Code-reading a bit, and I'm not sure of the exact definition of said bit; Couldn't really deduce from the comment "N-tuple filters supported" what falls under its jurisdiction and failed to find any other documentation.
I understand RFS acceleration is going to be disabled for an interface when this is unset, and some drivers also pro-actively take action when it's changed via set_features(). But there's seems to be some disagreement about the effect it has over ethtool's flow classification [ETHTOOL_SRXCLSRLINS] - Most drivers don't seem to care, but at least the intel drivers are blocking received configurations in case user removed the feature.
