Clean-up AVR stack colorization logic

arch/avr/Kconfig

@@ -32,6 +32,7 @@ endchoice
 config ARCH_FAMILY_AVR
 	bool
 	default n
+	select ARCH_HAVE_STACKCHECK
 
 config ARCH_FAMILY_AVR32
 	bool

arch/avr/src/avr/up_createstack.c

@@ -170,7 +170,7 @@ int up_create_stack(FAR struct tcb_s *tcb, size_t stack_size, uint8_t ttype)
        */
 
 #if defined(CONFIG_DEBUG) && defined(CONFIG_DEBUG_STACK)
-      memset(tcb->stack_alloc_ptr, 0xaa, stack_size);
+      memset(tcb->stack_alloc_ptr, STACK_COLOR, stack_size);
 #endif
 
       /* The AVR uses a push-down stack:  the stack grows toward lower

arch/avr/src/avr/up_usestack.c

@@ -112,7 +112,7 @@ int up_use_stack(struct tcb_s *tcb, void *stack, size_t stack_size)
    */
 
 #if defined(CONFIG_DEBUG) && defined(CONFIG_DEBUG_STACK)
-   memset(tcb->stack_alloc_ptr, 0xaa, stack_size);
+   memset(tcb->stack_alloc_ptr, STACK_COLOR, stack_size);
 #endif
 
   /* The AVR uses a push-down stack:  the stack grows toward loweraddresses in

arch/avr/src/avr32/up_createstack.c

@@ -170,7 +170,7 @@ int up_create_stack(FAR struct tcb_s *tcb, size_t stack_size, uint8_t ttype)
        */
 
 #if defined(CONFIG_DEBUG) && defined(CONFIG_DEBUG_STACK)
-      memset(tcb->stack_alloc_ptr, 0xaa, stack_size);
+      memset(tcb->stack_alloc_ptr, STACK_COLOR, stack_size);
 #endif
 
       /* The AVR32 uses a push-down stack:  the stack grows toward lower

arch/avr/src/avr32/up_usestack.c

@@ -107,6 +107,14 @@ int up_use_stack(struct tcb_s *tcb, void *stack, size_t stack_size)
 
   tcb->stack_alloc_ptr = stack;
 
+  /* If stack debug is enabled, then fill the stack with a recognizable value
+   * that we can use later to test for high water marks.
+   */
+
+#if defined(CONFIG_DEBUG) && defined(CONFIG_DEBUG_STACK)
+   memset(tcb->stack_alloc_ptr, STACK_COLOR, stack_size);
+#endif
+
   /* The AVR32 uses a push-down stack:  the stack grows
    * toward loweraddresses in memory.  The stack pointer
    * register, points to the lowest, valid work address

arch/avr/src/common/up_internal.h

@@ -73,6 +73,14 @@
 # define CONFIG_ARCH_INTERRUPTSTACK 0
 #endif
 
+/* This is the value used to mark the stack for subsequent stack monitoring
+ * logic.
+ */
+
+#define STACK_COLOR    's'
+#define INTSTACK_COLOR 's'
+#define HEAP_COLOR     'h'
+
 /****************************************************************************
  * Public Types
  ****************************************************************************/