Atomic Response Endianness

Migration to RDMA-Core-v1.0

Atomic Operation in Connect-IB (MT27600) are fully supported on big endian (BE) machines (e.g. PPC). Their support is limited to little-endian machines (e.g. x86).

When using ibv_exp_query_device on little-endian machines with Connect-IB, the attr.exp_atomic_cap is set to IBV_EXP_ATOMIC_HCA_REPLY_BE, which indicates that if enabled, the atomic operation replied value is big-endian and contradicts the host endianness.

Enabling atomic operation with this endianness contradiction is by setting the IBV_EXP_QP_CREATE_QTOMIC_BE_REPLY flag in exp_create_flag in ibv_exp_create_qp.

RDMA-Core libmlx5 will not verify any atomic QP creation flag upon secnifn Atomic operations.

If an application swaps data between BE and host endianness over legacy library, it shall continue doing so.

For further information, please contact Support.

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