[openib-general] Re: IPoIB

[Roland Dreier]

    Hal> A while ago, Tom brought up the issue of IPoIB link level
    Hal> broadcasting from user space (with the arping tool). Is it
    Hal> possible to do this from kernel space ? For example, how
    Hal> would/could sendto() work when sending to a IPoIB link layer
    Hal> address ? If all we wanted to support was broadcast, perhaps
    Hal> there could be a remapping of the ethernet MAC broadcast
    Hal> address to the all hosts MGID and QPN for that IPoIB
    Hal> interface. Or perhaps the entire ipoib pseudoheader should be
    Hal> supported in this mode. This is needed to support
    Hal> RARPing. Some hosts want to RARP for their IP address and
    Hal> this should be supported over IPoIB.

I think it should "just work" with the current setup.
ipoib_hard_header() will look at the skb it's passed, and if there's
no neighbour struct, it will just save off the destination link
address.  Then ipoib_start_xmit() will look at the destination address
and handle multicast link addresses correctly.

 - R.