The pain of porting

[sawyl]

We've spent the last few weeks battling to get versions of HDF & netCDF built and through their regression suites on the Power 7 under AIX 7.1 using the IBM XL compilers . In the process we've discovered that:

• the version of config.guess supplied with the software did not return the correct OS value for our platform causing some of the compiler and linker tests to fail in non-obvious ways
• that configure won't even try to build shared versions of the libraries unless you add -W,-brtl to LDFLAGS
• the header file supplied with GPFS v3.5 won't compile with the compiler in stdc99. To get GPFS support to work, it is necessary to add -qlanglvl=extc99 to CFLAGS
• the Fortan compiler chokes on fixed format F77 unless you set the FC environment variable to xlf_r
• the MPI-IO version of HDF5 always seems to fail its regression suite. Some of of the failures appear to be caused by our version of MPI — we've seen a number of internal "not owner" messages after an MPI_Type_commit call — and others which appear to indicate that the values being written out do not match the same values being read back in — something that isn't exactly reassuring in an IO library.

We think we've finally got all the serial stuff libraries build, both in static and shared forms, and the regression tests look OK, but it's been a long slog that required almost every nasty trick in the porting handbook...