Suspend/resume event tracing

modulename: trace.ko

configname: CONFIG_PM_TRACE_RTC

Linux Kernel Configuration
└─>Power management and ACPI options
└─>Suspend/resume event tracing
In linux kernel since version 4.2 (release Date: 2015-08-30)  
This enables some cheesy code to save the last PM event point in the
RTC across reboots, so that you can debug a machine that just hangs
during suspend (or more commonly, during resume).

To use this debugging feature you should attempt to suspend the
machine, reboot it and then run

dmesg -s 1000000 | grep 'hash matches'

CAUTION: this option will cause your machine's real-time clock to be
set to an invalid time after a resume.

source code: