[openib-general] Immediate data question

[Roland Dreier]

 > 	If I only want to send/recv 4 bytes with immediate data:

I assume you mean that you only want to send the 4 bytes of immediate
data, and nothing else.

 > On sender side:
 > 	opcode = IBV_WR_SEND_WITH_IMM;
 > 	imm_data = my_4_bytes_data;
 > 
 > 	Do I still need to specify sg_list and num_sge ?

Well, you should be able to specify num_sge = 0.  But to be honest I'm
not positive that 0-length sends are allowed; I know that 0-length
RDMA WRITE operations are allowed.

 > On receiver side, because the immediate data is inside the completion
 > structure, do I need to post a receive for above message ?

Yes, otherwise how would you get the immediate data?

 > If I need to post a receive, do I need to specify sg_list and num_sge
 > for the receive ?

I believe that a 0-length receive with num_sge = 0 should be fine, at
least to handle an RDMA write with immediate data.  But again I'm not positive.

 - R.