Hi Johannes, >>> No, as usual, that would break ABI. PAD is a regular attribute, just >>> empty and ignored for aligning 64-bit values. >> >> then I do not grok on how the nla_put_u64_64bit works, but that is >> fine. >> >> I assumed these are similar to the NL80211_SURVEY_INFO_MAX which we >> also always move, but also not expected to be part of the API as a >> fixed value. > > No no, the _MAX is just the token we use for knowing what we want as the > maximum when parsing etc. > > The _PAD is actually a real attribute, basically nla_put_u64_64bit() > will do "nla_put_flag(_PAD)" if and only if "offset % 8 == 0", in order > to actually 64-bit align the 64-bit value in the following attribute. > > (Note that offset % 8 can only be 0 or 4, due to the way netlink > attributes work.)
I get that part now. So the kernel is inserting a _PAD, but userspace is still not doing that. So for NL80211_ATTR_WDEV we should be doing the same actually? Regards Marcel
