On Apr 21, 2015, at 6:36 PM, Liran Liss <lir...@mellanox.com> wrote: > An ib_dev (or a port of) should be distinguished by 3 qualifiers: > - The link layer: > -- Ethernet (shared by iWARP, USNIC, and ROCE) > -- Infiniband > > - The transport (*) > -- IBTA transport (shared by IB and ROCE) > -- iWARP transport > -- USNIC transport
I haven't been following this discussion as closely as I could have, but I want to clarify something about usNIC. There are two "transports" used by usNIC: 1. The legacy RDMA_TRANSPORT_USNIC type, which indicates usNIC traffic will be Ethernet frames with Ethertype==0x8915 (like RoCE) but containing a custom, non-IBTA-sanctioned header format instead of a full GRH. This "transport" is still supported by the usnic_verbs kernel driver but in practice is no longer in use. For this "transport" there isn't really any clear L3/L4 header to point to. 2. The current RDMA_TRANSPORT_USNIC_UDP type, which indicates usNIC traffic will be standard UDP/IP/Ethernet packets. > (*) Transport means both: > - The L4 wire protocols (e.g., BTH+ headers of IBTA, optionally encapsulated > by UDP in ROCEv2, or the iWARP stack) > - The transport semantics (for example, there are slight semantic differences > between IBTA and iWARP) No usNIC hardware or software currently performs any hardware offload of RDMA features (only UD is supported), so there is no usNIC equivalent of the BTH+ to discuss right now. -Dave -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
