loader.conf — Configuration file for systemd-boot
ESP/loader/loader.confESP/loader/entries/*.conf
    systemd-boot(7)
    will read ESP/loader/loader.conf.conf" extension under
    ESP/loader/entries/
Each configuration file must consist of an option name, followed by
    whitespace, and the option value. "#" may be used to start
    a comment line. Empty and comment lines are ignored.
Boolean arguments may be written as
    "yes"/"y"/"true"/"t"/"on"/"1" or
    "no"/"n"/"false"/"f"/"off"/"0".
    
The following configuration options in loader.conf are understood:
A glob pattern to select the default entry. The default entry may be changed in the boot menu itself, in which case the name of the selected entry will be stored as an EFI variable, overriding this option.
If set to "@saved" the chosen entry will be saved as an EFI variable
        on every boot and automatically selected the next time the boot loader starts.
Table 1. Automatically detected entries will use the following names:
| Name | Description | 
|---|---|
| auto-efi-default | EFI Default Loader | 
| auto-efi-shell | EFI Shell | 
| auto-osx | macOS | 
| auto-reboot-to-firmware-setup | Reboot Into Firmware Interface | 
| auto-windows | Windows Boot Manager | 
How long the boot menu should be shown before the default entry is booted, in seconds. This may be changed in the boot menu itself and will be stored as an EFI variable in that case, overriding this option.
If set to "menu-hidden" or "0" (the default) no menu
        is shown and the default entry will be booted immediately. The menu can be shown
        by pressing and holding a key before systemd-boot is launched. Setting this to
        "menu-force" disables the timeout while always showing the menu.
This option configures the resolution of the console. Takes a number or one of the special values listed below. The following values may be used:
Takes a boolean argument. Enable (the default) or disable the editor. The editor should be disabled if the machine can be accessed by unauthorized persons.
Takes a boolean argument. Enable (the default) or disable entries for other boot entries found on the boot partition. In particular, this may be useful when loader entries are created to show replacement descriptions for those entries.
A boolean controlling the presence of the "Reboot into firmware" entry (enabled by default). If this is disabled, the firmware interface may still be reached by using the f key.
Takes one of "off", "with-system-token" and
        "always". If "off" no random seed data is read off the ESP, nor
        passed to the OS. If "with-system-token" (the default)
        systemd-boot will read a random seed from the ESP (from the file
        /loader/random-seed) only if the LoaderSystemToken EFI
        variable is set, and then derive the random seed to pass to the OS from the combination. If
        "always" the boot loader will do so even if LoaderSystemToken is
        not set. This mode is useful in environments where protection against OS image reuse is not a
        concern, and the random seed shall be used even with no further setup in place. Use bootctl
        random-seed to initialize both the random seed file in the ESP and the system token EFI
        variable.
See Random Seeds for further information.
# /boot/efi/loader/loader.conf
timeout 0
default 01234567890abcdef1234567890abdf0-*
editor no
    The menu will not be shown by default (the menu can still be shown by
    pressing and holding a key during boot). One of the entries with files with a
    name starting with "01234567890abcdef1234567890abdf0-" will be
    selected by default. If more than one entry matches, the one with the highest
    priority will be selected (generally the one with the highest version number).
    The editor will be disabled, so it is not possible to alter the kernel command
    line.