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<TITLE>RE: [openib-general] Reserved L_Key API</TITLE>
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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: Saturday, September 18, 2004 4:23 AM</FONT>
<BR><FONT SIZE=2>> </FONT>
<BR><FONT SIZE=2>> On the other hand even there I can think of hacks to get </FONT>
<BR><FONT SIZE=2>> around the problem -- the only systems where this limitation </FONT>
<BR><FONT SIZE=2>> really causes problems would be Intel IA-32 and EMT64T </FONT>
<BR><FONT SIZE=2>> systems with > 4 GB of RAM (since Intel has no IOMMU). And </FONT>
<BR><FONT SIZE=2>> for those systems the assumption that RAM starts at PCI </FONT>
<BR><FONT SIZE=2>> address 0 is valid, so you could just register a region from </FONT>
<BR><FONT SIZE=2>> 0 up to 0xfffffffff (ie the low 64 GB) and be happy.</FONT>
<BR><FONT SIZE=2>> </FONT>
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<P><FONT SIZE=2>Not sure I understand. If we do plan on supporting architectures</FONT>
<BR><FONT SIZE=2>that can't map the whole address space to DMA, then I think that</FONT>
<BR><FONT SIZE=2>the API should reflect it. When you try to create a DMA MR, then</FONT>
<BR><FONT SIZE=2>you should be able to request which is the address space that </FONT>
<BR><FONT SIZE=2>you need. Am I missing something ?</FONT>
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