diff --git a/make/compile.mk b/make/compile.mk
index d20ed27..1ac8790 100644
--- a/make/compile.mk
+++ b/make/compile.mk
@@ -4,9 +4,6 @@
 # ENDIANESS = {eb, el}
 # DEBUGGER = {gdb, mips, rom}
 
-TOOLCHAIN_PATH=$(MIPS_HOME)/toolchain/work/install/bin
-MIPSTOOLS_PATH=$(MIPS_HOME)/tools
-
 BOARD ?= ml402
 WITH_TLB ?= n
 ENDIANESS ?= eb
@@ -28,16 +25,5 @@ CFLAGS += $(ENDIAN_FLAGS)
 CFLAGS += -msoft-float -march=r3000
 CFLAGS += $(CFLAGS-$(BOARD))
 
-FLASHGEN_TLB-y := $(MIPSTOOLS_PATH)/flashgen_tlb
-FLASHGEN_TLB-n := $(MIPSTOOLS_PATH)/flashgen
-PACKHEX := $(MIPSTOOLS_PATH)/packhex
-
-AS=$(TOOLCHAIN_PATH)/mips-elf-as
-AR=$(TOOLCHAIN_PATH)/mips-elf-ar
-CC=$(TOOLCHAIN_PATH)/mips-elf-gcc
-LD=$(TOOLCHAIN_PATH)/mips-elf-gcc
-OBJDUMP=$(TOOLCHAIN_PATH)/mips-elf-objdump
-OBJCOPY=$(TOOLCHAIN_PATH)/mips-elf-objcopy
-FLASHGEN=$(FLASHGEN_TLB-$(WITH_TLB))
-
+include $(MIPS_HOME)/make/tools.mk
 
diff --git a/make/mips_boot.mk b/make/mips_boot.mk
index 3739ac0..d1c862d 100644
--- a/make/mips_boot.mk
+++ b/make/mips_boot.mk
@@ -7,18 +7,13 @@ WITH_TLB ?= n
 ENDIANESS ?= eb
 DEBUGGER ?= n
 		
-include ../../make/compile.mk
+include $(MIPS_HOME)/make/compile.mk
 
-CFLAGS += -Os -G0 -I. -I../libsys -I../libsys/boards/$(BOARD) -T $(MIPS_HOME)/link/bootloader.ld
+CFLAGS += -Os -G0 -I. -I../common/libsys -I../common/libsys/boards/$(BOARD) -T $(MIPS_HOME)/link/bootloader.ld
 
 BUILD_DIR=./build/$(BOARD)/$(ENDIANESS)
 		  
 LIBS=-lc
 CFLAGS += -DXCP_SIZE=4096
 		  
-CC=mips-elf-gcc
-LD=mips-elf-gcc
-OBJDUMP=mips-elf-objdump
-OBJCOPY=mips-elf-objcopy
-ROMGEN=romgen
 
diff --git a/make/tools.mk b/make/tools.mk
new file mode 100644
index 0000000..1a5c6d1
--- /dev/null
+++ b/make/tools.mk
@@ -0,0 +1,22 @@
+# environment vaiables read:
+# BOARD = {ml402, denano, sim}
+# WITH_TLB = {n, y}
+# ENDIANESS = {eb, el}
+# DEBUGGER = {gdb, mips, rom}
+
+TOOLCHAIN_PATH=$(MIPS_HOME)/toolchain/work/install/bin
+MIPSTOOLS_PATH=$(MIPS_HOME)/tools
+
+FLASHGEN_TLB-y := $(MIPSTOOLS_PATH)/flashgen_tlb
+FLASHGEN_TLB-n := $(MIPSTOOLS_PATH)/flashgen
+PACKHEX := $(MIPSTOOLS_PATH)/packhex
+
+AS=$(TOOLCHAIN_PATH)/mips-elf-as
+AR=$(TOOLCHAIN_PATH)/mips-elf-ar
+CC=$(TOOLCHAIN_PATH)/mips-elf-gcc
+LD=$(TOOLCHAIN_PATH)/mips-elf-gcc
+OBJDUMP=$(TOOLCHAIN_PATH)/mips-elf-objdump
+OBJCOPY=$(TOOLCHAIN_PATH)/mips-elf-objcopy
+FLASHGEN=$(FLASHGEN_TLB-$(WITH_TLB))
+ROMGEN=$(MIPSTOOLS_PATH)/romgen
+
diff --git a/src/bootloader/Makefile b/src/bootloader/Makefile
index a183b7b..f93d854 100644
--- a/src/bootloader/Makefile
+++ b/src/bootloader/Makefile
@@ -8,22 +8,22 @@ OBJS-ml402=$(addprefix $(BUILD_DIR)/, startup.o kernel.o cop0.o libsys.o srec.o
 OBJS-denano=$(addprefix $(BUILD_DIR)/, startup.o kernel.o cop0.o libsys.o srec.o board.o uart.o $(DBG_OBJ))
 OBJS-sim=$(addprefix $(BUILD_DIR)/, startup.o kernel.o cop0.o libsys.o srec.o board.o uart.o $(DBG_OBJ))
 		  
-$(BUILD_DIR)/cop0.o : ../libsys/cop0.c
+$(BUILD_DIR)/cop0.o : ../common/libsys/cop0.c
 	$(CC) $(CFLAGS) -c -o $@ $<
 
-$(BUILD_DIR)/uart.o : ../libsys/uart.c
+$(BUILD_DIR)/uart.o : ../common/libsys/uart.c
 	$(CC) $(CFLAGS) -c -o $@ $<
 
 $(BUILD_DIR)/board.o : boards/$(BOARD)/board.c
 	$(CC) $(CFLAGS) -c -o $@ $<
 
-$(BUILD_DIR)/mips_dbg.o : ../libsys/mips_dbg.c
+$(BUILD_DIR)/mips_dbg.o : ../common/libsys/mips_dbg.c
 	$(CC) $(CFLAGS) -c -o $@ $<
 
-$(BUILD_DIR)/mips_dis.o : ../libsys/mips_dis.c
+$(BUILD_DIR)/mips_dis.o : ../common/libsys/mips_dis.c
 	$(CC) $(CFLAGS) -c -o $@ $<
 
-$(BUILD_DIR)/gdb_stub.o : ../libsys/gdb_stub.c
+$(BUILD_DIR)/gdb_stub.o : ../common/libsys/gdb_stub.c
 	$(CC) $(CFLAGS) -c -o $@ $<
 
 $(BUILD_DIR)/%.o : %.c