diff --git a/arch/arm/src/common/up_exit.c b/arch/arm/src/common/up_exit.c
index 190382a2da3..a25d6daacdf 100644
--- a/arch/arm/src/common/up_exit.c
+++ b/arch/arm/src/common/up_exit.c
@@ -110,13 +110,18 @@ static void _up_dumponexit(FAR struct tcb_s *tcb, FAR void *arg)
       struct file_struct *filep = &streamlist->sl_streams[i];
       if (filep->fs_fd >= 0)
         {
-#if CONFIG_STDIO_BUFFER_SIZE > 0
-          sinfo("      fd=%d nbytes=%d\n",
-                filep->fs_fd,
-                filep->fs_bufpos - filep->fs_bufstart);
-#else
-          sinfo("      fd=%d\n", filep->fs_fd);
-#endif
+#ifndef CONFIG_STDIO_DISABLE_BUFFERING
+          if (filep->fs_bufstart != NULL)
+            {
+              sinfo("      fd=%d nbytes=%d\n",
+                    filep->fs_fd,
+                    filep->fs_bufpos - filep->fs_bufstart);
+            }
+          else
+Eendif
+            {
+              sinfo("      fd=%d\n", filep->fs_fd);
+            }
         }
     }
 #endif
diff --git a/arch/avr/src/common/up_exit.c b/arch/avr/src/common/up_exit.c
index d816ad1d9f7..a82c640d69d 100644
--- a/arch/avr/src/common/up_exit.c
+++ b/arch/avr/src/common/up_exit.c
@@ -109,13 +109,18 @@ static void _up_dumponexit(FAR struct tcb_s *tcb, FAR void *arg)
       struct file_struct *filep = &streamlist->sl_streams[i];
       if (filep->fs_fd >= 0)
         {
-#if CONFIG_STDIO_BUFFER_SIZE > 0
-          sinfo("      fd=%d nbytes=%d\n",
-                filep->fs_fd,
-                filep->fs_bufpos - filep->fs_bufstart);
-#else
-          sinfo("      fd=%d\n", filep->fs_fd);
+#ifndef CONFIG_STDIO_DISABLE_BUFFERING
+          if (filep->fs_bufstart != NULL)
+            {
+              sinfo("      fd=%d nbytes=%d\n",
+                    filep->fs_fd,
+                    filep->fs_bufpos - filep->fs_bufstart);
+            }
+          else
 #endif
+            {
+              sinfo("      fd=%d\n", filep->fs_fd);
+            }
         }
     }
 #endif
diff --git a/arch/hc/src/common/up_exit.c b/arch/hc/src/common/up_exit.c
index 54d9a2c45c2..9b20fc8abaf 100644
--- a/arch/hc/src/common/up_exit.c
+++ b/arch/hc/src/common/up_exit.c
@@ -109,13 +109,18 @@ static void _up_dumponexit(FAR struct tcb_s *tcb, FAR void *arg)
       struct file_struct *filep = &streamlist->sl_streams[i];
       if (filep->fs_fd >= 0)
         {
-#if CONFIG_STDIO_BUFFER_SIZE > 0
-          sinfo("      fd=%d nbytes=%d\n",
-                filep->fs_fd,
-                filep->fs_bufpos - filep->fs_bufstart);
-#else
-          sinfo("      fd=%d\n", filep->fs_fd);
+#ifndef CONFIG_STDIO_DISABLE_BUFFERING
+          if (filep->fs_bufstart != NULL)
+            {
+              sinfo("      fd=%d nbytes=%d\n",
+                    filep->fs_fd,
+                    filep->fs_bufpos - filep->fs_bufstart);
+            }
+          else
 #endif
+            {
+              sinfo("      fd=%d\n", filep->fs_fd);
+            }
         }
     }
 #endif
diff --git a/arch/mips/src/common/up_exit.c b/arch/mips/src/common/up_exit.c
index 1962c698e0a..d21a27e064d 100644
--- a/arch/mips/src/common/up_exit.c
+++ b/arch/mips/src/common/up_exit.c
@@ -111,13 +111,18 @@ static void _up_dumponexit(FAR struct tcb_s *tcb, FAR void *arg)
       struct file_struct *filep = &streamlist->sl_streams[i];
       if (filep->fs_fd >= 0)
         {
-#if CONFIG_STDIO_BUFFER_SIZE > 0
-          sinfo("      fd=%d nbytes=%d\n",
-                filep->fs_fd,
-                filep->fs_bufpos - filep->fs_bufstart);
-#else
-          sinfo("      fd=%d\n", filep->fs_fd);
+#ifndef CONFIG_STDIO_DISABLE_BUFFERING
+          if (filep->fs_bufstart != NULL)
+            {
+              sinfo("      fd=%d nbytes=%d\n",
+                    filep->fs_fd,
+                    filep->fs_bufpos - filep->fs_bufstart);
+            }
+          else
 #endif
+            {
+              sinfo("      fd=%d\n", filep->fs_fd);
+            }
         }
     }
 #endif
diff --git a/arch/misoc/src/lm32/lm32_exit.c b/arch/misoc/src/lm32/lm32_exit.c
index f6cf75f6f4d..8dd96b0a3ac 100644
--- a/arch/misoc/src/lm32/lm32_exit.c
+++ b/arch/misoc/src/lm32/lm32_exit.c
@@ -108,13 +108,18 @@ static void _up_dumponexit(FAR struct tcb_s *tcb, FAR void *arg)
       struct file_struct *filep = &streamlist->sl_streams[i];
       if (filep->fs_fd >= 0)
         {
-#if CONFIG_STDIO_BUFFER_SIZE > 0
-          sinfo("      fd=%d nbytes=%d\n",
-                filep->fs_fd,
-                filep->fs_bufpos - filep->fs_bufstart);
-#else
-          sinfo("      fd=%d\n", filep->fs_fd);
+#ifndef CONFIG_STDIO_DISABLE_BUFFERING
+          if (filep->fs_bufstart != NULL)
+            {
+              sinfo("      fd=%d nbytes=%d\n",
+                    filep->fs_fd,
+                    filep->fs_bufpos - filep->fs_bufstart);
+            }
+          else
 #endif
+            {
+              sinfo("      fd=%d\n", filep->fs_fd);
+            }
         }
     }
 #endif
diff --git a/arch/renesas/src/common/up_exit.c b/arch/renesas/src/common/up_exit.c
index ed61c7c299f..81843c5ccc1 100644
--- a/arch/renesas/src/common/up_exit.c
+++ b/arch/renesas/src/common/up_exit.c
@@ -109,13 +109,18 @@ static void _up_dumponexit(FAR struct tcb_s *tcb, FAR void *arg)
       struct file_struct *filep = &streamlist->sl_streams[i];
       if (filep->fs_fd >= 0)
         {
-#if CONFIG_STDIO_BUFFER_SIZE > 0
-          sinfo("      fd=%d nbytes=%d\n",
-                filep->fs_fd,
-                filep->fs_bufpos - filep->fs_bufstart);
-#else
-          sinfo("      fd=%d\n", filep->fs_fd);
+#ifndef CONFIG_STDIO_DISABLE_BUFFERING
+          if (filep->fs_bufstart != NULL)
+            {
+              sinfo("      fd=%d nbytes=%d\n",
+                    filep->fs_fd,
+                    filep->fs_bufpos - filep->fs_bufstart);
+            }
+          else
 #endif
+            {
+              sinfo("      fd=%d\n", filep->fs_fd);
+            }
         }
     }
 #endif
diff --git a/arch/risc-v/src/common/up_exit.c b/arch/risc-v/src/common/up_exit.c
index 3dcbd69f292..5456012aeee 100644
--- a/arch/risc-v/src/common/up_exit.c
+++ b/arch/risc-v/src/common/up_exit.c
@@ -111,13 +111,18 @@ static void _up_dumponexit(FAR struct tcb_s *tcb, FAR void *arg)
       struct file_struct *filep = &streamlist->sl_streams[i];
       if (filep->fs_fd >= 0)
         {
-#if CONFIG_STDIO_BUFFER_SIZE > 0
-          sinfo("      fd=%d nbytes=%d\n",
-                filep->fs_fd,
-                filep->fs_bufpos - filep->fs_bufstart);
-#else
-          sinfo("      fd=%d\n", filep->fs_fd);
+#ifndef CONFIG_STDIO_DISABLE_BUFFERING
+          if (filep->fs_bufstart != NULL)
+            {
+              sinfo("      fd=%d nbytes=%d\n",
+                    filep->fs_fd,
+                    filep->fs_bufpos - filep->fs_bufstart);
+            }
+          else
 #endif
+            {
+              sinfo("      fd=%d\n", filep->fs_fd);
+            }
         }
     }
 #endif
diff --git a/arch/x86/src/common/up_exit.c b/arch/x86/src/common/up_exit.c
index 66399be6db1..e5bcd30b465 100644
--- a/arch/x86/src/common/up_exit.c
+++ b/arch/x86/src/common/up_exit.c
@@ -109,13 +109,18 @@ static void _up_dumponexit(FAR struct tcb_s *tcb, FAR void *arg)
       struct file_struct *filep = &streamlist->sl_streams[i];
       if (filep->fs_fd >= 0)
         {
-#if CONFIG_STDIO_BUFFER_SIZE > 0
-          sinfo("      fd=%d nbytes=%d\n",
-                filep->fs_fd,
-                filep->fs_bufpos - filep->fs_bufstart);
-#else
-          sinfo("      fd=%d\n", filep->fs_fd);
+#ifndef CONFIG_STDIO_DISABLE_BUFFERING
+          if (filep->fs_bufstart != NULL)
+            {
+              sinfo("      fd=%d nbytes=%d\n",
+                    filep->fs_fd,
+                    filep->fs_bufpos - filep->fs_bufstart);
+            }
+          else
 #endif
+            {
+              sinfo("      fd=%d\n", filep->fs_fd);
+            }
         }
     }
 #endif
diff --git a/arch/xtensa/src/common/xtensa_exit.c b/arch/xtensa/src/common/xtensa_exit.c
index 7cb12c360fa..d8dafeb20c9 100644
--- a/arch/xtensa/src/common/xtensa_exit.c
+++ b/arch/xtensa/src/common/xtensa_exit.c
@@ -111,13 +111,18 @@ static void _xtensa_dumponexit(FAR struct tcb_s *tcb, FAR void *arg)
       struct file_struct *filep = &streamlist->sl_streams[i];
       if (filep->fs_fd >= 0)
         {
-#if CONFIG_STDIO_BUFFER_SIZE > 0
-          sinfo("      fd=%d nbytes=%d\n",
-                filep->fs_fd,
-                filep->fs_bufpos - filep->fs_bufstart);
-#else
-          sinfo("      fd=%d\n", filep->fs_fd);
+#ifndef CONFIG_STDIO_DISABLE_BUFFERING
+          if (filep->fs_bufstart != NULL)
+            {
+              sinfo("      fd=%d nbytes=%d\n",
+                    filep->fs_fd,
+                    filep->fs_bufpos - filep->fs_bufstart);
+            }
+          else
 #endif
+            {
+              sinfo("      fd=%d\n", filep->fs_fd);
+            }
         }
     }
 #endif
diff --git a/arch/z16/src/common/up_exit.c b/arch/z16/src/common/up_exit.c
index b142e6be215..58b2a542869 100644
--- a/arch/z16/src/common/up_exit.c
+++ b/arch/z16/src/common/up_exit.c
@@ -109,13 +109,18 @@ static void _up_dumponexit(FAR struct tcb_s *tcb, FAR void *arg)
       struct file_struct *filep = &streamlist->sl_streams[i];
       if (filep->fs_fd >= 0)
         {
-#if CONFIG_STDIO_BUFFER_SIZE > 0
-          sinfo("      fd=%d nbytes=%d\n",
-                filep->fs_fd,
-                filep->fs_bufpos - filep->fs_bufstart);
-#else
-          sinfo("      fd=%d\n", filep->fs_fd);
+#ifndef CONFIG_STDIO_DISABLE_BUFFERING
+          if (filep->fs_bufstart != NULL)
+            {
+              sinfo("      fd=%d nbytes=%d\n",
+                    filep->fs_fd,
+                    filep->fs_bufpos - filep->fs_bufstart);
+            }
+          else
 #endif
+            {
+              sinfo("      fd=%d\n", filep->fs_fd);
+            }
         }
     }
 #endif
diff --git a/arch/z80/src/common/up_exit.c b/arch/z80/src/common/up_exit.c
index bb65dbd7779..af42e69ce9a 100644
--- a/arch/z80/src/common/up_exit.c
+++ b/arch/z80/src/common/up_exit.c
@@ -111,13 +111,18 @@ static void _up_dumponexit(FAR struct tcb_s *tcb, FAR void *arg)
       struct file_struct *filep = &streamlist->sl_streams[i];
       if (filep->fs_fd >= 0)
         {
-#if CONFIG_STDIO_BUFFER_SIZE > 0
-          sinfo("      fd=%d nbytes=%d\n",
-                filep->fs_fd,
-                filep->fs_bufpos - filep->fs_bufstart);
-#else
-          sinfo("      fd=%d\n", filep->fs_fd);
+#ifndef CONFIG_STDIO_DISABLE_BUFFERING
+          if (filep->fs_bufstart != NULL)
+            {
+              sinfo("      fd=%d nbytes=%d\n",
+                    filep->fs_fd,
+                    filep->fs_bufpos - filep->fs_bufstart);
+            }
+          else
 #endif
+            {
+              sinfo("      fd=%d\n", filep->fs_fd);
+            }
         }
     }
 #endif
diff --git a/configs/eagle100/nettest/defconfig b/configs/eagle100/nettest/defconfig
index b782d836165..836fd24fe60 100644
--- a/configs/eagle100/nettest/defconfig
+++ b/configs/eagle100/nettest/defconfig
@@ -761,7 +761,7 @@ CONFIG_MM_REGIONS=1
 #
 # Standard C Library Options
 #
-CONFIG_STDIO_BUFFER_SIZE=0
+CONFIG_STDIO_DISABLE_BUFFERING=y
 CONFIG_STDIO_LINEBUFFER=y
 CONFIG_NUNGET_CHARS=0
 # CONFIG_LIBM is not set
diff --git a/configs/ez80f910200kitg/ostest/defconfig b/configs/ez80f910200kitg/ostest/defconfig
index ba597876aa2..98891cc5f7f 100644
--- a/configs/ez80f910200kitg/ostest/defconfig
+++ b/configs/ez80f910200kitg/ostest/defconfig
@@ -505,7 +505,7 @@ CONFIG_HEAP2_SIZE=0
 #
 # Standard C Library Options
 #
-CONFIG_STDIO_BUFFER_SIZE=0
+CONFIG_STDIO_DISABLE_BUFFERING=y
 CONFIG_STDIO_LINEBUFFER=y
 CONFIG_NUNGET_CHARS=0
 # CONFIG_LIBM is not set
diff --git a/configs/ez80f910200zco/dhcpd/defconfig b/configs/ez80f910200zco/dhcpd/defconfig
index 3e689691867..b696d03129a 100644
--- a/configs/ez80f910200zco/dhcpd/defconfig
+++ b/configs/ez80f910200zco/dhcpd/defconfig
@@ -658,7 +658,7 @@ CONFIG_HEAP2_SIZE=0
 #
 # Standard C Library Options
 #
-CONFIG_STDIO_BUFFER_SIZE=0
+CONFIG_STDIO_DISABLE_BUFFERING=y
 CONFIG_STDIO_LINEBUFFER=y
 CONFIG_NUNGET_CHARS=0
 # CONFIG_LIBM is not set
diff --git a/configs/ez80f910200zco/httpd/defconfig b/configs/ez80f910200zco/httpd/defconfig
index 76f27ba843b..4e2271d50d7 100644
--- a/configs/ez80f910200zco/httpd/defconfig
+++ b/configs/ez80f910200zco/httpd/defconfig
@@ -672,7 +672,7 @@ CONFIG_HEAP2_SIZE=0
 #
 # Standard C Library Options
 #
-CONFIG_STDIO_BUFFER_SIZE=0
+CONFIG_STDIO_DISABLE_BUFFERING=y
 CONFIG_STDIO_LINEBUFFER=y
 CONFIG_NUNGET_CHARS=0
 # CONFIG_LIBM is not set
diff --git a/configs/ez80f910200zco/nettest/defconfig b/configs/ez80f910200zco/nettest/defconfig
index 9096a41faac..4476ee44afe 100644
--- a/configs/ez80f910200zco/nettest/defconfig
+++ b/configs/ez80f910200zco/nettest/defconfig
@@ -664,7 +664,7 @@ CONFIG_HEAP2_SIZE=0
 #
 # Standard C Library Options
 #
-CONFIG_STDIO_BUFFER_SIZE=0
+CONFIG_STDIO_DISABLE_BUFFERING=y
 CONFIG_STDIO_LINEBUFFER=y
 CONFIG_NUNGET_CHARS=0
 # CONFIG_LIBM is not set
diff --git a/configs/ez80f910200zco/poll/defconfig b/configs/ez80f910200zco/poll/defconfig
index f48526690c2..74c3f5ea3c1 100644
--- a/configs/ez80f910200zco/poll/defconfig
+++ b/configs/ez80f910200zco/poll/defconfig
@@ -674,7 +674,7 @@ CONFIG_HEAP2_SIZE=0
 #
 # Standard C Library Options
 #
-CONFIG_STDIO_BUFFER_SIZE=0
+CONFIG_STDIO_DISABLE_BUFFERING=y
 CONFIG_STDIO_LINEBUFFER=y
 CONFIG_NUNGET_CHARS=0
 # CONFIG_LIBM is not set
diff --git a/configs/freedom-kl25z/nsh/defconfig b/configs/freedom-kl25z/nsh/defconfig
index 03f252e999a..ead5cbb0596 100644
--- a/configs/freedom-kl25z/nsh/defconfig
+++ b/configs/freedom-kl25z/nsh/defconfig
@@ -565,7 +565,7 @@ CONFIG_BUILTIN=y
 #
 # Standard C Library Options
 #
-CONFIG_STDIO_BUFFER_SIZE=0
+CONFIG_STDIO_DISABLE_BUFFERING=y
 CONFIG_STDIO_LINEBUFFER=y
 CONFIG_NUNGET_CHARS=0
 # CONFIG_LIBM is not set
diff --git a/configs/freedom-kl26z/nsh/defconfig b/configs/freedom-kl26z/nsh/defconfig
index f76176d5a75..120119687e0 100644
--- a/configs/freedom-kl26z/nsh/defconfig
+++ b/configs/freedom-kl26z/nsh/defconfig
@@ -556,7 +556,7 @@ CONFIG_BUILTIN=y
 #
 # Standard C Library Options
 #
-CONFIG_STDIO_BUFFER_SIZE=0
+CONFIG_STDIO_DISABLE_BUFFERING=y
 CONFIG_STDIO_LINEBUFFER=y
 CONFIG_NUNGET_CHARS=0
 # CONFIG_LIBM is not set
diff --git a/configs/lpcxpresso-lpc1115/nsh/defconfig b/configs/lpcxpresso-lpc1115/nsh/defconfig
index 3607e86da86..abafecbe2bb 100644
--- a/configs/lpcxpresso-lpc1115/nsh/defconfig
+++ b/configs/lpcxpresso-lpc1115/nsh/defconfig
@@ -528,7 +528,7 @@ CONFIG_BUILTIN=y
 #
 # Standard C Library Options
 #
-CONFIG_STDIO_BUFFER_SIZE=0
+CONFIG_STDIO_DISABLE_BUFFERING=y
 CONFIG_STDIO_LINEBUFFER=y
 CONFIG_NUNGET_CHARS=0
 # CONFIG_LIBM is not set
diff --git a/configs/lpcxpresso-lpc1768/dhcpd/defconfig b/configs/lpcxpresso-lpc1768/dhcpd/defconfig
index 418286f3460..c6c3e6ba808 100644
--- a/configs/lpcxpresso-lpc1768/dhcpd/defconfig
+++ b/configs/lpcxpresso-lpc1768/dhcpd/defconfig
@@ -746,7 +746,7 @@ CONFIG_MM_REGIONS=2
 #
 # Standard C Library Options
 #
-CONFIG_STDIO_BUFFER_SIZE=0
+CONFIG_STDIO_DISABLE_BUFFERING=y
 CONFIG_STDIO_LINEBUFFER=y
 CONFIG_NUNGET_CHARS=0
 # CONFIG_LIBM is not set
diff --git a/configs/micropendous3/hello/defconfig b/configs/micropendous3/hello/defconfig
index 6445bfec5c4..2876f12d1c5 100644
--- a/configs/micropendous3/hello/defconfig
+++ b/configs/micropendous3/hello/defconfig
@@ -340,7 +340,7 @@ CONFIG_MM_REGIONS=1
 #
 # Standard C Library Options
 #
-CONFIG_STDIO_BUFFER_SIZE=0
+CONFIG_STDIO_DISABLE_BUFFERING=y
 CONFIG_STDIO_LINEBUFFER=y
 CONFIG_NUNGET_CHARS=0
 # CONFIG_LIBM is not set
diff --git a/configs/misoc/nsh/defconfig b/configs/misoc/nsh/defconfig
index ec5d68bb9df..0bac0c89c72 100644
--- a/configs/misoc/nsh/defconfig
+++ b/configs/misoc/nsh/defconfig
@@ -472,7 +472,7 @@ CONFIG_MM_REGIONS=1
 #
 # Standard C Library Options
 #
-CONFIG_STDIO_BUFFER_SIZE=0
+CONFIG_STDIO_DISABLE_BUFFERING=y
 CONFIG_STDIO_LINEBUFFER=y
 CONFIG_NUNGET_CHARS=0
 # CONFIG_LIBM is not set
diff --git a/configs/moteino-mega/hello/defconfig b/configs/moteino-mega/hello/defconfig
index d78adaa6b7e..d63906adff2 100644
--- a/configs/moteino-mega/hello/defconfig
+++ b/configs/moteino-mega/hello/defconfig
@@ -397,7 +397,7 @@ CONFIG_MM_REGIONS=1
 #
 # Standard C Library Options
 #
-CONFIG_STDIO_BUFFER_SIZE=0
+CONFIG_STDIO_DISABLE_BUFFERING=y
 CONFIG_STDIO_LINEBUFFER=y
 CONFIG_NUNGET_CHARS=0
 # CONFIG_LIBM is not set
diff --git a/configs/moteino-mega/nsh/defconfig b/configs/moteino-mega/nsh/defconfig
index 3a72bd17af0..8dd38900b2d 100644
--- a/configs/moteino-mega/nsh/defconfig
+++ b/configs/moteino-mega/nsh/defconfig
@@ -406,7 +406,7 @@ CONFIG_MM_REGIONS=1
 #
 # Standard C Library Options
 #
-CONFIG_STDIO_BUFFER_SIZE=0
+CONFIG_STDIO_DISABLE_BUFFERING=y
 CONFIG_STDIO_LINEBUFFER=y
 CONFIG_NUNGET_CHARS=0
 CONFIG_LIB_HOMEDIR="/"
diff --git a/configs/ne64badge/ostest/defconfig b/configs/ne64badge/ostest/defconfig
index 284662823aa..4cffbda4f89 100644
--- a/configs/ne64badge/ostest/defconfig
+++ b/configs/ne64badge/ostest/defconfig
@@ -326,7 +326,7 @@ CONFIG_MM_REGIONS=1
 #
 # Standard C Library Options
 #
-CONFIG_STDIO_BUFFER_SIZE=0
+CONFIG_STDIO_DISABLE_BUFFERING=y
 CONFIG_STDIO_LINEBUFFER=y
 CONFIG_NUNGET_CHARS=0
 # CONFIG_LIBM is not set
diff --git a/configs/nutiny-nuc120/nsh/defconfig b/configs/nutiny-nuc120/nsh/defconfig
index 3b2c7b3ed38..f5dba7a48c0 100644
--- a/configs/nutiny-nuc120/nsh/defconfig
+++ b/configs/nutiny-nuc120/nsh/defconfig
@@ -574,7 +574,7 @@ CONFIG_SYMTAB_ORDEREDBYNAME=y
 #
 # Standard C Library Options
 #
-CONFIG_STDIO_BUFFER_SIZE=0
+CONFIG_STDIO_DISABLE_BUFFERING=y
 CONFIG_STDIO_LINEBUFFER=y
 CONFIG_NUNGET_CHARS=0
 # CONFIG_LIBM is not set
diff --git a/configs/olimex-lpc1766stk/nettest/defconfig b/configs/olimex-lpc1766stk/nettest/defconfig
index 020666d28c4..7f0e7390b66 100644
--- a/configs/olimex-lpc1766stk/nettest/defconfig
+++ b/configs/olimex-lpc1766stk/nettest/defconfig
@@ -752,7 +752,7 @@ CONFIG_MM_REGIONS=2
 #
 # Standard C Library Options
 #
-CONFIG_STDIO_BUFFER_SIZE=0
+CONFIG_STDIO_DISABLE_BUFFERING=y
 CONFIG_STDIO_LINEBUFFER=y
 CONFIG_NUNGET_CHARS=0
 # CONFIG_LIBM is not set
diff --git a/configs/p112/ostest/defconfig b/configs/p112/ostest/defconfig
index 455f6a52a60..4b93dc48123 100644
--- a/configs/p112/ostest/defconfig
+++ b/configs/p112/ostest/defconfig
@@ -334,7 +334,7 @@ CONFIG_GRAN_SINGLE=y
 #
 # Library Routines
 #
-CONFIG_STDIO_BUFFER_SIZE=0
+CONFIG_STDIO_DISABLE_BUFFERING=y
 CONFIG_STDIO_LINEBUFFER=y
 CONFIG_NUNGET_CHARS=0
 # CONFIG_LIBM is not set
diff --git a/configs/spark/composite/defconfig b/configs/spark/composite/defconfig
index 3b55a300c27..2dec57c31be 100644
--- a/configs/spark/composite/defconfig
+++ b/configs/spark/composite/defconfig
@@ -1017,7 +1017,7 @@ CONFIG_SYMTAB_ORDEREDBYNAME=y
 #
 # Standard C Library Options
 #
-CONFIG_STDIO_BUFFER_SIZE=0
+CONFIG_STDIO_DISABLE_BUFFERING=y
 CONFIG_STDIO_LINEBUFFER=y
 CONFIG_NUNGET_CHARS=2
 CONFIG_LIB_HOMEDIR="/"
diff --git a/configs/spark/nsh/defconfig b/configs/spark/nsh/defconfig
index 6f43b59ca41..a1f4763fa5d 100644
--- a/configs/spark/nsh/defconfig
+++ b/configs/spark/nsh/defconfig
@@ -1017,7 +1017,7 @@ CONFIG_SYMTAB_ORDEREDBYNAME=y
 #
 # Standard C Library Options
 #
-CONFIG_STDIO_BUFFER_SIZE=0
+CONFIG_STDIO_DISABLE_BUFFERING=y
 CONFIG_STDIO_LINEBUFFER=y
 CONFIG_NUNGET_CHARS=2
 CONFIG_LIB_HOMEDIR="/"
diff --git a/configs/spark/usbmsc/defconfig b/configs/spark/usbmsc/defconfig
index 66df842d96a..e75dd29766c 100644
--- a/configs/spark/usbmsc/defconfig
+++ b/configs/spark/usbmsc/defconfig
@@ -982,7 +982,7 @@ CONFIG_SYMTAB_ORDEREDBYNAME=y
 #
 # Standard C Library Options
 #
-CONFIG_STDIO_BUFFER_SIZE=0
+CONFIG_STDIO_DISABLE_BUFFERING=y
 CONFIG_STDIO_LINEBUFFER=y
 CONFIG_NUNGET_CHARS=2
 CONFIG_LIB_HOMEDIR="/"
diff --git a/configs/spark/usbserial/defconfig b/configs/spark/usbserial/defconfig
index dd4d595afa1..303fa1a49cb 100644
--- a/configs/spark/usbserial/defconfig
+++ b/configs/spark/usbserial/defconfig
@@ -992,7 +992,7 @@ CONFIG_SYMTAB_ORDEREDBYNAME=y
 #
 # Standard C Library Options
 #
-CONFIG_STDIO_BUFFER_SIZE=0
+CONFIG_STDIO_DISABLE_BUFFERING=y
 CONFIG_STDIO_LINEBUFFER=y
 CONFIG_NUNGET_CHARS=2
 CONFIG_LIB_HOMEDIR="/"
diff --git a/configs/stm3220g-eval/dhcpd/defconfig b/configs/stm3220g-eval/dhcpd/defconfig
index 48243187528..06f421502f7 100644
--- a/configs/stm3220g-eval/dhcpd/defconfig
+++ b/configs/stm3220g-eval/dhcpd/defconfig
@@ -1032,7 +1032,7 @@ CONFIG_MM_REGIONS=2
 #
 # Standard C Library Options
 #
-CONFIG_STDIO_BUFFER_SIZE=0
+CONFIG_STDIO_DISABLE_BUFFERING=y
 # CONFIG_STDIO_LINEBUFFER is not set
 CONFIG_NUNGET_CHARS=0
 # CONFIG_LIBM is not set
diff --git a/configs/stm3220g-eval/nettest/defconfig b/configs/stm3220g-eval/nettest/defconfig
index 4bf75d6522d..f52adbc0c5b 100644
--- a/configs/stm3220g-eval/nettest/defconfig
+++ b/configs/stm3220g-eval/nettest/defconfig
@@ -1037,7 +1037,7 @@ CONFIG_MM_REGIONS=1
 #
 # Standard C Library Options
 #
-CONFIG_STDIO_BUFFER_SIZE=0
+CONFIG_STDIO_DISABLE_BUFFERING=y
 CONFIG_STDIO_LINEBUFFER=y
 CONFIG_NUNGET_CHARS=0
 # CONFIG_LIBM is not set
diff --git a/configs/stm3240g-eval/dhcpd/defconfig b/configs/stm3240g-eval/dhcpd/defconfig
index 5138c8bed06..69eb3f61ace 100644
--- a/configs/stm3240g-eval/dhcpd/defconfig
+++ b/configs/stm3240g-eval/dhcpd/defconfig
@@ -1036,7 +1036,7 @@ CONFIG_MM_REGIONS=2
 #
 # Standard C Library Options
 #
-CONFIG_STDIO_BUFFER_SIZE=0
+CONFIG_STDIO_DISABLE_BUFFERING=y
 # CONFIG_STDIO_LINEBUFFER is not set
 CONFIG_NUNGET_CHARS=0
 # CONFIG_LIBM is not set
diff --git a/configs/stm3240g-eval/nettest/defconfig b/configs/stm3240g-eval/nettest/defconfig
index 22173822ada..e1e0eedc915 100644
--- a/configs/stm3240g-eval/nettest/defconfig
+++ b/configs/stm3240g-eval/nettest/defconfig
@@ -1041,7 +1041,7 @@ CONFIG_MM_REGIONS=2
 #
 # Standard C Library Options
 #
-CONFIG_STDIO_BUFFER_SIZE=0
+CONFIG_STDIO_DISABLE_BUFFERING=y
 CONFIG_STDIO_LINEBUFFER=y
 CONFIG_NUNGET_CHARS=0
 # CONFIG_LIBM is not set
diff --git a/configs/stm32ldiscovery/nsh/defconfig b/configs/stm32ldiscovery/nsh/defconfig
index 07c527576e7..4261827aa33 100644
--- a/configs/stm32ldiscovery/nsh/defconfig
+++ b/configs/stm32ldiscovery/nsh/defconfig
@@ -839,7 +839,7 @@ CONFIG_BINFMT_DISABLE=y
 #
 # Standard C Library Options
 #
-CONFIG_STDIO_BUFFER_SIZE=0
+CONFIG_STDIO_DISABLE_BUFFERING=y
 CONFIG_STDIO_LINEBUFFER=y
 CONFIG_NUNGET_CHARS=0
 # CONFIG_LIBM is not set
diff --git a/configs/teensy-2.0/hello/defconfig b/configs/teensy-2.0/hello/defconfig
index 7252b924f56..c1a3fe1b077 100644
--- a/configs/teensy-2.0/hello/defconfig
+++ b/configs/teensy-2.0/hello/defconfig
@@ -432,7 +432,7 @@ CONFIG_MM_REGIONS=1
 #
 # Standard C Library Options
 #
-CONFIG_STDIO_BUFFER_SIZE=0
+CONFIG_STDIO_DISABLE_BUFFERING=y
 CONFIG_STDIO_LINEBUFFER=y
 CONFIG_NUNGET_CHARS=0
 # CONFIG_LIBM is not set
diff --git a/configs/teensy-2.0/nsh/defconfig b/configs/teensy-2.0/nsh/defconfig
index a1e307241e5..905f64dff34 100644
--- a/configs/teensy-2.0/nsh/defconfig
+++ b/configs/teensy-2.0/nsh/defconfig
@@ -445,7 +445,7 @@ CONFIG_MM_REGIONS=1
 #
 # Standard C Library Options
 #
-CONFIG_STDIO_BUFFER_SIZE=0
+CONFIG_STDIO_DISABLE_BUFFERING=y
 CONFIG_STDIO_LINEBUFFER=y
 CONFIG_NUNGET_CHARS=0
 CONFIG_LIB_HOMEDIR="/"
diff --git a/configs/teensy-2.0/usbmsc/defconfig b/configs/teensy-2.0/usbmsc/defconfig
index 8ae953d22e5..437fecf2fe0 100644
--- a/configs/teensy-2.0/usbmsc/defconfig
+++ b/configs/teensy-2.0/usbmsc/defconfig
@@ -506,7 +506,7 @@ CONFIG_MM_REGIONS=1
 #
 # Standard C Library Options
 #
-CONFIG_STDIO_BUFFER_SIZE=0
+CONFIG_STDIO_DISABLE_BUFFERING=y
 CONFIG_STDIO_LINEBUFFER=y
 CONFIG_NUNGET_CHARS=0
 # CONFIG_LIBM is not set
diff --git a/configs/teensy-lc/nsh/defconfig b/configs/teensy-lc/nsh/defconfig
index 26a3e8aed9e..8a28b949a9d 100644
--- a/configs/teensy-lc/nsh/defconfig
+++ b/configs/teensy-lc/nsh/defconfig
@@ -577,7 +577,7 @@ CONFIG_BUILTIN=y
 #
 # Standard C Library Options
 #
-CONFIG_STDIO_BUFFER_SIZE=0
+CONFIG_STDIO_DISABLE_BUFFERING=y
 CONFIG_STDIO_LINEBUFFER=y
 CONFIG_NUNGET_CHARS=0
 # CONFIG_LIBM is not set
diff --git a/configs/us7032evb1/nsh/defconfig b/configs/us7032evb1/nsh/defconfig
index fbc84921425..82a725a488f 100644
--- a/configs/us7032evb1/nsh/defconfig
+++ b/configs/us7032evb1/nsh/defconfig
@@ -357,7 +357,7 @@ CONFIG_MM_REGIONS=1
 #
 # Standard C Library Options
 #
-CONFIG_STDIO_BUFFER_SIZE=0
+CONFIG_STDIO_DISABLE_BUFFERING=y
 CONFIG_STDIO_LINEBUFFER=y
 CONFIG_NUNGET_CHARS=0
 CONFIG_LIB_HOMEDIR="/"
diff --git a/configs/us7032evb1/ostest/defconfig b/configs/us7032evb1/ostest/defconfig
index 278a0eeff41..2b025f8ccec 100644
--- a/configs/us7032evb1/ostest/defconfig
+++ b/configs/us7032evb1/ostest/defconfig
@@ -354,7 +354,7 @@ CONFIG_MM_REGIONS=1
 #
 # Standard C Library Options
 #
-CONFIG_STDIO_BUFFER_SIZE=0
+CONFIG_STDIO_DISABLE_BUFFERING=y
 CONFIG_STDIO_LINEBUFFER=y
 CONFIG_NUNGET_CHARS=0
 # CONFIG_LIBM is not set
diff --git a/configs/xtrs/nsh/defconfig b/configs/xtrs/nsh/defconfig
index bfcbaf84fa3..057aa917d43 100644
--- a/configs/xtrs/nsh/defconfig
+++ b/configs/xtrs/nsh/defconfig
@@ -267,7 +267,7 @@ CONFIG_HEAP2_SIZE=0
 #
 # Library Routines
 #
-CONFIG_STDIO_BUFFER_SIZE=0
+CONFIG_STDIO_DISABLE_BUFFERING=y
 CONFIG_STDIO_LINEBUFFER=y
 CONFIG_NUNGET_CHARS=0
 # CONFIG_LIBM is not set
diff --git a/configs/xtrs/ostest/defconfig b/configs/xtrs/ostest/defconfig
index 328ce577c77..373e087c99d 100644
--- a/configs/xtrs/ostest/defconfig
+++ b/configs/xtrs/ostest/defconfig
@@ -266,7 +266,7 @@ CONFIG_HEAP2_SIZE=0
 #
 # Library Routines
 #
-CONFIG_STDIO_BUFFER_SIZE=0
+CONFIG_STDIO_DISABLE_BUFFERING=y
 CONFIG_STDIO_LINEBUFFER=y
 CONFIG_NUNGET_CHARS=0
 # CONFIG_LIBM is not set
diff --git a/configs/xtrs/pashello/defconfig b/configs/xtrs/pashello/defconfig
index b7a54c78449..4f05dd02565 100644
--- a/configs/xtrs/pashello/defconfig
+++ b/configs/xtrs/pashello/defconfig
@@ -266,7 +266,7 @@ CONFIG_HEAP2_SIZE=0
 #
 # Library Routines
 #
-CONFIG_STDIO_BUFFER_SIZE=0
+CONFIG_STDIO_DISABLE_BUFFERING=y
 CONFIG_STDIO_LINEBUFFER=y
 CONFIG_NUNGET_CHARS=0
 CONFIG_LIB_HOMEDIR="/"
diff --git a/configs/z80sim/nsh/defconfig b/configs/z80sim/nsh/defconfig
index 549fdf66e8a..a3fb674d317 100644
--- a/configs/z80sim/nsh/defconfig
+++ b/configs/z80sim/nsh/defconfig
@@ -267,7 +267,7 @@ CONFIG_HEAP2_SIZE=0
 #
 # Library Routines
 #
-CONFIG_STDIO_BUFFER_SIZE=0
+CONFIG_STDIO_DISABLE_BUFFERING=y
 CONFIG_STDIO_LINEBUFFER=y
 CONFIG_NUNGET_CHARS=0
 # CONFIG_LIBM is not set
diff --git a/configs/z80sim/ostest/defconfig b/configs/z80sim/ostest/defconfig
index 279e54df2b2..7f91b797699 100644
--- a/configs/z80sim/ostest/defconfig
+++ b/configs/z80sim/ostest/defconfig
@@ -266,7 +266,7 @@ CONFIG_HEAP2_SIZE=0
 #
 # Library Routines
 #
-CONFIG_STDIO_BUFFER_SIZE=0
+CONFIG_STDIO_DISABLE_BUFFERING=y
 CONFIG_STDIO_LINEBUFFER=y
 CONFIG_NUNGET_CHARS=0
 # CONFIG_LIBM is not set
diff --git a/configs/z80sim/pashello/defconfig b/configs/z80sim/pashello/defconfig
index 05658ccc6f6..0ad39d3b309 100644
--- a/configs/z80sim/pashello/defconfig
+++ b/configs/z80sim/pashello/defconfig
@@ -265,7 +265,7 @@ CONFIG_HEAP2_SIZE=0
 #
 # Library Routines
 #
-CONFIG_STDIO_BUFFER_SIZE=0
+CONFIG_STDIO_DISABLE_BUFFERING=y
 CONFIG_STDIO_LINEBUFFER=y
 CONFIG_NUNGET_CHARS=0
 CONFIG_LIB_HOMEDIR="/"
diff --git a/configs/z8encore000zco/ostest/defconfig b/configs/z8encore000zco/ostest/defconfig
index c63228ea73f..e294983e7a9 100644
--- a/configs/z8encore000zco/ostest/defconfig
+++ b/configs/z8encore000zco/ostest/defconfig
@@ -495,7 +495,7 @@ CONFIG_HEAP2_SIZE=0
 #
 # Standard C Library Options
 #
-CONFIG_STDIO_BUFFER_SIZE=0
+CONFIG_STDIO_DISABLE_BUFFERING=y
 CONFIG_STDIO_LINEBUFFER=y
 CONFIG_NUNGET_CHARS=0
 # CONFIG_LIBM is not set
diff --git a/configs/z8f64200100kit/ostest/defconfig b/configs/z8f64200100kit/ostest/defconfig
index a5e518b5bbb..dea4dffa3f5 100644
--- a/configs/z8f64200100kit/ostest/defconfig
+++ b/configs/z8f64200100kit/ostest/defconfig
@@ -496,7 +496,7 @@ CONFIG_HEAP2_SIZE=0
 #
 # Standard C Library Options
 #
-CONFIG_STDIO_BUFFER_SIZE=0
+CONFIG_STDIO_DISABLE_BUFFERING=y
 CONFIG_STDIO_LINEBUFFER=y
 CONFIG_NUNGET_CHARS=0
 # CONFIG_LIBM is not set
diff --git a/fs/vfs/fs_fdopen.c b/fs/vfs/fs_fdopen.c
index e69bb7b4324..c795d81630c 100644
--- a/fs/vfs/fs_fdopen.c
+++ b/fs/vfs/fs_fdopen.c
@@ -1,7 +1,7 @@
 /****************************************************************************
  * fs/vfs/fs_fdopen.c
  *
- *   Copyright (C) 2007-2014 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2007-2014, 2017 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -221,17 +221,18 @@ FAR struct file_struct *fs_fdopen(int fd, int oflags, FAR struct tcb_s *tcb)
         {
           /* Zero the structure */
 
-#if CONFIG_STDIO_BUFFER_SIZE > 0
+#ifndef CONFIG_STDIO_DISABLE_BUFFERING
           memset(stream, 0, sizeof(FILE));
 #elif CONFIG_NUNGET_CHARS > 0
           stream->fs_nungotten = 0;
 #endif
 
-#if CONFIG_STDIO_BUFFER_SIZE > 0
+#ifndef CONFIG_STDIO_DISABLE_BUFFERING
           /* Initialize the semaphore the manages access to the buffer */
 
           (void)sem_init(&stream->fs_sem, 0, 1);
 
+#if CONFIG_STDIO_BUFFER_SIZE > 0
           /* Allocate the IO buffer at the appropriate privilege level for
            * the group.
            */
@@ -251,12 +252,15 @@ FAR struct file_struct *fs_fdopen(int fd, int oflags, FAR struct tcb_s *tcb)
           stream->fs_bufpos  = stream->fs_bufstart;
           stream->fs_bufread = stream->fs_bufstart;
 
+#ifdef CONFIG_STDIO_LINEBUFFER
           /* Setup buffer flags */
 
-#ifdef CONFIG_STDIO_LINEBUFFER
           stream->fs_flags  |= __FS_FLAG_LBF; /* Line buffering */
-#endif
-#endif
+
+#endif /* CONFIG_STDIO_LINEBUFFER */
+#endif /* CONFIG_STDIO_BUFFER_SIZE > 0 */
+#endif /* !CONFIG_STDIO_DISABLE_BUFFERING */
+
           /* 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 6895ace9428..4509665266f 100644
--- a/include/nuttx/fs/fs.h
+++ b/include/nuttx/fs/fs.h
@@ -405,7 +405,7 @@ struct filelist
 struct file_struct
 {
   int                fs_fd;        /* File descriptor associated with stream */
-#if CONFIG_STDIO_BUFFER_SIZE > 0
+#ifndef CONFIG_STDIO_DISABLE_BUFFERING
   sem_t              fs_sem;       /* For thread safety */
   pid_t              fs_holder;    /* Holder of sem */
   int                fs_counts;    /* Number of times sem is held */
diff --git a/include/stdio.h b/include/stdio.h
index cc351730de7..c0aefded7f2 100644
--- a/include/stdio.h
+++ b/include/stdio.h
@@ -58,10 +58,12 @@
 
 #define FILENAME_MAX _POSIX_NAME_MAX
 
-/* The size of the I/O buffers */
+/* The (default) size of the I/O buffers */
 
-#if CONFIG_STDIO_BUFFER_SIZE > 0
-#  define BUFSIZ CONFIG_STDIO_BUFFER_SIZE
+#if defined(CONFIG_STDIO_BUFFER_SIZE) && CONFIG_STDIO_BUFFER_SIZE > 0
+#  define BUFSIZ   CONFIG_STDIO_BUFFER_SIZE
+#else
+#  define BUFSIZ   64
 #endif
 
 /* The following three definitions are for ANSI C, used by setvbuf */
diff --git a/libc/Kconfig b/libc/Kconfig
index e1781e41cf6..b250dbd87e1 100644
--- a/libc/Kconfig
+++ b/libc/Kconfig
@@ -5,12 +5,22 @@
 
 comment "Standard C Library Options"
 
+config STDIO_DISABLE_BUFFERING
+	bool "Disable I/O Buffering"
+	default n
+	---help---
+		Tiny systems may need to disable all support for I/O buffering in
+		order to minimum footprint.
+
 config STDIO_BUFFER_SIZE
 	int "C STDIO buffer size"
 	default 64
+	depends on !STDIO_DISABLE_BUFFERING
 	---help---
-		Size of buffers using within the C buffered I/O interfaces.
-		(printf, putchar, fwrite, etc.).
+		Size of buffers using within the C buffered I/O interfaces (printf,
+		putchar, fwrite, etc.).  This function sets the initial I/O buffer
+		size.  Zero disables I/O buffering.  That size may be subsequently
+		modified using setvbuf().
 
 config STDIO_LINEBUFFER
 	bool "STDIO line buffering"
diff --git a/libc/libc.h b/libc/libc.h
index 9e947009f23..44104013387 100644
--- a/libc/libc.h
+++ b/libc/libc.h
@@ -1,7 +1,7 @@
 /****************************************************************************
  * libc/libc.h
  *
- *   Copyright (C) 2007-2014, 2016 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2007-2014, 2016-2017 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -67,7 +67,7 @@
  * protection.
  */
 
-#if CONFIG_STDIO_BUFFER_SIZE <= 0
+#ifdef CONFIG_STDIO_DISABLE_BUFFERING
 #  define lib_sem_initialize(s)
 #  define lib_take_semaphore(s)
 #  define lib_give_semaphore(s)
@@ -186,7 +186,7 @@ int lib_wrflush(FAR FILE *stream);
 
 /* Defined in lib_sem.c */
 
-#if CONFIG_STDIO_BUFFER_SIZE > 0
+#ifndef CONFIG_STDIO_DISABLE_BUFFERING
 void lib_sem_initialize(FAR struct file_struct *stream);
 void lib_take_semaphore(FAR struct file_struct *stream);
 void lib_give_semaphore(FAR struct file_struct *stream);
diff --git a/libc/misc/Make.defs b/libc/misc/Make.defs
index ec3c76b94da..673591ea6af 100644
--- a/libc/misc/Make.defs
+++ b/libc/misc/Make.defs
@@ -35,9 +35,13 @@
 
 # Add the internal C files to the build
 
-CSRCS += lib_stream.c lib_filesem.c lib_utsname.c
+CSRCS += lib_stream.c lib_utsname.c
 CSRCS += lib_xorshift128.c lib_tea_encrypt.c lib_tea_decrypt.c
 
+ifneq ($(CONFIG_STDIO_DISABLE_BUFFERING),y)
+CSRCS += lib_filesem.c
+endif
+
 # Support for platforms that do not have long long types
 
 CSRCS += lib_umul32.c lib_umul64.c lib_umul32x64.c
diff --git a/libc/misc/lib_filesem.c b/libc/misc/lib_filesem.c
index 2fd5d1c9ebf..d84e46ef409 100644
--- a/libc/misc/lib_filesem.c
+++ b/libc/misc/lib_filesem.c
@@ -1,7 +1,7 @@
 /****************************************************************************
  * libc/misc/lib_filesem.c
  *
- *   Copyright (C) 2007, 2009, 2011 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2007, 2009, 2011, 2017 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -47,15 +47,7 @@
 
 #include "libc.h"
 
-#if CONFIG_STDIO_BUFFER_SIZE > 0
-
-/****************************************************************************
- * Pre-processor Definitions
- ****************************************************************************/
-
-/****************************************************************************
- * Private Data
- ****************************************************************************/
+#ifndef CONFIG_STDIO_DISABLE_BUFFERING
 
 /****************************************************************************
  * Public Functions
@@ -142,4 +134,5 @@ void lib_give_semaphore(FAR struct file_struct *stream)
       ASSERT(sem_post(&stream->fs_sem) == 0);
     }
 }
-#endif /* CONFIG_STDIO_BUFFER_SIZE */
+
+#endif /* CONFIG_STDIO_DISABLE_BUFFERING */
diff --git a/libc/misc/lib_stream.c b/libc/misc/lib_stream.c
index b6586ab9699..4ed03433455 100644
--- a/libc/misc/lib_stream.c
+++ b/libc/misc/lib_stream.c
@@ -1,7 +1,7 @@
 /****************************************************************************
  * libc/misc/lib_stream.c
  *
- *   Copyright (C) 2007, 2011, 2013-2014 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2007, 2011, 2013-2014, 2017 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -109,7 +109,7 @@ void lib_stream_initialize(FAR struct task_group_s *group)
 #endif /* CONFIG_NFILE_STREAMS > 0 */
 
 /****************************************************************************
- * Name: lib_stream_init
+ * Name: lib_stream_release
  *
  * Description:
  *   This function is called when a TCB is destroyed.  Note that it does not
@@ -122,7 +122,7 @@ void lib_stream_initialize(FAR struct task_group_s *group)
 void lib_stream_release(FAR struct task_group_s *group)
 {
   FAR struct streamlist *list;
-#if CONFIG_STDIO_BUFFER_SIZE > 0
+#ifndef CONFIG_STDIO_DISABLE_BUFFERING
   int i;
 #endif
 
@@ -139,9 +139,9 @@ void lib_stream_release(FAR struct task_group_s *group)
 
   (void)sem_destroy(&list->sl_sem);
 
+#ifndef CONFIG_STDIO_DISABLE_BUFFERING
   /* Release each stream in the list */
 
-#if CONFIG_STDIO_BUFFER_SIZE > 0
   for (i = 0; i < CONFIG_NFILE_STREAMS; i++)
     {
       FAR struct file_struct *stream = &list->sl_streams[i];
@@ -177,6 +177,6 @@ void lib_stream_release(FAR struct task_group_s *group)
     }
 #endif
 }
-#endif /* CONFIG_NFILE_STREAMS > 0 */
 
+#endif /* CONFIG_NFILE_STREAMS > 0 */
 #endif /* (!CONFIG_BUILD_PROTECTED &&7 !CONFIG_BUILD_KERNEL) || __KERNEL__ */
diff --git a/libc/stdio/Make.defs b/libc/stdio/Make.defs
index 478ac3f4aaa..9a3a36ddb17 100644
--- a/libc/stdio/Make.defs
+++ b/libc/stdio/Make.defs
@@ -65,13 +65,17 @@ 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 lib_libnoflush.c lib_libsnoflush.c
+CSRCS += lib_clearerr.c lib_libnoflush.c lib_libsnoflush.c
 
 endif
 
 ifeq ($(CONFIG_FS_WRITABLE),y)
 CSRCS += lib_tempnam.c lib_tmpnam.c
 endif
+
+ifneq ($(CONFIG_STDIO_DISABLE_BUFFERING),y)
+CSRCS += lib_setvbuf.c
+endif
 endif
 
 # Other support that depends on specific, configured features.
diff --git a/libc/stdio/lib_fclose.c b/libc/stdio/lib_fclose.c
index d02e6310ed5..022d7bde8eb 100644
--- a/libc/stdio/lib_fclose.c
+++ b/libc/stdio/lib_fclose.c
@@ -107,7 +107,7 @@ int fclose(FAR FILE *stream)
             }
         }
 
-#if CONFIG_STDIO_BUFFER_SIZE > 0
+#ifndef CONFIG_STDIO_DISABLE_BUFFERING
       /* Destroy the semaphore */
 
       sem_destroy(&stream->fs_sem);
@@ -123,6 +123,7 @@ int fclose(FAR FILE *stream)
       /* Clear the whole structure */
 
       memset(stream, 0, sizeof(FILE));
+
 #else
 #if CONFIG_NUNGET_CHARS > 0
       /* Reset the number of ungetc characters */
@@ -133,6 +134,7 @@ int fclose(FAR FILE *stream)
 
       stream->fs_oflags = 0;
 #endif
+
       /* Setting the file descriptor to -1 makes the stream available for reuse */
 
       stream->fs_fd = -1;
diff --git a/libc/stdio/lib_fseek.c b/libc/stdio/lib_fseek.c
index 789bcb9359d..4dbe0441702 100644
--- a/libc/stdio/lib_fseek.c
+++ b/libc/stdio/lib_fseek.c
@@ -1,7 +1,7 @@
 /****************************************************************************
  * libc/stdio/lib_fseek.c
  *
- *   Copyright (C) 2007, 2008, 2011, 2013 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2007, 2008, 2011, 2013, 2017 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -71,14 +71,7 @@
 
 int fseek(FAR FILE *stream, long int offset, int whence)
 {
-#if CONFIG_STDIO_BUFFER_SIZE > 0
-  /* Flush any valid read/write data in the buffer (also verifies stream) */
-
-  if (lib_rdflush(stream) < 0 || lib_wrflush(stream) < 0)
-    {
-      return ERROR;
-    }
-#else
+#ifdef CONFIG_DEBUG_FEATURES
   /* Verify that we were provided with a stream */
 
   if (!stream)
@@ -88,6 +81,15 @@ int fseek(FAR FILE *stream, long int offset, int whence)
     }
 #endif
 
+#ifndef CONFIG_STDIO_DISABLE_BUFFERING
+  /* Flush any valid read/write data in the buffer (also verifies stream) */
+
+  if (lib_rdflush(stream) < 0 || lib_wrflush(stream) < 0)
+    {
+      return ERROR;
+    }
+#endif
+
   /* On success or failure, discard any characters saved by ungetc() */
 
 #if CONFIG_NUNGET_CHARS > 0
diff --git a/libc/stdio/lib_ftell.c b/libc/stdio/lib_ftell.c
index a2e8069639b..ece1a245a60 100644
--- a/libc/stdio/lib_ftell.c
+++ b/libc/stdio/lib_ftell.c
@@ -1,7 +1,7 @@
 /****************************************************************************
  * libc/stdio/lib_ftell.c
  *
- *   Copyright (C) 2008, 2011, 2013 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2008, 2011, 2013, 2017 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -64,13 +64,13 @@
  *
  ****************************************************************************/
 
-#if CONFIG_STDIO_BUFFER_SIZE > 0
+#ifndef CONFIG_STDIO_DISABLE_BUFFERING
 static off_t lib_getrdoffset(FAR FILE *stream)
 {
   off_t rdoffset = 0;
   lib_take_semaphore(stream);
 
-  if (stream->fs_bufread != stream->fs_bufstart)
+  if (stream->fs_bufstart != NULL && stream->fs_bufread != stream->fs_bufstart)
     {
 #if CONFIG_NUNGET_CHARS > 0
       rdoffset = stream->fs_bufread - stream->fs_bufpos + stream->fs_nungotten;
diff --git a/libc/stdio/lib_libfflush.c b/libc/stdio/lib_libfflush.c
index dd98140c5cc..22172a66c76 100644
--- a/libc/stdio/lib_libfflush.c
+++ b/libc/stdio/lib_libfflush.c
@@ -1,7 +1,7 @@
 /****************************************************************************
  * libc/stdio/lib_libfflush.c
  *
- *   Copyright (C) 2007-2008, 2011-2014 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2007-2008, 2011-2014, 2017 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -73,10 +73,11 @@
 
 ssize_t lib_fflush(FAR FILE *stream, bool bforce)
 {
-#if CONFIG_STDIO_BUFFER_SIZE > 0
+#ifndef CONFIG_STDIO_DISABLE_BUFFERING
   FAR const unsigned char *src;
   ssize_t bytes_written;
   ssize_t nbuffer;
+  int ret;
 
   /* Return EBADF if the file is not opened for writing */
 
@@ -89,9 +90,19 @@ ssize_t lib_fflush(FAR FILE *stream, bool bforce)
 
   lib_take_semaphore(stream);
 
+  /* Check if there is an allocated I/O buffer */
+
+  if (stream->fs_bufstart == NULL)
+    {
+      /* No, then there can be nothing remaining in the buffer. */
+
+      ret = 0;
+      goto errout_with_sem;
+   }
+
   /* Make sure that the buffer holds valid data */
 
-  if (stream->fs_bufpos  != stream->fs_bufstart)
+  if (stream->fs_bufpos != stream->fs_bufstart)
     {
       /* Make sure that the buffer holds buffered write data.  We do not
        * support concurrent read/write buffer usage.
@@ -103,8 +114,8 @@ ssize_t lib_fflush(FAR FILE *stream, bool bforce)
            * remaining in the buffer."
            */
 
-          lib_give_semaphore(stream);
-          return 0;
+          ret = 0;
+          goto errout_with_sem;
         }
 
       /* How many bytes of write data are used in the buffer now */
@@ -126,8 +137,8 @@ ssize_t lib_fflush(FAR FILE *stream, bool bforce)
                */
 
               stream->fs_flags |= __FS_FLAG_ERROR;
-              lib_give_semaphore(stream);
-              return -get_errno();
+              ret = -get_errno();;
+              goto errout_with_sem;
             }
 
           /* Handle partial writes.  fflush() must either return with
@@ -162,6 +173,11 @@ ssize_t lib_fflush(FAR FILE *stream, bool bforce)
 
   lib_give_semaphore(stream);
   return stream->fs_bufpos - stream->fs_bufstart;
+
+errout_with_sem:
+  lib_give_semaphore(stream);
+  return ret;
+
 #else
   /* Return no bytes remaining in the buffer */
 
diff --git a/libc/stdio/lib_libfread.c b/libc/stdio/lib_libfread.c
index 94f7ce70381..a0aa588169e 100644
--- a/libc/stdio/lib_libfread.c
+++ b/libc/stdio/lib_libfread.c
@@ -1,7 +1,7 @@
 /****************************************************************************
  * libc/stdio/lib_libfread.c
  *
- *   Copyright (C) 2007-2009, 2011-2014 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2007-2009, 2011-2014, 2017 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -60,7 +60,7 @@ ssize_t lib_fread(FAR void *ptr, size_t count, FAR FILE *stream)
 {
   FAR unsigned char *dest  = (FAR unsigned char*)ptr;
   ssize_t bytes_read;
-#if CONFIG_STDIO_BUFFER_SIZE > 0
+#ifndef CONFIG_STDIO_DISABLE_BUFFERING
   int ret;
 #endif
 
@@ -96,170 +96,177 @@ ssize_t lib_fread(FAR void *ptr, size_t count, FAR FILE *stream)
         }
 #endif
 
-#if CONFIG_STDIO_BUFFER_SIZE > 0
-      /* If the buffer is currently being used for write access, then
-       * flush all of the buffered write data.  We do not support concurrent
-       * buffered read/write access.
-       */
+#ifndef CONFIG_STDIO_DISABLE_BUFFERING
+      /* Is there an I/O buffer? */
 
-      ret = lib_wrflush(stream);
-      if (ret < 0)
+      if (stream->bufstart != NULL)
         {
-          lib_give_semaphore(stream);
-          return ret;
-        }
-
-      /* Now get any other needed chars from the buffer or the file. */
-
-      while (count > 0)
-        {
-          /* Is there readable data in the buffer? */
-
-          while ((count > 0) && (stream->fs_bufpos < stream->fs_bufread))
-            {
-              /* Yes, copy a byte into the user buffer */
-
-              *dest++ = *stream->fs_bufpos++;
-              count--;
-            }
-
-          /* The buffer is empty OR we have already supplied the number of
-           * bytes requested in the read.  Check if we need to read
-           * more from the file.
+          /* If the buffer is currently being used for write access, then
+           * flush all of the buffered write data.  We do not support concurrent
+           * buffered read/write access.
            */
 
-          if (count > 0)
+          ret = lib_wrflush(stream);
+          if (ret < 0)
             {
-              size_t buffer_available;
+              lib_give_semaphore(stream);
+              return ret;
+            }
 
-              /* We need to read more data into the buffer from the file */
+          /* Now get any other needed chars from the buffer or the file. */
 
-              /* Mark the buffer empty */
+          while (count > 0)
+            {
+              /* Is there readable data in the buffer? */
 
-              stream->fs_bufpos = stream->fs_bufread = stream->fs_bufstart;
+              while ((count > 0) && (stream->fs_bufpos < stream->fs_bufread))
+                {
+                  /* Yes, copy a byte into the user buffer */
 
-              /* How much space is available in the buffer? */
+                  *dest++ = *stream->fs_bufpos++;
+                  count--;
+                }
 
-              buffer_available = stream->fs_bufend - stream->fs_bufread;
-
-              /* Will the number of bytes that we need to read fit into
-               * the buffer space that is available? If the read size is
-               * larger than the buffer, then read some of the data
-               * directly into the user's buffer.
+              /* The buffer is empty OR we have already supplied the number of
+               * bytes requested in the read.  Check if we need to read
+               * more from the file.
                */
 
-              if (count > buffer_available)
+              if (count > 0)
                 {
-                  bytes_read = read(stream->fs_fd, dest, count);
-                  if (bytes_read < 0)
+                  size_t buffer_available;
+
+                  /* We need to read more data into the buffer from the file */
+
+                  /* Mark the buffer empty */
+
+                  stream->fs_bufpos = stream->fs_bufread = stream->fs_bufstart;
+
+                  /* How much space is available in the buffer? */
+
+                  buffer_available = stream->fs_bufend - stream->fs_bufread;
+
+                  /* Will the number of bytes that we need to read fit into
+                   * the buffer space that is available? If the read size is
+                   * larger than the buffer, then read some of the data
+                   * directly into the user's buffer.
+                   */
+
+                  if (count > buffer_available)
                     {
-                      /* An error occurred on the read.  The error code is
-                       * in the 'errno' variable.
-                       */
-
-                      goto errout_with_errno;
-                    }
-                  else if (bytes_read == 0)
-                    {
-                      /* We are at the end of the file.  But we may already
-                       * have buffered data.  In that case, we will report
-                       * the EOF indication later.
-                       */
-
-                      goto shortread;
-                    }
-                  else
-                    {
-                      /* Some bytes were read. Adjust the dest pointer */
-
-                      dest  += bytes_read;
-
-                      /* Were all of the requested bytes read? */
-
-                      if ((size_t)bytes_read < count)
+                      bytes_read = read(stream->fs_fd, dest, count);
+                      if (bytes_read < 0)
                         {
-                          /* No.  We must be at the end of file. */
+                          /* An error occurred on the read.  The error code is
+                           * in the 'errno' variable.
+                           */
+
+                          goto errout_with_errno;
+                        }
+                      else if (bytes_read == 0)
+                        {
+                          /* We are at the end of the file.  But we may already
+                           * have buffered data.  In that case, we will report
+                           * the EOF indication later.
+                           */
 
                           goto shortread;
                         }
                       else
                         {
-                          /* Yes.  We are done. */
+                          /* Some bytes were read. Adjust the dest pointer */
 
-                          count = 0;
+                          dest  += bytes_read;
+
+                          /* Were all of the requested bytes read? */
+
+                          if ((size_t)bytes_read < count)
+                            {
+                              /* No.  We must be at the end of file. */
+
+                              goto shortread;
+                            }
+                          else
+                            {
+                              /* Yes.  We are done. */
+
+                              count = 0;
+                            }
                         }
                     }
-                }
-              else
-                {
-                  /* The number of bytes required to satisfy the read
-                   * is less than or equal to the size of the buffer
-                   * space that we have left. Read as much as we can
-                   * into the buffer.
-                   */
-
-                  bytes_read = read(stream->fs_fd, stream->fs_bufread, buffer_available);
-                  if (bytes_read < 0)
-                    {
-                      /* An error occurred on the read.  The error code is
-                       * in the 'errno' variable.
-                       */
-
-                      goto errout_with_errno;
-                    }
-                  else if (bytes_read == 0)
-                    {
-                      /* We are at the end of the file.  But we may already
-                       * have buffered data.  In that case, we will report
-                       * the EOF indication later.
-                       */
-
-                      goto shortread;
-                    }
                   else
                     {
-                      /* Some bytes were read */
+                      /* The number of bytes required to satisfy the read
+                       * is less than or equal to the size of the buffer
+                       * space that we have left. Read as much as we can
+                       * into the buffer.
+                       */
 
-                      stream->fs_bufread += bytes_read;
+                      bytes_read = read(stream->fs_fd, stream->fs_bufread, buffer_available);
+                      if (bytes_read < 0)
+                        {
+                          /* An error occurred on the read.  The error code is
+                           * in the 'errno' variable.
+                           */
+
+                          goto errout_with_errno;
+                        }
+                      else if (bytes_read == 0)
+                        {
+                          /* We are at the end of the file.  But we may already
+                           * have buffered data.  In that case, we will report
+                           * the EOF indication later.
+                           */
+
+                          goto shortread;
+                        }
+                      else
+                        {
+                          /* Some bytes were read */
+
+                          stream->fs_bufread += bytes_read;
+                        }
                     }
                 }
             }
-        }
 #else
-      /* Now get any other needed chars from the file. */
+          /* Now get any other needed chars from the file. */
 
-      while (count > 0)
-        {
-          bytes_read = read(stream->fs_fd, dest, count);
-          if (bytes_read < 0)
+          while (count > 0)
             {
-              /* An error occurred on the read.  The error code is
-               * in the 'errno' variable.
-               */
+              bytes_read = read(stream->fs_fd, dest, count);
+              if (bytes_read < 0)
+                {
+                  /* An error occurred on the read.  The error code is
+                   * in the 'errno' variable.
+                   */
 
-              goto errout_with_errno;
-            }
-          else if (bytes_read == 0)
-            {
-              /* We are at the end of the file.  But we may already
-               * have buffered data.  In that case, we will report
-               * the EOF indication later.
-               */
+                  goto errout_with_errno;
+                }
+              else if (bytes_read == 0)
+                {
+                  /* We are at the end of the file.  But we may already
+                   * have buffered data.  In that case, we will report
+                   * the EOF indication later.
+                   */
 
-              break;
-            }
-          else
-            {
-              dest  += bytes_read;
-              count -= bytes_read;
+                  break;
+                }
+              else
+                {
+                  dest  += bytes_read;
+                  count -= bytes_read;
+                }
             }
         }
 #endif
+
       /* Here after a successful (but perhaps short) read */
 
-#if CONFIG_STDIO_BUFFER_SIZE > 0
+#ifndef CONFIG_STDIO_DISABLE_BUFFERING
     shortread:
 #endif
+
       bytes_read = dest - (FAR unsigned char *)ptr;
 
       /* Set or clear the EOF indicator.  If we get here because of a
diff --git a/libc/stdio/lib_libfwrite.c b/libc/stdio/lib_libfwrite.c
index a9af1ab2a78..8cb067933fb 100644
--- a/libc/stdio/lib_libfwrite.c
+++ b/libc/stdio/lib_libfwrite.c
@@ -1,7 +1,7 @@
 /****************************************************************************
  * libc/stdio/lib_libfwrite.c
  *
- *   Copyright (C) 2007-2009, 2011, 2013-2014 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2007-2009, 2011, 2013-2014, 2017 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -57,12 +57,13 @@
  ****************************************************************************/
 
 ssize_t lib_fwrite(FAR const void *ptr, size_t count, FAR FILE *stream)
-#if CONFIG_STDIO_BUFFER_SIZE > 0
+#ifndef CONFIG_STDIO_DISABLE_BUFFERING
 {
   FAR const unsigned char *start = ptr;
   FAR const unsigned char *src   = ptr;
   ssize_t ret = ERROR;
   unsigned char *dest;
+  int ret;
 
   /* Make sure that writing to this stream is allowed */
 
@@ -72,12 +73,22 @@ ssize_t lib_fwrite(FAR const void *ptr, size_t count, FAR FILE *stream)
       return ret;
     }
 
+  /* Check if write access is permitted */
+
   if ((stream->fs_oflags & O_WROK) == 0)
     {
       set_errno(EBADF);
       goto errout;
     }
 
+  /* If there is no I/O buffer, then output data immediately */
+
+  if (stream->fs_bufstart == NULL)
+   {
+     ret = write(stream->fs_fd, ptr, count);
+     goto errout;
+   }
+
   /* Get exclusive access to the stream */
 
   lib_take_semaphore(stream);
@@ -165,4 +176,4 @@ errout:
 
   return ret;
 }
-#endif /* CONFIG_STDIO_BUFFER_SIZE */
+#endif /* CONFIG_STDIO_DISABLE_BUFFERING */
diff --git a/libc/stdio/lib_rdflush.c b/libc/stdio/lib_rdflush.c
index 7a44359aa26..284f59e7d7d 100644
--- a/libc/stdio/lib_rdflush.c
+++ b/libc/stdio/lib_rdflush.c
@@ -1,7 +1,7 @@
 /****************************************************************************
  * libc/stdio/lib_rdflush.c
  *
- *   Copyright (C) 2008, 2011 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2008, 2011, 2017 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -46,6 +46,8 @@
 
 #include "libc.h"
 
+#ifndef CONFIG_STDIO_DISABLE_BUFFERING
+
 /****************************************************************************
  * Public Functions
  ****************************************************************************/
@@ -59,15 +61,23 @@
  *
  ****************************************************************************/
 
-#if CONFIG_STDIO_BUFFER_SIZE > 0
 int lib_rdflush(FAR FILE *stream)
 {
-  if (!stream)
+  /* Sanity checking */
+
+  if (stream =- NULL)
     {
       set_errno(EBADF);
       return ERROR;
     }
 
+  /* Do nothing if there is no I/O buffer */
+
+  if (stream->fs_bufstart == NULL)
+    {
+      return OK;
+    }
+
   /* Get exclusive access to the stream */
 
   lib_take_semaphore(stream);
@@ -108,5 +118,5 @@ int lib_rdflush(FAR FILE *stream)
   lib_give_semaphore(stream);
   return OK;
 }
-#endif /* CONFIG_STDIO_BUFFER_SIZE */
 
+#endif /* CONFIG_STDIO_DISABLE_BUFFERING */
diff --git a/libc/stdio/lib_setvbuf.c b/libc/stdio/lib_setvbuf.c
index 3875b770b9c..10fbc0e6d0e 100644
--- a/libc/stdio/lib_setvbuf.c
+++ b/libc/stdio/lib_setvbuf.c
@@ -74,11 +74,6 @@
  * by the setvbuf() function. The contents of the array at any time are
  * unspecified.
  *
- * 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
  *  buffer - the user allocate buffer. If NULL, will allocates a buffer of
@@ -95,7 +90,7 @@
 
 int setvbuf(FAR FILE *stream, FAR char *buffer, int mode, size_t size)
 {
-#if CONFIG_STDIO_BUFFER_SIZE > 0
+#ifndef CONFIG_STDIO_DISABLE_BUFFERING
   FAR unsigned char *newbuf;
   uint8_t flags;
   int errcode;
@@ -127,18 +122,6 @@ int setvbuf(FAR FILE *stream, FAR char *buffer, int mode, size_t size)
       goto errout;
     }
 
-#if 1 /* REVISIT: _IONBF not yet supported */
-  /* Not all features are be available.  Without some additional logic,
-   * we cannot disable buffering if CONFIG_STDIO_BUFFER_SIZE > 0
-   */
-
-  if (mode == _IONBF)
-    {
-      errcode = ENOSYS;
-      goto errout;
-    }
-#endif
-
   /* My assumption is that if size is zero for modes {_IOFBF, _IOLBF} the
    * caller is only attempting to change the buffering mode.  In this case,
    * the existing buffer should be re-used (if there is one).  If there is no
@@ -149,7 +132,7 @@ int setvbuf(FAR FILE *stream, FAR char *buffer, int mode, size_t size)
   if ((mode == _IOFBF || mode == _IOLBF) && size == 0 &&
       stream->fs_bufstart == NULL)
     {
-      size = CONFIG_STDIO_BUFFER_SIZE;
+      size = BUFSIZE;
     }
 
   /* Make sure that we have exclusive access to the stream */
@@ -186,11 +169,7 @@ int setvbuf(FAR FILE *stream, FAR char *buffer, int mode, size_t size)
    * successful.
    */
 
-#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 or reuse the existing buffer it
    * is appropriate to do so.
@@ -247,14 +226,12 @@ int setvbuf(FAR FILE *stream, FAR char *buffer, int mode, size_t size)
         break;
 
       case _IONBF:
-#if 0 /* REVISIT: _IONBF not yet supported */
         /* No buffer needed... We must be performing unbuffered I/O */
 
         DEBUGASSERT(size == 0);
         newbuf = NULL;
         flags |= __FS_FLAG_NBF;
         break;
-#endif
 
       default:
         PANIC();
@@ -299,3 +276,5 @@ errout:
   return ERROR;
 #endif
 }
+
+#endif /* !CONFIG_STDIO_DISABLE_BUFFERING */
diff --git a/libc/stdio/lib_stdoutstream.c b/libc/stdio/lib_stdoutstream.c
index 1fcef637574..5884f70bf53 100644
--- a/libc/stdio/lib_stdoutstream.c
+++ b/libc/stdio/lib_stdoutstream.c
@@ -82,11 +82,23 @@ static void stdoutstream_putc(FAR struct lib_outstream_s *this, int ch)
  * Name: stdoutstream_flush
  ****************************************************************************/
 
-#if CONFIG_STDIO_BUFFER_SIZE > 0
+#ifndef CONFIG_STDIO_DISABLE_BUFFERING
 static int stdoutstream_flush(FAR struct lib_outstream_s *this)
 {
   FAR struct lib_stdoutstream_s *sthis = (FAR struct lib_stdoutstream_s *)this;
-  return lib_fflush(sthis->stream, true);
+  FAR struct file *stream;
+
+  DEBUGASSERT(sthis != NULL && sthis->stream != NULL);
+  stream = sthis->stream;
+
+  if (stream->fs_bufstart != NULL)
+    {
+      return lib_fflush(sthis->stream, true);
+    }
+  else
+    {
+      return OK;
+    }
 }
 #endif
 
@@ -125,8 +137,8 @@ void lib_stdoutstream(FAR struct lib_stdoutstream_s *outstream,
    * meaning.
    */
 
-#if CONFIG_STDIO_BUFFER_SIZE > 0
-  if ((stream->fs_oflags & O_BINARY) == 0)
+#ifndef CONFIG_STDIO_DISABLE_BUFFERING
+  if (stream->fs_bufstart != NULL && (stream->fs_oflags & O_BINARY) == 0)
     {
       outstream->public.flush = stdoutstream_flush;
     }
diff --git a/libc/stdio/lib_stdsostream.c b/libc/stdio/lib_stdsostream.c
index 01ebc932918..a9957f53c7c 100644
--- a/libc/stdio/lib_stdsostream.c
+++ b/libc/stdio/lib_stdsostream.c
@@ -82,11 +82,23 @@ static void stdsostream_putc(FAR struct lib_sostream_s *this, int ch)
  * Name: stdsostream_flush
  ****************************************************************************/
 
-#if CONFIG_STDIO_BUFFER_SIZE > 0
+#ifndef CONFIG_STDIO_DISABLE_BUFFERING
 static int stdsostream_flush(FAR struct lib_sostream_s *this)
 {
-  FAR struct lib_stdsostream_s *sthis = (FAR struct lib_stdsostream_s *)this;
-  return lib_fflush(sthis->stream, true);
+  FAR struct lib_stdsostream_s *sthis = (FAR struct lib_stdoutstream_s *)this;
+  FAR struct file *stream;
+
+  DEBUGASSERT(sthis != NULL && sthis->stream != NULL);
+  stream = sthis->stream;
+
+  if (stream->fs_bufstart != NULL)
+    {
+      return lib_fflush(sthis->stream, true);
+    }
+  else
+    {
+      return OK;  
+    }
 }
 #endif
 
@@ -138,8 +150,8 @@ void lib_stdsostream(FAR struct lib_stdsostream_s *outstream,
    * meaning.
    */
 
-#if CONFIG_STDIO_BUFFER_SIZE > 0
-  if ((stream->fs_oflags & O_BINARY) == 0)
+#ifndef CONFIG_STDIO_DISABLE_BUFFERING
+  if (stream->fs_bufstart != NULL && (stream->fs_oflags & O_BINARY) == 0)
     {
       outstream->public.flush = stdsostream_flush;
     }
diff --git a/libc/stdio/lib_wrflush.c b/libc/stdio/lib_wrflush.c
index cb65ef3e395..f9e02ddc330 100644
--- a/libc/stdio/lib_wrflush.c
+++ b/libc/stdio/lib_wrflush.c
@@ -1,7 +1,7 @@
 /****************************************************************************
  * libc/stdio/lib_wrflush.c
  *
- *   Copyright (C) 2008-2009, 2011-2012 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2008-2009, 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
@@ -60,16 +60,23 @@
 
 int lib_wrflush(FAR FILE *stream)
 {
-#if CONFIG_STDIO_BUFFER_SIZE > 0
+#ifndef CONFIG_STDIO_DISABLE_BUFFERING
   /* Verify that we were passed a valid (i.e., non-NULL) stream */
 
 #ifdef CONFIG_DEBUG_FEATURES
-  if (!stream)
+  if (stream == NULL)
     {
       return -EINVAL;
     }
 #endif
 
+  /* Do nothing if there is no I/O buffer */
+
+  if (stream->fs_bufstart == NULL)
+    {
+      return OK;
+    }
+
   /* Verify that the stream is opened for writing... lib_fflush will
    * return an error if it is called for a stream that is not opened for
    * writing.  Check that first so that this function will not fail in
@@ -91,6 +98,7 @@ int lib_wrflush(FAR FILE *stream)
    */
 
   return lib_fflush(stream, true);
+
 #else
   /* Verify that we were passed a valid (i.e., non-NULL) stream */