[svn-r12739] Added Direct I/O driver to VFD. It's only supported by SGI Altix (cobalt). There's a configure

option --enable-direct-vfd/--disable-direct-vfd to enable/disable Direct I/O support.  The default
is enabled.  There's a small test in test/vfd.c.  Another way to test it is to set environment
variable HDF5_DRIVER to "direct" and run "make check" in the test/ directory.  There'll be some
further improvement in the following checkin including allowing user to provide memory boundary
value, file block size, and copying buffer size.

1 files changed, 39 insertions, 0 deletions

diff --git a/configure.in b/configure.in
index f14cf56..b141e2c 100644
--- a/configure.in
+++ b/configure.in
@@ -2572,6 +2572,45 @@ if test "$STREAM_VFD" = "yes"; then
 fi
 
 dnl ----------------------------------------------------------------------
+dnl Check if Direct I/O driver is wanted by --enable-direct-vfd
+dnl
+
+AC_MSG_CHECKING([for Direct Virtual File Driver support])
+
+AC_ARG_ENABLE([direct-vfd],
+              [AC_HELP_STRING([--enable-direct-vfd],
+                              [Build the Direct I/O Virtual File Driver
+                               [default=yes]])],
+              [DIRECT_VFD=$enableval], [DIRECT_VFD=yes])
+
+if test "$DIRECT_VFD" = "yes"; then
+   AC_CACHE_VAL([hdf5_direct_io],
+       [AC_TRY_RUN([
+	  #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);
+          }], [hdf5_direct_io=yes], [hdf5_direct_io=no],)])
+
+   if test ${hdf5_direct_io} = "yes"; then
+      AC_MSG_RESULT([yes])
+      AC_DEFINE([HAVE_DIRECT], [1],
+                [Define if the direct I/O virtual file driver should be compiled])
+   else
+      AC_MSG_RESULT([no])
+   fi
+else
+      AC_MSG_RESULT([suppressed])
+fi
+ 
+dnl ----------------------------------------------------------------------
 dnl Decide whether the presence of user's exception handling functions is
 dnl checked and data conversion exceptions are returned.  This is mainly
 dnl for the speed optimization of hard conversions.  Soft conversions can