On 5/13/2022 8:46 AM, Jason Gunthorpe wrote:
On Fri, May 13, 2022 at 09:39:44AM +0000, Bernard Metzler wrote:
Not all providers support the transfer of private data in control
messages after connection establishment -
rdma_reject()/rdma_accept() being the last opportunity to send
private data in connections lifetime for e.g. iWarp
connections. Maybe that is why it is not exposed at the disconnect
API call? Would RoCE support it?
RoCE and IB have a place to put it, IB does not.
I think you meant "iWARP does not", but that's partially incorrect.
The Terminate message in iWARP carries a payload which is provided
by the layer which caused the termination.
The "layer" 4-bit field and RDMA/DDP/LLP ETypes in:
https://datatracker.ietf.org/doc/html/rfc5040#section-4.8
It has been discussed before to add additional values to iWARP,
to carry exactly this kind of "syndrome" data. The discussion
could certainly be had again!
The lack of support in iWarp is problematic, these APIs are supposed
to be fairly high level things.
Right. Especially we do not want to define a "protocol-in-protocol"
which allows arbitary data to be exchanged here. It needs an
interoperable, and testable, specification. For all RDMA protocols,
which all ULPs can rely on.
We clearly can't just extend the existing rdma_disconnect() due to
this, and some kind of negotiation would be needed so the ULP can
learn if the extra data is supported at all.
Yep.
Tom.
Jason
