[openib-general] [query]requirement of 'process_mad' in the HCA driver

[Devesh Sharma]

On similar lines I have a confusion about the mad agent creation:-
 there is a function in mad.c   ib_agent_port_open() which creates
_send_only_ SMAs for GSI and SMI per port.

There is a function in mthca_mad.c mthca_create_agents() which is
_again_ createing two send only mad agents for SMI and GSI.

Why this driver specific agent creation is required?

On 14 Dec 2006 08:57:11 -0500, Hal Rosenstock <halr at voltaire.com> wrote:
> On Wed, 2006-12-13 at 22:49, keshetti mahesh wrote:
> > thanks for your reply,
> >
> > >The driver is needed to obtain the information for the IB node to
> > fill
> > >in the MADs for response to the SMA query. It may also issue some
> > traps.
> > >Similarly for PMA as well.
> >
> > Do u mean to say that HCA driver is needed to pass the HCA related
> > information (like GID, GUID, port_info etc..) to the SMA so that it
> > can reply to query(or GET ) MADs.
>
> Yes.
>
> >  Isn't SMA capable of doing the same by using "query_(gid, pkey,
> > port)" verbs.
>
> One reason I can think of is that not all the needed information is
> available via verbs. I think there are some others as well.
>
> > And final  questions  if it is really required to implement
> > 'process_mad' in HCA driver then why it is not specified in the IB
> > specifications.
>
> IB spec is architecture not implementation.
>
> > Whose duty is this (replying to query MADs) according to the IB
> > psec.s(its duty of SMA right?)
>
> Depends on the MAD but if you are referring to the SMA queries, then yes
> it is the SMA's responsibility.
>
> > I have observed that process_mad is not implemented in the IBM's eHCA
> > driver. what is the case with it?
>
> With eHCA, QP0 is not exposed to the host (at least currently) and the
> SMA is totally implemented in firmware.
>
> > PS: I am considering only SMA in the host s/w here.
>
> This is a design choice.
>
> -- Hal
>
> > regards,
> > K.Mahesh.
> >
> >
> >
> >
> > Hal Rosenstock <halr at voltaire.com> wrote:
> >         On Wed, 2006-12-13 at 01:55, keshetti mahesh wrote:
> >         > Hello all,
> >         >
> >         > I want to know from u people that isi it necessary to
> >         implement the
> >         > process_mad for a HCA.
> >         >
> >         > After looking into the implementations of process_mad in
> >         ipath and
> >         > mthca drivers i have fount that they are used to reply the
> >         MADs with
> >         > port_info,gid_info,sm_info etc..
> >         >
> >         > But isn't it handled by SMA in the host......
> >
> >         The SMA can either be in the host on in firmware (as is
> >         typical with the
> >         Mellanox silicon).
> >
> >         > i am little bit confused now .
> >         > please just whether it is required to implement process_mad
> >         (suppose)
> >         > for new HCA driver....
> >
> >         It is. For an example of a host (software SMA), see
> >         drivers/infiniband/hw/ipath/ipath_mad.c
> >
> >         > if it is required why?
> >
> >         The driver is needed to obtain the information for the IB node
> >         to fill
> >         in the MADs for response to the SMA query. It may also issue
> >         some traps.
> >         Similarly for PMA as well.
> >
> >         -- Hal
> >
> >         > Please CC your replies to me.
> >         >
> >         > regards,
> >         > K.Mahesh.
> >         >
> >         >
> >         >
> >         >
> >         >
> >         >
> >         >
> >         >
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