From: Jesper Dangaard Brouer <[email protected]>
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.
