path: root/release_docs/RELEASE.txt

HDF5 version 1.10.6-snap1 currently under development
================================================================================


INTRODUCTION

This document describes the differences between this release and the previous
HDF5 release. It contains information on the platforms tested and known
problems in this release. For more details check the HISTORY*.txt files in the
HDF5 source.

Note that documentation in the links below will be updated at the time of each
final release.

Links to HDF5 documentation can be found on The HDF5 web page:

     https://portal.hdfgroup.org/display/HDF5/HDF5

The official HDF5 releases can be obtained from:

     https://www.hdfgroup.org/downloads/hdf5/

Changes from Release to Release and New Features in the HDF5-1.10.x release series
can be found at:

     https://portal.hdfgroup.org/display/HDF5/HDF5+Application+Developer%27s+Guide

If you have any questions or comments, please send them to the HDF Help Desk:

     help@hdfgroup.org


CONTENTS

- New Features
- Support for new platforms and languages
- Bug Fixes since HDF5-1.10.4
- Supported Platforms
- Tested Configuration Features Summary
- More Tested Platforms
- Known Problems
- CMake vs. Autotools installations


New Features
============

    Configuration:
    -------------
    - Add option to build only shared libs

      A request was made to prevent building static libraries and only build
      shared.  A new option was added to CMake, ONLY_SHARED_LIBS, which will
      skip building static libraries. Certain utility functions will build with
      static libs but are not published. Tests are adjusted to use the correct
      libraries depending on SHARED/STATIC settings.

      (ADB - 2019/06/12, HDFFV-10805)

    - Add options to enable or disable building tools and tests
    
      Configure options --enable-tests and --enable-tools were added for 
      autotools configure.  These options are enabled by default, and can be
      disabled with either --disable-tests (or tools) or --enable-tests=no 
      (or --enable-tools=no).  Build time is reduced ~20% when tools are 
      disabled, 35% when tests are disabled, 45% when both are disabled.
      Reenabling them after the initial build requires running configure
      again with the option(s) enabled.

      (LRK - 2019/06/12, HDFFV-9976)

    - Change tools test that test the error stack

      There are some use cases which can cause the error stack of tools to be
      different then the expected output. These tests now use grepTest.cmake,
      this was changed to allow the error file to be searched for an expected string.

      (ADB - 2019/04/15, HDFFV-10741)

    - Rework CMake command files to fix MPI testing.

      Added setup fixture to remove any test generated files and added DEPENDS
      to test properties to execute tests in order expected.

      (ADB - 2019/02/14, TRILABS-111)

    - Disable SZIP or ZLIB options if TGZ files are not available.

      Changed the TGZ option for SZip and ZLib to disable the options
      if the source tar.gz files are not found.

      (ADB - 2019/02/05, HDFFV-10697)

    - Added a new option to enable/disable using pread/pwrite instead of
      read/write in the sec2, log, and core VFDs.

      This option is enabled by default when pread/pwrite are detected.

      Autotools:    --enable-preadwrite
      CMake:        HDF5_ENABLE_PREADWRITE

      (DER - 2019/02/03, HDFFV-10696)

    - Rework CMake versioning for OSX platforms.

      Changed the current_version and compatibility_version flags from optional
      with HDF5_BUILD_WITH_INSTALL_NAME to always setting the flags for OSX.

      (ADB - 2019/01/22, HDFFV-10685)

    - Rework CMake command files to eliminate developer CMP005 warning

      Use variables without quotes in if () statements.

      (ADB - 2019/01/18, TILABS-105)

    - Rework CMake configure files to eliminate developer CMP0075 warning

      Renamed varname to HDF5_REQUIRED_LIBRARIES as the contents were not
      required for configuration. Also moved check includes calls to top of
      files.

      (ADB - 2019/01/03, HDFFV-10546)

    - Keep stderr and stdout separate in tests

      Changed test handling of output capture. Tests now keep the stderr
      output separate from the stdout output. It is up to the test to decide
      which output to check against a reference. Also added the option
      to grep for a string in either output.

      (ADB - 2018/12/12, HDFFV-10632)

    - Incorrectly installed private header files were removed from
      CMake installs.

      The CMake build files incorrectly flagged the following header files
      as public and installed them. They are private and will no longer be
      installed.

        HDF5 library private package files (H5Xpkg.h)
        H5Edefin.h
        H5Einit.h
        H5Eterm.h
        H5LTparse.h
        h5diff.h
        h5tools_dump.h
        h5tools.h
        h5tools_ref.h
        h5tools_str.h
        h5tools_utils.h
        h5trav.h

      (DER - 2018/10/26, HDFFV-10614, 10609)

    - Autotools installs now install H5FDwindows.h

      This is simply to align the installed header files between the
      autotools and CMake. H5FDwindows.h has no functionality on
      non-Windows systems.

      (DER - 2018/10/26, HDFFV-10614)


    Library:
    --------
    - The sec2, log, and core VFDs can now use pread/pwrite instead of
      read/write.

      pread and pwrite do not change the file offset, a feature that was
      requested by a user working with a multi-threaded application.

      The option to configure this feature is described above.

      (DER - 2019/02/03, HDFFV-10696)

    - Add ability to minimze dataset object headers.

      Creation of many, very small datasets resulted in extensive file bloat
      due to extra space in the dataset object headers -- this space is
      allocated by default to allow for the insertion of a small number of
      attributes within the object header and not require a continuation
      block, an unnecessary provision in the target use case.

      Inform the library to expect no attributes on created datasets, and to
      allocate the least space possible for the object headers.
      NOTE: A continuation block is created if attributes are added to a
      'minimized' dataset, which can reduce performance.
      NOTE: Some extra space is allocated for attributes essential to the
      correct behavior of the object header (store creation times, e.g.). This
      does not violate the design principle, as the space is calculated and
      allocated as needed at the time of dataset object header creation --
      unused space is not generated.
      New API calls:
      H5Fget_dset_no_attrs_hint
      H5Fset_dset_no_attrs_hint
      H5Pget_dset_no_attrs_hint
      H5Pset_dset_no_attrs_hint

      (JOS - 2019/01/04, TRILAB-45)

    - Added new chunk query functions

      The following public functions were added to discover information about
      the chunks in an HDF5 file.
        herr_t H5Dget_num_chunks(dset_id, fspace_id, *nchunks)
        herr_t H5Dget_chunk_info_by_coord(dset_id, *coord, *filter_mask, *addr, *size)
        herr_t H5Dget_chunk_info(dset_id, fspace_id, index, *coord, *filter_mask, *addr, *size)

      (BMR - 2018/11/07, HDFFV-10615)

    - Several empty public header files where removed from the distribution

      The following files were empty placeholders. They are for internal
      packages that are unlikely to ever have public functionality and have
      thus been removed.

        H5Bpublic.h
        H5B2public.h
        H5FSpublic.h
        H5HFpublic.h
        H5HGpublic.h
        H5HLpublic.h

      They were only installed in CMake builds.

      (DER - 2018/10/26, HDFFV-10614)


     Parallel Library:
    -----------------
    - Changed the default behavior in parallel when reading the same dataset in its entirety
      (i.e. H5S_ALL dataset selection) which is being read by all the processes collectively.
      The dataset must be contiguous, less than 2GB, and of an atomic datatype.
      The new behavior is the HDF5 library will use an MPI_Bcast to pass the data read from
      the disk by the root process to the remain processes in the MPI communicator associated
      with the HDF5 file.

      (MSB - 2019/01/02, HDFFV-10652)

    - All MPI-1 API calls have been replaced with MPI-2 equivalents.

      This was done to better support OpenMPI, as default builds no longer
      include MPI-1 support (as of OpenMPI 4.0).

      (DER - 2018/12/30, HDFFV-10566)

    Fortran Library:
    ----------------
    - Added wrappers for dataset object header minimization calls.
      (see the note for TRILAB-45, above)

      New API calls:

      h5fget_dset_no_attrs_hint_f
      h5fset_dset_no_attrs_hint_f
      h5pget_dset_no_attrs_hint_f
      h5pset_dset_no_attrs_hint_f

      (DER - 2019/01/09, TRILAB-45)

    - Added new Fortran derived type, c_h5o_info_t, which is interoperable with
      C's h5o_info_t. This is needed for callback functions which
      pass C's h5o_info_t data type definition.

      (MSB, 2019/01/08, HDFFV-10443)

    - Added new Fortran API, H5gmtime, which converts (C) 'time_t' structure
      to Fortran DATE AND TIME storage format.

      (MSB, 2019/01/08, HDFFV-10443)

    - Added new Fortran 'fields' optional parameter to: h5ovisit_f, h5oget_info_by_name_f,
      h5oget_info, h5oget_info_by_idx and h5ovisit_by_name_f.

      (MSB, 2019/01/08, HDFFV-10443)

    C++ Library:
    ------------
    - Added new wrappers for H5Pset/get_create_intermediate_group()
        LinkCreatPropList::setCreateIntermediateGroup()
        LinkCreatPropList::getCreateIntermediateGroup()

      (BMR - 2019/04/22, HDFFV-10622)

    - Added new function to the C++ interface

      Added wrapper for H5Ovisit2:
          H5Object::visit()

      (BMR - 2019/02/14, HDFFV-10532)


    Java Library:
    ----------------
    - Fix a failure in JUnit-TestH5P on 32-bit architectures

      (JTH - 2019/04/30)

    - Rewrote the JNI error handling to be much cleaner

      (JTH - 2019/02/12)

    - Add new functions to java interface

      Added wrappers for:
      H5Fset_libver_bounds
      H5Fget_dset_no_attrs_hint/H5Fset_dset_no_attrs_hint
      H5Pget_dset_no_attrs_hint/H5Pset_dset_no_attrs_hint

      (ADB - 2019/01/07, HDFFV-10664)

    - Fix java unit tests when Time is a natural number

      Time substitution in java/test/junit.sh.in doesn't
      handle the case when Time is a natural number. Fixed
      the regular expression.

      (ADB - 2019/01/07, HDFFV-10674)

    - Duplicate the data read/write functions of Datasets for Attributes.

      Region references could not be displayed for attributes as they could
      for datasets. Datasets had overloaded read and write functions for different
      datatypes that were not available for attributes. After adding similar
      functions, attribute region references work normally.

      (ADB - 2018/12/12, HDFVIEW-4)


    Tools:
    ------
    - The h5repart -family-to-sec2 argument was changed to -family-to-single

      In order to better support other single-file VFDs which could work with
      h5repart, the -family-to-sec2 argument was renamed to -family-to-single.
      This is just a name change and the functionality of the argument has not
      changed.

      The -family-to-sec2 argument has been kept for backwards-compatibility.
      This argument should be considered deprecated.

      (DER - 2018/11/14, HDFFV-10633)

    High-Level APIs:
    ---------------
    -

    C Packet Table API
    ------------------
    -

    Internal header file
    --------------------
    -

    Documentation
    -------------
    -

Support for new platforms, languages and compilers.
=======================================
    -

Bug Fixes since HDF5-1.10.4 release
==================================

    Library
    -------
    - Fixed a bug that would cause an error or cause fill values to be
      incorrectly read from a chunked dataset using the "single chunk" index if
      the data was held in cache and there was no data on disk.

      (NAF - 2019/03/06)

    - Fixed a bug that could cause an error or cause fill values to be
      incorrectly read from a dataset that was written to using H5Dwrite_chunk
      if the dataset was not closed after writing.

      (NAF - 2019/03/06, HDFFV-10716)

    - Fixed memory leak in scale offset filter

      In a special case where the MinBits is the same as the number of bits in
      the datatype's precision, the filter's data buffer was not freed, causing
      the memory usage to grow. In general the buffer was freed correctly.  The
      Minbits are the minimal number of bits to store the data values.  Please
      see the reference manual for H5Pset_scaleoffset for the detail.

      (RL - 2019/3/4, HDFFV-10705)

    - Fix hangs with collective metadata reads during chunked dataset I/O

      In the parallel library, it was discovered that when a particular
      sequence of operations following a pattern of:

      "write to chunked dataset" -> "flush file" -> "read from dataset"

      occurred with collective metadata reads enabled, hangs could be
      observed due to certain MPI ranks not participating in the collective
      metadata reads.

      To fix the issue, collective metadata reads are now disabled during
      chunked dataset raw data I/O.

      (JTH - 2019/02/11, HDFFV-10563, HDFFV-10688)

    - Performance issue when closing an object

      The slow down is due to the search of the "tag_list" to find
      out the "corked" status of an object and "uncork" it if so.

      Improve performance by skipping the search of the "tag_list"
      if there are no "corked" objects when closing an object.

      (VC - 2019/02/06)

    - Uninitialized bytes from a type conversion buffer could be written
      to disk in H5Dwrite calls where type conversion takes place
      and the type conversion buffer was created by the HDF5 library.

      When H5Dwrite is called and datatype conversion must be performed,
      the library will create a temporary buffer for type conversion if
      one is not provided by the user via H5Pset_buffer. This internal
      buffer is allocated via malloc and contains uninitialized data. In
      some datatype conversions (float to long double, possibly others),
      some of this uninitialized data could be written to disk.

      This was flagged by valgrind in the dtransform test and does not
      appear to be a common occurrence (it is flagged in one test out
      of the entire HDF5 test suite).

      Switching to calloc fixed the problem.

      (DER - 2019/02/03, HDFFV-10694)

    - There was missing protection against division by zero reported to
      The HDF Group as issue #CVE-2018-17434.

      Protection against division by zero was added to address the issue
      #CVE-2018-17434.

      (BMR - 2019/01/29, HDFFV-10586)

    - The issue CVE-2018-17437 was reported to The HDF Group

      Although CVE-2018-17437 reported a memory leak, the actual issue
      was invalid read. It was found that the attribute name length
      in an attribute message was corrupted, which caused the buffer
      pointer to be advanced too far and later caused an invalid read.

      A check was added to detect when the attribute name or its length
      was corrupted and report the potential of data corruption.

      (BMR - 2019/01/29, HDFFV-10588)

    - H5Ewalk did not stop when it was supposed to

      H5Ewalk was supposed to stop when the callback function stopped
      even though the errors in the stack were not all visited, but it
      did not.  This problem is now fixed.

      (BMR - 2019/01/29, HDFFV-10684)

    - Revert H5Oget_info* and H5Ovisit* functions

      In 1.10.3 new H5Oget_info*2 and H5Ovisit*2 functions were
      added for performance. Inadvertently, the original functions;
          H5Oget_info,
          H5Oget_info_by_name,
          H5Oget_info_by_idx,
          H5Ovisit,
          H5Ovisit_by_name
      were versioned to H5Oget_info*1 and H5Ovisit*1. This
      broke the API compatibility for a maintenance release. The
      original functions have been restored.

      (ADB - 2019/01/24, HDFFV-10686)

    - Fixed a potential invalid memory access and failure that could occur when
      decoding an unknown object header message (from a future version of the
      library).

      (NAF - 2019/01/07)

    - Deleting attributes in dense storage

      The library aborts with "infinite loop closing library" after
      attributes in dense storage are created and then deleted.

      When deleting the attribute nodes from the name index v2 B-tree,
      if an attribute is found in the intermediate B-tree nodes,
      which may be merged/redistributed in the process, we need to
      free the dynamically allocated spaces for the intermediate
      decoded attribute.

      (VC - 2018/12/26, HDFFV-10659)

    - There was missing protection against division by zero reported to
      The HDF Group as issue #CVE-2018-17233.

      Protection against division by zero was added to address the issue
      #CVE-2018-17233.  In addition, several similar occurrences in the same
      file were fixed as well.

      (BMR - 2018/12/23, HDFFV-10577)

    - Fixed an issue where the parallel filters tests would fail
      if zlib was not available on the system. Until support can
      be added in the tests for filters beyond gzip/zlib, the tests
      will be skipped if zlib is not available.

      (JTH - 2018/12/05)

    - A bug was discovered in the parallel library where an application
      would eventually consume all of the available MPI communicators
      when continually writing to a compressed dataset in parallel. This
      was due to internal copies of an HDF5 File Access Property List,
      which each contained a copy of the MPI communicator, not being
      closed at the end of each write operation. This problem was
      exacerbated by larger numbers of processors.

      (JTH - 2018/12/05, HDFFV-10629)


    Java Library:
    ----------------
    -

    Fortran
    --------
    - Fixed issue with Fortran not returning h5o_info_t field values
      meta_size%attr%index_size and  meta_size%attr%heap_size.

      (MSB, 2019/01/08, HDFFV-10443)

    - Added symbolic links libhdf5_hl_fortran.so to libhdf5hl_fortran.so and
      libhdf5_hl_fortran.a to libhdf5hl_fortran.a in hdf5/lib directory for
      autotools installs.  These were added to match the name of the files
      installed by cmake and the general pattern of hl lib files.  We will
      change the names of the installed lib files to the matching name in
      the next major release.

      (LRK - 2019/01/04, HDFFV-10596)

    - Made Fortran specific subroutines PRIVATE in generic procedures.

      Affected generic procedures were functions in H5A, H5D, H5P, H5R and H5T.

      (MSB, 2018/12/04, HDFFV-10511)


    Tools
    -----
    -

    High-Level APIs:
    ------
    -

    Fortran High-Level APIs:
    ------
    -

    Documentation
    -------------
    -

    F90 APIs
    --------
    -

    C++ APIs
    --------
    -

    Testing
    -------
    - Fixed a test failure in testpar/t_dset.c caused by
      the test trying to use the parallel filters feature
      on MPI-2 implementations.

      (JTH, 2019/2/7)


Supported Platforms
===================

    Linux 2.6.32-696.16.1.el6.ppc64 gcc (GCC) 4.4.7 20120313 (Red Hat 4.4.7-18)
    #1 SMP ppc64 GNU/Linux        g++ (GCC) 4.4.7 20120313 (Red Hat 4.4.7-18)
    (ostrich)                     GNU Fortran (GCC) 4.4.7 20120313 (Red Hat 4.4.7-18)
                                  IBM XL C/C++ V13.1
                                  IBM XL Fortran V15.1

    Linux 3.10.0-327.10.1.el7   GNU C (gcc), Fortran (gfortran), C++ (g++)
    #1 SMP x86_64 GNU/Linux       compilers:
    (kituo/moohan)                Version 4.8.5 20150623 (Red Hat 4.8.5-4)
                                    Version 4.9.3, Version 5.2.0
                                  Intel(R) C (icc), C++ (icpc), Fortran (icc)
                                  compilers:
                                     Version 17.0.0.098 Build 20160721
                                  MPICH 3.1.4 compiled with GCC 4.9.3

    SunOS 5.11 32- and 64-bit     Sun C 5.12 SunOS_sparc
    (emu)                         Sun Fortran 95 8.6 SunOS_sparc
                                  Sun C++ 5.12 SunOS_sparc

    Windows 7                     Visual Studio 2015 w/ Intel Fortran 16 (cmake)

    Windows 7 x64                 Visual Studio 2013
                                  Visual Studio 2015 w/ Intel Fortran 16 (cmake)
                                  Visual Studio 2015 w/ Intel C, Fortran 2018 (cmake)
                                  Visual Studio 2015 w/ MSMPI 8 (cmake)

    Windows 10                    Visual Studio 2015 w/ Intel Fortran 18 (cmake)

    Windows 10 x64                Visual Studio 2015 w/ Intel Fortran 18 (cmake)
                                  Visual Studio 2017 w/ Intel Fortran 18 (cmake)

    Mac OS X Yosemite 10.10.5     Apple clang/clang++ version 6.1 from Xcode 7.0
    64-bit                        gfortran GNU Fortran (GCC) 4.9.2
    (osx1010dev/osx1010test)      Intel icc/icpc/ifort version 15.0.3

    Mac OS X El Capitan 10.11.6   Apple clang/clang++ version 7.3.0 from Xcode 7.3
    64-bit                        gfortran GNU Fortran (GCC) 5.2.0
    (osx1011dev/osx1011test)      Intel icc/icpc/ifort version 16.0.2

    Mac OS Sierra 10.12.6         Apple LLVM version 8.1.0 (clang/clang++-802.0.42)
    64-bit                        gfortran GNU Fortran (GCC) 7.1.0
    (swallow/kite)                Intel icc/icpc/ifort version 17.0.2


Tested Configuration Features Summary
=====================================

    In the tables below
          y   = tested
          n   = not tested in this release
          C   = Cluster
          W   = Workstation
          x   = not working in this release
          dna = does not apply
          ( ) = footnote appears below second table
          <blank> = testing incomplete on this feature or platform

Platform                              C         F90/   F90      C++  zlib  SZIP
                                      parallel  F2003  parallel
Solaris2.11 32-bit                      n        y/y    n        y    y     y
Solaris2.11 64-bit                      n        y/n    n        y    y     y
Windows 7                               y        y/y    n        y    y     y
Windows 7 x64                           y        y/y    y        y    y     y
Windows 7 Cygwin                        n        y/n    n        y    y     y
Windows 7 x64 Cygwin                    n        y/n    n        y    y     y
Windows 10                              y        y/y    n        y    y     y
Windows 10 x64                          y        y/y    n        y    y     y
Mac OS X Mavericks 10.9.5 64-bit        n        y/y    n        y    y     y
Mac OS X Yosemite 10.10.5 64-bit        n        y/y    n        y    y     y
Mac OS X El Capitan 10.11.6 64-bit      n        y/y    n        y    y     y
Mac OS Sierra 10.12.6 64-bit            n        y/y    n        y    y     y
CentOS 7.2 Linux 2.6.32 x86_64 PGI      n        y/y    n        y    y     y
CentOS 7.2 Linux 2.6.32 x86_64 GNU      y        y/y    y        y    y     y
CentOS 7.2 Linux 2.6.32 x86_64 Intel    n        y/y    n        y    y     y
Linux 2.6.32-573.18.1.el6.ppc64         n        y/y    n        y    y     y


Platform                                 Shared  Shared    Shared    Thread-
                                         C libs  F90 libs  C++ libs  safe
Solaris2.11 32-bit                         y       y         y         y
Solaris2.11 64-bit                         y       y         y         y
Windows 7                                  y       y         y         y
Windows 7 x64                              y       y         y         y
Windows 7 Cygwin                           n       n         n         y
Windows 7 x64 Cygwin                       n       n         n         y
Windows 10                                 y       y         y         y
Windows 10 x64                             y       y         y         y
Mac OS X Mavericks 10.9.5 64-bit           y       n         y         y
Mac OS X Yosemite 10.10.5 64-bit           y       n         y         y
Mac OS X El Capitan 10.11.6 64-bit         y       n         y         y
Mac OS Sierra 10.12.6 64-bit               y       n         y         y
CentOS 7.2 Linux 2.6.32 x86_64 PGI         y       y         y         n
CentOS 7.2 Linux 2.6.32 x86_64 GNU         y       y         y         y
CentOS 7.2 Linux 2.6.32 x86_64 Intel       y       y         y         n
Linux 2.6.32-573.18.1.el6.ppc64            y       y         y         n

Compiler versions for each platform are listed in the preceding
"Supported Platforms" table.


More Tested Platforms
=====================
The following platforms are not supported but have been tested for this release.

    Linux 2.6.32-573.22.1.el6    GNU C (gcc), Fortran (gfortran), C++ (g++)
    #1 SMP x86_64 GNU/Linux       compilers:
    (mayll/platypus)                 Version 4.4.7 20120313
                                     Version 4.9.3, 5.3.0, 6.2.0
                                  PGI C, Fortran, C++ for 64-bit target on
                                  x86-64;
                                     Version 17.10-0
                                  Intel(R) C (icc), C++ (icpc), Fortran (icc)
                                  compilers:
                                     Version 17.0.4.196 Build 20170411
                                  MPICH 3.1.4 compiled with GCC 4.9.3

    Linux 3.10.0-327.18.2.el7     GNU C (gcc) and C++ (g++) compilers
    #1 SMP x86_64 GNU/Linux          Version 4.8.5 20150623 (Red Hat 4.8.5-4)
    (jelly)                       with NAG Fortran Compiler Release 6.1(Tozai)
                                  GCC Version 7.1.0
                                  OpenMPI 3.0.0-GCC-7.2.0-2.29,
                                     3.1.0-GCC-7.2.0-2.29
                                  Intel(R) C (icc) and C++ (icpc) compilers
                                     Version 17.0.0.098 Build 20160721
                                  with NAG Fortran Compiler Release 6.1(Tozai)

    Linux 3.10.0-327.10.1.el7     MPICH 3.2 compiled with GCC 5.3.0
    #1 SMP x86_64 GNU/Linux
    (moohan)

    Linux 2.6.32-573.18.1.el6.ppc64  MPICH mpich 3.1.4 compiled with
    #1 SMP ppc64 GNU/Linux           IBM XL C/C++ for Linux, V13.1
    (ostrich)                        and IBM XL Fortran for Linux, V15.1

    Debian 8.4 3.16.0-4-amd64 #1 SMP Debian 3.16.36-1 x86_64 GNU/Linux
                                  gcc, g++ (Debian 4.9.2-10) 4.9.2
                                  GNU Fortran (Debian 4.9.2-10) 4.9.2
                                  (cmake and autotools)

    Fedora 24  4.7.2-201.fc24.x86_64 #1 SMP x86_64 x86_64 x86_64 GNU/Linux
                                  gcc, g++ (GCC) 6.1.1 20160621
                                      (Red Hat 6.1.1-3)
                                  GNU Fortran (GCC) 6.1.1 20160621
                                      (Red Hat 6.1.1-3)
                                  (cmake and autotools)

    Ubuntu 16.04.1 4.4.0-38-generic #57-Ubuntu SMP x86_64 GNU/Linux
                                  gcc, g++ (Ubuntu 5.4.0-6ubuntu1~16.04.2)
                                      5.4.0 20160609
                                  GNU Fortran (Ubuntu 5.4.0-6ubuntu1~16.04.2)
                                      5.4.0 20160609
                                  (cmake and autotools)


Known Problems
==============

    At present, metadata cache images may not be generated by parallel
    applications.  Parallel applications can read files with metadata cache
    images, but since this is a collective operation, a deadlock is possible
    if one or more processes do not participate.

    Three tests fail with OpenMPI 3.0.0/GCC-7.2.0-2.29:
        testphdf5 (ecdsetw, selnone, cchunk1, cchunk3, cchunk4, and actualio)
        t_shapesame (sscontig2)
        t_pflush1/fails on exit
    The first two tests fail attempting collective writes.

    CPP ptable test fails on VS2017 with Intel compiler, JIRA issue: HDFFV-10628.
    This test will pass with VS2015 with Intel compiler.

    Older MPI libraries such as OpenMPI 2.0.1 and MPICH 2.1.5 were tested
    while attempting to resolve the Jira issue: HDFFV-10540.
    The known problems of reading or writing > 2GBs when using MPI-2 was
    partially resolved with the MPICH library. The proposed support recognizes
    IO operations > 2GB and if the datatype is not a derived type, the library
    breaks the IO into chunks which can be input or output with the existing
    MPI 2 limitations, i.e. size reporting and function API size/count
    arguments are restricted to be 32 bit integers.  For derived types larger
    than 2GB, MPICH 2.1.5 fails while attempting to read or write data.
    OpenMPI in contrast, implements MPI-3 APIs even in the older releases
    and thus does not suffer from the 32 bit size limitation described here.
    OpenMPI releases prior to v3.1.3 appear to have other datatype issues however,
    e.g. within a single parallel test (testphdf5) the subtests (cdsetr, eidsetr)
    report data verfication errors before eventually aborting.
    The most recent versions of OpenMPI (v3.1.3 or newer) have evidently
    resolved these isses and parallel HDF5 testing does not currently report
    errors though occasional hangs have been observed.

    Known problems in previous releases can be found in the HISTORY*.txt files
    in the HDF5 source. Please report any new problems found to
    help@hdfgroup.org.


CMake vs. Autotools installations
=================================
While both build systems produce similar results, there are differences.
Each system produces the same set of folders on linux (only CMake works
on standard Windows); bin, include, lib and share. Autotools places the
COPYING and RELEASE.txt file in the root folder, CMake places them in
the share folder.

The bin folder contains the tools and the build scripts. Additionally, CMake
creates dynamic versions of the tools with the suffix "-shared". Autotools
installs one set of tools depending on the "--enable-shared" configuration
option.
  build scripts
  -------------
  Autotools: h5c++, h5cc, h5fc
  CMake: h5c++, h5cc, h5hlc++, h5hlcc

The include folder holds the header files and the fortran mod files. CMake
places the fortran mod files into separate shared and static subfolders,
while Autotools places one set of mod files into the include folder. Because
CMake produces a tools library, the header files for tools will appear in
the include folder.

The lib folder contains the library files, and CMake adds the pkgconfig
subfolder with the hdf5*.pc files used by the bin/build scripts created by
the CMake build. CMake separates the C interface code from the fortran code by
creating C-stub libraries for each Fortran library. In addition, only CMake
installs the tools library. The names of the szip libraries are different
between the build systems.

The share folder will have the most differences because CMake builds include
a number of CMake specific files for support of CMake's find_package and support
for the HDF5 Examples CMake project.