NEWS/README: note that the POWER 7/BE block has been removed.

Also note that ARM and POWER users may experience hangs (until
open-mpi#4563 is fixed).

Signed-off-by: Jeff Squyres <jsquyres@cisco.com>

NEWS

@@ -55,6 +55,17 @@ included in the vX.Y.Z section and be denoted as:
    (** also appeared: A.B.C)  -- indicating that this item was previously
                                  included in release version vA.B.C.
 
+3.1.1 -- TBD
+------------
+
+Bug fixes/minor improvements:
+- Disable the POWER 7/BE block in configure.  Note that POWER 7/BE is
+  still not a supported platform, but it is no longer automatically
+  disabled.  See
+  https://github.com/open-mpi/ompi/issues/4349#issuecomment-374970982
+  for more information.
+
+
 3.1.0 -- March, 2018
 ----------------------
 

README

@@ -140,6 +140,15 @@ General notes
     using the clang-4.0 system compiler. A workaround is to build
     Open MPI using the GNU compiler.
 
+Platform Notes
+--------------
+
+- ARM and POWER users may experience intermittent hangs when Open MPI
+  is compiled with low optimization settings, due to an issue with our
+  atomic list implementation.  We recommend compiling with -O3
+  optimization, both for performance reasons and to avoid this hang.
+
+
 Compiler Notes
 --------------