[openib-general] optional function calls

[Roland Dreier]

    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).

    Sean> Or should we allow the minimal subset possible?

This is my vote.

    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).

 - R.