diff --git a/demos/ARM7-LPC214x-GCC-minimal/Makefile b/demos/ARM7-LPC214x-GCC-minimal/Makefile
index 3514a9090..1fe22d71a 100644
--- a/demos/ARM7-LPC214x-GCC-minimal/Makefile
+++ b/demos/ARM7-LPC214x-GCC-minimal/Makefile
@@ -127,16 +127,16 @@ ODFLAGS	= -x --syms
 
 # Thumb interwork enabled only if needed because it kills performance.
 ifneq ($(TSRC),)
+  CPFLAGS += -D THUMB_PRESENT
   ifneq ($(ASRC),)
-    # Both ARM and THUMB case
-    CPFLAGS += -mthumb-interwork -D THUMB
+    # Mixed ARM and THUMB case.
+    CPFLAGS += -mthumb-interwork
     LDFLAGS += -mthumb-interwork
-    ASFLAGS += -mthumb-interwork -D THUMB
   else
-    # Pure THUMB case, THUMB C code cannot be called by ARM asm code directly
-    CPFLAGS += -D THUMB
+    # Pure THUMB case, THUMB C code cannot be called by ARM asm code directly.
+    CPFLAGS += -D THUMB_NO_INTERWORKING
     LDFLAGS += -mthumb
-    ASFLAGS += -mthumb-interwork -D THUMB -D THUMB_NO_INTERWORKING
+    ASFLAGS += -D THUMB_NO_INTERWORKING
   endif
 endif
 
diff --git a/demos/ARM7-LPC214x-GCC-minimal/Makefile.thumb b/demos/ARM7-LPC214x-GCC-minimal/Makefile.thumb
index 76b3fd296..b00adef75 100644
--- a/demos/ARM7-LPC214x-GCC-minimal/Makefile.thumb
+++ b/demos/ARM7-LPC214x-GCC-minimal/Makefile.thumb
@@ -91,7 +91,7 @@ ULIBS =
 AOPT =
 
 # THUMB-specific options here
-TOPT = -mthumb
+TOPT = -mthumb -D THUMB
 
 # Common options here
 # NOTE: -ffixed-r7 is only needed if you enabled CH_CURRP_REGISTER_CACHE in
@@ -127,16 +127,16 @@ ODFLAGS	= -x --syms
 
 # Thumb interwork enabled only if needed because it kills performance.
 ifneq ($(TSRC),)
+  CPFLAGS += -D THUMB_PRESENT
   ifneq ($(ASRC),)
-    # Both ARM and THUMB case
-    CPFLAGS += -mthumb-interwork -D THUMB
+    # Mixed ARM and THUMB case.
+    CPFLAGS += -mthumb-interwork
     LDFLAGS += -mthumb-interwork
-    ASFLAGS += -mthumb-interwork -D THUMB
   else
-    # Pure THUMB case, THUMB C code cannot be called by ARM asm code directly
-    CPFLAGS += -D THUMB -D THUMB_NO_INTERWORKING
+    # Pure THUMB case, THUMB C code cannot be called by ARM asm code directly.
+    CPFLAGS += -D THUMB_NO_INTERWORKING
     LDFLAGS += -mthumb
-    ASFLAGS += -mthumb-interwork -D THUMB -D THUMB_NO_INTERWORKING
+    ASFLAGS += -D THUMB_NO_INTERWORKING
   endif
 endif
 
diff --git a/demos/ARM7-LPC214x-GCC/Makefile b/demos/ARM7-LPC214x-GCC/Makefile
index 13c32b4dc..5e49defda 100644
--- a/demos/ARM7-LPC214x-GCC/Makefile
+++ b/demos/ARM7-LPC214x-GCC/Makefile
@@ -130,16 +130,16 @@ ODFLAGS	= -x --syms
 
 # Thumb interwork enabled only if needed because it kills performance.
 ifneq ($(TSRC),)
+  CPFLAGS += -D THUMB_PRESENT
   ifneq ($(ASRC),)
-    # Both ARM and THUMB case
-    CPFLAGS += -mthumb-interwork -D THUMB
+    # Mixed ARM and THUMB case.
+    CPFLAGS += -mthumb-interwork
     LDFLAGS += -mthumb-interwork
-    ASFLAGS += -mthumb-interwork -D THUMB
   else
-    # Pure THUMB case, THUMB C code cannot be called by ARM asm code directly
-    CPFLAGS += -D THUMB
+    # Pure THUMB case, THUMB C code cannot be called by ARM asm code directly.
+    CPFLAGS += -D THUMB_NO_INTERWORKING
     LDFLAGS += -mthumb
-    ASFLAGS += -mthumb-interwork -D THUMB -D THUMB_NO_INTERWORKING
+    ASFLAGS += -D THUMB_NO_INTERWORKING
   endif
 endif
 
@@ -158,7 +158,7 @@ $(AOBJS) : %.o : %.c
 
 $(TOBJS) : %.o : %.c
 	@echo
-	$(CC) -c $(CPFLAGS) $(TOPT) -mthumb -I . $(INCDIR) $< -o $@
+	$(CC) -c $(CPFLAGS) $(TOPT) -I . $(INCDIR) $< -o $@
 
 $(ASMOBJS) : %.o : %.s
 	@echo
diff --git a/demos/ARM7-LPC214x-GCC/Makefile.thumb b/demos/ARM7-LPC214x-GCC/Makefile.thumb
index 93188a528..89ccdfdc2 100644
--- a/demos/ARM7-LPC214x-GCC/Makefile.thumb
+++ b/demos/ARM7-LPC214x-GCC/Makefile.thumb
@@ -94,7 +94,7 @@ ULIBS =
 AOPT =
 
 # THUMB-specific options here
-TOPT = -mthumb
+TOPT = -mthumb -D THUMB
 
 # Common options here
 # NOTE: -ffixed-r7 is only needed if you enabled CH_CURRP_REGISTER_CACHE in
@@ -130,16 +130,16 @@ ODFLAGS	= -x --syms
 
 # Thumb interwork enabled only if needed because it kills performance.
 ifneq ($(TSRC),)
+  CPFLAGS += -D THUMB_PRESENT
   ifneq ($(ASRC),)
-    # Both ARM and THUMB case
-    CPFLAGS += -mthumb-interwork -D THUMB
+    # Mixed ARM and THUMB case.
+    CPFLAGS += -mthumb-interwork
     LDFLAGS += -mthumb-interwork
-    ASFLAGS += -mthumb-interwork -D THUMB
   else
-    # Pure THUMB case, THUMB C code cannot be called by ARM asm code directly
-    CPFLAGS += -D THUMB -D THUMB_NO_INTERWORKING
+    # Pure THUMB case, THUMB C code cannot be called by ARM asm code directly.
+    CPFLAGS += -D THUMB_NO_INTERWORKING
     LDFLAGS += -mthumb
-    ASFLAGS += -mthumb-interwork -D THUMB -D THUMB_NO_INTERWORKING
+    ASFLAGS += -D THUMB_NO_INTERWORKING
   endif
 endif
 
diff --git a/ports/ARM7-LPC214x/GCC/chcore.c b/ports/ARM7-LPC214x/GCC/chcore.c
index c8e2c61f7..fc4c01942 100644
--- a/ports/ARM7-LPC214x/GCC/chcore.c
+++ b/ports/ARM7-LPC214x/GCC/chcore.c
@@ -33,64 +33,71 @@ void _IdleThread(void *p) {
   }
 }
 
-#ifdef THUMB
+/*
+ * The following functions are present only if there is in the system any
+ * code compiled as THUMB that may invoke them.
+ * NOTE: The undefs are there in case this module is compiled in ARM mode but
+ *       there are THUMB modules in the system.
+ */
+#ifdef THUMB_PRESENT
+#undef chSysLock
 void chSysLock(void) {
 
+#ifdef THUMB
   asm(".p2align 2,,                                             \n\t" \
       "mov      r0, pc                                          \n\t" \
       "bx       r0                                              \n\t" \
-      ".code 32                                                 \n\t" \
-      "msr      CPSR_c, #0x9F                                   \n\t" \
+      ".code 32                                                 \n\t");
+#endif
+
+  asm("msr      CPSR_c, #0x9F                                   \n\t" \
       "bx       lr                                              \n\t");
 }
 
+#undef chSysUnlock
 void chSysUnlock(void) {
 
+#ifdef THUMB
   asm(".p2align 2,,                                             \n\t" \
       "mov      r0, pc                                          \n\t" \
       "bx       r0                                              \n\t" \
-      ".code 32                                                 \n\t" \
-      "msr      CPSR_c, #0x1F                                   \n\t" \
+      ".code 32                                                 \n\t");
+#endif
+
+  asm("msr      CPSR_c, #0x1F                                   \n\t" \
       "bx       lr                                              \n\t");
 }
 #endif
 
 void chSysSwitchI(Context *oldp, Context *newp) {
 
-#ifdef CH_CURRP_REGISTER_CACHE
 #ifdef THUMB
   asm(".p2align 2,,                                             \n\t" \
       "mov      r2, pc                                          \n\t" \
       "bx       r2                                              \n\t" \
-      ".code 32                                                 \n\t" \
-      "stmfd    sp!, {r4, r5, r6, r8, r9, r10, r11, lr}         \n\t" \
-      "str      sp, [r0, #0]                                    \n\t" \
-      "ldr      sp, [r1, #0]                                    \n\t" \
-      "ldmfd    sp!, {r4, r5, r6, r8, r9, r10, r11, lr}         \n\t" \
-      "bx       lr                                              \n\t");
-#else /* !THUMB */
+      ".code 32                                                 \n\t");
+#endif
+
+#ifdef CH_CURRP_REGISTER_CACHE
   asm("stmfd    sp!, {r4, r5, r6, r8, r9, r10, r11, lr}         \n\t" \
       "str      sp, [r0, #0]                                    \n\t" \
-      "ldr      sp, [r1, #0]                                    \n\t" \
-      "ldmfd    sp!, {r4, r5, r6, r8, r9, r10, r11, pc}         \n\t");
-#endif /* !THUMB */
-#else /* !CH_CURRP_REGISTER_CACHE */
-#ifdef THUMB
-  asm(".p2align 2,,                                             \n\t" \
-      "mov      r2, pc                                          \n\t" \
-      "bx       r2                                              \n\t" \
-      ".code 32                                                 \n\t" \
-      "stmfd    sp!, {r4, r5, r6, r7, r8, r9, r10, r11, lr}     \n\t" \
-      "str      sp, [r0, #0]                                    \n\t" \
-      "ldr      sp, [r1, #0]                                    \n\t" \
-      "ldmfd    sp!, {r4, r5, r6, r7, r8, r9, r10, r11, lr}     \n\t" \
+      "ldr      sp, [r1, #0]                                    \n\t");
+#ifdef THUMB_PRESENT
+  asm("ldmfd    sp!, {r4, r5, r6, r8, r9, r10, r11, lr}         \n\t" \
       "bx       lr                                              \n\t");
-#else /* !THUMB */
+#else /* !THUMB_PRESENT */
+  asm("ldmfd    sp!, {r4, r5, r6, r8, r9, r10, r11, pc}         \n\t");
+#endif /* !THUMB_PRESENT */
+#else /* !CH_CURRP_REGISTER_CACHE */
   asm("stmfd    sp!, {r4, r5, r6, r7, r8, r9, r10, r11, lr}     \n\t" \
       "str      sp, [r0, #0]                                    \n\t" \
-      "ldr      sp, [r1, #0]                                    \n\t" \
-      "ldmfd    sp!, {r4, r5, r6, r7, r8, r9, r10, r11, pc}     \n\t");
-#endif /* !THUMB */
+      "ldr      sp, [r1, #0]                                    \n\t");
+#ifdef THUMB_PRESENT
+  asm("ldmfd    sp!, {r4, r5, r6, r7, r8, r9, r10, r11, lr}     \n\t" \
+      "bx       lr                                              \n\t");
+#else /* !THUMB_PRESENT */
+  asm("ldmfd    sp!, {r4, r5, r6, r7, r8, r9, r10, r11, pc}     \n\t");
+#endif /* !THUMB_PRESENT */
 #endif /* !CH_CURRP_REGISTER_CACHE */
 }
 
@@ -151,7 +158,7 @@ void IrqCommon(void) {
    */
   asm(".set     MODE_IRQ, 0x12                                  \n\t" \
       ".set     MODE_SYS, 0x1F                                  \n\t" \
-      ".set     F_BIT, 0x40                                      \n\t" \
+      ".set     F_BIT, 0x40                                     \n\t" \
       ".set     I_BIT, 0x80                                     \n\t" \
       "ldmfd    sp!, {r0-r3, r12, lr}                           \n\t" \
       "msr      CPSR_c, #MODE_SYS | I_BIT                       \n\t" \
diff --git a/readme.txt b/readme.txt
index 5b9082822..f8ad8dbcc 100644
--- a/readme.txt
+++ b/readme.txt
@@ -50,16 +50,22 @@ AVR-AT90CANx-GCC       - Port on AVR AT90CAN128, not complete yet.
   various mechanisms and the correct use cases.
 - RT Semaphores subsystem removed, the Mutexes implements a better solution
   for the same problem.
+- Added mutexes test cases to the test suite.
 - Modified the test suite in order to have each test case to have the same
   alignment enforced on functions. This is done to reduce MAM/Cache alignment
   effects on the measurement.
 - IRQ entry/exit code is now encapsulated into two new macros, see chcore.h
   for details.
 - All the asm code previously in chcore2.s is now inline asm code in chcore.c
-  (ARM port).
+  (ARM port), chcore2.s removed.
 - Moved all the board specific definitions/code into two new files: board.c
   and board.h. Moved all the files no more board-dependent under ports/
   (ARM port).
+- Improved the kernel performance in THUMB mode by better exploiting MAM
+  locality in some critical functions. The context switch benchmark shows 5%
+  improved speed.
+  NOTE: The interworking code generated by GCC (or any other compiler as far
+        I know) is not MAM-aware.
 
 *** 0.4.5 ***
 - Moved the serial IRQ handlers and VIC vectors initialization inside the