systemd-hibernate-resume@.service, systemd-hibernate-resume — Resume from hibernation
initiates the resume from hibernation. It is instantiated with the
device to resume from as the template argument.
systemd-hibernate-resume only supports
the in-kernel hibernation implementation, see
Internally, it works by writing the major:minor of specified
device node to
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 case, the boot is ordinarily continued.