Re: [RFC PATCH 1/5] IB/core: Add Core Capability flags to ib_device

Dave Goodell (dgoodell)
2015-05-12T17:56:05Z

On May 11, 2015, at 7:13 PM, Weiny, Ira <ira.weiny-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org> wrote:

>> Does my earlier email clarify the situation any? http://marc.info/?l=linux-
>> rdma&m=142972178630720&w=2
>
> Somewhat, is there any reason applications need to distinguish between the " The legacy RDMA_TRANSPORT_USNIC type" and " The current RDMA_TRANSPORT_USNIC_UDP type"?

Addressing is different between the two (Ethernet_MAC+QP# vs. IP+UDP_port, respectively).

Also, the received UD header format and size are different between them (40-byte synthetic GRH vs. 42-byte UDP/IP/Ethernet header).

> Or does the former no longer exist?

The former is no longer being deployed and should be rare to find in the wild at this point, though I do not know precisely how many customers may be using it still. It is definitely legacy at this point.

>> Arguably RDMA_TRANSPORT_USNIC_UDP could/should have simply been
>> named RDMA_TRANSPORT_UDP.
>
> I guess I'm wondering if there needs to be an RDMA_TRANSPORT_USNIC to represent the " The legacy RDMA_TRANSPORT_USNIC type" you mention in the link above.

It probably needs to exist for a little while still.

-Dave