diff --git a/src/bootloader/Makefile b/src/bootloader/Makefile
index 5170cd9..ba269a4 100644
--- a/src/bootloader/Makefile
+++ b/src/bootloader/Makefile
@@ -12,8 +12,8 @@ else
   ENDIAN_FLAGS=-EB
 endif
 
-CFLAGS=$(ENDIAN_FLAGS) -Os -I. -I../libsys -msoft-float -march=r3000 -G0 -I../libsys/boards/$(BOARD) -D$(BOARD)
-LFLAGS=$(ENDIAN_FLAGS) 
+CFLAGS=$(ENDIAN_FLAGS) -Os -flto -I. -I../libsys -msoft-float -march=r3000 -G0 -I../libsys/boards/$(BOARD) -D$(BOARD)
+LFLAGS=$(ENDIAN_FLAGS) -Os -flto
 
 ifeq ($(TLB),yes)
   CFLAGS+=-DSYS_IO_BASE=0xAC000000 -DSDRAM_BASE=0x80000000 -DFLASH_BASE_IO=0xA4000000 -DFLASH_BASE_MEM=0x88000000
diff --git a/src/bootloader/boards/denano/board.c b/src/bootloader/boards/denano/board.c
index 22e42c8..a915e7c 100644
--- a/src/bootloader/boards/denano/board.c
+++ b/src/bootloader/boards/denano/board.c
@@ -11,48 +11,38 @@
 #include "../../../libsys/uart.h"
 
 extern uart_if_t uart_if[];
+extern void handle_exception (unsigned long *registers);
 
 int gdb_stub(struct xcptcontext * xcp) __attribute__ ((section (".gdb")));
-
 int gdb_stub(struct xcptcontext * xcp)
 {
 	handle_exception((unsigned long *)xcp);
 	return 0;
 }
 
-inline void _dbg_writechar(uart_if_t const *pUart, char c)
+void dbg_putchar(char c)
 {
-	UART_writechar(pUart, c);
+	if (c == 0x0A)
+	{
+		UART_writechar(&uart_if[UART_DEBUGGER], 0x0D);
+	}
+	UART_writechar(&uart_if[UART_DEBUGGER], c);
 }
 
-inline char _dbg_readchar(uart_if_t const *pUart)
+char dbg_getchar()
 {
 	int c;
 
 	// busy read
 	do
 	{
-		c = UART_readchar(pUart);
+		c = UART_readchar(&uart_if[UART_DEBUGGER]);
 		
 	} while(c < 0);
 	
 	return (char)c;
 }
 
-void dbg_putchar(char c)
-{
-	if (c == 0x0A)
-	{
-		_dbg_writechar(&uart_if[UART_DEBUGGER], 0x0D);
-	}
-	_dbg_writechar(&uart_if[UART_DEBUGGER], c);
-}
-
-char dbg_getchar()
-{
-	return (char)_dbg_readchar(&uart_if[UART_DEBUGGER]);
-}
-
 void board_init(void)
 {
 
diff --git a/src/libsys/Makefile b/src/libsys/Makefile
index 2d828b1..316fc18 100644
--- a/src/libsys/Makefile
+++ b/src/libsys/Makefile
@@ -13,7 +13,7 @@ else
   ENDIAN_FLAGS=-EB
 endif
 		  
-CFLAGS=$(ENDIAN_FLAGS) -g -msoft-float -O2 -march=r3000 -I. -Iboards/$(BOARD) -D$(BOARD)
+CFLAGS=$(ENDIAN_FLAGS) -g -msoft-float -O2 -march=r3000 -I. -Iboards/$(BOARD) -D$(BOARD) -DWITH_ROM_GDBSTUB
 
 ifeq ($(TLB),yes)
   CFLAGS+=-DSYS_IO_BASE=0xAC000000 -DSDRAM_BASE=0x80000000 -DFLASH_BASE_IO=0xA4000000 -DFLASH_BASE_MEM=0x88000000
@@ -32,7 +32,7 @@ OBJCOPY=mips-elf-objcopy
 FLASHGEN=flashgen
 
 OBJS-ml402=$(addprefix $(BUILD_DIR)/, libsys.o xcpt.o syscalls.o cop0.o irq.o mips_dbg.o mips_dis.o mips_ps2.o mips_gfx.o console.o screen.o uart.o board.o gpio.o)
-OBJS-denano=$(addprefix $(BUILD_DIR)/, libsys.o xcpt.o syscalls.o cop0.o irq.o mips_dbg.o mips_dis.o console.o uart.o board.o)
+OBJS-denano=$(addprefix $(BUILD_DIR)/, libsys.o xcpt.o syscalls.o cop0.o irq.o mips_dbg.o mips_dis.o console.o uart.o board.o gdb_stub.o)
 
 all: $(BUILD_DIR) $(BUILD_DIR)/libsys.a
 	
diff --git a/src/libsys/boards/denano/board.c b/src/libsys/boards/denano/board.c
index 27ba691..9a4bba0 100644
--- a/src/libsys/boards/denano/board.c
+++ b/src/libsys/boards/denano/board.c
@@ -11,9 +11,19 @@
 #include "../../console.h"
 #include "../../regdef.h"
 
-const fp_xcpt_t dbg_func = (fp_xcpt_t)0xbfc01f00;
-
 extern uart_if_t uart_if[];
+extern void handle_exception (unsigned long *registers);
+
+int gdb_stub(struct xcptcontext * xcp)
+{
+	handle_exception((unsigned long *)xcp);
+	return 0;
+}
+#ifdef WITH_ROM_GDBSTUB
+const fp_xcpt_t dbg_func = (fp_xcpt_t)0xbfc01f00;
+#else
+const fp_xcpt_t dbg_func = (fp_xcpt_t)gdb_stub;
+#endif
 
 #define ARRAYSIZE(a)	(sizeof(a)/sizeof(a[0]))
 
@@ -48,9 +58,7 @@ void dbg_uart_isr(struct xcptcontext *xcp)
 void dbg_uart_setup()
 {
 	const int UART_INT = SYS_INT_UART1;
-	dbg_uart = (uart_if_t*)con_getInterfaceByName("UART-1")->pInst;
-	
-	*dbg_uart->pCTRL = SYS_UART_BIT_RX_INTEN;
+	*uart_if[UART_DEBUGGER].pCTRL = SYS_UART_BIT_RX_INTEN;
 	interrupt_register(UART_INT, dbg_uart_isr);
 	interrupt_enable(UART_INT);
 }
@@ -88,3 +96,26 @@ void board_init(void)
 
 	// Do some initializations here
 }
+
+void dbg_putchar(char c)
+{
+	if (c == 0x0A)
+	{
+		UART_writechar(&uart_if[UART_DEBUGGER], 0x0D);
+	}
+	UART_writechar(&uart_if[UART_DEBUGGER], c);
+}
+
+char dbg_getchar()
+{
+	int c;
+
+	// busy read
+	do
+	{
+		c = UART_readchar(&uart_if[UART_DEBUGGER]);
+		
+	} while(c < 0);
+	
+	return (char)c;
+}
diff --git a/src/libsys/boards/ml402/board.c b/src/libsys/boards/ml402/board.c
index d29d9c3..92bd132 100644
--- a/src/libsys/boards/ml402/board.c
+++ b/src/libsys/boards/ml402/board.c
@@ -11,9 +11,19 @@
 #include "../../console.h"
 #include "../../regdef.h"
 
-const fp_xcpt_t dbg_func = (fp_xcpt_t)0xbfc01f00;
-
 extern uart_if_t uart_if[];
+extern void handle_exception (unsigned long *registers);
+
+int gdb_stub(struct xcptcontext * xcp)
+{
+	handle_exception((unsigned long *)xcp);
+	return 0;
+}
+#ifdef WITH_ROM_GDBSTUB
+const fp_xcpt_t dbg_func = (fp_xcpt_t)0xbfc01f00;
+#else
+const fp_xcpt_t dbg_func = (fp_xcpt_t)gdb_stub;
+#endif
 
 #define ARRAYSIZE(a)	(sizeof(a)/sizeof(a[0]))
 
@@ -48,9 +58,7 @@ void dbg_uart_isr(struct xcptcontext *xcp)
 void dbg_uart_setup()
 {
 	const int UART_INT = SYS_INT_UART;
-	dbg_uart = (uart_if_t*)con_getInterfaceByName("UART-1")->pInst;
-	
-	*dbg_uart->pCTRL = SYS_UART_BIT_RX_INTEN;
+	*uart_if[UART_DEBUGGER].pCTRL = SYS_UART_BIT_RX_INTEN;
 	interrupt_register(UART_INT, dbg_uart_isr);
 	interrupt_enable(UART_INT);
 }
@@ -88,3 +96,26 @@ void board_init(void)
 
 	// Do some initializations here
 }
+
+void dbg_putchar(char c)
+{
+	if (c == 0x0A)
+	{
+		UART_writechar(&uart_if[UART_DEBUGGER], 0x0D);
+	}
+	UART_writechar(&uart_if[UART_DEBUGGER], c);
+}
+
+char dbg_getchar()
+{
+	int c;
+
+	// busy read
+	do
+	{
+		c = UART_readchar(&uart_if[UART_DEBUGGER]);
+		
+	} while(c < 0);
+	
+	return (char)c;
+}
diff --git a/src/libsys/gdb_stub.c b/src/libsys/gdb_stub.c
index ce90039..5f91490 100644
--- a/src/libsys/gdb_stub.c
+++ b/src/libsys/gdb_stub.c
@@ -92,8 +92,9 @@
 extern void dbg_putchar(char c);	/* write a single character      */
 extern char dbg_getchar();	/* read and return a single char */
 extern void ICACHE_invalidate_all();
-
-extern void flush_i_cache();
+extern int sputs(char const *pStr);
+extern void print_byte(char byte);
+extern void print_word(int word);
 
 void putDebugChar(char c)
 {
@@ -415,6 +416,7 @@ handle_exception (unsigned long *registers)
 	char remcomInBuffer[BUFMAX];
 	char remcomOutBuffer[BUFMAX];
 	
+	sputs("Entry\n");
 	unsigned long tt;			/* Trap type */
 	unsigned long sigval;
 	unsigned long addr;
@@ -466,6 +468,7 @@ handle_exception (unsigned long *registers)
 		switch (*ptr++)
 		{
 			case '?':
+				sputs("?\n");
 				remcomOutBuffer[0] = 'S';
 				remcomOutBuffer[1] = hexchars[sigval >> 4];
 				remcomOutBuffer[2] = hexchars[sigval & 0xf];
@@ -473,10 +476,12 @@ handle_exception (unsigned long *registers)
 				break;
 
 			case 'd':		/* toggle debug flag */
+				sputs("d\n");
 				break;
 
 			case 'g':		/* return the value of the CPU registers */
 			{
+				sputs("g\n");
 				ptr = remcomOutBuffer;
 				 /* R00 .. R31 */
 				ptr = mem2hex((char *)&registers[R00], ptr, 4*32, 0);
@@ -499,6 +504,7 @@ handle_exception (unsigned long *registers)
 
 			case 'G':	   /* set the value of the CPU registers - return OK */
 			{
+				sputs("G\n");
 				unsigned long *newsp, sr;
 				sr = registers[SR];
 
@@ -538,6 +544,7 @@ handle_exception (unsigned long *registers)
 			break;
 
 			case 'm':	  /* mAA..AA,LLLL  Read LLLL bytes at address AA..AA */
+			sputs("m\n");
 			/* Try to read %x,%x.  */
 
 			if (hexToInt(&ptr, &addr) && *ptr++ == ',' && hexToInt(&ptr, &length))
@@ -552,6 +559,7 @@ handle_exception (unsigned long *registers)
 			{
 				strcpy(remcomOutBuffer,"E01");
 			}
+			sputs("m:"); print_word(addr); sputs(",");print_word(length); sputs("\n");
 			break;
 
 			case 'M': /* MAA..AA,LLLL: Write LLLL bytes at address AA.AA return OK */
@@ -572,14 +580,17 @@ handle_exception (unsigned long *registers)
 			{
 				strcpy(remcomOutBuffer, "E02");
 			}
+			sputs("M:"); print_word(addr); sputs(",");print_word(length); sputs("\n");
 			break;
 
 			case 'c':    /* cAA..AA    Continue at address AA..AA(optional) */
 			/* try to read optional parameter, pc unchanged if no parm */
 
+			sputs("c: PC="); print_word(registers[PC]);sputs("\n");
 			if (hexToInt(&ptr, &addr))
 			{
 				registers[PC] = addr;
+				sputs("c: addr="); print_word(addr);sputs("\n");
 			}
 
 		/* Need to flush the instruction cache here, as we may have deposited a
@@ -592,6 +603,7 @@ handle_exception (unsigned long *registers)
 
 			/* kill the program */
 			case 'k' :		/* do nothing */
+				sputs("Kill\n");
 				break;
 		#if 0
 			case 't':		/* Test feature */
@@ -599,9 +611,12 @@ handle_exception (unsigned long *registers)
 		#endif
 			case 'r':		/* Reset */
 				// Perform reset
+				sputs("Reset\n");
 				break;
 		}	/* switch */
 		/* reply to the request */
 		putpacket(remcomOutBuffer);
 	}
+	sputs("Exit\n");
+
 }