On Fri, 2 Jul 2021 12:49:55 -0400 Alyssa Rosenzweig <alyssa@xxxxxxxxxxxxx> wrote: > > > Why is there padding instead of putting point first? > > > > We can move the point field first, but we need to keep the explicit > > padding: the struct has to be 64bit aligned because of the __u64 field > > (which the compiler takes care of) but if we don't have an explicit > > padding, the unused 32bits are undefined, which might cause trouble if > > we extend the struct at some point, since we sort of expect that old > > userspace keep this unused 32bit slot to 0, while new users set > > non-zero values if they have to. > > Makes sense. Reordering still probably makes sense. Actually, I can't re-order if I want the new in_syncs parser to work with the old ioctl(), which you and Steven asked me to do :-).
