[ofw] rdma_join_multicast not implemented??

[ljchrist at rockwellcollins.com]

Thanks for the response.  We have a need to use multicast and UD over 
infiniband on Windows so it would be great to have this functionality so 
that we could use the librdmacm.  In the mean time, I will look into using 
multicast and UD at the verbs level.

Layne




"Hefty, Sean" <sean.hefty at intel.com> 
01/25/2011 02:51 PM

To
"ljchrist at rockwellcollins.com" <ljchrist at rockwellcollins.com>, 
"ofw at lists.openfabrics.org" <ofw at lists.openfabrics.org>
cc

Subject
RE: [ofw] rdma_join_multicast not implemented??






> I just attended the RDMA programming class that OpenFabrics held.  I was
> interested in applying what I had learned to create an application that
> uses UD and multicast using the new WinOF 2.3 release.  I have not had 
much
> success in doing so, so I downloaded the source code and searched for 
the
> rdma_join_multicast() and rdma_leave_multicast() functions.  It looks 
like
> these functions are not currently implemented as they just have the
> following code: return rdma_seterrno(ENOSYS);

Correct - there were no current in-tree users of that code, so their 
implementations were deferred.

> I got the impression, from my class, that multicast should be there on 
the
> Linux side so this would appear to be a difference in functionality 
between
> Linux and Windows.  Is there any plan to implement these in the next
> release, or am I completely missing something.

OFED-Windows does support multicast at the verbs level (somewhat) and UD; 
it's the librdmacm port that does not.  The issue is that the underlying 
libraries and kernel drivers are missing the necessary features to support 
user space multicast.  To date, there haven't been requests to add this 
feature, so no plans have been made to implement UD support through the 
librdmacm.

This is not something I have time at the moment to implement, but I would 
be able to work with another developer to review any patches and merge 
them into the tree.

- Sean

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