From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hal Rosenstock Subject: Re: [PATCH v4 14/19] IB/core: Add IB_DEVICE_OPA_MAD_SUPPORT device cap flag Date: Thu, 12 Feb 2015 09:00:09 -0500 Message-ID: <54DCB1E9.7010309@dev.mellanox.co.il> References: <1423092585-26692-1-git-send-email-ira.weiny@intel.com> <1423092585-26692-15-git-send-email-ira.weiny@intel.com> <54D52589.8020305@dev.mellanox.co.il> <2807E5FD2F6FDA4886F6618EAC48510E0CC244A8@CRSMSX101.amr.corp.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <2807E5FD2F6FDA4886F6618EAC48510E0CC244A8-8k97q/ur5Z2krb+BlOpmy7fspsVTdybXVpNB7YpNyf8@public.gmane.org> Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: "Weiny, Ira" Cc: "roland-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org" , "linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" List-Id: linux-rdma@vger.kernel.org On 2/11/2015 10:40 AM, Weiny, Ira wrote: >> On 2/4/2015 6:29 PM, ira.weiny-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org wrote: >>> From: Ira Weiny >>> >>> 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 >>> >>> --- >>> 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 majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html