Provided by: systemd_257.4-1ubuntu3.1_amd64 

NAME
systemd-hibernate-resume.service, systemd-hibernate-clear.service, systemd-hibernate-resume - Resume from
hibernation
SYNOPSIS
systemd-hibernate-resume.service
systemd-hibernate-clear.service
/usr/lib/systemd/systemd-hibernate-resume
DESCRIPTION
systemd-hibernate-resume.service initiates the resume from hibernation.
systemd-hibernate-resume only supports the in-kernel hibernation implementation, see Swap suspend[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.
SEE ALSO
systemd(1), systemd-hibernate-resume-generator(8)
NOTES
1. Swap suspend
https://docs.kernel.org/power/swsusp.html
systemd 257.4 SYSTEMD-HIBERNATE-RESUME.SERVICE(8)