From: Jesper Dangaard Brouer <bro...@redhat.com> Date: Thu, 21 Jan 2016 12:27:30 +0100
> eth_type_trans() does two things: > > 1) determine skb->protocol > 2) setup skb->pkt_type = PACKET_{BROADCAST,MULTICAST,OTHERHOST} > > Could the HW descriptor deliver the "proto", or perhaps just some bits > on the most common proto's? > > The skb->pkt_type don't need many bits. And I bet the HW already have > the information. The BROADCAST and MULTICAST indication are easy. The > PACKET_OTHERHOST, can be turned around, by instead set a PACKET_HOST > indication, if the eth->h_dest match the devices dev->dev_addr (else a > SW compare is required). > > Is that doable in hardware? I feel like we've had this discussion before several years ago. I think having just the protocol value would be enough. skb->pkt_type we could deal with by using always an accessor and evaluating it lazily. Nothing needs it until we hit ip_rcv() or similar.