#define portNUM_CONFIGURABLE_REGIONS ( ( portLAST_CONFIGURABLE_REGION - portFIRST_CONFIGURABLE_REGION ) + 1 )\r
#define portTOTAL_NUM_REGIONS ( portNUM_CONFIGURABLE_REGIONS + 1 ) /* Plus one to make space for the stack region. */\r
\r
-#define portSWITCH_TO_USER_MODE() __asm volatile ( " mrs r0, control \n orr r0, #1 \n msr control, r0 " )\r
+#define portSWITCH_TO_USER_MODE() __asm volatile ( " mrs r0, control \n orr r0, #1 \n msr control, r0 " :::"r0" )\r
\r
typedef struct MPU_REGION_REGISTERS\r
{\r