[openib-general] Re: 2/2 libibverbs + libmthca changes for query QP

[Sean Hefty]

Roland Dreier wrote:
> This reminds me of something I've been meaning to ask: what is the
> attr_mask of the query QP function used for?  The verbs definition in
> the IB spec does not include an attribute mask.  Obviously we don't
> have to follow the spec precisely but I'm wondering what the advantage
> is in having an attribute mask for query QP.  None of the other query
> methods (including query SRQ) have an attribute mask.

My understanding of the original code that this came from is that it permitted 
querying attributes that may be stored in memory, rather than requiring reading 
the card.  E.g. if all you needed was the QPN, then you could obtain only that 
information.  Given that things like the QPN, QP type, etc. are already 
available through the API, I'm not sure that the mask is needed.

- Sean