systemd-bless-boot.service, systemd-bless-boot — Mark current boot process as successful
systemd-bless-boot.service is a system service that marks the current boot process as
successful. It's automatically pulled into the initial transaction when
detects that systemd-boot(7) style
boot counting is used.
Internally, the service operates based on the
LoaderBootCountPath EFI variable (of the
4a67b082-0a4c-41cf-b6c7-440b29bb8c4), which is passed from the boot loader to the
OS. It contains a file system path (relative to the EFI system partition) of the Boot Loader Specification compliant boot loader entry
file or unified kernel image file that was used to boot up the
system. systemd-bless-boot.service removes the two 'tries done' and 'tries left' numeric boot
counters from the filename, which indicates to future invocations of the boot loader that the entry has completed
booting successfully at least once. (This service will hence rename the boot loader entry file or unified kernel
image file on the first successful boot.)
/usr/lib/systemd/system-bless-boot executable may also be invoked from the
command line, taking one of the following command arguments:
The current status of the boot loader entry file or unified kernel image file is shown. This
outputs one of "
clean", depending on the state and previous invocations of the command. The string
indeterminate" is shown initially after boot, before it has been marked as "good" or
"bad". The string "
good" is shown after the boot was marked as "good" with the
good command below, and "bad" conversely after the
bad command was
invoked. The string "
clean" is returned when boot counting is currently not in effect.
This command is implied if no command argument is specified.
When invoked, the current boot loader entry file or unified kernel image file will be marked as
"good", executing the file rename operation described above. This command is intended to be invoked at the end
of a successful boot. The
systemd-bless-boot.service unit invokes this
When called the 'tries left' counter in the boot loader entry file name or unified kernel image file name is set to zero, marking the boot loader entry or kernel image as "bad", so that the boot loader won't consider it anymore on future boots (at least as long as there are other entries available that are not marked "bad" yet). This command is normally not executed, but can be used to instantly put an end to the boot counting logic if a problem is detected and persistently mark the boot entry as bad.
This command undoes any marking of the current boot loader entry file or unified kernel image
file as good or bad. This is implemented by renaming the boot loader entry file or unified kernel image file
back to the path encoded in the
LoaderBootCountPath EFI variable.