One of the new features of High Sierra is that it will constantly check your Mac’s firmware against Apple’s own database of what the company determines to be “good”. This was initially tweeted by one of Apple’s engineers, Xeno Kovah, but the tweets were later deleted but not before the folks at The Eclectic Light Company saved it.
How it works is, “The new utility eficheck, located in /usr/libexec/firmwarecheckers/eficheck, runs automatically once a week. It checks that Mac’s firmware against Apple’s database of what is known to be good. If it passes, you will see nothing of this, but if there are discrepancies, you will be invited to send a report to Apple.”
Hopefully this is not something that users will encounter too often, or at all, but basically the weekly checks will be a welcome feature to ensure that the firmware isn’t compromised or corrupted. macOS High Sierra was recently released and is available as a free update for all compatible Mac computers.