[openib-general] optional function calls

[Sean Hefty]

>    Sean> I'm trying to decide which IB function require checks to see
>    Sean> if they exist.  Should we go by the spec and assume that all
>    Sean> mandatory functions are implemented by the device driver?
>
>No, I don't think so.  I think we might as well make the stack useful
>not just with full HCA hardware but also on embedded hardware (running
>on switches and TCAs).  For example, a switch is unlikely to support
>memory windows (even though the MW verbs are mandatory).

This was my thinking as well, but wanted to see if anyone thought
differently.

>    Sean> Or should we allow the minimal subset possible?
>
>This is my vote.

If there's no disagreement, then I'll probably use the minimal subset in
your core_device.c file.

>    Sean> Also, if calls like ib_create_srq and ib_attach_mcast check
>    Sean> to see if the device implemented the functions, do we need
>    Sean> the same check on calls to ib_destroy_srq and
>    Sean> ib_detach_mcast?  I.e. should we only perform the check in
>    Sean> the creation calls?
>
>I think it's reasonable to only check the creation calls (and possibly
>put a check in the device registration function that if a device
>implements the create method, it implements all the other methods for
>an object -- although this falls down for things like CQ resize which
>might not be implemented).

I'll add checks to only the necessary calls then.  E.g. ib_create_srq,
ib_attach_mcast, ib_resize_cq, ib_query_qp, etc.