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    SubjectRe: [PATCH] seastar - SeaStar Ethernet driver
    > Ethernet Frame:     [6 bytes h_dest][6 bytes h_source][2 bytes h_proto][data...]
    > SeaStar DG Message: [2 bytes length][1 byte MBZ][1 byte msg type (2 << 5) for IP)][data...]
    >
    > I think it would be possible to re-factor it so that the Ethernet frame
    > is encapsulated in its entirety within a seastar message, rather than
    > the current scheme of jamming the critical info from the Ethernet header
    > into the seastar datagram header. I will pursue that if you want... the
    > drawback is that it would break compatibility with Cray's existing
    > proprietary IP over SeaStar driver, making this driver pretty much
    > useless for the kinds of things us and others would like to do (e.g.,
    > leave service nodes booted with Cray's proprietary software stack and
    > talking to compute nodes running this driver).

    Perhaps it shouldn't be pretending to be an ethernet driver - that is
    sort of the root cause of all the confusion and the fact things like the
    bridging layer will try and grab it etc ? If it claimed to be a new
    hardware type you'd take a brief hit on getting the new hw type into the
    tools but it would mean

    - tcpdump etc once coaxed would display seastar frames not fake ethernet
    - the config tools would actually report what it really was
    - non IP layers and userspace won't keep trying to do things you don't
    want (what does it do right now with vlans I wonder 8))
    - there will be no ARP confusion

    If it wants to stay compatible and pretend to be ethernet you probably
    need a message type for "encapsulated ethernet", you can then encapsulate
    anything not IP and stay compatible by keeping IP sent the way it is
    now ? Thats if it wants to in the first place.

    Alan


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