diff --git a/configure/os/CONFIG_SITE.cygwin-x86.cygwin-x86 b/configure/os/CONFIG_SITE.cygwin-x86.cygwin-x86
index dee6a86f0..97e3cb1f3 100644
--- a/configure/os/CONFIG_SITE.cygwin-x86.cygwin-x86
+++ b/configure/os/CONFIG_SITE.cygwin-x86.cygwin-x86
@@ -7,4 +7,5 @@
 #-------------------------------------------------------
  
 #  GNU_DIR used when COMMANDLINE_LIBRARY is READLINE
-#GNU_DIR=C:/cygwin
\ No newline at end of file
+#GNU_DIR=C:/cygwin
+
diff --git a/configure/os/CONFIG_SITE.win32-x86-cygwin.win32-x86-cygwin b/configure/os/CONFIG_SITE.win32-x86-cygwin.win32-x86-cygwin
index b28b04f64..139597f9c 100644
--- a/configure/os/CONFIG_SITE.win32-x86-cygwin.win32-x86-cygwin
+++ b/configure/os/CONFIG_SITE.win32-x86-cygwin.win32-x86-cygwin
@@ -1,3 +1,2 @@
 
 
-
diff --git a/configure/os/CONFIG_SITE.win32-x86-mingw.win32-x86-mingw b/configure/os/CONFIG_SITE.win32-x86-mingw.win32-x86-mingw
index 771a4ba87..259d1e0c8 100644
--- a/configure/os/CONFIG_SITE.win32-x86-mingw.win32-x86-mingw
+++ b/configure/os/CONFIG_SITE.win32-x86-mingw.win32-x86-mingw
@@ -14,3 +14,4 @@
 #AR = $(CMPLR_PREFIX)ar -rc
 #LD = $(CMPLR_PREFIX)ld -r
 #RANLIB = $(CMPLR_PREFIX)ranlib
+
diff --git a/src/libCom/osi/compiler/gcc/epicsAtomicCD.h b/src/libCom/osi/compiler/gcc/epicsAtomicCD.h
index 8b06bd7bb..7e961386a 100644
--- a/src/libCom/osi/compiler/gcc/epicsAtomicCD.h
+++ b/src/libCom/osi/compiler/gcc/epicsAtomicCD.h
@@ -50,6 +50,8 @@
     && GCC_ATOMIC_INTRINSICS_AVAIL_SIZE_T ) \
     || GCC_ATOMIC_INTRINSICS_AVAIL_EARLIER
 
+#define OSD_ATOMIC_INLINE_DEFINITION
+
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ -120,11 +122,6 @@ OSD_ATOMIC_INLINE EpicsAtomicPtrT epicsAtomicCmpAndSwapPtrT ( EpicsAtomicPtrT *
 #endif
 
 #else /* if GCC_ATOMIC_INTRINSICS_AVAIL */
-    
-#   if GCC_ATOMIC_INTRINSICS_GCC4_OR_BETTER && __i386
-        /* 386 hardware is probably rare today even in embedded systems */
-#       warning "this code will run much faster if specifying i486 or better"
-#   endif
 
     /*
      * not available as gcc intrinsics so we
diff --git a/src/libCom/osi/compiler/msvc/epicsAtomicCD.h b/src/libCom/osi/compiler/msvc/epicsAtomicCD.h
index 4923664e7..fa3ba8a81 100644
--- a/src/libCom/osi/compiler/msvc/epicsAtomicCD.h
+++ b/src/libCom/osi/compiler/msvc/epicsAtomicCD.h
@@ -66,6 +66,8 @@
 #   error unexpected target architecture, msvc version of epicsAtomicCD.h
 #endif
 
+#define OSD_ATOMIC_INLINE_DEFINITION
+
 /*
  * The windows doc appears to recommend defining InterlockedExchange
  * to be _InterlockedExchange to cause it to be an intrinsic, but that
diff --git a/src/libCom/osi/epicsAtomic.h b/src/libCom/osi/epicsAtomic.h
index 37313a5bb..aa389ea2f 100644
--- a/src/libCom/osi/epicsAtomic.h
+++ b/src/libCom/osi/epicsAtomic.h
@@ -80,25 +80,6 @@ epicsShareFunc EpicsAtomicPtrT epicsAtomicCmpAndSwapPtrT ( EpicsAtomicPtrT * pTa
                             EpicsAtomicPtrT oldVal, EpicsAtomicPtrT newVal );
 
 
-/*
- * the following are, never inline and always synchronized by a global 
- * mutual exclusion lock, implementations of the epicsAtomicXxxx interface
- * which may used to implement the epicsAtomicXxxx functions when 
- * more efficent primitives aren't available
- */
-epicsShareFunc size_t epicsLockedIncrSizeT ( size_t * pTarget );
-epicsShareFunc size_t epicsLockedDecrSizeT ( size_t * pTarget );
-epicsShareFunc void epicsLockedSetSizeT ( size_t * pTarget, size_t newVal );
-epicsShareFunc void epicsLockedSetUIntT ( unsigned * pTarget, unsigned newVal );
-epicsShareFunc void epicsLockedSetPtrT ( EpicsAtomicPtrT * pTarget, EpicsAtomicPtrT newVal );
-epicsShareFunc size_t epicsLockedGetSizeT ( const size_t * pTarget );
-epicsShareFunc unsigned epicsLockedGetUIntT ( const unsigned * pTarget );
-epicsShareFunc EpicsAtomicPtrT epicsLockedGetPtrT ( const EpicsAtomicPtrT * pTarget );
-epicsShareFunc unsigned epicsLockedCmpAndSwapUIntT ( unsigned * pTarget, 
-                                        unsigned oldval, unsigned newval );
-epicsShareFunc EpicsAtomicPtrT epicsLockedCmpAndSwapPtrT ( EpicsAtomicPtrT * pTarget, 
-                            EpicsAtomicPtrT oldVal, EpicsAtomicPtrT newVal );
-
 #ifdef __cplusplus
 } /* end of extern "C" */
 #endif
diff --git a/src/libCom/osi/epicsAtomicGuard.h b/src/libCom/osi/epicsAtomicGuard.h
new file mode 100644
index 000000000..7e5cf5334
--- /dev/null
+++ b/src/libCom/osi/epicsAtomicGuard.h
@@ -0,0 +1,54 @@
+
+/*************************************************************************\
+* Copyright (c) 2011 LANS LLC, as Operator of
+*     Los Alamos National Laboratory.
+* Copyright (c) 2011 UChicago Argonne LLC, as Operator of Argonne
+*     National Laboratory.
+* EPICS BASE is distributed subject to a Software License Agreement found
+* in file LICENSE that is included with this distribution. 
+\*************************************************************************/
+
+/*
+ *  Author Jeffrey O. Hill
+ *  johill@lanl.gov
+ */
+ 
+#ifndef epicsAtomicGuard_h
+#define epicsAtomicGuard_h
+
+//
+// This header file is intended only for use with the epicsAtomicLocked
+// header file. The intent is that an OS specific implementation of
+// epicsAtomicOSD.cpp might first include this file, next implement 
+// AtomicGuard depending on os specific capabilities, and finally include 
+// the epicsAtomicLocked header file to define the various epicsAtomicXxxx 
+// functions. 
+//
+// The AtomicGuard class is defined in a seperate header file 
+// from the epicsAtomicLocked header for two reasons. 
+// o First, it must be possible to have an inline definition of the 
+// AtomicGuard member functions, and that isnt possible if the
+// epicsAtomicXxxx function definitions in the epicsAtomicLocked
+// header file have already been seen by the translation unit.
+// o Second, we need to enforce a uniform interface for all definitions
+// of the the AtomicGuard constructor and destructor member functions
+// requiring that no exception are thrown. This is because the 
+// epicsAtomicXxxx functions in the epicsAtomicLocked header file are 
+// directly callable by C code.
+//
+// The epicsAtomicXxxx functions in the epicsAtomicLocked do not pass
+// any parameters to the AtomicGuard constructor, and therefore the lock
+// used by AtomicGuard is restricted to be a global lock for the entire
+// multithreaded executable. Therefore, AtomicGuard will typically
+// reference some translation unit scope limited global variable in 
+// the anonymous namespace for implementation of the locking primitive.
+//
+    
+namespace {
+    struct AtomicGuard {
+        AtomicGuard () throw (); 
+        ~AtomicGuard () throw ();
+    };
+} // end of anonymous namespace
+
+#endif // ifndef epicsAtomicGuard_h
\ No newline at end of file
diff --git a/src/libCom/osi/epicsAtomicLocked.h b/src/libCom/osi/epicsAtomicLocked.h
index 64cad6351..4707d66f9 100644
--- a/src/libCom/osi/epicsAtomicLocked.h
+++ b/src/libCom/osi/epicsAtomicLocked.h
@@ -11,86 +11,108 @@
  *  Author Jeffrey O. Hill
  *  johill@lanl.gov
  */
+ 
+//
+// The epicsAtomicXxxxx functions herein are implemented with C++ but directly 
+// callable by C code, and therefore they must not be instantiated inline. 
+// Therefore, this isnt a traditional header file because it has function
+// definitions that are not inline, and must therefore be included by only 
+// one module in the executable - typically this is the epicsAtomicOSD
+// c++ source file. These out-of-line function definitions are placed in a
+// header file so that there is potential code reuse when instantiating for 
+// a specific OS. An alternative option would have been to place these 
+// function definitions in a OS type conditionally compiled source file
+// but this wasnt done because I suspect that selecting the posix version
+// would require a proliferation of "SRCS_XXXX += xxx.cpp" in the libCom 
+// Makefile for every variety of Unix (a maintenance headache when new 
+// varieties of UNIX are configured).
+//
+// Aee also the comments in epicsAtomicGuard header.
+//
 
 #ifndef epicsAtomicLocked_h
 #define epicsAtomicLocked_h
 
-#if defined ( OSD_ATOMIC_INLINE )
+#ifndef __cplusplus
+#   error epicsAtomicLocked.h is intended only for use only by C++ code
+#endif
+
+#include "epicsAtomic.h" // always cross check the function prototypes
+#include "epicsAtomicGuard.h" 
 
-#ifdef __cplusplus
 extern "C" {
-#endif /* __cplusplus */
 
-OSD_ATOMIC_INLINE size_t epicsAtomicIncrSizeT ( size_t * pTarget )
+size_t epicsAtomicIncrSizeT ( size_t * pTarget )
 {
-    return epicsLockedIncrSizeT ( pTarget );
+    AtomicGuard atomicGuard;
+    return ++(*pTarget);
 }
 
-OSD_ATOMIC_INLINE size_t epicsAtomicDecrSizeT ( size_t * pTarget )
+size_t epicsAtomicDecrSizeT ( size_t * pTarget )
 {
-    return epicsLockedDecrSizeT ( pTarget );
+    AtomicGuard atomicGuard;
+    return --(*pTarget);
 }
 
-OSD_ATOMIC_INLINE void epicsAtomicSetSizeT ( size_t * pTarget, size_t newVal )
+void epicsAtomicSetSizeT ( size_t * pTarget, size_t newVal )
 {
-    epicsLockedSetSizeT ( pTarget, newVal );
+    AtomicGuard atomicGuard;
+    *pTarget = newVal;
 }
 
-OSD_ATOMIC_INLINE size_t epicsAtomicGetSizeT ( const size_t * pTarget )
+void epicsAtomicSetUIntT ( unsigned * pTarget, unsigned newVal )
 {
-    return epicsLockedGetSizeT ( pTarget );
+    AtomicGuard atomicGuard;
+    *pTarget = newVal;
 }
 
-OSD_ATOMIC_INLINE unsigned epicsAtomicGetUIntT ( const unsigned * pTarget )
+void epicsAtomicSetPtrT ( EpicsAtomicPtrT * pTarget, EpicsAtomicPtrT newVal )
 {
-    return epicsLockedGetUIntT ( pTarget );
+    AtomicGuard atomicGuard;
+    *pTarget = newVal;
 }
 
-OSD_ATOMIC_INLINE void epicsAtomicSetUIntT ( unsigned * pTarget, unsigned newVal )
+unsigned epicsAtomicGetUIntT ( const unsigned * pTarget )
 {
-    epicsLockedSetUIntT ( pTarget, newVal );
+    AtomicGuard atomicGuard;
+    return *pTarget;
 }
 
-OSD_ATOMIC_INLINE void epicsAtomicSetPtrT ( EpicsAtomicPtrT * pTarget, EpicsAtomicPtrT newVal )
+size_t epicsAtomicGetSizeT ( const size_t * pTarget )
 {
-    epicsLockedSetPtrT ( pTarget, newVal );
+    AtomicGuard atomicGuard;
+    return *pTarget;
 }
 
-OSD_ATOMIC_INLINE EpicsAtomicPtrT epicsAtomicGetPtrT ( const EpicsAtomicPtrT * pTarget )
+EpicsAtomicPtrT epicsAtomicGetPtrT ( const EpicsAtomicPtrT * pTarget )
 {
-    return epicsLockedGetPtrT ( pTarget );
+    AtomicGuard atomicGuard;
+    return *pTarget;
 }
 
-OSD_ATOMIC_INLINE unsigned epicsAtomicCmpAndSwapUIntT ( unsigned * pTarget, 
-                                        unsigned oldVal, unsigned newVal )
+unsigned epicsAtomicCmpAndSwapUIntT ( unsigned * pTarget, 
+                            unsigned oldval, unsigned newval )
 {
-    return epicsLockedCmpAndSwapUIntT ( pTarget, oldVal, newVal );
+    AtomicGuard atomicGuard;
+    const unsigned cur = *pTarget;
+    if ( cur == oldval ) {
+        *pTarget = newval;
+    }
+    return cur;
 }
 
-OSD_ATOMIC_INLINE EpicsAtomicPtrT epicsAtomicCmpAndSwapPtrT ( EpicsAtomicPtrT * pTarget, 
-                                        EpicsAtomicPtrT oldVal, EpicsAtomicPtrT newVal )
+EpicsAtomicPtrT epicsAtomicCmpAndSwapPtrT ( EpicsAtomicPtrT * pTarget, 
+                            EpicsAtomicPtrT oldval, EpicsAtomicPtrT newval )
 {
-    return epicsLockedCmpAndSwapPtrT ( pTarget, oldVal, newVal );
+    AtomicGuard atomicGuard;
+    const EpicsAtomicPtrT cur = *pTarget;
+    if ( cur == oldval ) {
+        *pTarget = newval;
+    }
+    return cur;
 }
 
-#ifdef __cplusplus
-} /* end of extern "C" */
-#endif /* __cplusplus */
-
-#else /* if defined ( OSD_ATOMIC_INLINE ) */
-
-#   define epicsAtomicIncrSizeT epicsLockedIncrSizeT
-#   define epicsAtomicDecrSizeT epicsLockedDecrSizeT
-#   define epicsAtomicSetSizeT epicsLockedSetSizeT
-#   define epicsAtomicSetUIntT epicsLockedSetUIntT
-#   define epicsAtomicSetPtrT epicsLockedSetPtrT
-#   define epicsAtomicGetSizeT epicsLockedGetSizeT
-#   define epicsAtomicGetUIntT epicsLockedGetUIntT
-#   define epicsAtomicGetPtrT epicsLockedGetPtrT
-#   define epicsAtomicCmpAndSwapUIntT epicsLockedCmpAndSwapUIntT
-#   define epicsAtomicCmpAndSwapPtrT epicsLockedCmpAndSwapPtrT
-
-#endif /* if defined ( OSD_ATOMIC_INLINE ) */
+} // end of extern "C"
 
 #endif /* epicsAtomicLocked_h */
 
diff --git a/src/libCom/osi/os/WIN32/epicsAtomicOSD.h b/src/libCom/osi/os/WIN32/epicsAtomicOSD.h
index 3b3ab6942..bcf48facd 100644
--- a/src/libCom/osi/os/WIN32/epicsAtomicOSD.h
+++ b/src/libCom/osi/os/WIN32/epicsAtomicOSD.h
@@ -30,6 +30,8 @@
 extern "C" {
 #endif /* __cplusplus */
 
+#define OSD_ATOMIC_INLINE_DEFINITION
+
 /* 
  * mingw doesnt currently provide MemoryBarrier
  * (this is mostly for testing purposes as the gnu
diff --git a/src/libCom/osi/os/default/epicsAtomicOSD.cpp b/src/libCom/osi/os/default/epicsAtomicOSD.cpp
new file mode 100644
index 000000000..ecb1ad7c9
--- /dev/null
+++ b/src/libCom/osi/os/default/epicsAtomicOSD.cpp
@@ -0,0 +1,26 @@
+
+/*************************************************************************\
+* Copyright (c) 2011 LANS LLC, as Operator of 
+*     Los Alamos National Laboratory.
+* EPICS BASE is distributed subject to a Software License Agreement found
+* in file LICENSE that is included with this distribution. 
+\*************************************************************************/
+
+/*
+ *  Author Jeffrey O. Hill
+ *  johill@lanl.gov
+ */
+
+#define epicsExportSharedSymbols
+#include "epicsAtomic.h"
+
+//
+// We need a default epicsAtopmicOSD.cpp which is empty for use when 
+// a compiler or inline OS specific implementation is provided. See 
+// "osi/os/posix/epicsAtomicOSD.cpp" for an example OS specific generic 
+// out-of-line implementation based on a mutex lock.
+//
+#if ! defined ( OSD_ATOMIC_INLINE_DEFINITION )
+#   error the epicsAtomicXxxxx functions definitions are misssing
+#endif
+
diff --git a/src/libCom/osi/os/default/epicsAtomicOSD.h b/src/libCom/osi/os/default/epicsAtomicOSD.h
index 0b250495b..bf09ae083 100644
--- a/src/libCom/osi/os/default/epicsAtomicOSD.h
+++ b/src/libCom/osi/os/default/epicsAtomicOSD.h
@@ -16,6 +16,4 @@
 #ifndef epicsAtomicOSD_h
 #define epicsAtomicOSD_h
 
-#include "epicsAtomicLocked.h"
-
 #endif /* epicsAtomicOSD_h */
diff --git a/src/libCom/osi/os/posix/epicsAtomicOSD.cpp b/src/libCom/osi/os/posix/epicsAtomicOSD.cpp
new file mode 100644
index 000000000..e6cf40d22
--- /dev/null
+++ b/src/libCom/osi/os/posix/epicsAtomicOSD.cpp
@@ -0,0 +1,71 @@
+
+/*************************************************************************\
+* Copyright (c) 2011 LANS LLC, as Operator of 
+*     Los Alamos National Laboratory.
+* EPICS BASE is distributed subject to a Software License Agreement found
+* in file LICENSE that is included with this distribution. 
+\*************************************************************************/
+
+/*
+ *  Author Jeffrey O. Hill
+ *  johill@lanl.gov
+ *
+ *  Provide a global mutex version of AtomicGuard on POSIX
+ *  systems for when we dont have more efficent compiler or 
+ *  OS primitives intriniscs to use instead.
+ *
+ *  We implement this mutex-based AtomicGuard primitive directly 
+ *  upon the standalone POSIX pthread library so that the epicsAtomic 
+ *  library can be used to implement other primitives such 
+ *  epicsThreadOnce.
+ *
+ *  We use a static initialized pthread mutex to minimize code 
+ *  size, and are also optimistic that this can be more efficent 
+ *  than pthread_once.
+ */
+
+#include <unistd.h>
+
+#define epicsExportSharedSymbols
+#include "epicsAtomic.h"
+
+// If we have an inline implementation then implement 
+// nothing that conflicts here
+#if ! defined ( OSD_ATOMIC_INLINE_DEFINITION )
+
+// get the interface for class AtomicGuard
+#include "epicsAtomicGuard.h"
+
+namespace {
+
+// a statically initialized mutex doesnt need to be destroyed 
+static pthread_mutex_t AtomicGuard :: mutex = PTHREAD_MUTEX_INITIALIZER;
+
+inline AtomicGuard :: AtomicGuard () throw ()
+{
+    unsigned countDown = 1000u;
+    while ( true ) {
+        status = pthread_mutex_lock ( & mutex );
+        if ( status != EINTR ) break;
+        static const useconds_t retryDelayUSec = 100000;
+        usleep ( retryDelayUSec );
+        countDown--;
+        assert ( countDown );
+    }
+    assert ( status == 0 );
+}
+
+inline AtomicGuard :: ~AtomicGuard () throw ()
+{
+    const int status = pthread_mutex_unlock ( & mutex );
+    assert ( status == 0 );
+}
+
+} // end of namespace anonymous
+
+// Define the epicsAtomicXxxx functions out-of-line using this 
+// implementation of AtomicGuard. Note that this isnt a traditional 
+// c++ header file.
+#include "epicsAtomicLocked.h"
+
+#endif // if ! defined ( #define OSD_ATOMIC_INLINE_DEFINITION )
diff --git a/src/libCom/osi/os/solaris/epicsAtomicOSD.h b/src/libCom/osi/os/solaris/epicsAtomicOSD.h
index 542997ccf..48c95824a 100644
--- a/src/libCom/osi/os/solaris/epicsAtomicOSD.h
+++ b/src/libCom/osi/os/solaris/epicsAtomicOSD.h
@@ -29,6 +29,8 @@
 #define __STDC_LIMIT_MACROS /* define SIZE_MAX for c++ */
 #include <stdint.h>
 
+#define OSD_ATOMIC_INLINE_DEFINITION
+
 #ifdef __cplusplus
 extern "C" {
 #endif /* __cplusplus */
@@ -97,10 +99,6 @@ OSD_ATOMIC_INLINE EpicsAtomicPtrT epicsAtomicGetPtrT ( const EpicsAtomicPtrT * p
 } /* end of extern "C" */
 #endif /* __cplusplus */
 
-#else /* ifdef __SunOS_5_10  */
-
-#include "epicsAtomicLocked.h"
-
 #endif /* ifdef __SunOS_5_10 */
 
 #endif /* if defined ( OSD_ATOMIC_INLINE ) */
diff --git a/src/libCom/osi/os/vxWorks/epicsAtomicOSD.h b/src/libCom/osi/os/vxWorks/epicsAtomicOSD.h
index e71f6d9b6..b46c66436 100644
--- a/src/libCom/osi/os/vxWorks/epicsAtomicOSD.h
+++ b/src/libCom/osi/os/vxWorks/epicsAtomicOSD.h
@@ -28,6 +28,8 @@
 
 #include <limits.h>
 #include <vxAtomicLib.h>
+
+#define OSD_ATOMIC_INLINE_DEFINITION
      
 #ifdef __cplusplus
 extern "C" {