On Fri, Apr 3, 2020 at 12:02 AM Michael Kerrisk (man-pages) <mtk.manpages@xxxxxxxxx> wrote: > Actually, there are 0 mentions of ENOTSUP in the kernel > (other than in tools and samples). The constant that appears > in the kernel is one called ENOTSUPP (2 P's) defined as 524 > in include/linux/errno.h !! Yikes! What a mess! > ... Fair enough! I didn't even see the extra P in ENOTSUPP when I was looking at the kernel code. Thanks for the detailed analysis. Eric