efibootdump

Dump boot entries from a file

$ efibootdump [[-f|--file]] [/sys/firmware/efi/efivars/Boot0000-8be4df61-93ca-11d2-aa0d-00e098032b8c]

efibootdump [OPTIONS...] [VARNAME...]

-V, --version
    Displays the version information of the efibootdump utility.

-h, --help
    Shows a brief help message and usage synopsis for the command.

-v, --verbose
    Provides more detailed or verbose output, potentially showing additional information during the dump process.

VARNAME...
    Specifies one or more particular EFI variable names (e.g., BootOrder, Boot0001) to dump. If no VARNAME is provided, efibootdump typically dumps all recognized boot-related variables.

efibootdump is a specialized diagnostic utility designed to display the raw contents of UEFI (Unified Extensible Firmware Interface) boot variables. These variables, stored in NVRAM (Non-Volatile Random-Access Memory), hold critical information regarding the system's boot configuration, including boot order, boot entries, and other EFI-specific settings.

Unlike efibootmgr, which offers a higher-level interface for managing these variables, efibootdump focuses on presenting the underlying, often hexadecimal, data. This low-level perspective is invaluable for debugging complex boot problems, analyzing firmware behavior, or understanding the precise byte-level structure of EFI variables. It assists system administrators and developers in identifying issues not apparent from standard efibootmgr output, providing a deep dive into the firmware's view of the boot process. It typically requires root privileges to access the EFI variable filesystem.

Requires root privileges to read EFI variables from the /sys/firmware/efi/efivars/ filesystem.
The output is raw, often in hexadecimal format, and requires an understanding of EFI variable structures for correct interpretation.
Only functional on systems with UEFI firmware and the efivars filesystem mounted and accessible.
This command is read-only; it cannot modify or delete EFI variables. Use efibootmgr for modifications.

The output produced by efibootdump is typically a raw hexadecimal dump of the EFI variable's contents. Interpreting this data often requires familiarity with the specific EFI variable structures defined by the UEFI specification, such as EFI_LOAD_OPTION for boot entries or GUIDs for variable names. Without this knowledge, the output can be difficult to understand.

On Linux systems, EFI variables are exposed as files within the pseudo-filesystem mounted at /sys/firmware/efi/efivars/. Each file in this directory corresponds to an EFI variable. efibootdump reads the contents of these files to present the variable data, which is why it requires root access to this protected filesystem.

efibootdump is part of the efibootmgr project, which originated to provide Linux systems with robust tools for interacting with UEFI firmware. As UEFI supplanted legacy BIOS as the dominant firmware interface, the need for Linux utilities to manage and debug EFI boot variables became paramount. Developed by Matt Domsch and others, the efibootmgr suite, including efibootdump, emerged to fill this gap. efibootdump specifically caters to diagnostic needs, offering a low-level view of boot variables that complements efibootmgr's higher-level management functions. Its evolution reflects Linux's continuous adaptation and integration with modern UEFI-based hardware.

efibootmgr(8), bootctl(1), dmidecode(8)