devreal · joe-explr · Oct 21, 2025 · Oct 24, 2025 · Oct 24, 2025 · Oct 25, 2025
diff --git a/.ci/mellanox/README.md b/.ci/mellanox/README.md
@@ -6,7 +6,7 @@
 CI is managed by [Azure Pipelines](https://docs.microsoft.com/en-us/azure/devops/pipelines/?view=azure-devops) service.
 
 Mellanox Open MPI CI includes:
-* Open MPI building with internal stable engineering versions of UCX and HCOLL. The building is run in Docker-based environment.
+* Open MPI building with internal stable engineering versions of UCX. The building is run in Docker-based environment.
 * Sanity functional testing.
 ### How to Run CI
 Mellanox Open MPI CI is triggered upon the following events:

diff --git a/.github/workflows/compile-examples.yaml b/.github/workflows/compile-examples.yaml
@@ -0,0 +1,19 @@
+name: Compile ignored components
+
+on: [pull_request]
+
+jobs:
+  compile-ignored:
+    runs-on: ubuntu-24.04
+    steps:
+    - uses: actions/checkout@v4
+      with:
+            submodules: recursive
+    - name: Remove .opal_ignore files so that we build all examples
+      run: |
+        find . -name .opal_ignore -exec rm -f {} \; -print
+    - name: Build Open MPI
+      run: |
+        ./autogen.pl
+        ./configure --prefix=${PWD}/install --disable-silent-rules
+        make -j
diff --git a/.github/workflows/hdf5-tests.yaml b/.github/workflows/hdf5-tests.yaml
@@ -20,9 +20,9 @@ jobs:
         make -j 8 && make install
     - name: Install HDF5
       run: |
-         wget --progress=dot:giga https://github.com/HDFGroup/hdf5/releases/latest/download/hdf5.tar.gz
-         tar -xzf hdf5.tar.gz
-         mv hdf5-1* hdf5
+         wget --progress=dot:giga https://github.com/HDFGroup/hdf5/releases/download/hdf5_1.14.6/hdf5-1.14.6.tar.gz
+         tar -xzf hdf5-1.14.6.tar.gz
+         mv hdf5-1.14.6 hdf5
          cd hdf5
          export PATH=/opt/openmpi/bin:${PATH}
          export LD_LIBRARY_PATH=/opt/openmpi/lib:${LD_LIBRARY_PATH}

diff --git a/3rd-party/openpmix b/3rd-party/openpmix
diff --git a/3rd-party/prrte b/3rd-party/prrte
diff --git a/VERSION b/VERSION
@@ -15,7 +15,7 @@
 # major, minor, and release are generally combined in the form
 # <major>.<minor>.<release>.
 
-major=5
+major=6
 minor=1
 release=0
 

diff --git a/config/ompi_check_libhcoll.m4 b/config/ompi_check_libhcoll.m4
diff --git a/config/ompi_check_ubcl.m4 b/config/ompi_check_ubcl.m4
@@ -0,0 +1,57 @@
+# -*- shell-script -*-
+#
+# Copyright (C) 2015-2017 Mellanox Technologies, Inc.
+#                         All rights reserved.
+# Copyright (c) 2015      Research Organization for Information Science
+#                         and Technology (RIST). All rights reserved.
+# Copyright (c) 2016      Los Alamos National Security, LLC. All rights
+#                         reserved.
+# Copyright (c) 2016 Cisco Systems, Inc.  All rights reserved.
+# Copyright (c) 2022      Amazon.com, Inc. or its affiliates.  All Rights reserved.
+# Copyright (c) 2024-2025 Bull S.A.S.  All rights reserved.
+# $COPYRIGHT$
+#
+# Additional copyrights may follow
+#
+# $HEADER$
+#
+
+# OMPI_CHECK_UBCL(prefix, [action-if-found], [action-if-not-found])
+# --------------------------------------------------------
+# check if UBCL support can be found.  sets prefix_{CPPFLAGS,
+# as needed and runs action-if-found if there is
+# support, otherwise executes action-if-not-found
+AC_DEFUN([OMPI_CHECK_UBCL],[
+    OPAL_VAR_SCOPE_PUSH([ompi_check_ubcl_dir ompi_check_ubcl_happy])
+
+    m4_ifblank([$1], [m4_fatal([First argument to OMPI_CHECK_UBCL cannot be blank])])
+
+    AC_ARG_WITH([ubcl],
+        [AS_HELP_STRING([--with-ubcl(=DIR)],
+            [Build with UBCL support])])
+
+    # UBCL is dlopen'd to avoid direct link to libubcl.so.
+    # OAC_CHECK_PACKAGE would add this explicit link, so it cannot be used.
+    # OPAL_CHECK_WITHDIR prints an error if the given path is invalid
+    OPAL_CHECK_WITHDIR([ubcl], [$with_ubcl], [include/ubcl_api.h])
+
+    AS_IF([test "$with_ubcl" == "no"],
+          [ompi_check_ubcl_happy="no"],
+
+          [test -z "$with_ubcl"],
+          [ompi_check_ubcl_happy="no"],
+
+          [ompi_check_ubcl_happy="yes"
+           $1_CPPFLAGS="${$1_CPPFLAGS} -I$with_ubcl/include/"
+           AC_MSG_NOTICE([$1_CPPFLAGS is set to: ${$1_CPPFLAGS}])])
+
+
+    OPAL_SUMMARY_ADD([Transports],[UBCL],[],[$ompi_check_ubcl_happy])
+
+    AS_IF([test "$ompi_check_ubcl_happy" = "yes"],
+          [$2],
+          [$3])
+
+    OPAL_VAR_SCOPE_POP
+])
+
diff --git a/config/ompi_fortran_check_big_count.m4 b/config/ompi_fortran_check_big_count.m4
@@ -0,0 +1,54 @@
+dnl -*- shell-script -*-
+dnl
+dnl Copyright (c) 2004-2005 The Trustees of Indiana University and Indiana
+dnl                         University Research and Technology
+dnl                         Corporation.  All rights reserved.
+dnl Copyright (c) 2004-2005 The University of Tennessee and The University
+dnl                         of Tennessee Research Foundation.  All rights
+dnl                         reserved.
+dnl Copyright (c) 2004-2005 High Performance Computing Center Stuttgart,
+dnl                         University of Stuttgart.  All rights reserved.
+dnl Copyright (c) 2004-2005 The Regents of the University of California.
+dnl                         All rights reserved.
+dnl Copyright (c) 2010-2014 Cisco Systems, Inc.  All rights reserved.
+dnl Copyright (c) 2022-2025 Triad National Security, LLC. All rights
+dnl                         reserved.
+dnl $COPYRIGHT$
+dnl
+dnl Additional copyrights may follow
+dnl
+dnl $HEADER$
+dnl
+
+# Check whether or not the Fortran compiler can build mpi_f08 using
+# the given compiler options.  This test is intended to
+# trap cases where default INTEGER KIND is equivalent to MPI_COUNT_KIND.
+
+# OMPI_FORTRAN_CHECK_BIG_COUNT([action if found],
+#                            [action if not found])
+# ----------------------------------------------------
+AC_DEFUN([OMPI_FORTRAN_CHECK_BIG_COUNT],[
+    AS_VAR_PUSHDEF([big_count_var], [ompi_cv_big_count_var])
+
+    AC_CACHE_CHECK([if Fortran compiler can compile interface containing MPI_KIND_COUNT arguments ], big_count_var,
+       [AC_LANG_PUSH([Fortran])
+        AC_COMPILE_IFELSE([AC_LANG_SOURCE([[module sendit_interfaces
+INTERFACE SendIt
+ subroutine SendIt_int(X)
+ INTEGER :: X
+ end subroutine SendIt_int
+ subroutine SendIt_big(x)
+ integer(KIND=$OMPI_MPI_COUNT_KIND)::X
+ end subroutine SendIt_big
+ end interface SendIt
+ end module sendit_interfaces]])],
+             [AS_VAR_SET(big_count_var, yes)],
+             [AS_VAR_SET(big_count_var, no)])
+        touch conftest_foo.mod
+        rm -rf *.mod 2>/dev/null
+        AC_LANG_POP([Fortran])
+       ])
+
+    AS_VAR_IF(big_count_var, [yes], [$1], [$2])
+    AS_VAR_POPDEF([big_count_var])dnl
+])
diff --git a/configure.ac b/configure.ac
@@ -896,6 +896,14 @@ AC_CHECK_MEMBERS([struct timespec.tv_nsec],
 #
 m4_ifdef([project_ompi], [OMPI_FIND_MPI_AINT_COUNT_OFFSET])
 
+#
+# now that we have MPI_COUNT_KIND set, try building
+# MPI F08 bindings if that level of fortran support is requested
+#
+m4_ifdef([project_ompi], [AS_IF([test $OMPI_BUILD_FORTRAN_BINDINGS -ge $OMPI_FORTRAN_USEMPIF08_BINDINGS],
+                                [OMPI_FORTRAN_CHECK_BIG_COUNT([],
+                                     [AC_MSG_ERROR([The mpi_f08 module cannot be compiled using the current set of Fortran compiler options ($FCFLAGS).  Either change compiler options or use --enable-mpi-fortran=usempi])])
+                                ])])
 # checkpoint results
 AC_CACHE_SAVE
 

diff --git a/contrib/amca-param-sets/ft-mpi b/contrib/amca-param-sets/ft-mpi
@@ -63,7 +63,7 @@ btl=^usnic
 # The following frameworks/components are UNTESTED, and probably won't work.
 # They should run without faults, and will probably crash/deadlock after a fault.
 # You may try at your own risk.
-#   coll    hcoll, portals4
+#   coll    portals4
 #   topo    (all)
 #   osc     (all)
 #   io      (all)
@@ -72,7 +72,7 @@ btl=^usnic
 # We will disable only the components for which good components are known to exist.
 # Other untested components are selectable but will issue a runtime warning at
 # initiation if FT is enabled.
-coll=^hcoll,portals4
+coll=^portals4
 
 #
 # The following frameworks/components are NOT WORKING. Do not enable these with FT.

diff --git a/contrib/platform/intel/bend/linux b/contrib/platform/intel/bend/linux
@@ -13,7 +13,7 @@ enable_ipv6=no
 enable_man_pages=no
 enable_mpi_fortran=no
 enable_memchecker=no
-enable_mca_no_build=memchecker,coll-adapt,coll-cuda,coll-demo,coll-ftagree,coll-han,coll-hcoll,coll-inter,coll-libnbc,coll-monitoring,coll-portals4,coll-tuned,common-monitoring,common-ompio,fbtl,fcoll,fs,io,mtl,osc,pml-cm,pml-monitoring,pml-ucx,pml-v,sharedfp,topo,vprotocol,btl-ofi,btl-portals4,btl-smcuda,btl-uct,btl-ugni,btl-usnic,common-cuda,common-ofi,common-ucx
+enable_mca_no_build=memchecker,coll-adapt,coll-cuda,coll-demo,coll-ftagree,coll-han,coll-inter,coll-libnbc,coll-monitoring,coll-portals4,coll-tuned,common-monitoring,common-ompio,fbtl,fcoll,fs,io,mtl,osc,pml-cm,pml-monitoring,pml-ucx,pml-v,sharedfp,topo,vprotocol,btl-ofi,btl-portals4,btl-smcuda,btl-uct,btl-ugni,btl-usnic,common-cuda,common-ofi,common-ucx
 enable_contrib_no_build=libompitrace
 with_memory_manager=no
 with_devel_headers=yes

diff --git a/contrib/platform/lanl/toss/README.md b/contrib/platform/lanl/toss/README.md
@@ -43,7 +43,6 @@ created.
       (change S to X; make sure numbers match those for the same entry in
       contrib/platform/lanl/toss/optimized-mlx.conf)
     - addition: pml = ob1 (disable MXM)
-    - addition: coll = ^hcoll (disable MXM)
 - toss3-hfi-optimized
   - copy of toss2-qib-optimized
 - toss3-hfi-optimized.conf

diff --git a/contrib/platform/lanl/toss/toss2-mlx-optimized.conf b/contrib/platform/lanl/toss/toss2-mlx-optimized.conf
@@ -106,4 +106,3 @@ ras_base_launch_orted_on_hn = true
 
 ## Disable MXM
 pml = ob1
-coll = ^hcoll
diff --git a/contrib/platform/mellanox/optimized b/contrib/platform/mellanox/optimized
@@ -22,11 +22,6 @@ if [ "$mellanox_autodetect" == "yes" ]; then
         with_ucx=$ucx_dir
     fi
 
-    hcoll_dir=${hcoll_dir:="$(pkg-config --variable=prefix hcoll)"}
-    if [ -d $hcoll_dir ]; then
-        with_hcoll=$hcoll_dir
-    fi
-
     slurm_dir=${slurm_dir:="/usr"}
     if [ -f $slurm_dir/include/slurm/slurm.h ]; then
         with_slurm=$slurm_dir

diff --git a/docs/building-apps/abi-compatibility.rst b/docs/building-apps/abi-compatibility.rst
@@ -11,7 +11,7 @@ application compiled with Open MPI v4.x can be executed with Open MPI
 .. important:: ABI is maintained for *most* of the Fortran MPI bindings, too |mdash| see below for additional information.
 
 There are however a few scenarios where an application compiled with
-Open MPI v4.x might not execute correctly with Open MPI 5.0.
+Open MPI v4.x might not execute correctly with Open MPI |ompi_series|.
 
 - Fortran compilers provide varying degrees of ABI guarantees between
   their releases.  As such, Open MPI can only provide ABI guarantees

diff --git a/docs/developers/gnu-autotools.rst b/docs/developers/gnu-autotools.rst
@@ -186,6 +186,13 @@ to at least the versions listed below.
      - 2.4.6
      - 2.5.35
      - 4.2.0
+   * - v6.0.x
+     - 1.4.17
+     - 2.69
+     - 1.15
+     - 2.4.6
+     - 2.5.35
+     - 4.2.0
    * - Git main
      - 1.4.17
      - 2.69

diff --git a/docs/developers/prerequisites.rst b/docs/developers/prerequisites.rst
@@ -59,7 +59,7 @@ the Open MPI build, such as (but not limited to):
 
 * When building from a Git clone:
 
-  * Generating the Fortran bindings
+  * Generating the C and Fortran bindings
 
   * Generating the "show help" messages
 

diff --git a/docs/features/ulfm.rst b/docs/features/ulfm.rst
@@ -87,7 +87,7 @@ non-blocking) use an optimized implementation on top of  ``ob1``.
 - Loopback (send-to-self)
 - TCP
 - UCT (InfiniBand)
-- uGNI (Cray Gemini, Aries)
+- OFI/libfabric
 - Shared Memory (FT supported with CMA and XPMEM; KNEM is untested)
 - Tuned and non-blocking collective communications
 
@@ -159,7 +159,7 @@ Running under a batch scheduler
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 ULFM can operate under a job/batch scheduler, and is tested routinely
-with ALPS, PBS, and Slurm. One difficulty comes from the fact that
+with PBS and Slurm. One difficulty comes from the fact that
 many job schedulers handle failures by triggering an immediate "cleanup"
 of the application as soon as any process fails. In addition, failure
 detection subsystems integrated into PRTE are not active in direct launch
@@ -333,7 +333,7 @@ correctly after a failure.
   * ``cuda``, ``inter``, ``sync``, ``sm``: **untested** (they have not
     been modified to handle faults, but we expect correct post-fault
     behavior)
-  * ``hcoll``, ``portals4`` **disabled** (they have not been modified
+  * ``portals4`` **disabled** (it has not been modified
     to handle faults, and we expect unspecified post-fault behavior)
 
 * ``osc``: MPI one-sided communications

diff --git a/docs/installing-open-mpi/compilers-and-flags.rst b/docs/installing-open-mpi/compilers-and-flags.rst
@@ -130,6 +130,14 @@ compatible, meaning that object files created by one compiler must be
 able to be linked with object files from the other compilers and
 produce correctly functioning executables.
 
+.. note:: Starting with Open MPI 6.0.0, the MPI 4.0 large count
+   C and Fortran ``mpi_f08`` interfaces are supported.  A consequence
+   of this is that users may specify Fortran compiler
+   options that conflict with the support for F08 interfaces that have
+   both default ``INTEGER`` and ``INTEGER(KIND=MPI_COUNT_KIND)`` 
+   procedures.  The Open MPI ``configure`` script will detect this condition 
+   and fail with an appropriate error message.
+
 Statically linking to the libraries of Intel compiler suite
 -----------------------------------------------------------
 

diff --git a/docs/installing-open-mpi/configure-cli-options/networking.rst b/docs/installing-open-mpi/configure-cli-options/networking.rst
@@ -14,15 +14,6 @@ can be used with ``configure``:
 
   FCA is the support library for Mellanox switches and HCAs.
 
-* ``--with-hcoll=DIR``:
-  Specify the directory where the Mellanox hcoll library and header
-  files are located.  This option is generally only necessary if the
-  hcoll headers and libraries are not in default compiler/linker
-  search paths.
-
-  hcoll is the support library for MPI collective operation offload on
-  Mellanox ConnectX-3 HCAs (and later).
-
 * ``--with-knem=DIR``:
   Specify the directory where the knem libraries and header files are
   located.  This option is generally only necessary if the knem headers
-Original file line number
+Diff line change
@@ Expand Up / @@ -15,7 +15,7 @@ @@
     # major, minor, and release are generally combined in the form
     # <major>.<minor>.<release>.
-    major=5
+    major=6
     minor=1
     release=0
@@ Expand Down @@
Original file line number	Diff line number	Diff line change
Expand Up		@@ -106,4 +106,3 @@ ras_base_launch_orted_on_hn = true

		## Disable MXM
		pml = ob1
		coll = ^hcoll