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<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>I have a kernel driver that uses the IB stack but is not instantiated
by the IB bus driver, so in not in the PnP tree of the hca.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>One of the little details that took some head scratching was
how to correctly get the physical address of buffers while correctly doing Windows
DMA. Currently, I have a piece of code that looks something like:<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> al_obj_t * internalHCAHandle;<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> internalHCAHandle = (al_obj_t *)hcaHandle;<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> nextLowerDevice =
IoGetAttachedDeviceReference((PDEVICE_OBJECT)(internalHCAHandle->p_ci_ca->verbs.p_hca_dev));<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>This basically does an ugly cast of a hca handle to its
internal data structure to retrieve the hca pdo device object. This all works
fine except for the little details that the shape of al_obj_t changes between a
checked build and free build. I’d love to remove this ugly code and use something
more “supported”.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Can someone suggest a better way to obtain the actual hca
device pdo (or appropriate lower device object) to pass to IoGetDMAAdapter. It
offhand seems like the IBAL interface is missing important functionality, as
you need physical addresses in QP work requests but don’t offhand see any
calls to get a dma adapter object given an hca/port? Drivers that are instantiated
by the IB bus driver automagically get put into the PnP tree of their hca, so
can just call IoGetDMAAdapter on the lower device passed to AddDevice (or the
miniport wrapper does all this on behalf of the driver for the IPoIB and SRP
drivers).<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Thanks.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Jan<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
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