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/* SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause) */
/*
* Copyright(c) 2018 Intel Corporation.
*
*/
#ifndef _HFI1_OPFN_H
#define _HFI1_OPFN_H
/**
* DOC: Omni Path Feature Negotion (OPFN)
*
* OPFN is a discovery protocol for Intel Omni-Path fabric that
* allows two RC QPs to negotiate a common feature that both QPs
* can support. Currently, the only OPA feature that OPFN
* supports is TID RDMA.
*
* Architecture
*
* OPFN involves the communication between two QPs on the HFI
* level on an Omni-Path fabric, and ULPs have no knowledge of
* OPFN at all.
*
* Implementation
*
* OPFN extends the existing IB RC protocol with the following
* changes:
* -- Uses Bit 24 (reserved) of DWORD 1 of Base Transport
* Header (BTH1) to indicate that the RC QP supports OPFN;
* -- Uses a combination of RC COMPARE_SWAP opcode (0x13) and
* the address U64_MAX (0xFFFFFFFFFFFFFFFF) as an OPFN
* request; The 64-bit data carried with the request/response
* contains the parameters for negotiation and will be
* defined in tid_rdma.c file;
* -- Defines IB_WR_RESERVED3 as IB_WR_OPFN.
*
* The OPFN communication will be triggered when an RC QP
* receives a request with Bit 24 of BTH1 set. The responder QP
* will then post send an OPFN request with its local
* parameters, which will be sent to the requester QP once all
* existing requests on the responder QP side have been sent.
* Once the requester QP receives the OPFN request, it will
* keep a copy of the responder QP's parameters, and return a
* response packet with its own local parameters. The responder
* QP receives the response packet and keeps a copy of the requester
* QP's parameters. After this exchange, each side has the parameters
* for both sides and therefore can select the right parameters
* for future transactions
*/
/* STL Verbs Extended */
#define IB_BTHE_E_SHIFT 24
#endif /* _HFI1_OPFN_H */
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