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I don't want to give any names, just to point out > > > > that there isn't any inherent limitation in the technology. > > > > > > Oh, you should tell me, maybe off-list then. 'Cause I don't know any. > > > > I hope the examples given in private will make you reconsider the > > validity of my argument about DMA timestamps. > > I may have lost track of what the argument is. There are devices > which will provide a DMA stamp for Tx and Rx. We need an API that'll > inform the user about it. > > To be clear I'm talking about drivers which are already in the tree, > not opening the door for some shoddy new HW in. So this is circling back to my original question (with emphasis on the last part): | Which drivers provide DMA timestamps, and how do they currently signal | that they do this? Do they do this for all packets that get timestamped, | or for "some"? https://lore.kernel.org/netdev/20230511203646.ihljeknxni77uu5j@skbuf/ If only "some" packets (unpredictable which) get DMA timestamps when a MAC timestamp isn't available, what UAPI can satisfactorily describe that? And who would want that?