On 2/11/2015 10:40 AM, Weiny, Ira wrote: >> On 2/4/2015 6:29 PM, [email protected] wrote: >>> From: Ira Weiny <[email protected]> >>> >>> OPA MADs share a common header with IBTA MADs but with a different >>> base version and an extended length. These "jumbo" MADs increase the >>> performance of management traffic. >>> >>> Sharing a common header with IBTA MADs allows us to share most of the >>> MAD processing code when dealing with OPA MADs in addition to >>> supporting some IBTA MADs on OPA devices. >>> >>> Add a device capability flag to indicate OPA MAD support on the device. >>> >>> Signed-off-by: Ira Weiny <[email protected]> >>> >>> --- >>> include/rdma/ib_verbs.h | 5 +++++ >>> 1 file changed, 5 insertions(+) >>> >>> diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h index >>> 3ab4033..2614233 100644 >>> --- a/include/rdma/ib_verbs.h >>> +++ b/include/rdma/ib_verbs.h >>> @@ -128,6 +128,10 @@ enum ib_device_cap_flags { >>> IB_DEVICE_ON_DEMAND_PAGING = (1<<31), >>> }; >>> >>> +enum ib_device_cap_flags2 { >>> + IB_DEVICE_OPA_MAD_SUPPORT = 1 >>> +}; >>> + >>> enum ib_signature_prot_cap { >>> IB_PROT_T10DIF_TYPE_1 = 1, >>> IB_PROT_T10DIF_TYPE_2 = 1 << 1, >>> @@ -210,6 +214,7 @@ struct ib_device_attr { >>> int sig_prot_cap; >>> int sig_guard_cap; >>> struct ib_odp_caps odp_caps; >>> + u64 device_cap_flags2; >>> u32 max_mad_size; >>> }; >>> >> >> Why is OPA support determined via a device capability flag ? What are the >> tradeoffs for doing it this way versus the other choices that have been used >> in >> the past for other RDMA technologies like RoCE, iWARP, usNIC, ... ? > > None of those technologies use the MAD stack for Subnet Management. Other > MAD support is very limited (ie IB compatible PMA queries on the local port > only). > > Do you have a suggestion for alternatives?
The desire to leverage the IB MAD infrastructure for OPA is understood but the current approach represents OPA as a device capability which does not seem appropriate because OPA is clearly a different type of RDMA technology than IB. -- Hal > Ira > > -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
