diff --git a/TESTS/mbedmicro-rtos-mbed/heap_and_stack/main.cpp b/TESTS/mbedmicro-rtos-mbed/heap_and_stack/main.cpp
index 91c1129cdb..e4c88a3c0f 100644
--- a/TESTS/mbedmicro-rtos-mbed/heap_and_stack/main.cpp
+++ b/TESTS/mbedmicro-rtos-mbed/heap_and_stack/main.cpp
@@ -15,7 +15,7 @@
  * limitations under the License.
  */
 
-#if defined(TARGET_CORTEX_A) || !DEVICE_USTICKER || !defined(MBED_CONF_RTOS_PRESENT)
+#if defined(TARGET_CORTEX_A) || !DEVICE_USTICKER
 #error [NOT_SUPPORTED] test not supported.
 #else
 
@@ -39,9 +39,9 @@ static const int test_timeout = 30;
 // Malloc fill pattern
 #define MALLOC_FILL                 0x55
 
-extern uint32_t mbed_heap_start;
+extern unsigned char *mbed_heap_start;
 extern uint32_t mbed_heap_size;
-extern uint32_t mbed_stack_isr_start;
+extern unsigned char *mbed_stack_isr_start;
 extern uint32_t mbed_stack_isr_size;
 
 #if defined(TOOLCHAIN_GCC_ARM) && defined(MBED_SPLIT_HEAP)
@@ -57,6 +57,27 @@ struct linked_list {
 };
 
 
+// Global test variables
+#define TEST_VALUE      789
+static struct Test {
+    Test() : val(TEST_VALUE) {}
+    ~Test() {}
+    int val;
+} t;
+
+int test_function()
+{
+    return TEST_VALUE;
+}
+static int global_int = test_function();
+
+/** Test global variables initialisation
+ */
+void test_global_variables_initialisation(void)
+{
+    TEST_ASSERT_EQUAL(TEST_VALUE, global_int);
+    TEST_ASSERT_EQUAL(TEST_VALUE, t.val);
+}
 
 /* TODO: add memory layout test.
  *
@@ -122,7 +143,7 @@ static void allocate_and_fill_heap(linked_list *&head)
         if (NULL == temp) {
             break;
         }
-        bool result = rangeinrange((uint32_t) temp, sizeof(linked_list), mbed_heap_start, mbed_heap_size);
+        bool result = rangeinrange((uint32_t) temp, sizeof(linked_list), (uint32_t)mbed_heap_start, mbed_heap_size);
 #if defined(TOOLCHAIN_GCC_ARM) && defined(MBED_SPLIT_HEAP)
         if (false == result) {
             result = rangeinrange((uint32_t) temp, sizeof(linked_list), (uint32_t)mbed_heap_start_0, mbed_heap_size_0);
@@ -174,7 +195,8 @@ void test_heap_in_range(void)
     initial_heap = (char *) malloc(1);
     TEST_ASSERT_NOT_NULL(initial_heap);
 
-    bool result = inrange((uint32_t) initial_heap, mbed_heap_start, mbed_heap_size);
+    bool result = inrange((uint32_t) initial_heap, (uint32_t)mbed_heap_start, mbed_heap_size);
+
 #if defined(TOOLCHAIN_GCC_ARM) && defined(MBED_SPLIT_HEAP)
     if (false == result) {
         result = inrange((uint32_t) initial_heap, (uint32_t)mbed_heap_start_0, mbed_heap_size_0);
@@ -184,6 +206,7 @@ void test_heap_in_range(void)
     free(initial_heap);
 }
 
+#if MBED_CONF_RTOS_PRESENT
 /** Test for Main thread stack
 
     Given a Main thread and its stack
@@ -203,6 +226,7 @@ void test_main_stack_in_range(void)
 
     TEST_ASSERT_TRUE_MESSAGE(result, "Main stack in wrong location");
 }
+#endif // #if MBED_CONF_RTOS_PRESENT
 
 /** Test for Scheduler/ISR thread stack
 
@@ -214,7 +238,7 @@ void test_isr_stack_in_range(void)
 {
     // MSP stack should be very near end (test using within 128 bytes)
     uint32_t msp = __get_MSP();
-    bool result = inrange(msp, mbed_stack_isr_start + mbed_stack_isr_size - 0x400, 0x400);
+    bool result = inrange(msp, (uint32_t)mbed_stack_isr_start + mbed_stack_isr_size - 0x400, 0x400);
 
     TEST_ASSERT_TRUE_MESSAGE(result, "Interrupt stack in wrong location");
 }
@@ -244,8 +268,11 @@ void test_heap_allocation_free(void)
 
 // Test cases
 Case cases[] = {
+    Case("Test global variables initialisation", test_global_variables_initialisation),
     Case("Test heap in range", test_heap_in_range),
+#if MBED_CONF_RTOS_PRESENT
     Case("Test main stack in range", test_main_stack_in_range),
+#endif
     Case("Test isr stack in range", test_isr_stack_in_range),
     Case("Test heap allocation and free", test_heap_allocation_free)
 };
@@ -263,4 +290,4 @@ int main()
     return !utest::v1::Harness::run(specification);
 }
 
-#endif // defined(TARGET_CORTEX_A) || !DEVICE_USTICKER || !defined(MBED_CONF_RTOS_PRESENT)
+#endif // defined(TARGET_CORTEX_A) || !DEVICE_USTICKER
diff --git a/platform/source/TARGET_CORTEX_M/TOOLCHAIN_IAR/cmain.S b/platform/source/TARGET_CORTEX_M/TOOLCHAIN_IAR/cmain.S
index 0da55009b3..3cfbeacd63 100644
--- a/platform/source/TARGET_CORTEX_M/TOOLCHAIN_IAR/cmain.S
+++ b/platform/source/TARGET_CORTEX_M/TOOLCHAIN_IAR/cmain.S
@@ -46,6 +46,7 @@
         EXTERN  exit
         EXTERN  __iar_dynamic_initialization
         EXTERN mbed_sdk_init
+        EXTWEAK __mbed_init
         EXTERN mbed_main
         EXTERN SystemInit
         
@@ -68,6 +69,9 @@ __cmain:
         FUNCALL __cmain, mbed_sdk_init
         BL      mbed_sdk_init
         MOVS    r0,#0             ;  No parameters        
+        FUNCALL __cmain, __mbed_init
+        BL      __mbed_init
+        MOVS    r0,#0             ;  No parameters
           FUNCALL __cmain, __iar_dynamic_initialization
         BL      __iar_dynamic_initialization   ; C++ dynamic initialization  
 
diff --git a/platform/source/mbed_retarget.cpp b/platform/source/mbed_retarget.cpp
index cee0c57436..42d5c83c43 100644
--- a/platform/source/mbed_retarget.cpp
+++ b/platform/source/mbed_retarget.cpp
@@ -561,23 +561,6 @@ std::FILE *fdopen(FileHandle *fh, const char *mode)
 extern "C" FILEHANDLE PREFIX(_open)(const char *name, int openflags)
 {
 #if defined(__MICROLIB) && (__ARMCC_VERSION>5030000)
-#if !defined(MBED_CONF_RTOS_PRESENT)
-    // valid only for mbed 2
-    // for ulib, this is invoked after RAM init, prior c++
-    // used as hook, as post stack/heap is not active there
-    extern void mbed_copy_nvic(void);
-    extern void mbed_sdk_init(void);
-
-    static int mbed_sdk_inited = 0;
-    if (!mbed_sdk_inited) {
-        mbed_copy_nvic();
-        mbed_sdk_init();
-#if DEVICE_USTICKER && MBED_CONF_TARGET_INIT_US_TICKER_AT_BOOT
-        us_ticker_init();
-#endif
-        mbed_sdk_inited = 1;
-    }
-#endif
     // Before version 5.03, we were using a patched version of microlib with proper names
     // This is the workaround that the microlib author suggested us
     static int n = 0;
diff --git a/platform/source/mbed_sdk_boot.c b/platform/source/mbed_sdk_boot.c
index b9f8922f91..9dc8141558 100644
--- a/platform/source/mbed_sdk_boot.c
+++ b/platform/source/mbed_sdk_boot.c
@@ -21,12 +21,20 @@
 #include "cmsis.h"
 #include "hal/us_ticker_api.h"
 
-/* This startup is for mbed 2 baremetal. There is no config for RTOS for mbed 2,
- * therefore we protect this file with MBED_CONF_RTOS_PRESENT
- * Note: The new consolidated started for mbed OS is in rtos/mbed_boot code file.
+/* This startup is for baremetal. There is no RTOS in baremetal,
+ * therefore we protect this file with MBED_CONF_RTOS_PRESENT.
+ * Note: The start-up code for mbed OS is in rtos/source/TARGET_CORTEX/mbed_boot code file.
  */
 #if !defined(MBED_CONF_RTOS_PRESENT)
 
+/* Heap limits - only used if set */
+extern unsigned char *mbed_heap_start;
+extern uint32_t mbed_heap_size;
+
+/* Stack limits */
+unsigned char *mbed_stack_isr_start = 0;
+uint32_t mbed_stack_isr_size = 0;
+
 /* mbed_main is a function that is called before main()
  * mbed_sdk_init() is also a function that is called before main(), but unlike
  * mbed_main(), it is not meant for user code, but for the SDK itself to perform
@@ -67,20 +75,7 @@ void mbed_copy_nvic(void)
 #endif /* !defined(__CORTEX_M0) && !defined(__CORTEX_A9) */
 }
 
-/* Toolchain specific main code */
-
-#if defined (__ARMCC_VERSION)
-
-int $Super$$main(void);
-
-int $Sub$$main(void)
-{
-    mbed_main();
-    mbed_error_initialize();
-    return $Super$$main();
-}
-
-void _platform_post_stackheap_init(void)
+void mbed_init(void)
 {
     mbed_copy_nvic();
     mbed_sdk_init();
@@ -88,21 +83,78 @@ void _platform_post_stackheap_init(void)
     us_ticker_init();
 #endif
 }
+
+/* Toolchain specific main code */
+
+#if defined (__ARMCC_VERSION)
+
+void $Sub$$__cpp_initialize__aeabi_(void);
+void $Super$$__cpp_initialize__aeabi_(void);
+void $Sub$$__cpp_initialize__aeabi_(void)
+{
+    /* This should invoke C++ initializers but we keep
+     * this empty and invoke them in mbed_toolchain_init.
+     */
+}
+
+void mbed_toolchain_init()
+{
+    /* Run the C++ global object constructors */
+    $Super$$__cpp_initialize__aeabi_();
+}
+
+void _platform_post_stackheap_init(void)
+{
+    mbed_init();
+}
+
+extern uint32_t               Image$$ARM_LIB_STACK$$ZI$$Base[];
+extern uint32_t               Image$$ARM_LIB_STACK$$ZI$$Length[];
+extern uint32_t               Image$$ARM_LIB_HEAP$$ZI$$Base[];
+extern uint32_t               Image$$ARM_LIB_HEAP$$ZI$$Length[];
+
+int $Super$$main(void);
+int $Sub$$main(void)
+{
+    mbed_stack_isr_start = (unsigned char *) Image$$ARM_LIB_STACK$$ZI$$Base;
+    mbed_stack_isr_size = (uint32_t) Image$$ARM_LIB_STACK$$ZI$$Length;
+    mbed_heap_start = (unsigned char *) Image$$ARM_LIB_HEAP$$ZI$$Base;
+    mbed_heap_size = (uint32_t) Image$$ARM_LIB_HEAP$$ZI$$Length;
+
+#if defined(__MICROLIB)
+    // post stack/heap is not active in microlib
+    // so call the function explicitly.
+    _platform_post_stackheap_init();
+#endif
+    mbed_toolchain_init();
+    mbed_main();
+    return $Super$$main();
+}
+
+
+
+
 //Define an empty os_cb_sections to remove a RTX warning when building with no RTOS due
 //to the --keep=os_cb_sections linker option
 const uint32_t os_cb_sections[] __attribute__((section(".rodata"))) = {};
 
 #elif defined (__GNUC__)
 
+extern uint32_t             __StackLimit;
+extern uint32_t             __StackTop;
+extern uint32_t             __end__;
+extern uint32_t             __HeapLimit;
+
 extern int __real_main(void);
 
 void software_init_hook(void)
 {
-    mbed_copy_nvic();
-    mbed_sdk_init();
-#if DEVICE_USTICKER && MBED_CONF_TARGET_INIT_US_TICKER_AT_BOOT
-    us_ticker_init();
-#endif
+    mbed_stack_isr_start = (unsigned char *) &__StackLimit;
+    mbed_stack_isr_size = (uint32_t) &__StackTop - (uint32_t) &__StackLimit;
+    mbed_heap_start = (unsigned char *) &__end__;
+    mbed_heap_size = (uint32_t) &__HeapLimit - (uint32_t) &__end__;
+
+    mbed_init();
     software_init_hook_rtos();
 }
 
@@ -110,19 +162,24 @@ void software_init_hook(void)
 int __wrap_main(void)
 {
     mbed_main();
-    mbed_error_initialize();
     return __real_main();
 }
 
 #elif defined (__ICCARM__)
 
-int __low_level_init(void)
+/* Defined by linker script */
+#pragma section="CSTACK"
+#pragma section="HEAP"
+
+void __mbed_init(void)
 {
-    mbed_copy_nvic();
-#if DEVICE_USTICKER && MBED_CONF_TARGET_INIT_US_TICKER_AT_BOOT
-    us_ticker_init();
-#endif
-    return 1;
+    mbed_heap_start = (unsigned char *)__section_begin("HEAP");
+    mbed_heap_size = (uint32_t)__section_size("HEAP");
+
+    mbed_stack_isr_start = (unsigned char *)__section_begin("CSTACK");
+    mbed_stack_isr_size = (uint32_t)__section_size("CSTACK");
+
+    mbed_init();
 }
 
 #endif