> On 2/4/2015 6:29 PM, ira.weiny@xxxxxxxxx wrote:
> > From: Ira Weiny <ira.weiny@xxxxxxxxx>
> >
> > 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 <ira.weiny@xxxxxxxxx>
> >
> > ---
> > 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?
Ira
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