diff --git a/.gitignore b/.gitignore
index 714413f..ec3d5c8 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,5 +1,8 @@
 *.swp
 *.o
-app/shell/curt_image.bin
-app/shell/curt_image.elf
-app/shell/flash-image
+*.map
+*.bin
+arch/arm/mach-pxa/curt_image.bin
+arch/arm/mach-pxa/curt_image.elf
+arch/arm/mach-pxa/flash-image
+arch/x86/CuRT-x86.img
diff --git a/Makefile b/Makefile
index 01a9e54..5118bbb 100644
--- a/Makefile
+++ b/Makefile
@@ -1,5 +1,59 @@
+ARCH = x86
+ARCH_SRC_DIR = arch/x86
+#ARCH = pxa255
+#ARCH_SRC_DIR = arch/arm/mach-pxa
+
+#######################################################################
+# path setting
+#######################################################################
+TOP_DIR = $(shell pwd)
+INCLUDE_DIR = -I$(TOP_DIR)/include/$(ARCH_SRC_DIR) -I$(TOP_DIR)/include
+
+#######################################################################
+# compiler / linker setting
+#######################################################################
+CFLAGS = \
+	$(INCLUDE_DIR) -Wall $(DEFS)\
+	-fno-builtin -O0 -g $(MACH_CFLAGS)
+
+LDFLAGS = \
+	-nostdlib -static --no-undefined -X
+
+#######################################################################
+# source / object file list
+#######################################################################
+# hardware indepedent
+KERNEL_SRC = \
+	$(TOP_DIR)/kernel/kernel.c \
+	$(TOP_DIR)/kernel/thread.c \
+	$(TOP_DIR)/kernel/list.c   \
+	$(TOP_DIR)/kernel/sync.c  \
+	$(TOP_DIR)/kernel/ipc.c
+
+LIB_SRC = \
+	$(TOP_DIR)/lib/stdio.c
+
+SHELL_SRC = \
+	$(TOP_DIR)/app/shell/main.c
+
+KERNEL_OBJ = $(KERNEL_SRC:.c=.o)
+SHELL_OBJ = $(SHELL_SRC:.c=.o)
+LIB_OBJ = $(LIB_SRC:.c=.o)
+
+export
+
+#######################################################################
+# Make Rules
+#######################################################################
+
+.PHONY: all run clean clean-all
+
 all:
-	$(MAKE) -C app/shell
+	$(MAKE) -C $(ARCH_SRC_DIR)
 
 clean:
-	$(MAKE) -C app/shell clean
+	rm -f $(KERNEL_OBJ) $(SHELL_OBJ) $(LIB_OBJ)
+	$(MAKE) -C $(ARCH_SRC_DIR) clean
+
+run: all
+	$(MAKE) -C $(ARCH_SRC_DIR) run
diff --git a/app/shell/Makefile b/app/shell/Makefile
index 1a98eb2..4705d90 100644
--- a/app/shell/Makefile
+++ b/app/shell/Makefile
@@ -7,7 +7,7 @@ LD = $(CROSS_COMPILE)ld
 OBJCOPY = $(CROSS_COMPILE)objcopy
 
 MACH_CFLAGS = -march=armv5te -mtune=xscale -Wa,-mcpu=xscale \
-	      -mabi=aapcs-linux -mno-thumb-interwork
+	      -mabi=aapcs-linux -mno-thumb-interwork -fno-stack-protector
 
 CFLAGS = \
 	-I../../includes/arch/arm/mach-pxa \
@@ -20,7 +20,8 @@ LDSCRIPT := ld-script.lds
 LDFLAGS = \
 	-nostdlib -static -e _start \
 	-p --no-undefined -X \
-	-T $(LDSCRIPT)
+	-T $(LDSCRIPT) \
+	-Map $(CURT_IMAGE).map
 
 OBJCOPYFLAGS = \
 	-O binary \
diff --git a/arch/arm/mach-pxa/Makefile b/arch/arm/mach-pxa/Makefile
new file mode 100644
index 0000000..3e0140a
--- /dev/null
+++ b/arch/arm/mach-pxa/Makefile
@@ -0,0 +1,71 @@
+# Tested on CodeSourcery G++ Lite 2008q1, 2010q1-202, 2011.03
+CROSS_COMPILE = arm-linux-gnueabi-
+CURT_IMAGE = curt_image
+
+CC = $(CROSS_COMPILE)gcc
+LD = $(CROSS_COMPILE)ld
+OBJCOPY = $(CROSS_COMPILE)objcopy
+
+MACH_CFLAGS = -march=armv5te -mtune=xscale -Wa,-mcpu=xscale \
+	      -mabi=aapcs-linux -mno-thumb-interwork -fno-stack-protector
+
+CFLAGS += $(MACH_CFLAGS)
+
+LDSCRIPT := ld-script.lds
+LDFLAGS += \
+	-e _start -p \
+	-T $(LDSCRIPT) \
+	-Map $(CURT_IMAGE).map
+
+OBJCOPYFLAGS = \
+	-O binary \
+	-R .note -R .note.gnu.build-id -R .comment \
+	-S
+
+#######################################################################
+# architecture dependence source
+#######################################################################
+HW_DEP_ASM_SRC = \
+	start.S \
+	asm_port.S \
+
+HW_DEP_C_SRC = \
+	device/serial.c \
+	port.c
+
+HW_DEP_C_OBJ = $(HW_DEP_C_SRC:.c=.o)
+HW_DEP_ASM_OBJ = $(HW_DEP_ASM_SRC:.S=.o)
+
+ALL_OBJS = $(SHELL_OBJ) $(HW_DEP_C_OBJ) $(HW_DEP_ASM_OBJ) $(KERNEL_OBJ) $(LIB_OBJ)
+#######################################################################
+# Make Rules
+#######################################################################
+all: flash-image
+
+flash-image: $(CURT_IMAGE).bin
+	./prepare-flash
+
+$(CURT_IMAGE).bin: $(CURT_IMAGE).elf
+	$(OBJCOPY) $(OBJCOPYFLAGS) $< $@
+
+$(CURT_IMAGE).elf: $(ALL_OBJS)
+	$(LD) $(LDFLAGS) \
+		-o $(CURT_IMAGE).elf $(ALL_OBJS)
+
+$(HW_DEP_C_OBJ) : %.o : %.c
+	$(CC) -c $(CFLAGS) $< -o $@
+
+$(HW_DEP_ASM_OBJ) : %.o : %.S
+	$(CC) -c $(CFLAGS) $< -o $@
+
+$(SHELL_OBJ) $(LIB_OBJ) $(KERNEL_OBJ) : %.o : %.c
+	$(CC) -c $(CFLAGS) $< -o $@
+
+run:
+	./run-on-connex
+
+clean:
+	rm -f ./*.o
+
+distclean:
+	rm -f $(CURT_IMAGE).bin $(CURT_IMAGE).elf flash-image
diff --git a/device/serial.c b/arch/arm/mach-pxa/device/serial.c
similarity index 100%
rename from device/serial.c
rename to arch/arm/mach-pxa/device/serial.c
diff --git a/app/shell/ld-script.lds b/arch/arm/mach-pxa/ld-script.lds
similarity index 88%
rename from app/shell/ld-script.lds
rename to arch/arm/mach-pxa/ld-script.lds
index e931dc6..20cf344 100644
--- a/app/shell/ld-script.lds
+++ b/arch/arm/mach-pxa/ld-script.lds
@@ -7,7 +7,7 @@ SECTIONS
 
 	. = ALIGN(4);
 	.text : 
-	{ 	../../arch/arm/mach-pxa/start.o (.text)
+	{ 	start.o (.text)
 		*(.text) 
 	}
 	. = ALIGN(4);
diff --git a/app/shell/prepare-flash b/arch/arm/mach-pxa/prepare-flash
similarity index 100%
rename from app/shell/prepare-flash
rename to arch/arm/mach-pxa/prepare-flash
diff --git a/app/shell/run-on-connex b/arch/arm/mach-pxa/run-on-connex
similarity index 100%
rename from app/shell/run-on-connex
rename to arch/arm/mach-pxa/run-on-connex
diff --git a/app/shell/run-on-connex-debug b/arch/arm/mach-pxa/run-on-connex-debug
similarity index 100%
rename from app/shell/run-on-connex-debug
rename to arch/arm/mach-pxa/run-on-connex-debug
diff --git a/arch/x86/Makefile b/arch/x86/Makefile
new file mode 100644
index 0000000..f7f1a8a
--- /dev/null
+++ b/arch/x86/Makefile
@@ -0,0 +1,44 @@
+TARGET = CuRT-x86.img
+
+CC = gcc
+LD = ld
+
+.SUFFIXES:.asm .bin .c .s .o .S
+.PHONY:	all run clean
+
+HW_DEP_ASM_SRC =
+
+HW_DEP_ASM_OBJ = $(HW_DEP_ASM_SRC:.S=.o)
+
+HW_DEP_C_SRC =
+
+HW_DEP_C_OBJ = $(HW_DEP_C_SRC:.c=.o)
+
+BOOT_OBJ = boot/boot.o boot/boot.bin
+
+ALL_OBJS = $(SHELL_OBJ) $(KERNEL_OBJ) $(LIB_OBJ) \
+	$(HW_DEP_ASM_OBJ) $(HW_DEP_C_OBJ) $(BOOT_OBJ)
+
+CFLAGS += -fno-stack-protector
+LDFLAGS +=
+
+all: $(TARGET)
+
+$(TARGET): boot/boot.bin
+	dd if=/dev/zero of=$(TARGET) bs=512 count=2880
+	dd if=boot/boot.bin of=$(TARGET) bs=512 seek=0 conv=notrunc
+
+boot/boot.bin: boot/boot.o
+	$(LD) $(LDFLAGS) --oformat binary -o boot/boot.bin -T boot/boot.ld $^
+
+%.o:%.c
+	$(CC) -c $(CFLAGS) $< -o $@
+
+%.o:%.S
+	$(CC) -c $(CFLAGS) $< -o $@
+
+clean:
+	rm -f $(ALL_OBJS)
+
+run: $(TARGET)
+	qemu-system-x86_64 -m 32 -fda $< -boot a
diff --git a/arch/x86/boot/boot.S b/arch/x86/boot/boot.S
new file mode 100644
index 0000000..a4d30ac
--- /dev/null
+++ b/arch/x86/boot/boot.S
@@ -0,0 +1,19 @@
+.code16
+
+.text
+	mov %cs, %ax
+	mov %ax, %ds
+	mov %ax, %es
+
+	mov $message, %ax
+	mov %ax, %bp
+	mov $19, %cx
+	mov $0x1301, %ax
+	mov $0x0009, %bx
+	mov $0, %dl
+	int $0x10
+	jmp .
+
+message: .ascii "bootloader testing!"
+.org 510
+.word 0xaa55
diff --git a/arch/x86/boot/boot.ld b/arch/x86/boot/boot.ld
new file mode 100644
index 0000000..4b678bc
--- /dev/null
+++ b/arch/x86/boot/boot.ld
@@ -0,0 +1,8 @@
+SECTIONS
+{
+	.text  0x7c00 :
+	{
+		code = .; _code = .; __code = .;
+		*(.text)
+	}
+}
diff --git a/includes/arch/arm/mach-pxa/port.h b/include/arch/arm/mach-pxa/port.h
similarity index 95%
rename from includes/arch/arm/mach-pxa/port.h
rename to include/arch/arm/mach-pxa/port.h
index 94f1ccd..e659565 100644
--- a/includes/arch/arm/mach-pxa/port.h
+++ b/include/arch/arm/mach-pxa/port.h
@@ -5,7 +5,7 @@
 #include "kernel/types.h"
 #include "kernel/thread.h"
 
-#define PXA255_TMR_CLK 3686400 
+#define PXA255_TMR_CLK 3686400
 #define OS_TICKS_PER_SEC 10
 
 stk_t *init_thread_stack(THREAD_FUNC func,
diff --git a/includes/arch/arm/mach-pxa/pxa255.h b/include/arch/arm/mach-pxa/pxa255.h
similarity index 98%
rename from includes/arch/arm/mach-pxa/pxa255.h
rename to include/arch/arm/mach-pxa/pxa255.h
index 8579888..e00f10f 100644
--- a/includes/arch/arm/mach-pxa/pxa255.h
+++ b/include/arch/arm/mach-pxa/pxa255.h
@@ -7,17 +7,17 @@
 /* --------------------------------------- */
 /** Memory Controller */
 #define MSC_BASE	0x48000000
-#define MSC_REG(_x_)	*(vulong *)(MSC_BASE + _x_)	
+#define MSC_REG(_x_)	*(vulong *)(MSC_BASE + _x_)
 
 
 //---------------------------------------
 /** UARTs */
 #define FF_UART_BASE		0x40100000	/* Full Function UART Base Address */
-#define FF_UART_REG(_x_)	*(vulong *)(FF_UART_BASE + _x_)	
+#define FF_UART_REG(_x_)	*(vulong *)(FF_UART_BASE + _x_)
 #define BT_UART_BASE		0x40200000	/* Bluetooth UART Base Address */
-#define BT_UART_REG(_x_)	*(vulong *)(BT_UART_BASE + _x_)	
+#define BT_UART_REG(_x_)	*(vulong *)(BT_UART_BASE + _x_)
 #define STD_UART_BASE		0x40700000	/* Standard UART Base Address */
-#define STD_UART_REG(_x_)	*(vulong *)(STD_UART_BASE + _x_)	
+#define STD_UART_REG(_x_)	*(vulong *)(STD_UART_BASE + _x_)
 
 #define UART_RBR	0x00	/* Receive Buffer Register (read only) */
 #define UART_THR	0x00	/* Transmit Holding Register (write only) */
@@ -35,8 +35,8 @@
 
 /* --------------------------------------- */
 /** OS Timer */
-#define TMR_BASE	0x40A00000   
-#define TMR_REG(_x_)	*(vulong *)(TMR_BASE + _x_)	
+#define TMR_BASE	0x40A00000
+#define TMR_REG(_x_)	*(vulong *)(TMR_BASE + _x_)
 #define TMR_OSMR0	0x00	/* OS timer match registers<3:0> */
 #define TMR_OSMR1	0x04	/* */
 #define TMR_OSMR2	0x08	/* */
@@ -50,7 +50,7 @@
 /* --------------------------------------- */
 /** Interrupt Control */
 #define INT_BASE	0x40D00000	/* Interrupt controller IRQ pending register */
-#define INT_REG(_x_)	*(vulong *)(INT_BASE + _x_)	
+#define INT_REG(_x_)	*(vulong *)(INT_BASE + _x_)
 #define INT_ICIP	0x00	/* Interrupt controller IRQ pending register */
 #define INT_ICMR	0x04	/* Interrupt controller mask register */
 #define INT_ICLR	0x08	/* Interrupt controller level register */
diff --git a/includes/kernel/ipc.h b/include/kernel/ipc.h
similarity index 100%
rename from includes/kernel/ipc.h
rename to include/kernel/ipc.h
diff --git a/includes/kernel/kernel.h b/include/kernel/kernel.h
similarity index 100%
rename from includes/kernel/kernel.h
rename to include/kernel/kernel.h
diff --git a/includes/kernel/list.h b/include/kernel/list.h
similarity index 100%
rename from includes/kernel/list.h
rename to include/kernel/list.h
diff --git a/includes/kernel/sync.h b/include/kernel/sync.h
similarity index 100%
rename from includes/kernel/sync.h
rename to include/kernel/sync.h
diff --git a/includes/kernel/thread.h b/include/kernel/thread.h
similarity index 100%
rename from includes/kernel/thread.h
rename to include/kernel/thread.h
diff --git a/includes/kernel/types.h b/include/kernel/types.h
similarity index 100%
rename from includes/kernel/types.h
rename to include/kernel/types.h
diff --git a/includes/lib/stdio.h b/include/lib/stdio.h
similarity index 100%
rename from includes/lib/stdio.h
rename to include/lib/stdio.h
diff --git a/lib/stdio.c b/lib/stdio.c
index 23ef88d..7b7d4da 100644
--- a/lib/stdio.c
+++ b/lib/stdio.c
@@ -167,12 +167,12 @@ static void _PrintHex(char *fmt, int l)
 {
 	int i, j;
 	char c, *s = fmt, tol[10];
-	bool flag0 = false, flagl = false;
+	bool flag0 = false;
 	long flagcnt = 0;
 	bool leading_zero = true;
 	char uHex, lHex;
-	int cnt;	/* note: the format like "% 5x" only prints
-			   the number of 5. */
+
+	/* note: the format like "% 5x" only prints the number of 5. */
 
 	/* format like "%081" is interpreted for '0', '8', 'l'
 	 * individually. */
@@ -189,8 +189,6 @@ static void _PrintHex(char *fmt, int l)
 		}
 		else if (c == '0')
 			flag0 = true;
-		else if (c == 'l')
-			flagl = true;
 		else
 			continue;
 	}
@@ -224,7 +222,7 @@ static void _PrintHex(char *fmt, int l)
 		}
 
 		/* byte-level data, the output Hex */
-		for (cnt = 0, i = (8 - flagcnt) / 2; i < 4; i++) {
+		for (i = (8 - flagcnt) / 2; i < 4; i++) {
 			c = s[i];
 				
 			/* get upper 4 bits and lower 4 bits. */
@@ -411,7 +409,6 @@ unsigned long strtoul(const char *str, char **endptr, int requestedbase)
 	int base = 10;
 	int nchars = 0;
 	int leadingZero = 0;
-	unsigned char strtoul_err = 0;
 	
 	while ((c = *str) != 0) {
 		if (nchars == 0 && c == '0') {
@@ -438,11 +435,9 @@ unsigned long strtoul(const char *str, char **endptr, int requestedbase)
 			digit = c - 'A' + 10;
 		}
 		else {
-			strtoul_err = 3;
 			return 0;
 		}
 		if (digit >= base) {
-			strtoul_err = 4;
 			return 0;
 		}
 		num *= base;