diff --git a/drivers/syslog/syslog_emergstream.c b/drivers/syslog/syslog_emergstream.c
index e0cc2be6ed9..2ea230b63cc 100644
--- a/drivers/syslog/syslog_emergstream.c
+++ b/drivers/syslog/syslog_emergstream.c
@@ -1,7 +1,7 @@
 /****************************************************************************
  * drivers/syslog/syslog_emergtream.c
  *
- *   Copyright (C) 2016 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2016-2017 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -109,8 +109,6 @@ static void emergstream_putc(FAR struct lib_outstream_s *this, int ch)
 void emergstream(FAR struct lib_outstream_s *stream)
 {
   stream->put   = emergstream_putc;
-#ifdef CONFIG_STDIO_LINEBUFFER
   stream->flush = lib_noflush;
-#endif
   stream->nput  = 0;
 }
diff --git a/drivers/syslog/syslog_stream.c b/drivers/syslog/syslog_stream.c
index 491da95c266..8305089b8bd 100644
--- a/drivers/syslog/syslog_stream.c
+++ b/drivers/syslog/syslog_stream.c
@@ -109,8 +109,6 @@ static void syslogstream_putc(FAR struct lib_outstream_s *this, int ch)
 void syslogstream(FAR struct lib_outstream_s *stream)
 {
   stream->put   = syslogstream_putc;
-#ifdef CONFIG_STDIO_LINEBUFFER
   stream->flush = lib_noflush;
-#endif
   stream->nput  = 0;
 }
diff --git a/fs/vfs/fs_fdopen.c b/fs/vfs/fs_fdopen.c
index 85abbf79897..eae7b019f80 100644
--- a/fs/vfs/fs_fdopen.c
+++ b/fs/vfs/fs_fdopen.c
@@ -251,6 +251,12 @@ FAR struct file_struct *fs_fdopen(int fd, int oflags, FAR struct tcb_s *tcb)
           stream->fs_bufpos  = stream->fs_bufstart;
           stream->fs_bufpos  = stream->fs_bufstart;
           stream->fs_bufread = stream->fs_bufstart;
+
+          /* Setup buffer flags */
+
+#ifdef CONFIG_STDIO_LINEBUFFER
+          stream->fs_flags  |= __FS_FLAG_LBF; /* Line buffering */
+#endif
 #endif
           /* Save the file description and open flags.  Setting the
            * file descriptor locks this stream.
diff --git a/include/nuttx/fs/fs.h b/include/nuttx/fs/fs.h
index 1edad05011d..6895ace9428 100644
--- a/include/nuttx/fs/fs.h
+++ b/include/nuttx/fs/fs.h
@@ -65,7 +65,8 @@
 
 #define __FS_FLAG_EOF   (1 << 0) /* EOF detected by a read operation */
 #define __FS_FLAG_ERROR (1 << 1) /* Error detected by any operation */
-#define __FS_FLAG_UBF   (1 << 2) /* Buffer allocated by caller of setvbuf */
+#define __FS_FLAG_LBF   (1 << 2) /* Line buffered */
+#define __FS_FLAG_UBF   (1 << 3) /* Buffer allocated by caller of setvbuf */
 
 /* Inode i_flag values:
  *
diff --git a/include/nuttx/streams.h b/include/nuttx/streams.h
index eb7ad678449..9d48c6d3931 100644
--- a/include/nuttx/streams.h
+++ b/include/nuttx/streams.h
@@ -70,9 +70,7 @@ struct lib_instream_s
 struct lib_outstream_s
 {
   lib_putc_t             put;     /* Put one character to the outstream */
-#ifdef CONFIG_STDIO_LINEBUFFER
   lib_flush_t            flush;   /* Flush any buffered characters in the outstream */
-#endif
   int                    nput;    /* Total number of characters put.  Written
                                    * by put method, readable by user */
 };
@@ -101,9 +99,7 @@ struct lib_sistream_s
 struct lib_sostream_s
 {
   lib_soputc_t           put;     /* Put one character to the outstream */
-#ifdef CONFIG_STDIO_LINEBUFFER
   lib_soflush_t          flush;   /* Flush any buffered characters in the outstream */
-#endif
   lib_soseek_t           seek;    /* Seek a position in the output stream */
   int                    nput;    /* Total number of characters put.  Written
                                    * by put method, readable by user */
@@ -389,23 +385,21 @@ void emergstream(FAR struct lib_outstream_s *stream);
  *
  * Description:
  *  lib_noflush() provides a common, dummy flush method for output streams
- *  that are not flushable.  Only used if CONFIG_STDIO_LINEBUFFER is selected.
+ *  that are not flushable.
  *
  * Return:
  *  Always returns OK
  *
  ****************************************************************************/
 
-#ifdef CONFIG_STDIO_LINEBUFFER
 int lib_noflush(FAR struct lib_outstream_s *stream);
-#endif
 
 /****************************************************************************
  * Name: lib_snoflush
  *
  * Description:
  *  lib_snoflush() provides a common, dummy flush method for seekable output
- *  streams that are not flushable.  Only used if CONFIG_STDIO_LINEBUFFER
+ *  streams that are not flushable.
  *  is selected.
  *
  * Return:
@@ -413,9 +407,7 @@ int lib_noflush(FAR struct lib_outstream_s *stream);
  *
  ****************************************************************************/
 
-#ifdef CONFIG_STDIO_LINEBUFFER
 int lib_snoflush(FAR struct lib_sostream_s *this);
-#endif
 
 /****************************************************************************
  * Name: lib_sprintf and lib_vsprintf
diff --git a/libc/stdio/Make.defs b/libc/stdio/Make.defs
index 96516e95613..478ac3f4aaa 100644
--- a/libc/stdio/Make.defs
+++ b/libc/stdio/Make.defs
@@ -65,7 +65,7 @@ CSRCS += lib_rdflush.c lib_wrflush.c lib_fputc.c lib_puts.c lib_fputs.c
 CSRCS += lib_ungetc.c lib_vprintf.c lib_fprintf.c lib_vfprintf.c
 CSRCS += lib_stdinstream.c lib_stdoutstream.c lib_stdsistream.c
 CSRCS += lib_stdsostream.c lib_perror.c lib_feof.c lib_ferror.c
-CSRCS += lib_clearerr.c lib_setvbuf.c
+CSRCS += lib_clearerr.c lib_setvbuf.c lib_libnoflush.c lib_libsnoflush.c
 
 endif
 
@@ -80,10 +80,6 @@ ifeq ($(CONFIG_LIBC_FLOATINGPOINT),y)
 CSRCS += lib_dtoa.c
 endif
 
-ifeq ($(CONFIG_STDIO_LINEBUFFER),y)
-CSRCS += lib_libnoflush.c lib_libsnoflush.c
-endif
-
 # Add the stdio directory to the build
 
 DEPPATH += --dep-path stdio
diff --git a/libc/stdio/lib_fputc.c b/libc/stdio/lib_fputc.c
index 6ef0b810081..e93231bc356 100644
--- a/libc/stdio/lib_fputc.c
+++ b/libc/stdio/lib_fputc.c
@@ -1,7 +1,7 @@
 /****************************************************************************
  * libc/stdio/lib_fputc.c
  *
- *   Copyright (C) 2007, 2008, 2011-2012 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2007, 2008, 2011-2012, 2017 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -58,8 +58,7 @@ int fputc(int c, FAR FILE *stream)
     {
       /* Flush the buffer if a newline is output */
 
-#ifdef CONFIG_STDIO_LINEBUFFER
-      if (c == '\n')
+      if (c == '\n' && (stream->fs_flags & __FS_FLAG_LBF) != 0)
         {
           ret = lib_fflush(stream, true);
           if (ret < 0)
@@ -67,7 +66,7 @@ int fputc(int c, FAR FILE *stream)
               return EOF;
             }
         }
-#endif
+
       return c;
     }
   else
diff --git a/libc/stdio/lib_fputs.c b/libc/stdio/lib_fputs.c
index 27dddc5cdf5..701076ff055 100644
--- a/libc/stdio/lib_fputs.c
+++ b/libc/stdio/lib_fputs.c
@@ -1,7 +1,7 @@
 /****************************************************************************
  * libc/stdio/lib_fputs.c
  *
- *   Copyright (C) 2007, 2008, 2011-2012 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2007, 2008, 2011-2012, 2017 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -90,52 +90,7 @@ int fputs(FAR const char *s, FAR FILE *stream)
 
       /* Flush the buffer if a newline was written to the buffer */
 
-#ifdef CONFIG_STDIO_LINEBUFFER
-      if (ch == '\n')
-        {
-          ret = lib_fflush(stream, true);
-          if (ret < 0)
-            {
-              return EOF;
-            }
-        }
-#endif
-    }
-
-  return nput;
-}
-
-#elif defined(CONFIG_STDIO_LINEBUFFER)
-int fputs(FAR const char *s, FAR FILE *stream)
-{
-  int nput;
-  int ret;
-
-  /* Make sure that a string was provided. */
-
-#ifdef CONFIG_DEBUG_FEATURES /* Most parameter checking is disabled if DEBUG is off */
-  if (!s)
-    {
-      set_errno(EINVAL);
-      return EOF;
-    }
-#endif
-
-  /* Write the string.  Loop until the null terminator is encountered */
-
-  for (nput = 0; *s; nput++, s++)
-    {
-      /* Write the next character to the stream buffer */
-
-      ret = lib_fwrite(s, 1, stream);
-      if (ret <= 0)
-        {
-          return EOF;
-        }
-
-      /* Flush the buffer if a newline was written to the buffer */
-
-      if (*s == '\n')
+      if (ch == '\n' && (stream->fs_flags & __FS_FLAG_LBF) != 0)
         {
           ret = lib_fflush(stream, true);
           if (ret < 0)
@@ -151,34 +106,75 @@ int fputs(FAR const char *s, FAR FILE *stream)
 #else
 int fputs(FAR const char *s, FAR FILE *stream)
 {
-  int ntowrite;
   int nput;
 
   /* Make sure that a string was provided. */
 
 #ifdef CONFIG_DEBUG_FEATURES /* Most parameter checking is disabled if DEBUG is off */
-  if (!s)
+  if (s == NULL || stream == NULL)
     {
       set_errno(EINVAL);
       return EOF;
     }
 #endif
 
-  /* Get the length of the string. */
+  /* If line buffering is enabled, then we will have to output one character
+   * at a time, checking for a newline character each time.
+   */
 
-  ntowrite = strlen(s);
-  if (ntowrite == 0)
+  if ((stream->fs_flags & __FS_FLAG_LBF) != 0)
     {
-      return 0;
+      int ret;
+
+      /* Write the string.  Loop until the null terminator is encountered */
+
+      for (nput = 0; *s; nput++, s++)
+        {
+          /* Write the next character to the stream buffer */
+
+          ret = lib_fwrite(s, 1, stream);
+          if (ret <= 0)
+            {
+              return EOF;
+            }
+
+          /* Flush the buffer if a newline was written to the buffer */
+
+          if (*s == '\n')
+            {
+              ret = lib_fflush(stream, true);
+              if (ret < 0)
+                {
+                  return EOF;
+                }
+            }
+        }
     }
 
-  /* Write the string */
+  /* Without line buffering, we can write the whole string in one operation. */
 
-  nput = lib_fwrite(s, ntowrite, stream);
-  if (nput < 0)
+  else
     {
-      return EOF;
+      int ntowrite;
+
+      /* Get the length of the string. */
+
+      ntowrite = strlen(s);
+      if (ntowrite == 0)
+        {
+          return 0;
+        }
+
+      /* Write the string */
+
+      nput = lib_fwrite(s, ntowrite, stream);
+      if (nput < 0)
+        {
+          return EOF;
+        }
+
     }
+
   return nput;
 }
 #endif
diff --git a/libc/stdio/lib_libnoflush.c b/libc/stdio/lib_libnoflush.c
index 5ad27c4b815..f862cd68748 100644
--- a/libc/stdio/lib_libnoflush.c
+++ b/libc/stdio/lib_libnoflush.c
@@ -1,7 +1,7 @@
 /****************************************************************************
  * libc/stdio/lib_libnoflush.c
  *
- *   Copyright (C) 2011-2012 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2011-2012, 2017 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -49,8 +49,6 @@
 
 #include "libc.h"
 
-#ifdef CONFIG_STDIO_LINEBUFFER
-
 /****************************************************************************
  * Public Functions
  ****************************************************************************/
@@ -60,7 +58,7 @@
  *
  * Description:
  *  lib_noflush() provides a common, dummy flush method for output streams
- *  that are not flushable.  Only used if CONFIG_STDIO_LINEBUFFER is selected.
+ *  that are not flushable.
  *
  * Return:
  *  Always returns OK
@@ -71,6 +69,3 @@ int lib_noflush(FAR struct lib_outstream_s *this)
 {
   return OK;
 }
-
-#endif /* CONFIG_STDIO_LINEBUFFER */
-
diff --git a/libc/stdio/lib_libsnoflush.c b/libc/stdio/lib_libsnoflush.c
index e472784a1c7..652b977cf69 100644
--- a/libc/stdio/lib_libsnoflush.c
+++ b/libc/stdio/lib_libsnoflush.c
@@ -1,7 +1,7 @@
 /****************************************************************************
  * libc/stdio/lib_libsnoflush.c
  *
- *   Copyright (C) 2014 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2014, 2017 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -48,8 +48,6 @@
 
 #include "libc.h"
 
-#ifdef CONFIG_STDIO_LINEBUFFER
-
 /****************************************************************************
  * Public Functions
  ****************************************************************************/
@@ -59,8 +57,7 @@
  *
  * Description:
  *  lib_snoflush() provides a common, dummy flush method for seekable output
- *  streams that are not flushable.  Only used if CONFIG_STDIO_LINEBUFFER
- *  is selected.
+ *  streams that are not flushable.
  *
  * Return:
  *  Always returns OK
@@ -71,6 +68,3 @@ int lib_snoflush(FAR struct lib_sostream_s *this)
 {
   return OK;
 }
-
-#endif /* CONFIG_STDIO_LINEBUFFER */
-
diff --git a/libc/stdio/lib_libvsprintf.c b/libc/stdio/lib_libvsprintf.c
index 6153cd54b86..894f0404538 100644
--- a/libc/stdio/lib_libvsprintf.c
+++ b/libc/stdio/lib_libvsprintf.c
@@ -1193,14 +1193,13 @@ int lib_vsprintf(FAR struct lib_outstream_s *obj, FAR const IPTR char *src,
 
            /* Flush the buffer if a newline is encountered */
 
-#ifdef CONFIG_STDIO_LINEBUFFER
            if (FMT_CHAR == '\n')
              {
                /* Should return an error on a failure to flush */
 
                (void)obj->flush(obj);
              }
-#endif
+
            /* Process the next character in the format */
 
            continue;
diff --git a/libc/stdio/lib_lowoutstream.c b/libc/stdio/lib_lowoutstream.c
index 788f3f18146..8447051d39d 100644
--- a/libc/stdio/lib_lowoutstream.c
+++ b/libc/stdio/lib_lowoutstream.c
@@ -1,7 +1,7 @@
 /****************************************************************************
  * libc/stdio/lib_lowoutstream.c
  *
- *   Copyright (C) 2007-2009, 2011-2012 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2007-2009, 2011-2012, 2017 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -88,9 +88,7 @@ static void lowoutstream_putc(FAR struct lib_outstream_s *this, int ch)
 void lib_lowoutstream(FAR struct lib_outstream_s *stream)
 {
   stream->put   = lowoutstream_putc;
-#ifdef CONFIG_STDIO_LINEBUFFER
   stream->flush = lib_noflush;
-#endif
   stream->nput  = 0;
 }
 
diff --git a/libc/stdio/lib_memoutstream.c b/libc/stdio/lib_memoutstream.c
index 1c658512ea9..28137d07ed7 100644
--- a/libc/stdio/lib_memoutstream.c
+++ b/libc/stdio/lib_memoutstream.c
@@ -1,7 +1,7 @@
 /****************************************************************************
  * libc/stdio/lib_memoutstream.c
  *
- *   Copyright (C) 2007-2009, 2011-2012, 2014 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2007-2009, 2011-2012, 2014, 2017 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -93,9 +93,7 @@ void lib_memoutstream(FAR struct lib_memoutstream_s *outstream,
                       FAR char *bufstart, int buflen)
 {
   outstream->public.put   = memoutstream_putc;
-#ifdef CONFIG_STDIO_LINEBUFFER
   outstream->public.flush = lib_noflush;
-#endif
   outstream->public.nput  = 0;          /* Will be buffer index */
   outstream->buffer       = bufstart;   /* Start of buffer */
   outstream->buflen       = buflen - 1; /* Save space for null terminator */
diff --git a/libc/stdio/lib_memsostream.c b/libc/stdio/lib_memsostream.c
index 6570ef8942b..93c19facad1 100644
--- a/libc/stdio/lib_memsostream.c
+++ b/libc/stdio/lib_memsostream.c
@@ -1,7 +1,7 @@
 /****************************************************************************
  * libc/stdio/lib_memsostream.c
  *
- *   Copyright (C) 2014 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2014, 2017 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -137,9 +137,7 @@ void lib_memsostream(FAR struct lib_memsostream_s *outstream,
                      FAR char *bufstart, int buflen)
 {
   outstream->public.put   = memsostream_putc;
-#ifdef CONFIG_STDIO_LINEBUFFER
   outstream->public.flush = lib_snoflush;
-#endif
   outstream->public.seek  = memsostream_seek;
   outstream->public.nput  = 0;          /* Total number of characters written */
   outstream->buffer       = bufstart;   /* Start of buffer */
diff --git a/libc/stdio/lib_nulloutstream.c b/libc/stdio/lib_nulloutstream.c
index 89a5a2524df..47f2acd58a4 100644
--- a/libc/stdio/lib_nulloutstream.c
+++ b/libc/stdio/lib_nulloutstream.c
@@ -1,7 +1,7 @@
 /****************************************************************************
  * libc/stdio/lib_nulloutstream.c
  *
- *   Copyright (C) 2007-2009, 2011-2012 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2007-2009, 2011-2012, 2017 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -76,9 +76,7 @@ static void nulloutstream_putc(FAR struct lib_outstream_s *this, int ch)
 void lib_nulloutstream(FAR struct lib_outstream_s *nulloutstream)
 {
   nulloutstream->put   = nulloutstream_putc;
-#ifdef CONFIG_STDIO_LINEBUFFER
   nulloutstream->flush = lib_noflush;
-#endif
   nulloutstream->nput  = 0;
 }
 
diff --git a/libc/stdio/lib_puts.c b/libc/stdio/lib_puts.c
index 7818b45da8f..e301f4af736 100644
--- a/libc/stdio/lib_puts.c
+++ b/libc/stdio/lib_puts.c
@@ -76,15 +76,18 @@ int puts(FAR const char *s)
         {
           nput = nwritten + 1;
 
-          /* Flush the buffer after the newline is output. */
+          /* Flush the buffer after the newline is output if line buffering
+           * is enabled.
+           */
 
-#ifdef CONFIG_STDIO_LINEBUFFER
-          ret = lib_fflush(stream, true);
-          if (ret < 0)
+          if ((stream->fs_flags & __FS_FLAG_LBF) != 0)
             {
-              nput = EOF;
+              ret = lib_fflush(stream, true);
+              if (ret < 0)
+                {
+                  nput = EOF;
+                }
             }
-#endif
         }
     }
 
diff --git a/libc/stdio/lib_rawoutstream.c b/libc/stdio/lib_rawoutstream.c
index aed1fc5272e..ab333147ba0 100644
--- a/libc/stdio/lib_rawoutstream.c
+++ b/libc/stdio/lib_rawoutstream.c
@@ -1,7 +1,7 @@
 /****************************************************************************
  * libc/stdio/lib_rawsostream.c
  *
- *   Copyright (C) 2014 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2014, 2017 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -119,9 +119,7 @@ static off_t rawsostream_seek(FAR struct lib_sostream_s *this, off_t offset,
 void lib_rawsostream(FAR struct lib_rawsostream_s *outstream, int fd)
 {
   outstream->public.put   = rawsostream_putc;
-#ifdef CONFIG_STDIO_LINEBUFFER
   outstream->public.flush = lib_snoflush;
-#endif
   outstream->public.seek  = rawsostream_seek;
   outstream->public.nput  = 0;
   outstream->fd           = fd;
diff --git a/libc/stdio/lib_rawsostream.c b/libc/stdio/lib_rawsostream.c
index 3c0b96dfa8d..30c71cce42d 100644
--- a/libc/stdio/lib_rawsostream.c
+++ b/libc/stdio/lib_rawsostream.c
@@ -108,9 +108,7 @@ static void rawoutstream_putc(FAR struct lib_outstream_s *this, int ch)
 void lib_rawoutstream(FAR struct lib_rawoutstream_s *outstream, int fd)
 {
   outstream->public.put   = rawoutstream_putc;
-#ifdef CONFIG_STDIO_LINEBUFFER
   outstream->public.flush = lib_noflush;
-#endif
   outstream->public.nput  = 0;
   outstream->fd           = fd;
 }
diff --git a/libc/stdio/lib_setvbuf.c b/libc/stdio/lib_setvbuf.c
index 154396dcf8d..4da52ff77d5 100644
--- a/libc/stdio/lib_setvbuf.c
+++ b/libc/stdio/lib_setvbuf.c
@@ -76,16 +76,10 @@
  * by the setvbuf() function. The contents of the array at any time are
  * unspecified.
  *
- * REVISIT: This initial version of setvbuf has some severe limitations and
- * not all features features required by the specification are available.
- * These the limitations are the result of hard-coded stream logic based
- * the static configuration.  This logic cannot support variable behaviors
- * without some additional logic.  Specifically, we cannot support:
- *
- *  - Any line buffering state that is inconsistent with the configuration
- *    setting CONFIG_STDIO_LINEBUFFER
- *  - We cannot support disabling stream buffering if
- *    CONFIG_STDIO_BUFFER_SIZE > 0
+ * REVISIT: This initial version of setvbuf has some limitations and not
+ * all features features required by the specification are available.
+ * Specifically, this current implementation cannot support sisabling
+ * stream buffering if CONFIG_STDIO_BUFFER_SIZE > 0
  *
  * Parmeters:
  *  stream - the stream to flush
@@ -141,21 +135,17 @@ int setvbuf(FAR FILE *stream, FAR char *buffer, int mode, size_t size)
       goto errout;
     }
 
+#if 1 /* REVISIT */
   /* Not all features are be available.  Without some additional logic,
-   * we cannot support (1) any line buffering state that is inconsistent
-   * with CONFIG_STDIO_LINEBUFFER nor can we (2) disable buffering if
-   * CONFIG_STDIO_BUFFER_SIZE > 0
+   * we cannot disable buffering if CONFIG_STDIO_BUFFER_SIZE > 0
    */
 
-#ifdef CONFIG_STDIO_LINEBUFFER
-  if (mode != _IOLBF)
-#else
-  if (mode != _IOFBF)
-#endif
+  if (mode == _IONBF)
     {
       errcode = ENOSYS;
       goto errout;
     }
+#endif
 
   /* Make sure that we have exclusive access to the stream */
 
@@ -189,7 +179,11 @@ int setvbuf(FAR FILE *stream, FAR char *buffer, int mode, size_t size)
    * successful.
    */
 
-  flags = stream->fs_flags & ~__FS_FLAG_UBF;
+#if 1 /* REVISIT: _IONBF not yet supported */
+  flags = stream->fs_flags & ~(__FS_FLAG_LBF | __FS_FLAG_UBF);
+#else
+  flags = stream->fs_flags & ~(__FS_FLAG_LBF | __FS_FLAG_NBF | __FS_FLAG_UBF);
+#endif
 
   /* Allocate a new buffer if one is needed.  We have already verified that:
    *
@@ -200,7 +194,7 @@ int setvbuf(FAR FILE *stream, FAR char *buffer, int mode, size_t size)
    * That simplifies the following check:
    */
 
-#if 0 /* size should always be > 0 in the currently supported configurations */
+#if 0 /* REVISIT: _IONBF not yet supported */
   if (size > 0)
 #else
   DEBUGASSERT(size > 0);
@@ -246,7 +240,23 @@ int setvbuf(FAR FILE *stream, FAR char *buffer, int mode, size_t size)
       stream->fs_bufend   = newbuf;
       stream->fs_bufpos   = newbuf;
       stream->fs_bufread  = newbuf;
+
+      /* Check for line buffering */
+
+      if (mode == _IOLBF)
+        {
+          flags |= __FS_FLAG_LBF;
+        }
     }
+#if 0 /* REVISIT: _IONBF not yet supported */
+  else
+    {
+      /* No buffer needed... We must be performing unbuffered I/O */
+
+      DEBUGASSERT(mode == _IONBF);
+      flags |= __FS_FLAG_NBF;
+    }
+#endif
 
   /* Update the stream flags and return success */
 
diff --git a/libc/stdio/lib_stdoutstream.c b/libc/stdio/lib_stdoutstream.c
index b30e8151608..1fcef637574 100644
--- a/libc/stdio/lib_stdoutstream.c
+++ b/libc/stdio/lib_stdoutstream.c
@@ -82,7 +82,7 @@ static void stdoutstream_putc(FAR struct lib_outstream_s *this, int ch)
  * Name: stdoutstream_flush
  ****************************************************************************/
 
-#if defined(CONFIG_STDIO_LINEBUFFER) && CONFIG_STDIO_BUFFER_SIZE > 0
+#if CONFIG_STDIO_BUFFER_SIZE > 0
 static int stdoutstream_flush(FAR struct lib_outstream_s *this)
 {
   FAR struct lib_stdoutstream_s *sthis = (FAR struct lib_stdoutstream_s *)this;
@@ -125,7 +125,6 @@ void lib_stdoutstream(FAR struct lib_stdoutstream_s *outstream,
    * meaning.
    */
 
-#ifdef CONFIG_STDIO_LINEBUFFER
 #if CONFIG_STDIO_BUFFER_SIZE > 0
   if ((stream->fs_oflags & O_BINARY) == 0)
     {
@@ -136,7 +135,6 @@ void lib_stdoutstream(FAR struct lib_stdoutstream_s *outstream,
     {
       outstream->public.flush = lib_noflush;
     }
-#endif
 
   /* Set the number of bytes put to zero and remember the stream */
 
diff --git a/libc/stdio/lib_stdsostream.c b/libc/stdio/lib_stdsostream.c
index 4e196b1a22b..01ebc932918 100644
--- a/libc/stdio/lib_stdsostream.c
+++ b/libc/stdio/lib_stdsostream.c
@@ -1,7 +1,7 @@
 /****************************************************************************
  * libc/stdio/lib_stdsostream.c
  *
- *   Copyright (C) 2014 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2014, 2017 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -82,7 +82,7 @@ static void stdsostream_putc(FAR struct lib_sostream_s *this, int ch)
  * Name: stdsostream_flush
  ****************************************************************************/
 
-#if defined(CONFIG_STDIO_LINEBUFFER) && CONFIG_STDIO_BUFFER_SIZE > 0
+#if CONFIG_STDIO_BUFFER_SIZE > 0
 static int stdsostream_flush(FAR struct lib_sostream_s *this)
 {
   FAR struct lib_stdsostream_s *sthis = (FAR struct lib_stdsostream_s *)this;
@@ -138,7 +138,6 @@ void lib_stdsostream(FAR struct lib_stdsostream_s *outstream,
    * meaning.
    */
 
-#ifdef CONFIG_STDIO_LINEBUFFER
 #if CONFIG_STDIO_BUFFER_SIZE > 0
   if ((stream->fs_oflags & O_BINARY) == 0)
     {
@@ -149,7 +148,6 @@ void lib_stdsostream(FAR struct lib_stdsostream_s *outstream,
     {
       outstream->public.flush = lib_snoflush;
     }
-#endif
 
   /* Select the seek operation */