efibootmgr.8 - Online Linux Manual Page

EFIBOOTMGR - Online Linux Manual PageSection : 8
Updated : 28 September 2021
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NAMEefibootmgr − change the UEFI Boot Manager configuration

SYNOPSISefibootmgr [ -a ] [ -A ] [ -b XXXX ] [ -B ] [ -c ] [ -d DISK ] [ -D ] [ -e 1|3|-1 ] [ -E NUM ] [ --full-dev-path | --file-dev-path ] [ -f ] [ -F ] [ -g ] [ -i NAME ] [ -l NAME ] [ -L LABEL ] [ -m t|f ] [ -M X ] [ -n XXXX ] [ -N ] [ -o XXXX,YYYY,ZZZZ ... ] [ -O ] [ -p PART ] [ -q ] [ -r | -y ] [ -t seconds ] [ -T ] [ -u ] [ -v ] [ -V ] [ -w ] [ -@ file ]

DESCRIPTIONefibootmgr is a userspace application used to modify the UEFI Boot Manager. This application can create and destroy boot entries, change the boot order, change the next running boot option, and more. Details on the UEFI Boot Manager are available from the UEFI Specification, v1.02 or later, available from: http://www.uefi.org Note:" efibootmgr requires that the kernel support access to EFI non-volatile variables through /sys/firmware/efi/vars or /sys/firmware/efi/efivars/.

OPTIONSThe following is a list of options accepted by efibootmgr: -a | --active Set bootnum active. -A | --inactive Set bootnum inactive. -b | --bootnum XXXX Modify BootXXXX (hex). -B | --delete-bootnum Delete bootnum. -c | --create Create new variable bootnum and add to bootorder. -C | --create-only Create new variable bootnum and and do not add to bootorder. -d | --disk DISK The disk containing the loader (defaults to /dev/sda). -D | --remove-dups Remove duplicated entries from BootOrder. -e | --edd 1|3 Force EDD 1.0 or 3.0 creation variables. Use -e 1 together with -E if you are using a very old system which uses UEFI to boot, but requires legacy CSM (BIOS) device drivers for storage devices. -e 3 is now deprecated, and is an alias for --full-dev-path. -E | --edd-device NUM EDD 1.0 device number (defaults to 0x80). See --edd. --full-dev-path Force creation of boot entries use a full UEFI device path, starting at the PCIe root or equivalent on the current platform. The default is to use a hard disk based HD() abbreviated path. You shouldn't need to use this option unless the system firmware won't boot off of your device using an abbreviated HD() device path. Note that forcing a full path will fail if we don't know what the system device root is, how the specified device is connected to it, or how to encode any one of those. --file-dev-path Force creation of boot entries use an abbreviated UEFI device path which starts with the File() portion of the path. The default is to use a hard disk based HD() abbreviated path. -f | --reconnect Re-connect devices after driver is loaded. Only applicable for driver entries. -F | --do-not-reconnect Do not reconnect devices after driver is loaded. Only applicable for driver entries. -g | --gpt Force disk with invalid PMBR to be treated as GPT. -i | --iface NAME Create a netboot entry for the named interface. -k | --keep NAME Keep old entries when adjusting order. -l | --loader NAME Specify a loader (defaults to \EFI\\fedora\\grub.efi\fR). -L | --label LABEL Boot manager display label (defaults to "Linux"). -m | --mirror-below-4G t|f Set t if you want to mirror memory below 4GB. -M | --mirror-above-4G X X percentage memory to mirror above 4GB. Floating-point value with up to 2 decimal places is accepted. -n | --bootnext XXXX Set BootNext to XXXX (hex). -N | --delete-bootnext Delete BootNext. -o | --bootorder XXXX,YYYY,ZZZZ Explicitly set BootOrder (hex). Any value from 0 to FFFF is accepted so long as it corresponds to an existing Boot#### variable, and zero padding is not required. -O | --delete-bootorder Delete BootOrder. -p | --part PART Partition number containing the bootloader (defaults to 1). -q | --quiet Quiet mode - suppresses output. -r | --driver Operate on Driver#### variables instead of Boot#### variables. -t | --timeout seconds Boot Manager timeout, in seconds. -T | --delete-timeout Delete Timeout variable. -u | --unicode | --UCS-2 Handle extra command line arguments as UCS-2 (default is ASCII). -v | --verbose Verbose mode - prints additional information. -V | --version Just print version string and exit. -w | --write-signature Write unique signature to the MBR if needed. -y | --sysprep Operate on SysPrep#### variables instead of Boot#### variables. -@ | --append-binary-args Append extra variable args from file (use - to read from stdin). Data in file is appended as command line arguments to the boot loader command, with no modification to the data, so you can pass any binary or text data necessary.

EXAMPLES

Displaying the current settings (must be root): [root@localhost ~]# efibootmgr BootCurrent: 0004 BootNext: 0003 BootOrder: 0004,0000,0001,0002,0003 Timeout: 30 seconds Boot0000* Diskette Drive(device:0) Boot0001* CD-ROM Drive(device:FF) Boot0002* Hard Drive(Device:80)/HD(Part1,Sig00112233) Boot0003* PXE Boot: MAC(00D0B7C15D91) Boot0004* LinuxEach of the above are boot variables, which are defined as follows: • BootCurrent - the boot entry used to start the currently running system • BootOrder - the boot order as would appear in the boot manager. The boot manager tries to boot the first active entry in this list. If unsuccessful, it tries the next entry, and so on. • BootNext - the boot entry which is scheduled to be run on next boot. This supersedes BootOrder for one boot only, and is deleted by the boot manager after first use. This allows you to change the next boot behavior without changing BootOrder. • Timeout - the time in seconds between when the boot manager appears on the screen until when it automatically chooses the startup value from BootNext or BootOrder. • Five boot entries (0000 - 0004), along with the active/inactive flag (* means active) and the name displayed on the screen.

Creating a new boot optionAn OS installer would call efibootmgr -c. This assumes that /dev/sda1 is your EFI System Partition, and is mounted at /boot/efi. This creates a new boot option, called "Linux", and puts it at the top of the boot order list. Options may be passed to modify the default behavior. The default OS Loader is \EFI\\fedora\\grub.efi\fR\&.

Changing the boot orderAssuming the configuration in the first example, efibootmgr -o 3,4 could be called to specify PXE boot first, then Linux boot.

Changing the boot order for the next boot onlyAssuming the configuration in the first example, efibootmgr -n 4 could be called to specify that the Linux entry be taken on next boot.

Deleting a boot optionAssuming the configuration in the first example, efibootmgr -b 4 -B could be called to delete entry 4 and remove it from the BootOrder.

Creating network boot entriesA system administrator wants to create a boot option to network boot. You create the boot entry with: efibootmgr -c -i eth0 -L netboot [ -l '\filename.efi' ]\fR

BUGSPlease direct any bugs, features, patches, etc. to the Red Hat bootloader team at https://github.com/rhboot/efibootmgr .

AUTHORThis man page was generated by dann frazier <dannf@debian.org> for the Debian GNU/Linux operating system and updated by Robert Bisewski <contact@ibiscybernetics.com>, but may be used by others. It has subsequently been modified by Robbie Harwood <rharwood@redhat.com> for the efibootmgr project. 0

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