path: root/release_docs/RELEASE.txt

HDF5 version 1.10.7-1 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
- Bug Fixes since HDF5-1.10.6
- Supported Platforms
- Tested Configuration Features Summary
- More Tested Platforms
- Known Problems
- CMake vs. Autotools installations


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

    Configuration:
    -------------
    - Disable memory sanity checks in the Autotools in release branches

      The library can be configured to use internal memory sanity checking,
      which replaces C API calls like malloc(3) and free(3) with our own calls
      which add things like heap canaries. These canaries can cause problems
      when external filter plugins reallocate canary-marked buffers.

      For this reason, the default will be to not use the memory allocation
      sanity check feature in release branches (e.g., hdf5_1_10_7).
      Debug builds in development branches (e.g., develop, hdf5_1_10) will
      still use them by default.

      This change only affects Autotools debug builds. Non-debug autotools
      builds and all CMake builds do not enable this feature by default.

      (DER - 2020/08/19)

    - Add file locking configure and CMake options

      HDF5 1.10.0 introduced a file locking scheme, primarily to help
      enforce SWMR setup. Formerly, the only user-level control of the scheme
      was via the HDF5_USE_FILE_LOCKING environment variable.

      This change introduces configure-time options that control whether
      or not file locking will be used and whether or not the library
      ignores errors when locking has been disabled on the file system
      (useful on some HPC Lustre installations).

      In both the Autotools and CMake, the settings have the effect of changing
      the default property list settings (see the H5Pset/get_file_locking()
      entry, below).

      The yes/no/best-effort file locking configure setting has also been
      added to the libhdf5.settings file.

      Autotools:

        An --enable-file-locking=(yes|no|best-effort) option has been added.

        yes:          Use file locking.
        no:           Do not use file locking.
        best-effort:  Use file locking and ignore "disabled" errors.

      CMake:

        Two self-explanatory options have been added:

        HDF5_USE_FILE_LOCKING
        HDF5_IGNORE_DISABLED_FILE_LOCKS

        Setting both of these to ON is the equivalent to the Autotools'
        best-effort setting.

      NOTE:
      The precedence order of the various file locking control mechanisms is:

        1) HDF5_USE_FILE_LOCKING environment variable (highest)

        2) H5Pset_file_locking()

        3) configure/CMake options (which set the property list defaults)

        4) library defaults (currently best-effort)

      (DER - 2020/07/30, HDFFV-11092)

    - CMake option to link the generated Fortran MOD files into the include
      directory.

      The Fortran generation of MOD files by a Fortran compile can produce
      different binary files between SHARED and STATIC compiles with different
      compilers and/or different platforms. Note that it has been found that
      different versions of Fortran compilers will produce incompatible MOD
      files. Currently, CMake will locate these MOD files in subfolders of
      the include directory and add that path to the Fortran library target
      in the CMake config file, which can be used by the CMake find library
      process. For other build systems using the binary from a CMake install,
      a new CMake configuration can be used to copy the pre-chosen version
      of the Fortran MOD files into the install include directory.

      The default will depend on the configuration of
      BUILD_STATIC_LIBS and BUILD_SHARED_LIBS:
            YES                   YES         Default to SHARED
            YES                   NO          Default to STATIC
            NO                    YES         Default to SHARED
            NO                    NO          Default to SHARED
      The defaults can be overriden by setting the config option
         HDF5_INSTALL_MOD_FORTRAN to one of NO, SHARED, or STATIC

      (ADB - 2020/07/09, HDFFV-11116)

    - CMake option to use AEC (open source SZip) library instead of SZip

      The open source AEC library is a replacement library for SZip. In
      order to use it for hdf5, the libaec CMake source was changed to add
      "-fPIC" and exclude test files. A new option USE_LIBAEC is required
      to compensate for the different files produced by AEC build.

      Autotools does not build the compression libraries within hdf5 builds, 
      but will use an installed libaec when configured as before with the 
      option --with-libsz=<path to libaec directory>.

      (ADB - 2020/04/22, OESS-65)

    - CMake ConfigureChecks.cmake file now uses CHECK_STRUCT_HAS_MEMBER

      Some handcrafted tests in HDFTests.c have been removed and the CMake
      CHECK_STRUCT_HAS_MEMBER module has been used.

      (ADB - 2020/03/24, TRILAB-24)

    - Both build systems use same set of warnings flags

      GNU C, C++ and gfortran warnings flags were moved to files in a config
      sub-folder named gnu-warnings. Flags that only are available for a specific
      version of the compiler are in files named with that version.
      Clang C warnings flags were moved to files in a config sub-folder
      named clang-warnings.
      Intel C, Fortran warnings flags were moved to files in a config sub-folder
      named intel-warnings.

      There are flags in named "error-xxx" files with warnings that may
      be promoted to errors. Some source files may still need fixes.

      There are also pairs of files named "developer-xxx" and "no-developer-xxx"
      that are chosen by the CMake option:HDF5_ENABLE_DEV_WARNINGS or the
      configure option:--enable-developer-warnings.

      In addition, CMake no longer applies these warnings for examples.

      (ADB - 2020/03/24, TRILAB-192)

    - Update CMake minimum version to 3.12

      Updated CMake minimum version to 3.12 and added version checks
      for Windows features.

      (ADB - 2020/02/05, TRILABS-142)

    - Fixed CMake include properties for Fortran libraries

      Corrected the library properties for Fortran to use the
      correct path for the Fortran module files.

      (ADB - 2020/02/04, HDFFV-11012)

    - Added common warnings files for gnu and intel

      Added warnings files to use one common set of flags
      during configure for both autotools and CMake build
      systems. The initial implementation only affects a
      general set of flags for gnu and intel compilers.

      (ADB - 2020/01/17)

    - Added new options to CMake for control of testing

      Added CMake options (default ON);
          HDF5_TEST_SERIAL AND/OR HDF5_TEST_PARALLEL
          combined with:
            HDF5_TEST_TOOLS
            HDF5_TEST_EXAMPLES
            HDF5_TEST_SWMR
            HDF5_TEST_FORTRAN
            HDF5_TEST_CPP
            HDF5_TEST_JAVA

      (ADB - 2020/01/15, HDFFV-11001)

    - Added Clang sanitizers to CMake for analyzer support if compiler is clang.

      Added CMake code and files to execute the Clang sanitizers if
      HDF5_ENABLE_SANITIZERS is enabled and the USE_SANITIZER option
      is set to one of the following:
          Address
          Memory
          MemoryWithOrigins
          Undefined
          Thread
          Leak
          'Address;Undefined'

      (ADB - 2019/12/12, TRILAB-135)


    Library:
    --------
    - Add metadata cache optimization to reduce skip list usage

      On file flush or close, the metadata cache attempts to write out
      all dirty entries in increasing address order.  To do this, it needs
      an address sorted list of metadata entries.  Further, since flushing
      one metadata cache entry can dirty another, this list must support 
      efficient insertion and deletion.

      The metadata cache uses a skip list of all dirty entries for this 
      purpose.  Before this release, this skip list was maintained at all 
      times.  However, since profiling indicates that this imposes a 
      significant cost, we now construct and maintain the skip list only 
      when needed.  Specifically, we enable the skip list and load it with 
      a list of all dirty entries in the metadata cache just before a flush, 
      and disable it after the flush.

      (JRM - 2020/08/17, HDFFV-11034)

    - Add BEST_EFFORT value to HDF5_USE_FILE_LOCKING environment variable

      This change adds a BEST_EFFORT to the TRUE/FALSE, 1/0 settings that
      were previously accepted. This option turns on file locking but
      ignores locking errors when the library detects that file locking
      has been disabled on a file system (useful on some HPC Lustre
      installations).

      The capitalization of BEST_EFFORT is mandatory.

      See the configure option discussion for HDFFV-11092 (above) for more
      information on the file locking feature and how it's controlled.

      (DER - 2020/07/30, HDFFV-11092)


    - Add H5Pset/get_file_locking() API calls

      This change adds new API calls which can be used to set or get the
      file locking parameters. The single API call sets both the "use file
      locking" flag and the "ignore disabled file locking" flag.

      When opening a file multiple times without closing, the file MUST be
      opened with the same file locking settings. Opening a file with different
      file locking settings will fail (this is similar to the behavior of
      H5Pset_fclose_degree()).

      See the configure option discussion for HDFFV-11092 (above) for more
      information on the file locking feature and how it's controlled.

      (DER - 2020/07/30, HDFFV-11092)

    - Add Mirror VFD

      Use TCP/IP sockets to perform write-only (W/O) file I/O on a remote
      machine. Must be used in conjunction with the Splitter VFD.

      (JOS - 2020/03/13, TBD)

    - Add Splitter VFD

      Maintain separate R/W and W/O channels for "concurrent" file writes
      to two files using a single HDF5 file handle.

      (JOS - 2020/03/13, TBD)

    - Fixed an assertion failure in the parallel library when collectively
      filling chunks. As it is required that chunks be written in
      monotonically non-decreasing order of offset in the file, this assertion
      was being triggered when the list of chunk file space allocations being
      passed to the collective chunk filling routine was not sorted according
      to this particular requirement.

      The addition of a sort of the out of order chunks trades a bit of
      performance for the elimination of this assertion and of any complaints
      from MPI implementations about the file offsets used being out of order.

      (JTH - 2019/10/07)

    Fortran Library:
    ----------------
    - Add wrappers for H5Pset/get_file_locking() API calls

      h5pget_file_locking_f()
      h5pset_file_locking_f()

      See the configure option discussion for HDFFV-11092 (above) for more
      information on the file locking feature and how it's controlled.

      (DER - 2020/07/30, HDFFV-11092)

    - Added new Fortran parameters:

        H5F_LIBVER_ERROR_F
        H5F_LIBVER_NBOUNDS_F
        H5F_LIBVER_V18_F
        H5F_LIBVER_V110_F

    - Added new Fortran API: h5pget_libver_bounds_f

      (MSB - 2020/02/11, HDFFV-11018)

    C++ Library:
    ------------
    - Add wrappers for H5Pset/get_file_locking() API calls

      FileAccPropList::setFileLocking()
      FileAccPropList::getFileLocking()

      See the configure option discussion for HDFFV-11092 (above) for more
      information on the file locking feature and how it's controlled.

      (DER - 2020/07/30, HDFFV-11092)

    Java Library:
    ----------------
    - Add wrappers for H5Pset/get_file_locking() API calls

      H5Pset_file_locking()
      H5Pget_use_file_locking()
      H5Pget_ignore_disabled_file_locking()

      Unlike the C++ and Fortran wrappers, there are separate getters for the
      two file locking settings, each of which returns a boolean value.

      See the configure option discussion for HDFFV-11092 (above) for more
      information on the file locking feature and how it's controlled.

      (DER - 2020/07/30, HDFFV-11092)

    Tools:
    ------
    - h5repack added options to control how external links are handled.

      Currently h5repack preserves external links and cannot copy and merge
      data from the external files. Two options, merge and prune, were added to
      control how to merge data from an external link into the resulting file.
       --merge             Follow external soft link recursively and merge data.
       --prune             Do not follow external soft links and remove link.
       --merge --prune     Follow external link, merge data and remove dangling link.

      (ADB - 2020/08/05, HDFFV-9984)


Bug Fixes since HDF5-1.10.6 release
==================================

    Library
    -------
    - Avoid setting up complex MPI types with 0-length vectors, which some
        MPI implementations don't handle well.  (In particular, IBM
        SpectrumScale MPI on the Summit system at ORNL)

      (QAK - 2020/08/21)

    - Fixed use-of-uninitialized-value error

      Appropriate initialization of local structs was added to remove the
      use-of-uninitialized-value errors reported by MemorySanitizer.

      (BMR - 2020/8/13, HDFFV-11101)

    - Creation of dataset with optional filter

      When the combination of type, space, etc doesn't work for filter
      and the filter is optional, it was supposed to be skipped but it was
      not skipped and the creation failed.

      A fix is applied to allow the creation of a dataset in such
      situation, as specified in the user documentation.

      (BMR - 2020/8/13, HDFFV-10933)

    - Explicitly declared dlopen to use RTLD_LOCAL

      dlopen documentation states that if neither RTLD_GLOBAL nor
      RTLD_LOCAL are specified, then the default behavior is unspecified.
      The default on linux is usually RTLD_LOCAL while macos will default
      to RTLD_GLOBAL.

      (ADB - 2020/08/12, HDFFV-11127)

    - Fixed issues CVE-2018-13870 and CVE-2018-13869

      When a buffer overflow occurred because a name length was corrupted
      and became very large, h5dump crashed on memory access violation.

      A check for reading past the end of the buffer was added to multiple
      locations to prevent the crashes and h5dump now simply fails with an
      error message when this error condition occurs.

      (BMR - 2020/7/31, HDFFV-11120 and HDFFV-11121)

    - Fixed the segmentation fault when reading attributes with multiple threads

      It was reported that the reading of attributes with variable length string
      datatype will crash with segmentation fault particularly when the number 
      of threads is high (>16 threads).  The problem was due to the file pointer 
      that was set in the variable length string datatype for the attribute.  
      That file pointer was already closed when the attribute was accessed.

      The problem was fixed by setting the file pointer to the current opened 
      file pointer when the attribute was accessed.  Similar patch up was done 
      before when reading dataset with variable length string datatype.

      (VC - 2020/07/13, HDFFV-11080)

    -  Fixed issue CVE-2018-17438 

      A division by zero was discovered in H5D__select_io() of H5Dselect.c.
        https://security-tracker.debian.org/tracker/CVE-2018-17438

      A check was added to protect against division by zero.  When such
      situation occurs again, the normal HDF5 error handling will be invoked,
      instead of segmentation fault.

      (BMR, DER - 2020/07/09, HDFFV-10587)

    - Fixed CVE-2018-17435

      The tool h52gif produced a segfault when the size of an attribute message 
      was corrupted and caused a buffer overflow.

      The problem was fixed by verifying the attribute message's size against the 
      buffer size before accessing the buffer.  h52gif was also fixed to display
      the failure instead of silently exiting after the segfault was eliminated.

      (BMR - 2020/6/19, HDFFV-10591)

    - Improved peformance when creating a large number of small datasets by
      retrieving default property values from the API context instead of doing
      skip list searches.

      (CJH - 2019/12/10, HDFFV-10658)

    - Fixed user-created data access properties not existing in the property list
      returned by H5Dget_access_plist. Thanks to Steven Varga for submitting a
      reproducer and a patch.

      (CJH - 2019/12/9, HDFFV-10934)

    - Fixed a bug caused by bad tag value when condensing object header
      messages

      There was an assertion failure when moving meessages from running a
      user test program with library release hdf5.1.10.4. It was because
      the tag value (object header's address) was not set up when entering
      the library routine H5O__chunk_update_idx(), which will eventually
      verifies the metadata tag value when protecting the object header.

      The problem was fixed by replacing FUNC_ENTER_PACKAGE in H5O__chunk_update_idx()
      with FUNC_ENTER_PACKAGE_TAG(oh->cache_info.addr) to set up the metadata tag.

      (VC - 2019/08/23, HDFFV-10873)

    - Fixed the test failure from test_metadata_read_retry_info() in
      test/swmr.c

      The test failure is due to the incorrect number of bins returned for
      retry info (info.nbins).  The # of bins expected for 101 read attempts
      is 3 instead of 2.  The routine H5F_set_retries() in src/H5Fint.c
      calculates the # of bins by first obtaining the log10 value for
      (read attempts - 1).  For PGI/19, the log10 value for 100 read attempts
      is 1.9999999999999998 instead of 2.00000.  When casting the log10 value
      to unsigned later on, the decimal part is chopped off causing the test
      failure.

      This was fixed by obtaining the rounded integer value (HDceil) for the
      log10 value of read attempts first before casting the result to unsigned.

      (VC - 2019/8/14, HDFFV-10813)

    - Fixed an issue where creating a file with non-default file space info
      together with library high bound setting to H5F_LIBVER_V18.

      When setting non-default file space info in fcpl via
      H5Pset_file_space_strategy() and then creating a file with
      both high and low library bounds set to
      H5F_LIBVER_V18 in fapl, the library succeeds in creating the file.
      File creation should fail because the feature of setting non-default
      file space info does not exist in library release 1.8 or earlier.

      This was fixed by setting and checking the proper version in the
      file space info message based on the library low and high bounds
      when creating and opening the HDF5 file.

      (VC - 2019/6/25, HDFFV-10808)

    - Fixed an issue where copying a version 1.8 dataset between files using
      H5Ocopy fails due to an incompatible fill version

      When using the HDF5 1.10.x H5Ocopy() API call to copy a version 1.8
      dataset to a file created with both high and low library bounds set to
      H5F_LIBVER_V18, the H5Ocopy() call will fail with the error stack indicating
      that the fill value version is out of bounds.

      This was fixed by changing the fill value message version to H5O_FILL_VERSION_3
      (from H5O_FILL_VERSION_2) for H5F_LIBVER_V18.

      (VC - 2019/6/14, HDFFV-10800)

    - 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)

    - fcntl(2)-based file locking incorrectly passed the lock argument struct
      instead of a pointer to the struct, causing errors on systems where
      flock(2) is not available.

      File locking is used when files are opened to enforce SWMR semantics. A
      lock operation takes place on all file opens unless the
      HDF5_USE_FILE_LOCKING environment variable is set to the string "FALSE".
      flock(2) is preferentially used, with fcntl(2) locks as a backup if
      flock(2) is unavailable on a system (if neither is available, the lock
      operation fails). On these systems, the file lock will often fail, which
      causes HDF5 to not open the file and report an error.

      This bug only affects POSIX systems. Win32 builds on Windows use a no-op
      locking call which always succeeds. Systems which exhibit this bug will
      have H5_HAVE_FCNTL defined but not H5_HAVE_FLOCK in the configure output.

      This bug affects HDF5 1.10.0 through 1.10.5.

      fcntl(2)-based file locking now correctly passes the struct pointer.

      (DER - 2019/08/27, HDFFV-10892)

    - Inappropriate linking with deprecated MPI C++ libraries

      HDF5 does not define *_SKIP_MPICXX in the public headers, so applications
      can inadvertently wind up linking to the deprecated MPI C++ wrappers.

      MPICH_SKIP_MPICXX and OMPI_SKIP_MPICXX have both been defined in H5public.h
      so this should no longer be an issue. HDF5 makes no use of the deprecated
      MPI C++ wrappers.

      (DER - 2019/09/17, HDFFV-10893)

    - Don't allocate an empty (0-dimensioned) chunked dataset's chunk
      index, until the dataset's dimensions are increased.

      (QAK - 2020/05/07)

    - H5Sset_extent_none() sets the dataspace class to H5S_NO_CLASS which
      causes asserts/errors when passed to other dataspace API calls.

      H5S_NO_CLASS is an internal class value that should not have been
      exposed via a public API call.

      In debug builds of the library, this can cause asserts to trip. In
      non-debug builds, it will produce normal library errors.

      The new library behavior is for H5Sset_extent_none() to convert
      the dataspace into one of type H5S_NULL, which is better handled
      by the library and easier for developers to reason about.

      (DER - 2020/07/27, HDFFV-11027)


    Configuration
    -------------
    - Stopped addition of szip header and include directory path for 
      incompatible libsz

      szlib.h is the same for both 32-bit and 64-bit szip, and the header file
      and its path were added to the HDF5 binary even though the configure
      check of a function in libsz later failed and szip compression was not
      enabled.  The header file and include path are now added only when the 
      libsz function passes the configure check.

      (LRK - 2020/08/17, HDFFV-10830)

    - Added -fsanitize=address autotools configure option for Clang compiler

      Clang sanitizer options were also added for Clang compilers with CMake.

      (LRK, 2020/08/05, HDFFV-10836)

    - Updated testh5cc.sh.in for functions versioned in HDF5 1.10.

      testh5cc.sh previously tested that the correct version of a function 
      versioned in HDF5 1.6 or 1.8 was compiled when one of 
      H5_NO_DEPRECATED_SYMBOLS or H5_USE_16_API_DEFAULT were defined.  This
      test was extended for additional testing with H5_USE_18_API_DEFAULT. 

      (LRK, 2020/06/22, HDFFV-11000)

    - Fixed CMake include properties for Fortran libraries

      Corrected the library properties for Fortran to use the
      correct path for the Fortran module files.

      (ADB - 2020/02/04, HDFFV-11012)

    - Correct option for default API version

      CMake options for default API version are not mutually exclusive.
      Change the multiple BOOL options to a single STRING option with the
      strings; v16, v18, v110.

      (ADB - 2019/08/12, HDFFV-10879)

    Fortran
    --------
    - Corrected INTERFACE INTENT(IN) to INTENT(OUT) for buf_size in h5fget_file_image_f.

      (MSB - 2020/2/18, HDFFV-11029)

    - Fixed configure issue when building HDF5 with NAG Fortran 7.0.

      HDF5 now accounts for the addition of half-precision floating-point
      in NAG 7.0 with a KIND=16.

      (MSB - 2020/02/28, HDFFV-11033)

    Tools
    -----
    - The tools library was updated by standardizing the error stack process.

      General sequence is:
          h5tools_setprogname(PROGRAMNAME);
          h5tools_setstatus(EXIT_SUCCESS);
          h5tools_init();
          ... process the command-line (check for error-stack enable) ...
          h5tools_error_report();
          ... (do work) ...
          h5diff_exit(ret);

      (ADB - 2020/07/20, HDFFV-11066)

    - h5diff fixed a command line parsing error.

      h5diff would ignore the argument to -d (delta) if it is smaller than DBL_EPSILON.
      The macro H5_DBL_ABS_EQUAL was removed and a direct value comparision was used.

      (ADB - 2020/07/20, HDFFV-10897)

    - h5diff added a command line option to ignore attributes.

      h5diff would ignore all objects with a supplied path if the exclude-path argument is used.
      Adding the exclude-attribute argument will only eclude attributes, with the supplied path,
      from comparision.

      (ADB - 2020/07/20, HDFFV-5935)

    - h5diff added another level to the verbose argument to print filenames.

      Added verbose level 3 that is level 2 plus the filenames. The levels are:
          0 : Identical to '-v' or '--verbose'
          1 : All level 0 information plus one-line attribute status summary
          2 : All level 1 information plus extended attribute status report
          3 : All level 2 information plus file names

      (ADB - 2020/07/20, HDFFV-10005)

    - h5repack was fixed to repack the reference attributes properly.
      The code line that checks if the update of reference inside a compound
      datatype is misplaced outside the code block loop that carries out the
      check. In consequence, the next attribute that is not the reference
      type was repacked again as the reference type and caused the failure of
      repacking. The fix is to move the corresponding code line to the correct
      code block.

      (KY -2020/02/10, HDFFV-11014)

    - h5repack was fixed to repack datasets with external storage
      to other types of storage.

      New test added to repack files and verify the correct data using h5diff.

      (JS - 2019/09/25, HDFFV-10408)
      (ADB - 2019/10/02, HDFFV-10918)


    High-Level APIs:
    ------
    - The H5DSis_scale function was updated to return "not a dimension scale" (0)
      instead of failing (-1), when CLASS or DIMENSION_SCALE attributes are 
      not written according to Dimension Scales Specification. 

     (EIP - 2020/08/12, HDFFV-10436)


    Testing
    -------
    - Stopped java/test/junit.sh.in installing libs for testing under ${prefix}

      Lib files needed are now copied to a subdirectory in the java/test
      directory, and on Macs the loader path for libhdf5.xxxs.so is changed
      in the temporary copy of libhdf5_java.dylib.

      (LRK, 2020/7/2, HDFFV-11063)


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

    Linux 3.10.0-1127.10.1.el7    gcc (GCC) 4.8.5 20150623 (Red Hat 4.8.5-39)
    #1 SMP ppc64 GNU/Linux        g++ (GCC) 4.8.5 20150623 (Red Hat 4.8.5-39)
    (echidna)                     GNU Fortran (GCC) 4.8.5 20150623 (Red Hat 4.8.5-39)

    Linux 2.6.32-754.31.1.el6     IBM XL C/C++ V13.1
    #1 SMP ppc64 GNU/Linux        IBM XL Fortran V15.1
    (ostrich)

    Linux 3.10.0-327.18.2.el7     GNU C (gcc), Fortran (gfortran), C++ (g++)
    #1 SMP x86_64 GNU/Linux       compilers:
    (jelly/kituo/moohan)          Version 4.8.5 20150623 (Red Hat 4.8.5-4)
                                    Version 4.9.3, Version 5.3.0, Version 6.3.0,
                                    Version 7.2.0, Version 8.3.0, Version 9.1.0
                                  Intel(R) C (icc), C++ (icpc), Fortran (icc)
                                  compilers:
                                     Version 17.0.0.098 Build 20160721
                                  MPICH 3.3 compiled with GCC 7.2.0
                                  OpenMPI 4.0.0 compiled with GCC 7.2.0

    SunOS 5.11 11.4.5.12.5.0      Sun C 5.15 SunOS_sparc 2017/05/30
    32- and 64-bit                Studio 12.6 Fortran 95 8.8 SunOS_sparc 2017/05/30
    (hedgehog)                    Sun C++ 5.15 SunOS_sparc 2017/05/30

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

    Windows 10 x64                Visual Studio 2015 w/ Intel Fortran 18 (cmake)
                                  Visual Studio 2017 w/ Intel Fortran 19 (cmake)
                                  Visual Studio 2019 w/ Intel Fortran 19 (cmake)
                                  Visual Studio 2019 w/ MSMPI 10.1 (cmake)

    macOS Mojave 10.14.6          Apple LLVM version 10.0.1 (clang-1001.0.46.4)
    64-bit                        gfortran GNU Fortran (GCC) 6.3.0
    (swallow)                     Intel icc/icpc/ifort version 19.0.4.233 20190416

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 x64                           y        y/y    y        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 El Capitan 10.11.6 64-bit      n        y/y    n        y    y     y
MacOS Sierra 10.12.6 64-bit             n        y/y    n        y    y     y
MacOS High Sierra 10.13.6 64-bit        n        y/y    n        y    y     y
MacOS Mojave 10.14.6 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 x64                              y       y         y         y
Windows 10                                 y       y         y         y
Windows 10 x64                             y       y         y         y
Mac OS X El Capitan 10.11.6 64-bit         y       n         y         y
MacOS Sierra 10.12.6 64-bit                y       n         y         y
MacOS High Sierra 10.13.6 64-bit           y       n         y         y
MacOS Mojave 10.14.6 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:
    (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 19.10-0
                                  MPICH 3.1.4 compiled with GCC 4.9.3

    Linux 2.6.32-754.31.1.el6     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)

    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 2.1.6-GCC-7.2.0-2.29,
                                     3.1.3-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 3.1.4 compiled with GCC 4.9.3
    #1 SMP x86_64 GNU/Linux
    (moohan)

    Linux-3.10.0-1127.0.0.1chaos  openmpi-4.0.0
    #1 SMP x86_64 GNU/Linux           clang/3.9.0, 8.0.1
    (quartz)                          gcc/7.3.0, 8.1.0
                                      intel/16.0.4

    Linux-4.14.0-115.10.1.1       spectrum-mpi/rolling-release
    #1 SMP ppc64le GNU/Linux          clang/coral-2018.08.08
    (lassen)                          gcc/7.3.1
                                      xl/2019.02.07

    Linux-4.12.14-150.52-default  cray-mpich/7.7.10
    #1 SMP x86_64 GNU/Linux           gcc/7.3.0, 8.2.0
    (cori)                            intel/19.0.3

    Linux-4.4.180-94.107-default  cray-mpich/7.7.6
    # 1SMP x86_64 GNU/Linux           gcc/7.2.0, 8.2.0
    (mutrino)                         intel/17.0.4, 18.0.2, 19.0.4

    Fedora 32 5.7.15-200.fc32.x86_64  Clang version 10.0.0 (Fedora 10.0.0-2.fc32)
    #1 SMP x86_64  GNU/Linux      GNU gcc (GCC) 10.2.1 20200723 (Red Hat 10.2.1-1)
                                  GNU Fortran (GCC) 10.2.1 20200723 (Red Hat 10.2.1)
                                     (cmake and autotools)

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

    macOS Sierra 10.12.6          Apple LLVM version 9.0.0 (clang-900.39.2)
    64-bit                        gfortran GNU Fortran (GCC) 7.4.0
    (kite)                        Intel icc/icpc/ifort version 17.0.2

    macOS High Sierra 10.13.6     Apple LLVM version 10.0.0 (clang-1000.10.44.4)
    64-bit                        gfortran GNU Fortran (GCC) 6.3.0
    (bear)                        Intel icc/icpc/ifort version 19.0.4.233 20190416

    SunOS 5.11 11.3               Sun C 5.15 SunOS_sparc
    32- and 64-bit                Sun Fortran 95 8.8 SunOS_sparc
    (emu)                         Sun C++ 5.15 SunOS_sparc


Known Problems
==============
    CMake files do not behave correctly with paths containing spaces.
    Do not use spaces in paths because the required escaping for handling spaces
    results in very complex and fragile build files.
    ADB - 2019/05/07

    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.

    Two tests fail attempting collective writes with OpenMPI 3.0.0/GCC-7.2.0-2.29:
        testphdf5 (ecdsetw, selnone, cchunk1, cchunk3, cchunk4, and actualio)
        t_shapesame (sscontig2)

    CPP ptable test fails on both VS2017 and VS2019 with Intel compiler, JIRA
    issue: HDFFV-10628.  This test will pass with VS2015 with Intel compiler.

    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
the share folder.

The bin folder contains the tools and the build scripts. Additionally, 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.