[ewg] OFED 1.2 and backwards binary compatibility

[Roland Dreier]

 > Is intended that OFED 1.2 verbs library aren't binary backwards compatible ? In 1.2-rc4 libraries are still called :
 >  
 > /usr/lib/libibverbs.so.1
 > /usr/lib/libibverbs.so.1.0.0
 > /usr/lib64/libibverbs.so.1
 > /usr/lib64/libibverbs.so.1.0.0
 > 
 > Which is the same as in 1.0 and 1.1 and this indicates binary compatibility (at least to a naive user like myself).
 > 
 > The problem though is that I have applications compiled with OFED 1.0 and 1.1 (those releases are binary compatible btw, as far as my testing goes) that hang when running on OFED 1.2...

The intention is that libibverbs 1.0 and 1.1 *are* binary compatible
via a versioned ABI.  Applications linked against libibverbs 1.0 will
link against the IBVERBS_1.0 ABI, and should still work when run with
libibverbs 1.1.

It would be useful to get more information about where and how your
applications hang.  During development of the compatibility code of
libibverbs 1.1, I tested various things such as building Open MPI
against libibverbs 1.0 and running with libibverbs 1.1, and it all
worked.  However it's quite possible that there are bugs in the ABI
compatibility code.

 - R.