfg' > /tmp/grub.cfg
 +
# grub-mkstandalone -d /usr/lib/grub/i386-efi -O i386-efi --modules="part_gpt part_msdos" --locales="en@quot" --themes="" -o "''/mnt/usb/''EFI/boot/bootia32.efi" "boot/grub/grub.cfg=/tmp/grub.cfg" -v
 +
 +
* Create {{ic|''/mnt/usb''/EFI/boot/grub.cfg}} with the following contents (replace {{ic|ARCH_YYYYMM}} with the required archiso label e.g. {{ic|ARCH_201507}}):
 +
 +
{{Tip|
 +
* The archiso label can be aquired from the ''.iso'' file with {{ic|isoinfo}} from {{Pkg|cdrtools}} or {{ic|iso-info}} from {{Pkg|libcdio}}.
 +
* The given configuration entries can also be entered inside a [[GRUB#Using_the_command_shell|GRUB command-shell]].
 +
}}
 +
 +
For the official ISO:
 +
 +
{{hc|''/mnt/usb''/EFI/boot/grub.cfg|2=
 +
insmod part_gpt
 +
insmod part_msdos
 +
insmod fat
 +
 +
insmod efi_gop
 +
insmod efi_uga
 +
insmod video_bochs
 +
insmod video_cirrus
 +
 +
insmod font
 +
 +
if loadfont "${prefix}/fonts/unicode.pf2" ; then
 +
    insmod gfxterm
 +
    set gfxmode="1024x768x32;auto"
 +
    terminal_input console
 +
    terminal_output gfxterm
 +
fi
 +
 +
menuentry "Arch Linux archiso x86_64 UEFI USB" {
 +
    set gfxpayload=keep
 +
    search --no-floppy --set=root --label ''ARCH_YYYYMM''
 +
    linux /arch/boot/x86_64/vmlinuz archisobasedir=arch archisolabel=''ARCH_YYYYMM'' add_efi_memmap
 +
    initrd /arch/boot/intel_ucode.img /arch/boot/x86_64/archiso.img
 +
}
 +
}}
 +
 +
Durring installation, in the [[Installation guide#Boot loader|boot loader installation step]], [[GRUB#Installation_2|install GRUB]] using the option {{ic|1=--target=i386-efi}}.
  
 
== Testing UEFI in systems without native support ==
 
== Testing UEFI in systems without native support ==
  
=== OVMF for Virtual Machines ===
+
=== OVMF for virtual machines ===
  
[https://tianocore.github.io/ovmf/ OVMF] is a tianocore project to enable UEFI support for Virtual Machines. OVMF contains a sample UEFI firmware and a separate non-volatile variable store for QEMU.
+
[https://tianocore.github.io/ovmf/ OVMF] is a TianoCore project to enable UEFI support for Virtual Machines. OVMF contains a sample UEFI firmware and a separate non-volatile variable store for QEMU.
  
 
You can install {{pkg|ovmf}} from the extra repository.
 
You can install {{pkg|ovmf}} from the extra repository.
  
It is [http://www.linux-kvm.org/downloads/lersek/ovmf-whitepaper-c770f8c.txt advised] to make a local copy of the non-volatile variable store for your virtual machine:
+
It is [https://www.linux-kvm.org/downloads/lersek/ovmf-whitepaper-c770f8c.txt advised] to make a local copy of the non-volatile variable store for your virtual machine:
  
  $ cp /usr/share/ovmf/ovmf_vars_x64.bin my_uefi_vars.bin
+
  $ cp /usr/share/ovmf/x64/OVMF_VARS.fd my_uefi_vars.bin
  
 
To use the OVMF firmware and this variable store, add following to your QEMU command:
 
To use the OVMF firmware and this variable store, add following to your QEMU command:
  
  -drive if=pflash,format=raw,readonly,file=/usr/share/ovmf/ovmf_code_x64.bin \
+
  -drive if=pflash,format=raw,readonly,file=/usr/share/ovmf/x64/OVMF_CODE.fd \
 
  -drive if=pflash,format=raw,file=my_uefi_vars.bin
 
  -drive if=pflash,format=raw,file=my_uefi_vars.bin
  
 
For example:
 
For example:
  
  $ qemu-system-x86_64 -enable-kvm -m 1G -drive if=pflash,format=raw,readonly,file=/usr/share/ovmf/ovmf_code_x64.bin -drive if=pflash,format=raw,file=efi_vars.bin …
+
  $ qemu-system-x86_64 -enable-kvm -m 1G -drive if=pflash,format=raw,readonly,file=/usr/share/ovmf/x64/OVMF_CODE.fd -drive if=pflash,format=raw,file=my_uefi_vars.bin …
  
 
=== DUET for BIOS only systems ===
 
=== DUET for BIOS only systems ===
  
DUET is a tianocore project that enables chainloading a full UEFI environment from a BIOS system, in a way similar to BIOS OS booting. This method is being discussed extensively in http://www.insanelymac.com/forum/topic/186440-linux-and-windows-uefi-boot-using-tianocore-duet-firmware/. Pre-build DUET images can be downloaded from one of the repos at https://gitorious.org/tianocore_uefi_duet_builds {{Dead link|2016|08|21}}. Specific instructions for setting up DUET is available at https://gitorious.org/tianocore_uefi_duet_builds/tianocore_uefi_duet_installer/blobs/raw/master/Migle_BootDuet_INSTALL.txt {{Dead link|2016|08|21}}.
+
DUET was a TianoCore project that enabled chainloading a full UEFI environment from a BIOS system, in a way similar to BIOS OS booting. This method is being discussed extensively in https://www.insanelymac.com/forum/topic/186440-linux-and-windows-uefi-boot-using-tianocore-duet-firmware/. Pre-build DUET images can be downloaded from one of the repos at https://gitlab.com/tianocore_uefi_duet_builds/tianocore_uefi_duet_installer. Specific instructions for setting up DUET is available at https://gitlab.com/tianocore_uefi_duet_builds/tianocore_uefi_duet_installer/blob/master/Migle_BootDuet_INSTALL.txt . However, as of November 2018, the DUET code has been removed from TianoCore git repository.
  
You can also try http://sourceforge.net/projects/cloverefiboot/ which provides modified DUET images that may contain some system specific fixes and is more frequently updated compared to the gitorious repos.
+
You can also try https://sourceforge.net/projects/cloverefiboot/ which provides modified DUET images that may contain some system specific fixes and is more frequently updated compared to the gitlab repos.
  
 
== Troubleshooting ==
 
== Troubleshooting ==
  
=== Windows 7 will not boot in UEFI Mode ===
+
=== Windows 7 will not boot in UEFI mode ===
 +
 
 +
{{Note|Windows 7 can boot in pure UEFI class 3 without CSM support, though installation requires CSM ([https://support.microsoft.com/en-us/kb/2828074 specifically INT 10 H]).}}
  
 
If you have installed Windows to a different hard disk with GPT partitioning and still have a MBR partitioned hard disk in your computer, then it is possible that the firmware (UEFI) is starting its CSM support (for booting MBR partitions) and therefore Windows will not boot. To solve this merge your MBR hard disk to GPT partitioning or disable the SATA port where the MBR hard disk is plugged in or unplug the SATA connector from this hard disk.
 
If you have installed Windows to a different hard disk with GPT partitioning and still have a MBR partitioned hard disk in your computer, then it is possible that the firmware (UEFI) is starting its CSM support (for booting MBR partitions) and therefore Windows will not boot. To solve this merge your MBR hard disk to GPT partitioning or disable the SATA port where the MBR hard disk is plugged in or unplug the SATA connector from this hard disk.
Line 328: Line 404:
 
=== Windows changes boot order ===
 
=== Windows changes boot order ===
  
If you [[dual boot with Windows]] and your motherboard just boots Windows immediately instead of your chosen UEFI application, there are several possible causes and workarounds.
+
If you [[dual boot with Windows]] and your motherboard just boots Windows immediately instead of your chosen EFI application, there are several possible causes and workarounds.
  
 
* Ensure [[Dual boot with Windows#Fast_Start-Up|Fast Startup]] is disabled in your Windows power options
 
* Ensure [[Dual boot with Windows#Fast_Start-Up|Fast Startup]] is disabled in your Windows power options
 
* Ensure [[Secure Boot]] is disabled in your BIOS (if you are not using a signed boot loader)
 
* Ensure [[Secure Boot]] is disabled in your BIOS (if you are not using a signed boot loader)
 
* Ensure your UEFI boot order does not have Windows Boot Manager set first e.g. using [[#efibootmgr]] and what you see in the configuration tool of the UEFI. Some motherboards override by default any settings set with efibootmgr by Windows if it detects it. This is confirmed in a Packard Bell laptop.
 
* Ensure your UEFI boot order does not have Windows Boot Manager set first e.g. using [[#efibootmgr]] and what you see in the configuration tool of the UEFI. Some motherboards override by default any settings set with efibootmgr by Windows if it detects it. This is confirmed in a Packard Bell laptop.
* If your motherboard is booting the default UEFI path ({{ic|\EFI\BOOT\BOOTX64.EFI}}), this file may have been overwritten with the Windows boot loader. Try setting the correct boot path e.g. using [[#efibootmgr]].
+
* If your motherboard is booting the default boot path ({{ic|\EFI\BOOT\BOOTX64.EFI}}), this file may have been overwritten with the Windows boot loader. Try setting the correct boot path e.g. using [[#efibootmgr]].
* If the previous steps do not work, you can tell the Windows boot loader to run a different UEFI application. From a Windows Administrator command prompt: {{bc|# bcdedit /set "{bootmgr}" path "\EFI\''path''\''to''\''app.efi''"}}
+
* If the previous steps do not work, you can tell the Windows boot loader to run a different EFI application. From a Windows Administrator command prompt: {{bc|# bcdedit /set "{bootmgr}" path "\EFI\''path''\''to''\''app.efi''"}}
 
* Alternatively, you can set a startup script in Windows that ensures that the boot order is set correctly every time you boot Windows.
 
* Alternatively, you can set a startup script in Windows that ensures that the boot order is set correctly every time you boot Windows.
 
*# Open a command prompt with admin privlages. Run {{ic|bcdedit /enum firmware}} and find your desired boot entry.
 
*# Open a command prompt with admin privlages. Run {{ic|bcdedit /enum firmware}} and find your desired boot entry.
Line 346: Line 422:
 
This issue can occur due to [[KMS]] issue. Try [[Kernel mode setting#Disabling_modesetting|Disabling KMS]] while booting the USB.
 
This issue can occur due to [[KMS]] issue. Try [[Kernel mode setting#Disabling_modesetting|Disabling KMS]] while booting the USB.
  
=== Booting 64-bit kernel on 32-bit UEFI ===
+
=== UEFI boot loader does not show up in firmware menu ===
  
Both Official ISO ([[Archiso]]) and [[Archboot]] iso use EFISTUB (via [[systemd-boot]] Boot Manager for menu) for booting the kernel in UEFI mode. To boot 64-bit kernel with 32-bit UEFI you have to use [[GRUB]] as the USB's UEFI bootloader by following the below section.
+
On certain UEFI motherboards like some boards with an Intel Z77 chipset, adding entries with {{ic|efibootmgr}} or {{ic|bcfg}} from the UEFI Shell will not work because they do not show up on the boot menu list after being added to NVRAM.
  
==== Using GRUB ====
+
This issue is caused because the motherboards can only load Microsoft Windows. To solve this you have to place the ''.efi'' file in the location that Windows uses.
{{Tip|The given configuration entries can also be entered inside a [[GRUB#Using_the_command_shell|GRUB command-shell]].}}
 
  
* [[USB flash installation media#Using_manual_formatting|Create an editable USB Flash Installation]]. Since we are going to use GRUB, you only need to follow the steps up until the {{ic|syslinux}} part
+
Copy the {{ic|bootx64.efi}} file from the Arch Linux installation medium ({{ic|FSO:}}) to the Microsoft directory your [[ESP]] partition on your hard drive ({{ic|FS1:}}). Do this by booting into EFI shell and typing:
  
* Backup {{ic|EFI/boot/loader.efi}} to {{ic|EFI/boot/gummiboot.efi}}
+
Shell> mkdir FS1:\EFI\Microsoft
 +
Shell> mkdir FS1:\EFI\Microsoft\Boot
 +
Shell> cp FS0:\EFI\BOOT\bootx64.efi FS1:\EFI\Microsoft\Boot\bootmgfw.efi
  
* [[GRUB/Tips and tricks#GRUB standalone|Create a GRUB standalone image]] for i686 system and copy the generated {{ic|grub*.efi}} to the USB as {{ic|EFI/boot/loader.efi}} and/or {{ic|EFI/boot/bootia32.efi}}
+
After reboot, any entries added to NVRAM should show up in the boot menu.
  
* Create {{ic|EFI/boot/grub.cfg}} with the following contents (replace {{ic|ARCH_YYYYMM}} with the required archiso label e.g. {{ic|ARCH_201507}}):
+
=== System boots to EFI shell after hardware change or starting other operating system ===
  
{{hc|grub.cfg for Official ISO|<nowiki>
+
{{Style|Too GRUB-specific, most boot loader install commands have an option to install to the default/fallback boot path. Duplicates [[#Windows changes boot order]] and [[GRUB#Default/fallback boot path]].}}
insmod part_gpt
 
insmod part_msdos
 
insmod fat
 
  
insmod efi_gop
+
EFI stores state on the motherboard, called EFIVARS. Your bootloader (e.g. GRUB) may need to set up these variables in a certain way in order to boot. If your hardware configuration changes, or you boot into another operating system which overwrites these variables (Windows), you may be dumped into the EFI shell upon attempting to boot Arch Linux since the EFIVARS are incorrect and EFI can no longer find your bootloader.
insmod efi_uga
 
insmod video_bochs
 
insmod video_cirrus
 
  
insmod font
+
At this point, you can use the EFI shell to find and boot your bootloader manually. Usually something like:
  
if loadfont "${prefix}/fonts/unicode.pf2" ; then
+
Shell> ls fs0:
    insmod gfxterm
+
  EFI\
    set gfxmode="1024x768x32;auto"
+
  grub\
    terminal_input console
+
    terminal_output gfxterm
+
Shell> ls fs0:EFI\
fi
+
  GRUB\
 +
 +
Shell> ls fs0:EFI\GRUB\
 +
  grubx64.efi
 +
 +
Shell> fs0:EFI\GRUB\grubx64.efi
 +
  Starting fs0:EFI\GRUB\grubx64.efi...
  
menuentry "Arch Linux archiso x86_64" {
+
To prevent this happening again, you can install your bootloader to the default EFI boot location. In this setup, EFI will always find your bootloader on this drive since it is in the default location, which doesn't depend on the EFIVARS being correct. Your system should continue to boot even if another OS has changed the EFIVARS, or your hardware configuration has made the EFIVARS no longer correct for your system.
    set gfxpayload=keep
 
    search --no-floppy --set=root --label ARCH_YYYYMM
 
    linux /arch/boot/x86_64/vmlinuz archisobasedir=arch archisolabel=ARCH_YYYYMM add_efi_memmap
 
    initrd /arch/boot/x86_64/archiso.img
 
}
 
  
menuentry "UEFI Shell x86_64 v2" {
+
To do this with GRUB's {{ic|grub-install}}, use the {{ic|--removable}} flag. For example (update {{ic|/boot/}} to be the path to your EFI partition):
    search --no-floppy --set=root --label ARCH_YYYYMM
 
    chainloader /EFI/shellx64_v2.efi
 
}
 
  
menuentry "UEFI Shell x86_64 v1" {
+
# grub-install --target=x86_64-efi --efi-directory=/boot/ --bootloader-id=GRUB --removable
    search --no-floppy --set=root --label ARCH_YYYYMM
 
    chainloader /EFI/shellx64_v1.efi
 
}
 
</nowiki>}}
 
  
{{hc|grub.cfg for Archboot ISO|<nowiki>
+
=== Boot entries created with efibootmgr fail to show up in UEFI ===
insmod part_gpt
 
insmod part_msdos
 
insmod fat
 
 
 
insmod efi_gop
 
insmod efi_uga
 
insmod video_bochs
 
insmod video_cirrus
 
 
 
insmod font
 
 
 
if loadfont "${prefix}/fonts/unicode.pf2" ; then
 
    insmod gfxterm
 
    set gfxmode="1024x768x32;auto"
 
    terminal_input console
 
    terminal_output gfxterm
 
fi
 
 
 
menuentry "Arch Linux x86_64 Archboot" {
 
    set gfxpayload=keep
 
    search --no-floppy --set=root --file /boot/vmlinuz_x86_64
 
    linux /boot/vmlinuz_x86_64 cgroup_disable=memory loglevel=7 add_efi_memmap
 
    initrd /boot/initramfs_x86_64.img
 
}
 
 
 
menuentry "UEFI Shell x86_64 v2" {
 
    search --no-floppy --set=root --file /boot/vmlinuz_x86_64
 
    chainloader /EFI/tools/shellx64_v2.efi
 
}
 
  
menuentry "UEFI Shell x86_64 v1" {
+
''efibootmgr'' can fail to detect EDD 3.0 and as a result create unusable boot entries in NVRAM. See [https://github.com/rhboot/efibootmgr/issues/86 efibootmgr issue 86] for the details.
    search --no-floppy --set=root --file /boot/vmlinuz_x86_64
 
    chainloader /EFI/tools/shellx64_v1.efi
 
}
 
</nowiki>}}
 
  
=== UEFI boot loader does not show up in firmware menu ===
+
To work around this, when creating boot entries manually, add the {{ic|-e 3}} option to the ''efibootmgr'' command. E.g.
  
On certain UEFI motherboards like some boards with an Intel Z77 chipset, adding entries with {{ic|efibootmgr}} or {{ic|bcfg}} from the EFI Shell will not work because they do not show up on the boot menu list after being added to NVRAM.
+
# efibootmgr --create --disk /dev/sda --part 1 --loader /EFI/refind/refind_x64.efi --label "rEFInd Boot Manager" --verbose '''-e 3'''
  
This issue is caused because the motherboards can only load Microsoft Windows. To solve this you have to place the {{ic|.efi}} file in the location that Windows uses.
+
To fix boot loader installers, like {{ic|grub-install}} and {{ic|refind-install}}, create a wrapper script {{ic|/usr/local/bin/efibootmgr}} and make it [[executable]]:
  
Copy the {{ic|bootx64.efi}} file from the Arch Linux installation medium ({{ic|FSO:}}) to the Microsoft directory your [[ESP]] partition on your hard drive ({{ic|FS1:}}). Do this by booting into EFI shell and typing:
+
{{hc|/usr/local/bin/efibootmgr|
 +
#!/bin/sh
  
FS1:
+
exec /usr/bin/efibootmgr -e 3 "$@"
cd EFI
+
}}
mkdir Microsoft
 
cd Microsoft
 
mkdir Boot
 
cp FS0:\EFI\BOOT\bootx64.efi FS1:\EFI\Microsoft\Boot\bootmgfw.efi
 
 
 
After reboot, any entries added to NVRAM should show up in the boot menu.
 
  
 
== See also ==
 
== See also ==
  
 
* [[Wikipedia:UEFI]]
 
* [[Wikipedia:UEFI]]
* [http://www.uefi.org/home/ UEFI Forum] - contains the official [http://uefi.org/specifications UEFI Specifications] - GUID Partition Table is part of UEFI Specification
+
* [https://www.uefi.org/home/ UEFI Forum] - contains the official [https://uefi.org/specifications UEFI Specifications] - GUID Partition Table is part of UEFI Specification
 
* [https://www.happyassassin.net/2014/01/25/uefi-boot-how-does-that-actually-work-then/ UEFI boot: how does that actually work, then? - A blog post by AdamW]
 
* [https://www.happyassassin.net/2014/01/25/uefi-boot-how-does-that-actually-work-then/ UEFI boot: how does that actually work, then? - A blog post by AdamW]
* [https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/plain/Documentation/x86/x86_64/uefi.txt Linux Kernel x86_64 UEFI Documentation]
+
* [https://www.kernel.org/doc/Documentation/x86/x86_64/uefi.txt Linux Kernel x86_64 UEFI Documentation]
* [http://www.intel.com/technology/efi/ Intel's page on EFI]{{Dead link|2016|07|16}}
+
* [https://www.intel.com/content/www/us/en/architecture-and-technology/unified-extensible-firmware-interface/efi-homepage-general-technology.html Intel's page on EFI]
* [http://firmware.intel.com/ Intel Architecture Firmware Resource Center]
+
* [https://firmware.intel.com/ Intel Architecture Firmware Resource Center]
* [http://firmware.intel.com/blog/linux-efi-boot-stub Matt Fleming - The Linux EFI Boot Stub]
+
* [https://firmware.intel.com/blog/linux-efi-boot-stub Matt Fleming - The Linux EFI Boot Stub]
* [http://firmware.intel.com/blog/accessing-uefi-variables-linux Matt Fleming - Accessing UEFI Variables from Linux]
+
* [https://firmware.intel.com/blog/accessing-uefi-variables-linux Matt Fleming - Accessing UEFI Variables from Linux]
* [http://www.rodsbooks.com/linux-uefi/ Rod Smith - Linux on UEFI: A Quick Installation Guide]
+
* [https://www.rodsbooks.com/linux-uefi/ Rod Smith - Linux on UEFI: A Quick Installation Guide]
 
* [https://lkml.org/lkml/2011/6/8/322 UEFI Boot problems on some newer machines (LKML)]
 
* [https://lkml.org/lkml/2011/6/8/322 UEFI Boot problems on some newer machines (LKML)]
* [http://linuxplumbers.ubicast.tv/videos/plumbing-uefi-into-linux/ LPC 2012 Plumbing UEFI into Linux]
+
* [https://linuxplumbers.ubicast.tv/videos/plumbing-uefi-into-linux/ LPC 2012 Plumbing UEFI into Linux]
* [http://linuxplumbers.ubicast.tv/videos/uefi-tutorial-part-1/ LPC 2012 UEFI Tutorial : part 1]
+
* [https://linuxplumbers.ubicast.tv/videos/uefi-tutorial-part-1/ LPC 2012 UEFI Tutorial : part 1]
* [http://linuxplumbers.ubicast.tv/videos/uefi-tutorial-part-2/ LPC 2012 UEFI Tutorial : part 2]
+
* [https://linuxplumbers.ubicast.tv/videos/uefi-tutorial-part-2/ LPC 2012 UEFI Tutorial : part 2]
* [http://sourceforge.net/apps/mediawiki/tianocore/index.php?title=Welcome_to_TianoCore Intel's Tianocore Project] for Open-Source UEFI firmware which includes DuetPkg for direct BIOS based booting and OvmfPkg used in QEMU and Oracle VirtualBox
+
* [https://www.tianocore.org/ Intel's TianoCore Project] for Open-Source UEFI firmware which includes DuetPkg for direct BIOS based booting and OvmfPkg used in QEMU and Oracle VirtualBox
 
* [https://jdebp.eu/FGA/efi-boot-process.html FGA: The EFI boot process]
 
* [https://jdebp.eu/FGA/efi-boot-process.html FGA: The EFI boot process]
* [http://www.microsoft.com/whdc/device/storage/GPT_FAQ.mspx Microsoft's Windows and GPT FAQ]
+
* [https://docs.microsoft.com/en-us/windows-hardware/manufacture/desktop/windows-and-gpt-faq Microsoft's Windows and GPT FAQ]
* [https://gitorious.org/tianocore_uefi_duet_builds/pages/Windows_x64_BIOS_to_UEFI Convert Windows x64 from BIOS-MBR mode to UEFI-GPT mode without Reinstall]{{Dead link|2016|08|21}}
+
* [https://gitlab.com/tianocore_uefi_duet_builds/tianocore_uefi_duet_installer/wikis/Windows_x64_BIOS_to_UEFI Convert Windows x64 from BIOS-MBR mode to UEFI-GPT mode without Reinstall]
* [https://gitorious.org/tianocore_uefi_duet_builds/pages/Linux_Windows_BIOS_UEFI_boot_USB Create a Linux BIOS+UEFI and Windows x64 BIOS+UEFI bootable USB drive]{{Dead link|2016|08|21}}
+
* [https://gitlab.com/tianocore_uefi_duet_builds/tianocore_uefi_duet_installer/wikis/Linux_Windows_BIOS_UEFI_boot_USB Create a Linux BIOS+UEFI and Windows x64 BIOS+UEFI bootable USB drive]
* [http://rodsbooks.com/bios2uefi/ Rod Smith - A BIOS to UEFI Transformation]
+
* [https://rodsbooks.com/bios2uefi/ Rod Smith - A BIOS to UEFI Transformation]
* [http://software.intel.com/en-us/articles/efi-shells-and-scripting/ EFI Shells and Scripting - Intel Documentation]
+
* [https://software.intel.com/en-us/articles/efi-shells-and-scripting/ EFI Shells and Scripting - Intel Documentation]
* [http://software.intel.com/en-us/articles/uefi-shell/ UEFI Shell  - Intel Documentation]
+
* [https://software.intel.com/en-us/articles/uefi-shell/ UEFI Shell  - Intel Documentation]
* [http://www.hpuxtips.es/?q=node/293 UEFI Shell - bcfg command info]
+
* [https://web.archive.org/web/20130929114218/http://www.hpuxtips.es/?q=node/293 UEFI Shell - bcfg command info]

Latest revision as of 12:46, 22 November 2019

Warning: While the choice to install in UEFI mode is forward looking, early vendor UEFI implementations may carry more bugs than their BIOS counterparts. It is advised to do a search relating to your particular motherboard model before proceeding.

The Unified Extensible Firmware Interface (UEFI or EFI for short) is a new model for the interface between operating systems and firmware. It provides a standard environment for booting an operating system and running pre-boot applications.

It is distinct from the commonly used "MBR boot code" method followed for BIOS systems. See Arch boot process for their differences and the boot process using UEFI. To set up UEFI boot loaders, see Arch boot process#Boot loader.

UEFI versions

  • UEFI started as Intel's EFI in versions 1.x.
  • Later, a group of companies called the UEFI Forum took over its development, which renamed it as Unified EFI starting with version 2.0.
  • Unless specified as EFI 1.x, EFI and UEFI terms are used interchangeably to denote UEFI 2.x firmware.
  • Apple's EFI implementation is neither a EFI 1.x version nor UEFI 2.x version but mixes up both. This kind of firmware does not fall under any one (U)EFI specification and therefore is not a standard UEFI firmware. Unless stated explicitly, these instructions are general and some of them may not work or may be different in Apple Macs.

The latest UEFI specification can be found at https://uefi.org/specifications.

UEFI firmware bitness

Under UEFI, every program whether it is an OS loader or a utility (e.g. a memory testing app or recovery tool), should be a EFI application corresponding to the UEFI firmware bitness/architecture.

The vast majority of UEFI firmwares, including recent Apple Macs, use x86_64 UEFI firmware. The only known devices that use IA32 (32-bit) UEFI are older (pre 2008) Apple Macs, Intel Atom System-on-Chip systems (as on 2 November 2013)[1] and some older Intel server boards that are known to operate on Intel EFI 1.10 firmware.

An x86_64 UEFI firmware does not include support for launching 32-bit EFI applications (unlike x86_64 Linux and Windows versions which include such support). Therefore the EFI application must be compiled for that specific firmware processor bitness/architecture.

Note: The official ISO does not support booting on 32-bit (IA32) UEFI systems, see #Booting 64-bit kernel on 32-bit UEFI for available workarounds. The installed system will require using a boot loader that supports IA32 UEFI, for example, GRUB with the i386-efi target.

Checking the firmware bitness

The firmware bitness can be checked from a booted operating system.

From Linux

On distributions running Linux kernel 4.0 or newer, the UEFI firmware bitness can be found via the sysfs interface. Run:

$ cat /sys/firmware/efi/fw_platform_size

It will return 64 for a 64-bit (x86_64) UEFI or 32 for a 32-bit (IA32) UEFI. If the file does not exist, then you have not booted in UEFI mode.

From macOS

Pre-2008 Macs mostly have IA32 EFI firmware while >=2008 Macs have mostly x86_64 EFI. All Macs capable of running Mac OS X Snow Leopard 64-bit Kernel have x86_64 EFI 1.x firmware.

To find out the arch of the EFI firmware in a Mac, type the following into the Mac OS X terminal:

$ ioreg -l -p IODeviceTree | grep firmware-abi

If the command returns EFI32 then it is IA32 (32-bit) EFI firmware. If it returns EFI64 then it is x86_64 EFI firmware. Most of the Macs do not have UEFI 2.x firmware as Apple's EFI implementation is not fully compliant with UEFI 2.x specification.

From Microsoft Windows

64-bit versions of Windows do not support booting on a 32-bit UEFI. So, if you have a 32-bit version of Windows booted in UEFI mode, you have a 32-bit UEFI.

To check the bitness run msinfo32.exe. In the System Summary section look at the values of "System Type" and "BIOS mode".

For a 64-bit Windows on a 64-bit UEFI it will be System Type: x64-based PC and BIOS mode: UEFI, for a 32-bit Windows on a 32-bit UEFI - System Type: x86-based PC and BIOS mode: UEFI. If the "BIOS mode" is not UEFI, then Windows is not installed in UEFI mode.

Linux kernel config options for UEFI

The required Linux Kernel configuration options[2] for UEFI systems are:

CONFIG_RELOCATABLE=y
CONFIG_EFI=y
CONFIG_EFI_STUB=y
CONFIG_X86_SYSFB=y
CONFIG_FB_SIMPLE=y
CONFIG_FRAMEBUFFER_CONSOLE=y

UEFI Runtime Variables Support (efivarfs filesystem - /sys/firmware/efi/efivars). This option is important as this is required to manipulate UEFI runtime variables using tools like /usr/bin/efibootmgr. The below config option has been added in kernel 3.10 and above.

CONFIG_EFIVAR_FS=y

UEFI Runtime Variables Support (old efivars sysfs interface - /sys/firmware/efi/vars). This option should be disabled to prevent any potential issues with both efivarfs and sysfs-efivars enabled.

CONFIG_EFI_VARS=n

GUID Partition Table (GPT) config option - mandatory for UEFI support

CONFIG_EFI_PARTITION=y

EFI mixed-mode support - to boot a x64_64 kernel on a IA32 UEFI.

CONFIG_EFI_MIXED=y
Note: All of the above options are enabled in Arch Linux kernels in the official repositories.

UEFI variables

UEFI defines variables through which an operating system can interact with the firmware. UEFI boot variables are used by the boot loader and used by the OS only for early system start-up. UEFI runtime variables allow an OS to manage certain settings of the firmware like the UEFI boot manager or managing the keys for UEFI Secure Boot protocol etc. You can get the list using:

$ efivar --list

UEFI variables support in Linux kernel

Linux kernel exposes UEFI variables data to userspace via efivarfs (EFI VARiable FileSystem) interface (CONFIG_EFIVAR_FS) - mounted using efivarfs kernel module at /sys/firmware/efi/efivars - it has no maximum per-variable size limitation and supports UEFI Secure Boot variables. Introduced in kernel 3.8.

Requirements for UEFI variable support

  1. Kernel should be booted in UEFI mode via EFISTUB (optionally using a boot manager) or by a UEFI boot loader (using either the EFI handover protocol or the UEFI LoadImage function), not via BIOS or CSM, or Apple's Boot Camp which is also a CSM.
  2. EFI Runtime Services support should be present in the kernel (CONFIG_EFI=y, check if present with zgrep CONFIG_EFI /proc/config.gz).
  3. EFI Runtime Services in the kernel SHOULD NOT be disabled via kernel cmdline, i.e. noefi kernel parameter SHOULD NOT be used.
  4. efivarfs filesystem should be mounted at /sys/firmware/efi/efivars, otherwise follow #Mount efivarfs section below.
  5. efivar should list (option -l/--list) the UEFI variables without any error.

If UEFI Variables support does not work even after the above conditions are satisfied, try the below workarounds:

  1. If any userspace tool is unable to modify UEFI variable data, check for existence of /sys/firmware/efi/efivars/dump-* files. If they exist, delete them, reboot and retry again.
  2. If the above step does not fix the issue, try booting with efi_no_storage_paranoia kernel parameter to disable kernel UEFI variable storage space check that may prevent writing/modification of UEFI variables.
Warning: efi_no_storage_paranoia should only be used when needed and should not be left as a normal boot option. The effect of this kernel command line parameter turns off a safeguard that was put in place to help avoid the bricking of machines when the NVRAM gets too full. See FS#34641 for more information.

Mount efivarfs

If efivarfs is not automatically mounted at /sys/firmware/efi/efivars by systemd during boot, then you need to manually mount it to expose UEFI variables to userspace tools like efibootmgr:

# mount -t efivarfs efivarfs /sys/firmware/efi/efivars
Note: The above command should be run both outside (before) and inside the chroot, if any.

See efivarfs.txt for kernel documentation.

Userspace tools

There are few tools that can access/modify the UEFI variables, namely

  • efivar — Library and Tool to manipulate UEFI variables (used by efibootmgr)
https://github.com/rhboot/efivar || efivar, efivar-gitAUR
  • efibootmgr — Tool to manipulate UEFI Firmware Boot Manager Settings
https://github.com/rhboot/efibootmgr || efibootmgr
  • uefivars — Dumps list of UEFI variables with some additional PCI related info (uses efibootmgr code internally)
https://github.com/fpmurphy/Various/tree/master/uefivars-2.0 || uefivars-gitAUR
  • efitools — Tools for manipulating UEFI secure boot platforms
https://git.kernel.org/pub/scm/linux/kernel/git/jejb/efitools.git || efitools
  • Ubuntu's Firmware Test Suite — Test suite that performs sanity checks on Intel/AMD PC firmware
https://wiki.ubuntu.com/FirmwareTestSuite/ || fwts-gitAUR

efibootmgr

You will have to install the efibootmgr package.

Note:
  • If efibootmgr does not work on your system, you can reboot into #UEFI Shell and use bcfg to create a boot entry for the bootloader.
  • If you are unable to use efibootmgr, some UEFI firmwares allow users to directly manage UEFI boot entries from within its boot-time interface. For example, some firmwares have an "Add New Boot Option" choice which enables you to select a local EFI system partition and manually enter the EFI application location e.g. \EFI\refind\refind_x64.efi.
  • The below commands use rEFInd boot manager as example.

To add a new boot option using efibootmgr you need to know three things:

  1. The disk containing the EFI system partition (ESP). E.g.: /dev/sda, /dev/nvme0n1.
  2. The partition number of the ESP on that disk. The Y in /dev/sdaY or /dev/nvme0n1pY.
  3. The path to the EFI application (relative to the root of the ESP)

For example, if you want to add a boot option for /efi/EFI/refind/refind_x64.efi where /efi is the mount point of the ESP, run

$ findmnt /efi
TARGET SOURCE    FSTYPE OPTIONS
/efi   /dev/sda1 vfat   rw,flush,tz=UTC

In this example, this indicates that the ESP is on disk /dev/sda and has partition number 1. The path to the EFI application relative to the root of the ESP is /EFI/refind/refind_x64.efi. So you would create the boot entry as follows:

# efibootmgr --create --disk /dev/sda --part 1 --loader /EFI/refind/refind_x64.efi --label "rEFInd Boot Manager" --verbose

Tango-inaccurate.pngThe factual accuracy of this article or section is disputed.Tango-inaccurate.png

Reason: /dev/nvme0n1p1 is a partition not a disk, the partition number should be specified using the --part option. (Discuss in Talk:Unified Extensible Firmware Interface#)
# efibootmgr --create --disk /dev/nvme0n1p1 --loader /EFI/refind/refind_x64.efi --label "rEFINd Boot Manager" --verbose

See efibootmgr(8) or efibootmgr README for more info.

Note: UEFI uses backward slash \ as path separator but efibootmgr automatically converts UNIX-style / path separators.

UEFI Shell

The UEFI Shell is a shell/terminal for the firmware which allows launching EFI applications which include UEFI bootloaders. Apart from that, the shell can also be used to obtain various other information about the system or the firmware like memory map (memmap), modifying boot manager variables (bcfg), running partitioning programs (diskpart), loading UEFI drivers, editing text files (edit), hexedit etc.

Obtaining UEFI Shell

You can download a BSD licensed UEFI Shell from Intel's TianoCore UDK/EDK2 project:

Shell v2 works best in UEFI 2.3+ systems and is recommended over Shell v1 in those systems. Shell v1 should work in all UEFI systems irrespective of the spec. version the firmware follows. More info at ShellPkg and this mail.

Launching UEFI Shell

Few Asus and other AMI Aptio x86_64 UEFI firmware based motherboards (from Sandy Bridge onwards) provide an option called "Launch EFI Shell from filesystem device" . For those motherboards, download the x86_64 UEFI Shell and copy it to your EFI system partition as <EFI_SYSTEM_PARTITION>/shellx64.efi.

Systems with Phoenix SecureCore Tiano UEFI firmware are known to have embedded UEFI Shell which can be launched using either F6, F11 or F12 key.

Note: If you are unable to launch UEFI Shell from the firmware directly using any of the above mentioned methods, create a FAT32 USB pen drive with Shell.efi copied as (USB)/EFI/BOOT/BOOTx64.EFI. This USB should come up in the firmware boot menu. Launching this option will launch the UEFI Shell for you.

Important UEFI Shell commands

UEFI Shell commands usually support -b option which makes output pause after each page. Run help -b to list available internal commands. Available commands are either built into the shell or discrete EFI applications.

For more info see Intel Scripting Guide 2008 and Intel "Course" 2011.

bcfg

bcfg modifies the UEFI NVRAM entries which allows the user to change the boot entries or driver options. This command is described in detail in page 96 (Section 5.3) of the UEFI Shell Specification 2.2 document.

Note:
  • Try bcfg only if efibootmgr fails to create working boot entries on your system.
  • UEFI Shell v1 official binary does not support bcfg command. See #Obtaining UEFI Shell for a modified UEFI Shell v2 binary which may work in UEFI pre-2.3 firmwares.

To dump a list of current boot entries:

Shell> bcfg boot dump -v

To add a boot menu entry for rEFInd (for example) as 4th (numbering starts from zero) option in the boot menu:

Shell> bcfg boot add 3 FS0:\EFI\refind\refind_x64.efi "rEFInd"

where FS0: is the mapping corresponding to the EFI system partition and FS0:\EFI\refind\refind_x64.efi is the file to be launched.

To add an entry to boot directly into your system without a bootloader, configure a boot option using your kernel as an EFISTUB:

Shell> bcfg boot add N fsV:\vmlinuz-linux "Arch Linux"
Shell> bcfg boot -opt N "root=/dev/sdX# initrd=\initramfs-linux.img"

where N is the priority, V is the volume number of your EFI system partition, and /dev/sdX# is your root partition.

To remove the 4th boot option:

Shell> bcfg boot rm 3

To move the boot option #3 to #0 (i.e. 1st or the default entry in the UEFI Boot menu):

Shell> bcfg boot mv 3 0

For bcfg help text:

Shell> help bcfg -v -b

or:

Shell> bcfg -? -v -b

map

map displays a list of device mappings i.e. the names of available file systems (FS0) and storage devices (blk0).

Before running file system commands such as cd or ls, you need to change the shell to the appropriate file system by typing its name:

Shell> FS0:
FS0:\> cd EFI/

edit

edit provides a basic text editor with an interface similar to nano, but slightly less functional. It handles UTF-8 encoding and takes care or LF vs CRLF line endings.

For example, to edit rEFInd's refind.conf in the EFI system partition (FS0: in the firmware),

Shell> edit FS0:\EFI\refind\refind.conf

Type Ctrl-E for help.

UEFI drivers

Tango-view-fullscreen.pngThis article or section needs expansion.Tango-view-fullscreen.png

Reason: Explain what are and how to use UEFI drivers. (Discuss in Talk:Unified Extensible Firmware Interface#)

UEFI bootable media

Create UEFI bootable USB from ISO

Follow USB flash installation media#BIOS and UEFI bootable USB.

Remove UEFI boot support from optical media

Note:
  • This section mentions removing UEFI boot support from a CD/DVD only (Optical Media booting via EL Torito), not from a USB flash drive.
  • In order to hide the UEFI equipment on USB stick, use a partition editor after having copied the ISO to the flash drive. Remove the partition of type EF. Do not accept offers to convert to GPT.

Most of the 32-bit EFI Macs and some 64-bit EFI Macs refuse to boot from a UEFI(X64)+BIOS bootable CD/DVD. If one wishes to proceed with the installation using optical media, it might be necessary to remove UEFI support first.

  • Mount the official installation media and obtain the archisolabel as shown in the previous section.
# mount -o loop input.iso /mnt/iso
  • Then rebuild the ISO, excluding the UEFI optical media booting support, using xorriso from libisoburn. Be sure to set the correct archisolabel, e.g. "ARCH_201411" or similar:
$ xorriso -as mkisofs -iso-level 3 \
    -full-iso9660-filenames\
    -volid "archisolabel" \
    -appid "Arch Linux CD" \
    -publisher "Arch Linux <https://www.archlinux.org>" \
    -preparer "prepared by $USER" \
    -eltorito-boot isolinux/isolinux.bin \
    -eltorito-catalog isolinux/boot.cat \
    -no-emul-boot -boot-load-size 4 -boot-info-table \
    -isohybrid-mbr "/mnt/iso/isolinux/isohdpfx.bin" \
    -output output.iso /mnt/iso/
  • Burn output.iso to optical media and proceed with installation normally.

Booting 64-bit kernel on 32-bit UEFI

Official ISO (Archiso) does not support booting on 32-bit (IA32) UEFI systems (FS#53182) since it uses EFISTUB (via systemd-boot boot manager for menu) for booting the kernel in UEFI mode. To boot a 64-bit kernel with 32-bit UEFI you have to use a boot loader that does not rely on EFI boot stub for launching kernels.

Tip: Archboot iso supports booting on 32-bit (IA32) UEFI systems.

Using GRUB

This section describes how to setup GRUB as the USB's UEFI bootloader.

# echo 'configfile ${cmdpath}/grub.cfg' > /tmp/grub.cfg
# grub-mkstandalone -d /usr/lib/grub/i386-efi -O i386-efi --modules="part_gpt part_msdos" --locales="en@quot" --themes="" -o "/mnt/usb/EFI/boot/bootia32.efi" "boot/grub/grub.cfg=/tmp/grub.cfg" -v
  • Create /mnt/usb/EFI/boot/grub.cfg with the following contents (replace ARCH_YYYYMM with the required archiso label e.g. ARCH_201507):
Tip:
  • The archiso label can be aquired from the .iso file with isoinfo from cdrtools or iso-info from libcdio.
  • The given configuration entries can also be entered inside a GRUB command-shell.

For the official ISO:

/mnt/usb/EFI/boot/grub.cfg
insmod part_gpt
insmod part_msdos
insmod fat

insmod efi_gop
insmod efi_uga
insmod video_bochs
insmod video_cirrus

insmod font

if loadfont "${prefix}/fonts/unicode.pf2" ; then
    insmod gfxterm
    set gfxmode="1024x768x32;auto"
    terminal_input console
    terminal_output gfxterm
fi

menuentry "Arch Linux archiso x86_64 UEFI USB" {
    set gfxpayload=keep
    search --no-floppy --set=root --label ARCH_YYYYMM
    linux /arch/boot/x86_64/vmlinuz archisobasedir=arch archisolabel=ARCH_YYYYMM add_efi_memmap
    initrd /arch/boot/intel_ucode.img /arch/boot/x86_64/archiso.img
}

Durring installation, in the boot loader installation step, install GRUB using the option --target=i386-efi.

Testing UEFI in systems without native support

OVMF for virtual machines

OVMF is a TianoCore project to enable UEFI support for Virtual Machines. OVMF contains a sample UEFI firmware and a separate non-volatile variable store for QEMU.

You can install ovmf from the extra repository.

It is advised to make a local copy of the non-volatile variable store for your virtual machine:

$ cp /usr/share/ovmf/x64/OVMF_VARS.fd my_uefi_vars.bin

To use the OVMF firmware and this variable store, add following to your QEMU command:

-drive if=pflash,format=raw,readonly,file=/usr/share/ovmf/x64/OVMF_CODE.fd \
-drive if=pflash,format=raw,file=my_uefi_vars.bin

For example:

$ qemu-system-x86_64 -enable-kvm -m 1G -drive if=pflash,format=raw,readonly,file=/usr/share/ovmf/x64/OVMF_CODE.fd -drive if=pflash,format=raw,file=my_uefi_vars.bin …

DUET for BIOS only systems

DUET was a TianoCore project that enabled chainloading a full UEFI environment from a BIOS system, in a way similar to BIOS OS booting. This method is being discussed extensively in https://www.insanelymac.com/forum/topic/186440-linux-and-windows-uefi-boot-using-tianocore-duet-firmware/. Pre-build DUET images can be downloaded from one of the repos at https://gitlab.com/tianocore_uefi_duet_builds/tianocore_uefi_duet_installer. Specific instructions for setting up DUET is available at https://gitlab.com/tianocore_uefi_duet_builds/tianocore_uefi_duet_installer/blob/master/Migle_BootDuet_INSTALL.txt . However, as of November 2018, the DUET code has been removed from TianoCore git repository.

You can also try https://sourceforge.net/projects/cloverefiboot/ which provides modified DUET images that may contain some system specific fixes and is more frequently updated compared to the gitlab repos.

Troubleshooting

Windows 7 will not boot in UEFI mode

Note: Windows 7 can boot in pure UEFI class 3 without CSM support, though installation requires CSM (specifically INT 10 H).

If you have installed Windows to a different hard disk with GPT partitioning and still have a MBR partitioned hard disk in your computer, then it is possible that the firmware (UEFI) is starting its CSM support (for booting MBR partitions) and therefore Windows will not boot. To solve this merge your MBR hard disk to GPT partitioning or disable the SATA port where the MBR hard disk is plugged in or unplug the SATA connector from this hard disk.

Mainboards with this kind of problem:

  • Gigabyte Z77X-UD3H rev. 1.1 (UEFI version F19e)
    • The firmware option for booting "UEFI Only" does not prevent the firmware from starting CSM.

Windows changes boot order

If you dual boot with Windows and your motherboard just boots Windows immediately instead of your chosen EFI application, there are several possible causes and workarounds.

  • Ensure Fast Startup is disabled in your Windows power options
  • Ensure Secure Boot is disabled in your BIOS (if you are not using a signed boot loader)
  • Ensure your UEFI boot order does not have Windows Boot Manager set first e.g. using #efibootmgr and what you see in the configuration tool of the UEFI. Some motherboards override by default any settings set with efibootmgr by Windows if it detects it. This is confirmed in a Packard Bell laptop.
  • If your motherboard is booting the default boot path (\EFI\BOOT\BOOTX64.EFI), this file may have been overwritten with the Windows boot loader. Try setting the correct boot path e.g. using #efibootmgr.
  • If the previous steps do not work, you can tell the Windows boot loader to run a different EFI application. From a Windows Administrator command prompt:
    # bcdedit /set "{bootmgr}" path "\EFI\path\to\app.efi"
  • Alternatively, you can set a startup script in Windows that ensures that the boot order is set correctly every time you boot Windows.
    1. Open a command prompt with admin privlages. Run bcdedit /enum firmware and find your desired boot entry.
    2. Copy the Identifier, including the brackets, e.g. {31d0d5f4-22ad-11e5-b30b-806e6f6e6963}
    3. Create a batch file with the command bcdedit /set "{fwbootmgr}" DEFAULT "{copied boot identifier}"
    4. Open gpedit.msc and under Local Computer Policy > Computer Configuration > Windows Settings > Scripts(Startup/Shutdown), choose Startup
    5. Under the Scripts tab, choose the Add button, and select your batch file

USB media gets struck with black screen

This issue can occur due to KMS issue. Try Disabling KMS while booting the USB.

UEFI boot loader does not show up in firmware menu

On certain UEFI motherboards like some boards with an Intel Z77 chipset, adding entries with efibootmgr or bcfg from the UEFI Shell will not work because they do not show up on the boot menu list after being added to NVRAM.

This issue is caused because the motherboards can only load Microsoft Windows. To solve this you have to place the .efi file in the location that Windows uses.

Copy the bootx64.efi file from the Arch Linux installation medium (FSO:) to the Microsoft directory your ESP partition on your hard drive (FS1:). Do this by booting into EFI shell and typing:

Shell> mkdir FS1:\EFI\Microsoft
Shell> mkdir FS1:\EFI\Microsoft\Boot
Shell> cp FS0:\EFI\BOOT\bootx64.efi FS1:\EFI\Microsoft\Boot\bootmgfw.efi

After reboot, any entries added to NVRAM should show up in the boot menu.

System boots to EFI shell after hardware change or starting other operating system

Tango-edit-clear.pngThis article or section needs language, wiki syntax or style improvements. See Help:Style for reference.Tango-edit-clear.png

Reason: Too GRUB-specific, most boot loader install commands have an option to install to the default/fallback boot path. Duplicates #Windows changes boot order and GRUB#Default/fallback boot path. (Discuss in Talk:Unified Extensible Firmware Interface#)

EFI stores state on the motherboard, called EFIVARS. Your bootloader (e.g. GRUB) may need to set up these variables in a certain way in order to boot. If your hardware configuration changes, or you boot into another operating system which overwrites these variables (Windows), you may be dumped into the EFI shell upon attempting to boot Arch Linux since the EFIVARS are incorrect and EFI can no longer find your bootloader.

At this point, you can use the EFI shell to find and boot your bootloader manually. Usually something like:

Shell> ls fs0:
  EFI\
  grub\

Shell> ls fs0:EFI\
  GRUB\

Shell> ls fs0:EFI\GRUB\
  grubx64.efi

Shell> fs0:EFI\GRUB\grubx64.efi
  Starting fs0:EFI\GRUB\grubx64.efi...

To prevent this happening again, you can install your bootloader to the default EFI boot location. In this setup, EFI will always find your bootloader on this drive since it is in the default location, which doesn't depend on the EFIVARS being correct. Your system should continue to boot even if another OS has changed the EFIVARS, or your hardware configuration has made the EFIVARS no longer correct for your system.

To do this with GRUB's grub-install, use the --removable flag. For example (update /boot/ to be the path to your EFI partition):

# grub-install --target=x86_64-efi --efi-directory=/boot/ --bootloader-id=GRUB --removable

Boot entries created with efibootmgr fail to show up in UEFI

efibootmgr can fail to detect EDD 3.0 and as a result create unusable boot entries in NVRAM. See efibootmgr issue 86 for the details.

To work around this, when creating boot entries manually, add the -e 3 option to the efibootmgr command. E.g.

# efibootmgr --create --disk /dev/sda --part 1 --loader /EFI/refind/refind_x64.efi --label "rEFInd Boot Manager" --verbose -e 3

To fix boot loader installers, like grub-install and refind-install, create a wrapper script /usr/local/bin/efibootmgr and make it executable:

/usr/local/bin/efibootmgr
#!/bin/sh

exec /usr/bin/efibootmgr -e 3 "$@"

See also