Hi! This has probably been asked already, but I can‘t seem to find it: Last year I upgraded the firmware of my Mac Pro 4,1 to the one from 5,1 for Sierra. Now I just downloaded the final version of High Sierra, and at the start of the installation it says that it has to do a firmware upgrade for High Sierra. I‘m confused. Since my machine is not officially supported, why would it be offered a firmware upgrade? Does it do the same on an actual 5,1? And, most importantly, is it safe? Thanks!