[svn-r26378] Bring revisions #26220 - #26324 from trunk to revise_chunks. h5committested.

1 files changed, 127 insertions, 557 deletions

diff --git a/configure b/configure
index 65f8407..7daf063 100755
--- a/configure
+++ b/configure
@@ -921,7 +921,6 @@ enable_using_memchecker
 enable_parallel
 with_mpe
 enable_filters
-with_default_vfd
 enable_direct_vfd
 with_default_plugindir
 enable_dconv_exception
@@ -1617,8 +1616,9 @@ Optional Features:
   --enable-filters=all    Turn on all internal I/O filters. One may also
                           specify a comma-separated list of filters or the
                           word no. The default is all internal I/O filters.
-  --enable-direct-vfd     Build the Direct I/O Virtual File Driver
-                          [default=yes]
+  --enable-direct-vfd     Build the direct I/O virtual file driver (VFD). This
+                          is based on the POSIX (sec2) VFD and requires the
+                          open() call to take the O_DIRECT flag. [default=no]
   --enable-dconv-exception
                           if exception handling functions is checked during
                           data conversions [default=yes]
@@ -1659,8 +1659,6 @@ Optional Packages:
   --with-pthread=DIR      Specify alternative path to Pthreads library when
                           thread-safe capability is built
   --with-mpe=DIR          Use MPE instrumentation [default=no]
-  --with-default-vfd=driver
-                          Specify default file driver [default=sec2]
   --with-default-plugindir=location
                           Specify default location for plugins
                           [default="/usr/local/hdf5/lib/plugin"]
@@ -2682,79 +2680,6 @@ $as_echo "$ac_res" >&6; }
   eval $as_lineno_stack; ${as_lineno_stack:+:} unset as_lineno
 
 } # ac_fn_c_check_decl
-
-# ac_fn_c_check_member LINENO AGGR MEMBER VAR INCLUDES
-# ----------------------------------------------------
-# Tries to find if the field MEMBER exists in type AGGR, after including
-# INCLUDES, setting cache variable VAR accordingly.
-ac_fn_c_check_member ()
-{
-  as_lineno=${as_lineno-"$1"} as_lineno_stack=as_lineno_stack=$as_lineno_stack
-  { $as_echo "$as_me:${as_lineno-$LINENO}: checking for $2.$3" >&5
-$as_echo_n "checking for $2.$3... " >&6; }
-if eval \${$4+:} false; then :
-  $as_echo_n "(cached) " >&6
-else
-  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
-$5
-#ifdef FC_DUMMY_MAIN
-#ifndef FC_DUMMY_MAIN_EQ_F77
-#  ifdef __cplusplus
-     extern "C"
-#  endif
-   int FC_DUMMY_MAIN() { return 1; }
-#endif
-#endif
-int
-main ()
-{
-static $2 ac_aggr;
-if (ac_aggr.$3)
-return 0;
-  ;
-  return 0;
-}
-_ACEOF
-if ac_fn_c_try_compile "$LINENO"; then :
-  eval "$4=yes"
-else
-  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
-$5
-#ifdef FC_DUMMY_MAIN
-#ifndef FC_DUMMY_MAIN_EQ_F77
-#  ifdef __cplusplus
-     extern "C"
-#  endif
-   int FC_DUMMY_MAIN() { return 1; }
-#endif
-#endif
-int
-main ()
-{
-static $2 ac_aggr;
-if (sizeof ac_aggr.$3)
-return 0;
-  ;
-  return 0;
-}
-_ACEOF
-if ac_fn_c_try_compile "$LINENO"; then :
-  eval "$4=yes"
-else
-  eval "$4=no"
-fi
-rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
-fi
-rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
-fi
-eval ac_res=\$$4
-	       { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5
-$as_echo "$ac_res" >&6; }
-  eval $as_lineno_stack; ${as_lineno_stack:+:} unset as_lineno
-
-} # ac_fn_c_check_member
 cat >config.log <<_ACEOF
 This file contains any messages produced by compilers while
 running configure, to aid debugging if configure makes a mistake.
@@ -6695,13 +6620,13 @@ $as_echo_n "checking if Fortran compiler version compatible with Fortran 2003 HD
       program main
 
 
-	USE iso_c_binding
-	IMPLICIT NONE
-	TYPE(C_PTR) :: ptr
-	TYPE(C_FUNPTR) :: funptr
-	CHARACTER(LEN=80, KIND=c_char), TARGET :: ichr
+        USE iso_c_binding
+        IMPLICIT NONE
+        TYPE(C_PTR) :: ptr
+        TYPE(C_FUNPTR) :: funptr
+        CHARACTER(LEN=80, KIND=c_char), TARGET :: ichr
 
-	ptr = C_LOC(ichr(1:1))
+        ptr = C_LOC(ichr(1:1))
 
 
       end
@@ -22540,113 +22465,6 @@ $as_echo "#define TIME_WITH_SYS_TIME 1" >>confdefs.h
 fi
 
 
-## ----------------------------------------------------------------------
-## Check for these two functions before the time headers are checked
-## for, otherwise they are not detected correctly on Solaris (the
-## configure test will fail due to multiply-defined symbols).
-##
-for ac_func in difftime
-do :
-  ac_fn_c_check_func "$LINENO" "difftime" "ac_cv_func_difftime"
-if test "x$ac_cv_func_difftime" = xyes; then :
-  cat >>confdefs.h <<_ACEOF
-#define HAVE_DIFFTIME 1
-_ACEOF
-
-fi
-done
-
-for ac_func in gettimeofday
-do :
-  ac_fn_c_check_func "$LINENO" "gettimeofday" "ac_cv_func_gettimeofday"
-if test "x$ac_cv_func_gettimeofday" = xyes; then :
-  cat >>confdefs.h <<_ACEOF
-#define HAVE_GETTIMEOFDAY 1
-_ACEOF
- have_gettime="yes"
-else
-  have_gettime="no"
-fi
-done
-
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for library containing clock_gettime" >&5
-$as_echo_n "checking for library containing clock_gettime... " >&6; }
-if ${ac_cv_search_clock_gettime+:} false; then :
-  $as_echo_n "(cached) " >&6
-else
-  ac_func_search_save_LIBS=$LIBS
-cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
-
-/* Override any GCC internal prototype to avoid an error.
-   Use char because int might match the return type of a GCC
-   builtin and then its argument prototype would still apply.  */
-#ifdef __cplusplus
-extern "C"
-#endif
-char clock_gettime ();
-#ifdef FC_DUMMY_MAIN
-#ifndef FC_DUMMY_MAIN_EQ_F77
-#  ifdef __cplusplus
-     extern "C"
-#  endif
-   int FC_DUMMY_MAIN() { return 1; }
-#endif
-#endif
-int
-main ()
-{
-return clock_gettime ();
-  ;
-  return 0;
-}
-_ACEOF
-for ac_lib in '' rt posix4; do
-  if test -z "$ac_lib"; then
-    ac_res="none required"
-  else
-    ac_res=-l$ac_lib
-    LIBS="-l$ac_lib  $ac_func_search_save_LIBS"
-  fi
-  if ac_fn_c_try_link "$LINENO"; then :
-  ac_cv_search_clock_gettime=$ac_res
-fi
-rm -f core conftest.err conftest.$ac_objext \
-    conftest$ac_exeext
-  if ${ac_cv_search_clock_gettime+:} false; then :
-  break
-fi
-done
-if ${ac_cv_search_clock_gettime+:} false; then :
-
-else
-  ac_cv_search_clock_gettime=no
-fi
-rm conftest.$ac_ext
-LIBS=$ac_func_search_save_LIBS
-fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_search_clock_gettime" >&5
-$as_echo "$ac_cv_search_clock_gettime" >&6; }
-ac_res=$ac_cv_search_clock_gettime
-if test "$ac_res" != no; then :
-  test "$ac_res" = "none required" || LIBS="$ac_res $LIBS"
-
-fi
-
-for ac_func in clock_gettime
-do :
-  ac_fn_c_check_func "$LINENO" "clock_gettime" "ac_cv_func_clock_gettime"
-if test "x$ac_cv_func_clock_gettime" = xyes; then :
-  cat >>confdefs.h <<_ACEOF
-#define HAVE_CLOCK_GETTIME 1
-_ACEOF
- have_clock_gettime="yes"
-else
-  have_clock_gettime="no"
-fi
-done
-
-
 ## Unix
 for ac_header in sys/resource.h sys/time.h unistd.h sys/ioctl.h sys/stat.h
 do :
@@ -23102,19 +22920,28 @@ case "$host_cpu-$host_vendor-$host_os" in
     ## Add POSIX support on Linux systems, so <features.h> defines
     ## __USE_POSIX, which is required to get the prototype for fdopen
     ## defined correctly in <stdio.h>.
+    ##
     ## This flag was removed from h5cc as of 2009-10-17 when it was found
     ## that the flag broke compiling netCDF-4 code with h5cc, but kept in
     ## H5_CPPFLAGS because fdopen and HDfdopen fail without it. HDfdopen
     ## is used only by H5_debug_mask which is used only when debugging in
     ## H5_init_library (all in H5.c).  When the flag was removed this was
     ## the only compile failure noted.
+    ##
     ## This was originally defined as _POSIX_SOURCE which was updated to
     ## _POSIX_C_SOURCE=199506L to expose a greater amount of POSIX
     ## functionality so clock_gettime and CLOCK_MONOTONIC are defined
-    ## correctly.
+    ## correctly. This was later updated to 200112L so that
+    ## posix_memalign() is visible for the direct VFD code on Linux
+    ## systems.
+    ##
     ## POSIX feature information can be found in the gcc manual at:
     ## http://www.gnu.org/s/libc/manual/html_node/Feature-Test-Macros.html
-    H5_CPPFLAGS="-D_POSIX_C_SOURCE=199506L $H5_CPPFLAGS"
+    H5_CPPFLAGS="-D_POSIX_C_SOURCE=200112L $H5_CPPFLAGS"
+
+    ## Need to add this so that O_DIRECT is visible for the direct
+    ## VFD on Linux systems.
+    AM_CPPFLAGS="-D_GNU_SOURCE $AM_CPPFLAGS"
 
     ## Also add BSD support on Linux systems, so <features.h> defines
     ## __USE_BSD, which is required to get the prototype for strdup
@@ -26328,42 +26155,6 @@ $as_echo "no" >&6; }
 fi
 rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
 
-## check if `struct tm' has a `__tm_gmtoff' member.
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for __tm_gmtoff in struct tm" >&5
-$as_echo_n "checking for __tm_gmtoff in struct tm... " >&6; }
-cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
-
-  #include <sys/time.h>
-  #include <time.h>
-#ifdef FC_DUMMY_MAIN
-#ifndef FC_DUMMY_MAIN_EQ_F77
-#  ifdef __cplusplus
-     extern "C"
-#  endif
-   int FC_DUMMY_MAIN() { return 1; }
-#endif
-#endif
-int
-main ()
-{
-struct tm tm; tm.__tm_gmtoff=0;
-  ;
-  return 0;
-}
-_ACEOF
-if ac_fn_c_try_compile "$LINENO"; then :
-
-$as_echo "#define HAVE___TM_GMTOFF 1" >>confdefs.h
-
-     { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
-$as_echo "yes" >&6; }
-else
-  { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
-$as_echo "no" >&6; }
-fi
-rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
-
 ## Check whether the global variable `timezone' is defined.
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking for global timezone variable" >&5
 $as_echo_n "checking for global timezone variable... " >&6; }
@@ -26410,217 +26201,6 @@ rm -f core conftest.err conftest.$ac_objext \
     ;;
 esac
 
-## Check whether `struct timezone' is defined.
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether struct tm is in sys/time.h or time.h" >&5
-$as_echo_n "checking whether struct tm is in sys/time.h or time.h... " >&6; }
-if ${ac_cv_struct_tm+:} false; then :
-  $as_echo_n "(cached) " >&6
-else
-  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
-#include <sys/types.h>
-#include <time.h>
-
-#ifdef FC_DUMMY_MAIN
-#ifndef FC_DUMMY_MAIN_EQ_F77
-#  ifdef __cplusplus
-     extern "C"
-#  endif
-   int FC_DUMMY_MAIN() { return 1; }
-#endif
-#endif
-int
-main ()
-{
-struct tm tm;
-				     int *p = &tm.tm_sec;
-				     return !p;
-  ;
-  return 0;
-}
-_ACEOF
-if ac_fn_c_try_compile "$LINENO"; then :
-  ac_cv_struct_tm=time.h
-else
-  ac_cv_struct_tm=sys/time.h
-fi
-rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
-fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_struct_tm" >&5
-$as_echo "$ac_cv_struct_tm" >&6; }
-if test $ac_cv_struct_tm = sys/time.h; then
-
-$as_echo "#define TM_IN_SYS_TIME 1" >>confdefs.h
-
-fi
-
-ac_fn_c_check_member "$LINENO" "struct tm" "tm_zone" "ac_cv_member_struct_tm_tm_zone" "#include <sys/types.h>
-#include <$ac_cv_struct_tm>
-
-"
-if test "x$ac_cv_member_struct_tm_tm_zone" = xyes; then :
-
-cat >>confdefs.h <<_ACEOF
-#define HAVE_STRUCT_TM_TM_ZONE 1
-_ACEOF
-
-
-fi
-
-if test "$ac_cv_member_struct_tm_tm_zone" = yes; then
-
-$as_echo "#define HAVE_TM_ZONE 1" >>confdefs.h
-
-else
-  ac_fn_c_check_decl "$LINENO" "tzname" "ac_cv_have_decl_tzname" "#include <time.h>
-"
-if test "x$ac_cv_have_decl_tzname" = xyes; then :
-  ac_have_decl=1
-else
-  ac_have_decl=0
-fi
-
-cat >>confdefs.h <<_ACEOF
-#define HAVE_DECL_TZNAME $ac_have_decl
-_ACEOF
-
-  { $as_echo "$as_me:${as_lineno-$LINENO}: checking for tzname" >&5
-$as_echo_n "checking for tzname... " >&6; }
-if ${ac_cv_var_tzname+:} false; then :
-  $as_echo_n "(cached) " >&6
-else
-  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
-#include <time.h>
-#if !HAVE_DECL_TZNAME
-extern char *tzname[];
-#endif
-
-#ifdef FC_DUMMY_MAIN
-#ifndef FC_DUMMY_MAIN_EQ_F77
-#  ifdef __cplusplus
-     extern "C"
-#  endif
-   int FC_DUMMY_MAIN() { return 1; }
-#endif
-#endif
-int
-main ()
-{
-return tzname[0][0];
-  ;
-  return 0;
-}
-_ACEOF
-if ac_fn_c_try_link "$LINENO"; then :
-  ac_cv_var_tzname=yes
-else
-  ac_cv_var_tzname=no
-fi
-rm -f core conftest.err conftest.$ac_objext \
-    conftest$ac_exeext conftest.$ac_ext
-fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_var_tzname" >&5
-$as_echo "$ac_cv_var_tzname" >&6; }
-  if test $ac_cv_var_tzname = yes; then
-
-$as_echo "#define HAVE_TZNAME 1" >>confdefs.h
-
-  fi
-fi
-
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for struct timezone" >&5
-$as_echo_n "checking for struct timezone... " >&6; }
-cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
-
-  #include <sys/types.h>
-  #include <sys/time.h>
-  #include <time.h>
-#ifdef FC_DUMMY_MAIN
-#ifndef FC_DUMMY_MAIN_EQ_F77
-#  ifdef __cplusplus
-     extern "C"
-#  endif
-   int FC_DUMMY_MAIN() { return 1; }
-#endif
-#endif
-int
-main ()
-{
-struct timezone tz; tz.tz_minuteswest=0;
-  ;
-  return 0;
-}
-_ACEOF
-if ac_fn_c_try_compile "$LINENO"; then :
-
-$as_echo "#define HAVE_STRUCT_TIMEZONE 1" >>confdefs.h
-
-    have_struct_tz="yes"
-    { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
-$as_echo "yes" >&6; }
-else
-  { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
-$as_echo "no" >&6; }
-fi
-rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
-
-## If gettimeofday() is going to be used, make sure it uses the timezone struct
-
-if test "$have_gettime" = "yes" -a "$have_struct_tz" = "yes"; then
-   { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether gettimeofday() gives timezone" >&5
-$as_echo_n "checking whether gettimeofday() gives timezone... " >&6; }
-   if ${hdf5_cv_gettimeofday_tz+:} false; then :
-  $as_echo_n "(cached) " >&6
-else
-  if test "$cross_compiling" = yes; then :
-  { { $as_echo "$as_me:${as_lineno-$LINENO}: error: in \`$ac_pwd':" >&5
-$as_echo "$as_me: error: in \`$ac_pwd':" >&2;}
-as_fn_error $? "cannot run test program while cross compiling
-See \`config.log' for more details" "$LINENO" 5; }
-else
-  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
-
-          #include <time.h>
-          #include <sys/time.h>
-          int main(void)
-          {
-             struct timeval tv;
-             struct timezone tz;
-             tz.tz_minuteswest = 7777;  /* Initialize to an unreasonable number */
-             tz.tz_dsttime = 7;
-             gettimeofday(&tv, &tz);
-                /* Check whether the function returned any value at all */
-             if(tz.tz_minuteswest == 7777 && tz.tz_dsttime == 7)
-                exit(1);
-             else exit (0);
-          }
-_ACEOF
-if ac_fn_c_try_run "$LINENO"; then :
-  hdf5_cv_gettimeofday_tz=yes
-else
-  hdf5_cv_gettimeofday_tz=no
-fi
-rm -f core *.core core.conftest.* gmon.out bb.out conftest$ac_exeext \
-  conftest.$ac_objext conftest.beam conftest.$ac_ext
-fi
-
-fi
-
-
-   if test ${hdf5_cv_gettimeofday_tz} = "yes"; then
-      { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
-$as_echo "yes" >&6; }
-
-$as_echo "#define GETTIMEOFDAY_GIVES_TZ 1" >>confdefs.h
-
-   else
-      { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
-$as_echo "no" >&6; }
-   fi
-fi
 
 ## ----------------------------------------------------------------------
 ## Does the struct stat have the st_blocks field?  This field is not Posix.
@@ -26840,7 +26420,73 @@ rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
 ## ----------------------------------------------------------------------
 ## Check for functions.
 ##
-for ac_func in alarm BSDgettimeofday fork frexpf frexpl
+## NOTE: clock_gettime may require linking to the rt or posix4 library
+##       so we'll search for it before calling AC_CHECK_FUNCS.
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for library containing clock_gettime" >&5
+$as_echo_n "checking for library containing clock_gettime... " >&6; }
+if ${ac_cv_search_clock_gettime+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  ac_func_search_save_LIBS=$LIBS
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+/* Override any GCC internal prototype to avoid an error.
+   Use char because int might match the return type of a GCC
+   builtin and then its argument prototype would still apply.  */
+#ifdef __cplusplus
+extern "C"
+#endif
+char clock_gettime ();
+#ifdef FC_DUMMY_MAIN
+#ifndef FC_DUMMY_MAIN_EQ_F77
+#  ifdef __cplusplus
+     extern "C"
+#  endif
+   int FC_DUMMY_MAIN() { return 1; }
+#endif
+#endif
+int
+main ()
+{
+return clock_gettime ();
+  ;
+  return 0;
+}
+_ACEOF
+for ac_lib in '' rt posix4; do
+  if test -z "$ac_lib"; then
+    ac_res="none required"
+  else
+    ac_res=-l$ac_lib
+    LIBS="-l$ac_lib  $ac_func_search_save_LIBS"
+  fi
+  if ac_fn_c_try_link "$LINENO"; then :
+  ac_cv_search_clock_gettime=$ac_res
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext
+  if ${ac_cv_search_clock_gettime+:} false; then :
+  break
+fi
+done
+if ${ac_cv_search_clock_gettime+:} false; then :
+
+else
+  ac_cv_search_clock_gettime=no
+fi
+rm conftest.$ac_ext
+LIBS=$ac_func_search_save_LIBS
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_search_clock_gettime" >&5
+$as_echo "$ac_cv_search_clock_gettime" >&6; }
+ac_res=$ac_cv_search_clock_gettime
+if test "$ac_res" != no; then :
+  test "$ac_res" = "none required" || LIBS="$ac_res $LIBS"
+
+fi
+
+for ac_func in alarm clock_gettime difftime fork frexpf frexpl
 do :
   as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
 ac_fn_c_check_func "$LINENO" "$ac_func" "$as_ac_var"
@@ -26852,7 +26498,7 @@ _ACEOF
 fi
 done
 
-for ac_func in gethostname getpwuid getrusage lstat
+for ac_func in gethostname getpwuid getrusage gettimeofday
 do :
   as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
 ac_fn_c_check_func "$LINENO" "$ac_func" "$as_ac_var"
@@ -26864,7 +26510,7 @@ _ACEOF
 fi
 done
 
-for ac_func in rand_r random setsysinfo
+for ac_func in lstat rand_r random setsysinfo
 do :
   as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
 ac_fn_c_check_func "$LINENO" "$ac_func" "$as_ac_var"
@@ -27833,7 +27479,7 @@ $as_echo_n "checking whether a simple MPI-IO Fortran program can be linked... "
       cat > conftest.$ac_ext <<_ACEOF
 
           PROGRAM main
-          USE mpi
+          INCLUDE 'mpif.h'
           INTEGER :: comm, amode, info, fh, ierror
           CHARACTER(LEN=1) :: filename
           CALL MPI_File_open( comm, filename, amode, info, fh, ierror)
@@ -28267,6 +27913,7 @@ $as_echo "#define HAVE_MPE 1" >>confdefs.h
   fi
 fi
 
+
 ## ----------------------------------------------------------------------
 ## Turn on internal I/O filters by setting macros in header files
 ## Internal I/O filters are contained entirely within the library and do
@@ -28340,147 +27987,70 @@ $as_echo "#define HAVE_FILTER_SCALEOFFSET 1" >>confdefs.h
   done
 fi
 
-## ----------------------------------------------------------------------
-## This is defined only when we're using CodeWarrior, since it has a
-## broken "open()" call.
-#
-if test 1 = 2; then
-
-$as_echo "#define NO_SHARED_WRITING 1" >>confdefs.h
-
-fi
 
-## --------------------------------------------------------------------------
-## Should the Default Virtual File Driver be compiled?
+## ----------------------------------------------------------------------
+## Check if Direct I/O driver is enabled by --enable-direct-vfd
 ##
 
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for Default Virtual File Driver definition" >&5
-$as_echo_n "checking for Default Virtual File Driver definition... " >&6; }
+## Check these regardless. If the checks are moved inside the main
+## direct VFD block, the output is nested.
 
-# Check whether --with-default-vfd was given.
-if test "${with_default_vfd+set}" = set; then :
-  withval=$with_default_vfd;
+if ${hdf5_cv_direct_io+:} false; then :
+  $as_echo_n "(cached) " >&6
 else
-  withval=sec2
+  ac_fn_c_check_decl "$LINENO" "O_DIRECT" "ac_cv_have_decl_O_DIRECT" "#include <fcntl.h>
+"
+if test "x$ac_cv_have_decl_O_DIRECT" = xyes; then :
+  hdf5_cv_direct_io=yes
+else
+  hdf5_cv_direct_io=no
 fi
 
+fi
 
-if test "X$withval" = "Xsec2"; then
-    { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
-$as_echo "yes" >&6; }
-    default_vfd=yes
-    vfd_define=H5FD_SEC2
-elif test "X$withval" = "Xstdio"; then
-    { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
-$as_echo "yes" >&6; }
-    default_vfd=yes
-    vfd_define=H5FD_STDIO
+if ${hdf5_cv_posix_memalign+:} false; then :
+  $as_echo_n "(cached) " >&6
 else
-    { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
-$as_echo "no" >&6; }
-    default_vfd=no
+  ac_fn_c_check_func "$LINENO" "posix_memalign" "ac_cv_func_posix_memalign"
+if test "x$ac_cv_func_posix_memalign" = xyes; then :
+  hdf5_cv_posix_memalign=yes
+else
+  hdf5_cv_posix_memalign=no
 fi
 
-if test "X$default_vfd" = "Xyes"; then
-
-cat >>confdefs.h <<_ACEOF
-#define DEFAULT_VFD $vfd_define
-_ACEOF
-
 fi
 
-## ----------------------------------------------------------------------
-## Check if Direct I/O driver is enabled by --enable-direct-vfd
-##
 
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for Direct Virtual File Driver support" >&5
-$as_echo_n "checking for Direct Virtual File Driver support... " >&6; }
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking if the direct I/O virtual file driver (VFD) is enabled" >&5
+$as_echo_n "checking if the direct I/O virtual file driver (VFD) is enabled... " >&6; }
 
 # Check whether --enable-direct-vfd was given.
 if test "${enable_direct_vfd+set}" = set; then :
   enableval=$enable_direct_vfd; DIRECT_VFD=$enableval
 else
-  DIRECT_VFD=yes
+  DIRECT_VFD=no
 fi
 
 
-if test "$DIRECT_VFD" = "yes"; then
-   if ${hdf5_cv_direct_io+:} false; then :
-  $as_echo_n "(cached) " >&6
-else
-  if test "$cross_compiling" = yes; then :
-  { { $as_echo "$as_me:${as_lineno-$LINENO}: error: in \`$ac_pwd':" >&5
-$as_echo "$as_me: error: in \`$ac_pwd':" >&2;}
-as_fn_error $? "cannot run test program while cross compiling
-See \`config.log' for more details" "$LINENO" 5; }
-else
-  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
-
-	  #include <sys/types.h>
-	  #include <sys/stat.h>
-	  #include <fcntl.h>
-          int main(void)
-          {
-             int fid;
-             if((fid=open("tst_file", O_CREAT | O_TRUNC | O_DIRECT, 0755))<0)
-		exit(1);
-             close(fid);
-             remove("tst_file");
-             exit (0);
-          }
-_ACEOF
-if ac_fn_c_try_run "$LINENO"; then :
-  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
-
-#ifdef FC_DUMMY_MAIN
-#ifndef FC_DUMMY_MAIN_EQ_F77
-#  ifdef __cplusplus
-     extern "C"
-#  endif
-   int FC_DUMMY_MAIN() { return 1; }
-#endif
-#endif
-int
-main ()
-{
-posix_memalign()
-  ;
-  return 0;
-}
-_ACEOF
-if ac_fn_c_try_link "$LINENO"; then :
-  hdf5_cv_direct_io=yes
-else
-  hdf5_cv_direct_io=no
-fi
-rm -f core conftest.err conftest.$ac_objext \
-    conftest$ac_exeext conftest.$ac_ext
-else
-  hdf5_cv_direct_io=no
-fi
-rm -f core *.core core.conftest.* gmon.out bb.out conftest$ac_exeext \
-  conftest.$ac_objext conftest.beam conftest.$ac_ext
-fi
-
-fi
-
-
-   if test ${hdf5_cv_direct_io} = "yes"; then
-      { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
+if test "X$DIRECT_VFD" = "Xyes"; then
+    if test ${hdf5_cv_direct_io} = "yes" && test ${hdf5_cv_posix_memalign} = "yes" ; then
+        { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
 $as_echo "yes" >&6; }
 
 $as_echo "#define HAVE_DIRECT 1" >>confdefs.h
 
-   else
-      { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+    else
+        { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
 $as_echo "no" >&6; }
-      DIRECT_VFD=no
-   fi
+        DIRECT_VFD=no
+        as_fn_error $? "The direct VFD was requested but cannot be built. This is either
+                     due to O_DIRECT not being found in fcntl.h or a lack of
+                     posix_memalign() on your system. Please re-configure without
+                     specifying --enable-direct-vfd." "$LINENO" 5
+    fi
 else
-      { $as_echo "$as_me:${as_lineno-$LINENO}: result: suppressed" >&5
-$as_echo "suppressed" >&6; }
+    { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
 fi
 
  if test "X$DIRECT_VFD" = "Xyes"; then