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<p class="MsoNormal"><span style="color:#1F497D">Hi,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">This is Han Lung, Director of HPC Group, Fujitsu America, Inc.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">I am working on WRF 3.7+PNetcdf 1.3.0 and got some errors. The test case is conus12km.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">I was told by wrfhelp that this error is related to internal of PNetCDF, so I am writing to you and hope I can get some help from you.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">I traced the error to ncmpix_put_size_t(void **xpp, const MPI_Offset lp, int sizeof_t) in ncx.c of parallel-netcdf-1.3.0. Here is the part of the code that caused the error:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"> <o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"> <o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">#ifdef WORDS_BIGENDIAN<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"> MPI_Offset *ptr = (MPI_Offset*) (*xpp); /* typecast to 8-byte integer */<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"> *ptr = lp; <span class="apple-converted-space">
</span></span><span style="font-family:Wingdings;color:red">ç</span><span class="apple-converted-space"><span style="color:red"> </span></span><span style="color:red">error here</span><span style="color:#1F497D"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">#else<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"> ……<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"> <o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">This is an operation for 8-byte integer lp (sizeof_t = 8). However, *xpp is incremented each time by 4 or 8, depending on sizeof_t: *xpp = (void *)((char *)(*xpp) + sizeof_t);<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"> <o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Now when *xpp is not on 8-byte boundary (due to previous operation of 4-byte increment) the operation "*ptr = lp;" will cause the address not aligned error (BUS_ADRALN). <o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">In my case, for most of the time, sizeof_t is 4, and there is no problem. The first two times when sizeof_t is 8, *xpp is 591725472 and 591725720, respectively, which are at 8-byte boundary, so there is no problem,
either. The third time when sizeof_t is 8, *xpp is 591725972, which is not at 8-byte boundary, and that caused the problem.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">I modified ncx.c to pad a 4-byte space if it’s not on 8-byte boundary. It did solve this mis-alignment problem but died at the free() call later. I am also not sure if this padding is a right approach since
the padded parts are all garbage.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Do you see this kind of error before? Any advice on how to resolve it?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Thanks,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Han<o:p></o:p></span></p>
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