from FreeBSD: Don't reject FAT file systems with a number of "Heads" greater than 255; USB keychains exist that use 256 as the number of heads.  This check has also been removed in Darwin (along with most of the other head/sector sanity checks).
from FreeBSD:
Don't reject FAT file systems with a number of "Heads" greater than
255; USB keychains exist that use 256 as the number of heads.  This
check has also been removed in Darwin (along with most of the other
head/sector sanity checks).

this fixes pr 4988, ok pedro

orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars