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<TITLE>RE: [openib-general] agent_mad_send</TITLE>
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<P><FONT SIZE=2>The reason for this is that for special QPs the driver insert the AV to the packet and not the HW.</FONT>
<BR><FONT SIZE=2>In regular QP the HW reads the AV only when is actually doing the send and thus you have to wait </FONT>
<BR><FONT SIZE=2>and not destroy the AV till the send completes.</FONT>
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<P><FONT SIZE=2>Tziporet</FONT>
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<P><FONT SIZE=2>-----Original Message-----</FONT>
<BR><FONT SIZE=2>From: Roland Dreier [<A HREF="mailto:roland@topspin.com">mailto:roland@topspin.com</A>]</FONT>
<BR><FONT SIZE=2>Sent: Wednesday, October 27, 2004 6:18 AM</FONT>
<BR><FONT SIZE=2>To: Sean Hefty</FONT>
<BR><FONT SIZE=2>Cc: openib-general@openib.org</FONT>
<BR><FONT SIZE=2>Subject: Re: [openib-general] agent_mad_send</FONT>
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<P><FONT SIZE=2> Sean> In agent_mad_send, a call is made to create an address</FONT>
<BR><FONT SIZE=2> Sean> handle. Immediately after calling ib_post_send_mad, the</FONT>
<BR><FONT SIZE=2> Sean> address handle is destroyed. I think that we want to wait</FONT>
<BR><FONT SIZE=2> Sean> until the send is completed before destroying the address</FONT>
<BR><FONT SIZE=2> Sean> handle, and require this of all callers of ib_post_send_mad.</FONT>
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<P><FONT SIZE=2>Yes, that's correct. Because of a quirk in the way Mellanox HCA's</FONT>
<BR><FONT SIZE=2>implement special QPs, it's actually OK to destroy the AH immediately</FONT>
<BR><FONT SIZE=2>after posting the send, but for an ordinary QP this will lead to some</FONT>
<BR><FONT SIZE=2>bizarre problems.</FONT>
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<P><FONT SIZE=2> - R.</FONT>
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