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<TITLE>problems with dma_alloc_coherent and consistent_alloc </TITLE>
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<P><FONT SIZE=2 FACE="Courier New">(Sorry, I had trouble outlook and messed up the subject line)</FONT>
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<P><FONT SIZE=2 FACE="Courier New">We are using a PPC 750 with 512m of RAM. </FONT>
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<P><FONT SIZE=2 FACE="Courier New">1) When we try to allocate memory using consistent_alloc we get a </FONT>
<BR><FONT SIZE=2 FACE="Courier New">failure with get_pteptr - there is no pte. </FONT>
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<P><FONT SIZE=2 FACE="Courier New">2) When we try using dma_alloc_coherent the system locks up when</FONT>
<BR><FONT SIZE=2 FACE="Courier New">we try to access that memory.</FONT>
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<P><FONT SIZE=2 FACE="Courier New">I'm guessing these problems stem from the memory being allocated</FONT>
<BR><FONT SIZE=2 FACE="Courier New">is from the 384 bytes of RAM that gets handed over to BATs 2 AND 3,</FONT>
<BR><FONT SIZE=2 FACE="Courier New">not the remaining memory handled by the page table.</FONT>
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<P><FONT SIZE=2 FACE="Courier New">In the first case, pages are allocated, but since if came from the</FONT>
<BR><FONT SIZE=2 FACE="Courier New">BAT region, will not have a page table mapping.</FONT>
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<P><FONT SIZE=2 FACE="Courier New">In the second case, if dma_alloc_init gets memory from the BAT</FONT>
<BR><FONT SIZE=2 FACE="Courier New">region, then we have the BAT and page management mechanisms</FONT>
<BR><FONT SIZE=2 FACE="Courier New">both trying to control the memory.</FONT>
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<P><FONT SIZE=2 FACE="Courier New">Does this sound like a good theory? Has anybody encountered</FONT>
<BR><FONT SIZE=2 FACE="Courier New">this problem before?</FONT>
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<P><FONT SIZE=2 FACE="Courier New">Thanks</FONT>
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<P><FONT SIZE=2 FACE="Arial">--</FONT>
<BR><FONT SIZE=2 FACE="Arial">Earl Olsen</FONT>
<BR><FONT SIZE=2 FACE="Arial">Senior Software Engineer</FONT>
<BR><FONT SIZE=2 FACE="Arial">Dilithium Networks</FONT><FONT SIZE=2 FACE="Arial">, Inc.</FONT>
<BR><FONT SIZE=2 FACE="Arial">T</FONT><FONT SIZE=2 FACE="Arial">EL</FONT><FONT SIZE=2 FACE="Arial">:+1 707-792-3925</FONT>
<BR><FONT SIZE=2 FACE="Arial">e</FONT><FONT SIZE=2 FACE="Arial">arl.</FONT><FONT SIZE=2 FACE="Arial">o</FONT><FONT SIZE=2 FACE="Arial">lsen@dilithiumnetworks.com</FONT>
<BR><A HREF="file://www.dilithiumnetworks.com"><U><FONT COLOR="#0000FF" SIZE=2 FACE="Arial">www.dilithiumnetworks.com</FONT></U></A>
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