While working to improve packaging and testing of the python-pypet package, I found that very many tests (approximately half) fail due to apparent endian issues in pandas.HDFStore.

Here is a typical example:

======================================================================
ERROR: test_storage_and_loading (unittests.annotations_test.AnnotationsTest.test_storage_and_loading)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/builddir/build/BUILDROOT/python-pypet-0.5.2-30.fc40.s390x/usr/lib/python3.12/site-packages/pypet/tests/unittests/annotations_test.py", line 94, in test_storage_and_loading
    self.traj.f_store()
  File "/builddir/build/BUILDROOT/python-pypet-0.5.2-30.fc40.s390x/usr/lib/python3.12/site-packages/pypet/utils/decorators.py", line 163, in new_func
    return func(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^
  File "/builddir/build/BUILDROOT/python-pypet-0.5.2-30.fc40.s390x/usr/lib/python3.12/site-packages/pypet/utils/decorators.py", line 163, in new_func
    return func(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^
  File "/builddir/build/BUILDROOT/python-pypet-0.5.2-30.fc40.s390x/usr/lib/python3.12/site-packages/pypet/utils/decorators.py", line 121, in new_func
    return func(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^
  File "/builddir/build/BUILDROOT/python-pypet-0.5.2-30.fc40.s390x/usr/lib/python3.12/site-packages/pypet/trajectory.py", line 2872, in f_store
    self._storage_service.store(pypetconstants.TRAJECTORY, self,
  File "/builddir/build/BUILDROOT/python-pypet-0.5.2-30.fc40.s390x/usr/lib/python3.12/site-packages/pypet/storageservice.py", line 1337, in store
    self._srvc_closing_routine(opened)
  File "/builddir/build/BUILDROOT/python-pypet-0.5.2-30.fc40.s390x/usr/lib/python3.12/site-packages/pypet/storageservice.py", line 1556, in _srvc_closing_routine
    os.fsync(f_fd)
OverflowError: Python int too large to convert to C int

I suspect the file descriptor is being loaded from HDF5 with the wrong endianness. I can’t find anywhere this would be happening in pypet; I think it is a pandas.HDFStore bug. Note that pandas does not test big-endian support but will happily accept patches to improve it: https://github.com/pandas-dev/pandas/issues/4737#issuecomment-1090931741

For now, I plan to add “ExcludeArch: s390x” to python-pypet. This bug is the tracking bug required under https://docs.fedoraproject.org/en-US/packaging-guidelines/#_architecture_build_failures.