diff --git a/arch/arc/arcem/port_s.s b/arch/arc/arcem/port_s.s
index 7918c93e..5609507c 100644
--- a/arch/arc/arcem/port_s.s
+++ b/arch/arc/arcem/port_s.s
@@ -11,7 +11,6 @@
 .global k_curr_task
 .global k_next_task
 
-.global g_exc_nest_count
 .global g_context_switch_reqflg
 
 .global tos_knl_irq_enter
@@ -142,9 +141,9 @@ exc_entry_cpu:
     mov	blink,	sp
     mov	r3, sp		/* as exception handler's para(p_excinfo) */
 
-    ld	r0, [g_exc_nest_count]
+    ld	r0, [k_irq_nest_cnt]
     add	r1, r0, 1
-    st	r1, [g_exc_nest_count]
+    st	r1, [k_irq_nest_cnt]
     brne	r0, 0, exc_handler_1
 /* change to exception stack if interrupt happened in task context */
     mov	sp, _e_stack
@@ -166,7 +165,7 @@ exc_handler_1:
 /* interrupts are not allowed */
 ret_exc:
     POP	sp
-    mov	r1, g_exc_nest_count
+    mov	r1, k_irq_nest_cnt
     ld	r0, [r1]
     sub	r0, r0, 1
     st	r0, [r1]
@@ -233,9 +232,9 @@ exc_entry_int:
     mov	blink, sp
 
     clri	/* disable interrupt */
-    ld	r3, [g_exc_nest_count]
+    ld	r3, [k_irq_nest_cnt]
     add	r2, r3, 1
-    st	r2, [g_exc_nest_count]
+    st	r2, [k_irq_nest_cnt]
     seti	/* enable higher priority interrupt */
 
     brne	r3, 0, irq_handler_1
@@ -279,7 +278,7 @@ ret_int:
     clri			/* disable interrupt */
     POP	r3		/* irq priority */
     POP	sp
-    mov	r1, g_exc_nest_count
+    mov	r1, k_irq_nest_cnt
     ld	r0, [r1]
     sub	r0, r0, 1
     st	r0, [r1]
diff --git a/arch/arc/common/tos_cpu.c b/arch/arc/common/tos_cpu.c
index 5ab6fe3f..8c05fd38 100644
--- a/arch/arc/common/tos_cpu.c
+++ b/arch/arc/common/tos_cpu.c
@@ -200,7 +200,6 @@ __KNL__ void cpu_standby_mode_enter(void)
 #endif /* TOS_CFG_PWR_MGR_EN */
 
 uint32_t g_context_switch_reqflg;
-uint32_t g_exc_nest_count;
 
 extern void start_r(void);
 
diff --git a/board/ARC_NSIM_EM/hello_world/Makefile b/board/ARC_NSIM_EM/hello_world/Makefile
index 8a5ab471..f66ee1f0 100644
--- a/board/ARC_NSIM_EM/hello_world/Makefile
+++ b/board/ARC_NSIM_EM/hello_world/Makefile
@@ -86,6 +86,7 @@ MDB_ARG_FILE := $(EMBARC_OUT_DIR)/embARC_generated/mdb.arg
 else
 COMPILER_ARG_FILE := $(EMBARC_OUT_DIR)/embARC_generated/gcc.arg
 LDF_FILE := $(EMBARC_OUT_DIR)/linker_gnu.ldf
+NSIM_PROPS := $(EMBARC_OUT_DIR)/embARC_generated/nsim.props
 endif
 
 ######################################
@@ -120,7 +121,7 @@ PREFIX =
 CC = $(PREFIX)ccac
 AS = $(PREFIX)ccac
 
-SZ = $(PREFIX)size
+SZ = $(PREFIX)sizeac
 
 OBJCOPY	= $(PREFIX)elf2bin
 ELF2HEX	= $(PREFIX)elf2hex
@@ -129,7 +130,16 @@ ELF2HEX_INOPT = -Q -I
 ELF2HEX_OUTOPT = -o
 ELF2BIN_OPT =
 else
+PREFIX = arc-elf32-
+CC = $(PREFIX)gcc
+AS = $(PREFIX)gcc -x assembler-with-cpp
+SZ = $(PREFIX)size
+OBJCOPY = $(PREFIX)objcopy
+ELF2HEX	= $(OBJCOPY)
 
+ELF2HEX_INOPT = -O ihex
+ELF2HEX_OUTOPT =
+ELF2BIN_OPT = -O binary -S
 endif
 
 #######################################
@@ -201,6 +211,11 @@ CFLAGS =  @$(COMPILER_ARG_FILE) -Hnoccm -Hnosdata -Wincompatible-pointer-types -
 LDFLAGS = -Hhostlink @$(COMPILER_ARG_FILE) -Hnocopyr -Hnosdata -Hnocrt -Hldopt=-Coutput=$(BUILD_DIR)/mw_arcem.map -Hldopt=-Csections -Hldopt=-Ccrossfunc -Hldopt=-Csize -zstdout $(LDF_FILE)
 else
 
+ASFLAGS = @$(COMPILER_ARG_FILE) -fdata-sections -ffunction-sections -mno-sdata -$(OLEVEL) -g $(C_DEFS) $(C_INCLUDES) -x assembler-with-cpp
+
+CFLAGS =  @$(COMPILER_ARG_FILE) -fdata-sections -ffunction-sections -mno-sdata -$(OLEVEL) -g $(C_DEFS) $(C_INCLUDES) -std=gnu99
+
+LDFLAGS = --specs=nsim.specs @$(COMPILER_ARG_FILE) -mno-sdata -nostartfiles -Wl,-M,-Map=$(BUILD_DIR)/gnu_arcem.map -lm -Wl,--script=$(LDF_FILE)
 endif
 # default action: build all
 all: $(BUILD_DIR)/$(TARGET).elf $(BUILD_DIR)/$(TARGET).hex $(BUILD_DIR)/$(TARGET).bin
@@ -264,6 +279,13 @@ nsim_debug : $(BUILD_DIR)/$(TARGET).elf
 #######################################
 # dependencies
 #######################################
+run : $(BUILD_DIR)/$(TARGET).elf
+ifeq ($(TOOLCHAIN),mw)
+	mdb -nooptions -nogoifmain -toggle=include_local_symbols=1 -nsim -off=binary_stdin -off=binary_stdout  -on=load_at_paddr -on=reset_upon_restart -off=flush_pipe -off=cr_for_more -OKN @$(MDB_ARG_FILE) -run $<
+else
+	nsimdrv -p nsim_emt=1 -propsfile $(NSIM_PROPS) $<
+endif
+
 -include $(wildcard $(BUILD_DIR)/*.d)
 
 # *** EOF ***
\ No newline at end of file