systemd-hibernate-resume.service, systemd-hibernate-clear.service, systemd-hibernate-resume - Resume from

       systemd-hibernate-resume.service initiates the resume from hibernation.

       systemd-hibernate-resume only supports the in-kernel hibernation implementation, see Swapsuspend[1].
       Internally, it works by writing the major:minor of selected device node to /sys/power/resume, along with
       the offset in memory pages (/sys/power/resume_offset) if supported.

       The resume device node is either passed directly through arguments, or automatically acquired from kernel
       command line options and/or HibernateLocation EFI variable. The latter will normally be cleared by
       systemd-hibernate-resume.service on resumption. If a stale variable is detected, it would be cleared by
       systemd-hibernate-clear.service.

       Failing to initiate a resume is not an error condition. It may mean that there was no resume image (e. g.
       if the system has been simply powered off and not hibernated). In such cases, the boot is ordinarily
       continued.

       systemd-hibernate-resume.service, systemd-hibernate-clear.service, systemd-hibernate-resume - Resume from
       hibernation

        1. Swap suspend
           https://docs.kernel.org/power/swsusp.html

systemd 257.7                                                                SYSTEMD-HIBERNATE-RESUME.SERVICE(8)

systemd(1), systemd-hibernate-resume-generator(8)

       systemd-hibernate-resume.service

       systemd-hibernate-clear.service

       /usr/lib/systemd/systemd-hibernate-resume