Re: [PATCH v2 01/17] IB/Verbs: Implement new callback query_transport() for each HW

From: Doug Ledford
Date: Fri Apr 10 2015 - 14:18:16 EST

On Fri, 2015-04-10 at 13:50 -0400, Tom Talpey wrote:
> On 4/10/2015 1:10 PM, Doug Ledford wrote:
> > As per my above statement, rdma_transport* tests were testing the high
> > level transport type, rdma_port* types were testing link layers. iWARP
> > has an Eth link layer, so technically port_is_iwarp makes no sense. But
> > since all the other types had a check too, I included port_is_iwarp just
> > to be complete, and if you are going to ask if a specific port is iwarp
> > as a link layer, it makes sense to say yes if the transport is iwarp,
> > not if the link layer is eth.
> Not wanting to split hairs, but I would not rule out the possibility
> of a future device supporting iWARP on one port and another RDMA
> protocol on another. One could also imagine softiWARP and softROCE
> co-existing atop a single ethernet NIC.
> So, I disagree that port_is_iwarp() is a nonsequitur.

Agreed, but that wasn't what I was calling non-sense. I was referring
to the fact that in my quick little write up, the rdma_port* functions
were all intended to test link layers, not high level transports. There
is no such thing as an iWARP link layer. It was still a port specific
test, and would work in all the situations you described, it's just that
asking if a port's link layer is iWARP makes no sense, so I returned
true if the transport was iWARP regardless of what the link layer
actually was.

Doug Ledford <dledford@xxxxxxxxxx>

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