with `:` in which case the kernel command line option takes precedence, if it
is specified as well.
+* `$SYSTEMD_REBOOT_TO_FIRMWARE_SETUP` — if set overrides systemd-logind's
+ built-in EFI logic of requesting a reboot into the firmware. Takes a
+ boolean. If set to false the functionality is turned off entirely. If set to
+ true instead of requesting a reboot into the firmware setup UI through EFI a
+ file `/run/systemd/reboot-to-firmware-setup` is created whenever this is
+ requested. This file may be checked for by services run during system
+ shutdown in order to request the appropriate operation from the firmware in
+ an alternative fashion.
+
+* `$SYSTEMD_REBOOT_TO_BOOT_LOADER_MENU` — similar to the above, allows
+ overriding of systemd-logind's built-in EFI logic of requesting a reboot into
+ the boot loader menu. Takes a boolean. If set to false the functionality is
+ turned off entirely. If set to true instead of requesting a reboot into the
+ boot loader menu through EFI a file `/run/systemd/reboot-to-boot-loader-menu`
+ is created whenever this is requested. The file contains the requested boot
+ loader menu timeout in µs, formatted in ASCII decimals, or zero in case no
+ time-out is requested. This file may be checked for by services run during
+ system shutdown in order to request the appropriate operation from the boot
+ loader in an alternative fashion.
+
+* `$SYSTEMD_REBOOT_TO_BOOT_LOADER_ENTRY` — similar to the above, allows
+ overriding of systemd-logind's built-in EFI logic of requesting a reboot into
+ a specific boot loader entry. Takes a boolean. If set to false the
+ functionality is turned off entirely. If set to true instead of requesting a
+ reboot into a specific boot loader entry through EFI a file
+ `/run/systemd/reboot-to-boot-loader-entry` is created whenever this is
+ requested. The file contains the requested boot loader entry identifier. This
+ file may be checked for by services run during system shutdown in order to
+ request the appropriate operation from the boot loader in an alternative
+ fashion. Note that by default only boot loader entries which follow the [Boot
+ Loader Specification](https://systemd.io/BOOT_LOADER_SPECIFICATION) and are
+ placed in the ESP or the Extended Boot Loader partition may be selected this
+ way. However, if a directory `/run/boot-loader-entries/` exists, the entries
+ are loaded from there instead. The directory should contain the usual
+ directory hierarchy mandated by the Boot Loader Specification, i.e. the entry
+ drop-ins should be placed in
+ `/run/boot-loader-entries/loader/entries/*.conf`, and the files referenced by
+ the drop-ins (including the kernels and initrds) somewhere else below
+ `/run/boot-loader-entries/`. Note that all these files may be (and are
+ supposed to be) symlinks. systemd-logind will load these files on-demand,
+ these files can hence be updated (ideally atomically) whenever the boot
+ loader configuration changes. A foreign boot loader installer script should
+ hence synthesize drop-in snippets and symlinks for all boot entries at boot
+ or whenever they change if it wants to integrate with systemd-logind's APIs.
+
installed systemd tests:
* `$SYSTEMD_TEST_DATA` — override the location of test data. This is useful if