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In trying to upgrade our build of mpich to 4. 2. 2 from 4. 1. 2, I notice that the libraries are not completely binary compatible - at least, not in the way that our system presumes will be the case. We currently support users bringing their own
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<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif;color:black">In trying to upgrade our build of mpich to 4.2.2 from 4.1.2, I notice that the libraries are not completely binary compatible - at least, not in the way that our system presumes
will be the case. We currently support users bringing their own MPI, providing it is ABI-compatible with our "primary" MPI, which is whatever current release of mpich we're using. In the past, this has meant that in practice, because nothing we do needs the
very latest functionality provided by mpich, even very old mpich-derivative MPIs would work.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif;color:black">With mpich-4.2.2, I see from the CHANGES file that many of the functions that were implemented as macros (e.g. MPI_Comm_f2c) are now "real" functions – to support the requirements
of the MPI-4.1 standard. I notice further that the implementation of those functions is basically the same as the old macro.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif;color:black">For now, I'm planning to work around this by effectively using the old macro definitions for cases where a user-supplied MPI library doesn't provide the necessary entry points.
Does that seem reasonable?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif;color:black"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif;color:black">In fact, I note this PR
<a href="https://urldefense.us/v3/__https://github.com/pmodels/mpich/pull/6711__;!!G_uCfscf7eWS!Z3GeBsC316MCjTu8YURSwe1I9OQ3wkymnX6m94M4N_viWPFXmLUnJV1U9cRUS2NzyVUG2yyB642BD1o$">https://github.com/pmodels/mpich/pull/6711</a> in which Ken Raffenetti says:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif;color:black"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif;color:black">“Just thinking from the ABI perspective, I don't think there is any backwards compatibility concern. Apps compiled when these were macros will continue to work with newer MPICH
libraries.”<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif;color:black"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif;color:black">So, I infer from that comment that the approach I’m contemplating should be fine.
<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif;color:black">I imagine the other ABI-compatible libraries listed here
<a href="https://urldefense.us/v3/__https://www.mpich.org/abi/__;!!G_uCfscf7eWS!Z3GeBsC316MCjTu8YURSwe1I9OQ3wkymnX6m94M4N_viWPFXmLUnJV1U9cRUS2NzyVUG2yyBNJ9d9P8$">https://www.mpich.org/abi/</a> will eventually adopt this change too – I don’t suppose there is any known timeline when this might happen?<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif;color:black">Cheers,<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif;color:black">Edric.<o:p></o:p></span></p>
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