[mpich-discuss] Change in SOVERSION of mpich 3.4 ?

Alastair McKinstry mckinstry at debian.org
Wed Jan 6 03:54:35 CST 2021

Dear MPICH developers,

I see that MPICH 3.4 has been released - Happy New Year and 
congratulations to all involved.

I'm one of the Debian Maintainers of MPICH, and have a question though : 
should the SOMAJOR version not have been increased?

 From the CHANGES log, the following look concerning:

# Change the signature of MPID_Init to include requested and provided
   thread levels.

# Remove support for logical reduction operations on floating point

# Remove MPIX_Mutex interfaces.

Typically when functionality is removed from a library, or signatures 
change, the major version is incremented (the minor version can be for 
additions, such as the other functionality added. Are these changes 
purely internal to MPICH, or has the ABI changed ?

This matters to the distributions such as Debian because we ship the 
shared libs based on SOVERSION; ie the binary package "libmpich12" 
currently contains libmpich.so.12.18 and libmpich.so.12 , and if mpich 
3.4 is packaged as-is, will contain libmpich.so.12.1.9 (ansd symlink 
libmpich.so.12)  and it is necessary for applications to be able to use 
this as a drop-in replacement. On seeing these changes in the release 
logs, I had been anticipating that the next version would be 
libmpich13.0.0 (or similar), shipped in "libmpich13".  This enables 
upgrades; both libmpich12 and libmpich13  can co-exist.

Can you confirm whether the ABI changes, and this is a drop-in replacement ?


Alastair McKinstry

Alastair McKinstry, <alastair at sceal.ie>, <mckinstry at debian.org>, https://diaspora.sceal.ie/u/amckinstry
Misentropy: doubting that the Universe is becoming more disordered.

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