diff --git a/commands/i386/gas2ack/asm86.c b/commands/i386/gas2ack/asm86.c
index 29c5b7ba9..adde7c531 100644
--- a/commands/i386/gas2ack/asm86.c
+++ b/commands/i386/gas2ack/asm86.c
@@ -75,6 +75,7 @@ int isregister(const char *name)
 		"eax", "ebx", "ecx", "edx", "esi", "edi", "ebp", "esp",
 		"cs", "ds", "es", "fs", "gs", "ss",
 		"cr0", "cr1", "cr2", "cr3", "cr4",
+		"dr0", "dr1", "dr2", "dr3", "dr6", "dr7",
 		"st",
 	};
 	int reg;
diff --git a/commands/i386/gas2ack/gas2ack.c b/commands/i386/gas2ack/gas2ack.c
index 2b6088d16..f1dfc2c5f 100644
--- a/commands/i386/gas2ack/gas2ack.c
+++ b/commands/i386/gas2ack/gas2ack.c
@@ -1,7 +1,7 @@
-/*	asmconv 1.11 - convert 80X86 assembly		Author: Kees J. Bot
+/*	asmconv 1.12 - convert 80X86 assembly		Author: Kees J. Bot
  *								24 Dec 1993
  */
-static char version[] = "1.11";
+static char version[] = "1.12";
 
 #define nil 0
 #include <stdio.h>
diff --git a/docs/UPDATING b/docs/UPDATING
index 872fe1525..31848400f 100644
--- a/docs/UPDATING
+++ b/docs/UPDATING
@@ -70,4 +70,6 @@
         The hello driver (/dev/hello) added to the distribution:
         # cd /usr/src/commands/scripts && make clean install
         # cd /dev && MAKEDEV hello
+20100318:
+        Gas2ack updates: Run 'make install' in commands/i386/gas2ack
 
diff --git a/kernel/arch/i386/Makefile b/kernel/arch/i386/Makefile
index 69eb76017..d4a10b566 100644
--- a/kernel/arch/i386/Makefile
+++ b/kernel/arch/i386/Makefile
@@ -9,7 +9,9 @@ ARCHAR=$(ARCH).a
 # by an upper level Makefile.
 
 OBJS=	arch_do_vmctl.o \
+	breakpoints.o \
 	clock.o \
+	debugreg.o \
 	do_int86.o \
 	do_iopenable.o \
 	do_readbios.o \
@@ -56,6 +58,11 @@ apic_asm.o: apic_asm.S
 	gas2ack -u $@.tmp $@.s
 	$(CC) $(CFLAGS) -c -o $@ $@.s
 
+debugreg.o: debugreg.S
+	$(CC) $(CFLAGS) -E -D__ASSEMBLY__ -o $@.tmp $<
+	gas2ack -u $@.tmp $@.s
+	$(CC) $(CFLAGS) -c -o $@ $@.s
+
 $(HEAD): mpx386.o
 	cp $< $@
 
diff --git a/kernel/arch/i386/breakpoints.c b/kernel/arch/i386/breakpoints.c
new file mode 100644
index 000000000..0e9d40785
--- /dev/null
+++ b/kernel/arch/i386/breakpoints.c
@@ -0,0 +1,60 @@
+#include "../../kernel.h"
+#include "proto.h"
+
+#include "debugreg.h"
+
+int breakpoint_set(phys_bytes linaddr, int bp, int flags)
+{
+	u32_t dr7, dr7flags;
+	
+	if (bp >= BREAKPOINT_COUNT)
+		return EINVAL;
+	
+	/* convert flags */
+	dr7flags = 0;
+	switch (flags & BREAKPOINT_FLAG_RW_MASK) {
+		case BREAKPOINT_FLAG_RW_EXEC:  dr7flags |= DR7_RW_EXEC(bp);  break;
+		case BREAKPOINT_FLAG_RW_WRITE: dr7flags |= DR7_RW_WRITE(bp); break;
+		case BREAKPOINT_FLAG_RW_RW:    dr7flags |= DR7_RW_RW(bp);    break;
+		default: return EINVAL;			
+	}
+	switch (flags & BREAKPOINT_FLAG_LEN_MASK) {
+		case BREAKPOINT_FLAG_LEN_1: dr7flags |= DR7_LN_1(bp); break;
+		case BREAKPOINT_FLAG_LEN_2: dr7flags |= DR7_LN_2(bp); break;
+		case BREAKPOINT_FLAG_LEN_4: dr7flags |= DR7_LN_4(bp); break;
+		default: return EINVAL;	
+	}
+	switch (flags & BREAKPOINT_FLAG_MODE_MASK) {
+		case BREAKPOINT_FLAG_MODE_OFF: break;
+		case BREAKPOINT_FLAG_MODE_LOCAL: dr7flags |= DR7_L(bp); break;
+		case BREAKPOINT_FLAG_MODE_GLOBAL: dr7flags |= DR7_G(bp); break;
+		default: return EINVAL;	
+	}
+	
+	/* disable breakpoint before setting address */
+	dr7 = st_dr7();
+	dr7 &= ~(DR7_L(bp) | DR7_G(bp) | DR7_RW_MASK(bp) | DR7_LN_MASK(bp));
+printf("ld_dr7(0x%x)\n",dr7);
+	ld_dr7(dr7);
+
+	/* need to set new breakpoint? */	
+	if ((flags & BREAKPOINT_FLAG_MODE_MASK) == BREAKPOINT_FLAG_MODE_OFF)
+		return 0;
+			
+	/* set breakpoint address */
+	switch (bp) {
+		case 0: ld_dr0(linaddr); break;
+		case 1: ld_dr1(linaddr); break;
+		case 2: ld_dr2(linaddr); break;
+		case 3: ld_dr3(linaddr); break;
+		default: panic(__FILE__, "invalid breakpoint index", __LINE__);
+	}
+printf("ld_dr%d(0x%x, 0x%x)\n",bp,linaddr);
+	
+	/* set new flags */
+	dr7 |= dr7flags;
+	ld_dr7(dr7);
+printf("ld_dr7(0x%x)\n",dr7);
+	return 0;
+}
+
diff --git a/kernel/arch/i386/debugreg.S b/kernel/arch/i386/debugreg.S
new file mode 100644
index 000000000..9d60c5bc0
--- /dev/null
+++ b/kernel/arch/i386/debugreg.S
@@ -0,0 +1,26 @@
+.text
+
+#define LD_ST_REG(reg)							;\
+.globl	ld_##reg							;\
+.globl	st_##reg							;\
+									;\
+ld_##reg:								;\
+	mov	4(%esp), %eax						;\
+	mov	%eax,	%reg						;\
+	ret								;\
+									;\
+st_##reg:								;\
+	mov	%reg,	%eax						;\
+	ret
+
+/*
+ * void ld_dr0(u32_t value)
+ * u32_t st_dr0(void)
+ */
+LD_ST_REG(dr0)
+LD_ST_REG(dr1)
+LD_ST_REG(dr2)
+LD_ST_REG(dr3)
+LD_ST_REG(dr6)
+LD_ST_REG(dr7)
+
diff --git a/kernel/arch/i386/debugreg.h b/kernel/arch/i386/debugreg.h
new file mode 100644
index 000000000..8590fea5a
--- /dev/null
+++ b/kernel/arch/i386/debugreg.h
@@ -0,0 +1,44 @@
+#ifndef __DEBUGREG_H__
+#define __DEBUGREG_H__
+
+/* DR6: status flags */
+#define DR6_B(bp)	(1 << (bp))	/* breakpoint was triggered */
+#define DR6_BD		(1 << 13)	/* debug register access detected */
+#define DR6_BS		(1 << 14)	/* single step */
+#define DR6_BT		(1 << 15)	/* task switch */
+
+/* DR7: control flags */
+#define	DR7_L(bp)	(1 << (2*(bp)))		/* breakpoint armed locally */
+#define	DR7_G(bp)	(1 << (1+2*(bp)))	/* breakpoint armed globally */
+#define	DR7_LE		(1 << 8)		/* exact local breakpoints */
+#define	DR7_GE		(1 << 9)		/* exact global breakpoints */
+#define	DR7_GD		(1 << 13)		/* detect debug reg movs */
+
+#define	DR7_RW_MASK(bp)		(3 << (16+4*(bp)))	
+#define	DR7_RW_EXEC(bp)		(0 << (16+4*(bp)))	/* execute */
+#define	DR7_RW_WRITE(bp)	(1 << (16+4*(bp)))	/* write */
+#define	DR7_RW_IO(bp)		(2 << (16+4*(bp)))	/* IO */
+#define	DR7_RW_RW(bp)		(3 << (16+4*(bp)))	/* read or write */
+
+#define	DR7_LN_MASK(bp)	(3 << (18+4*(bp)))
+#define	DR7_LN_1(bp)	(0 << (18+4*(bp)))	/* 1 byte */
+#define	DR7_LN_2(bp)	(1 << (18+4*(bp)))	/* 2 bytes */
+#define	DR7_LN_8(bp)	(2 << (18+4*(bp)))	/* 8 bytes */
+#define	DR7_LN_4(bp)	(3 << (18+4*(bp)))	/* 4 bytes */
+
+/* debugreg.S */
+void ld_dr0(u32_t value);
+void ld_dr1(u32_t value);
+void ld_dr2(u32_t value);
+void ld_dr3(u32_t value);
+void ld_dr6(u32_t value);
+void ld_dr7(u32_t value);
+u32_t st_dr0(void); 
+u32_t st_dr1(void); 
+u32_t st_dr2(void); 
+u32_t st_dr3(void); 
+u32_t st_dr6(void); 
+u32_t st_dr7(void); 
+
+#endif /* __DEBUGREG_H__ */
+
diff --git a/kernel/arch/i386/proto.h b/kernel/arch/i386/proto.h
index b6f00631c..5e7c55f3d 100644
--- a/kernel/arch/i386/proto.h
+++ b/kernel/arch/i386/proto.h
@@ -156,6 +156,23 @@ _PROTOTYPE(void __copy_msg_from_user_end, (void));
 _PROTOTYPE(void __copy_msg_to_user_end, (void));
 _PROTOTYPE(void __user_copy_msg_pointer_failure, (void));
 
+/* breakpoints.c */
+#define BREAKPOINT_COUNT		4
+#define BREAKPOINT_FLAG_RW_MASK		(3 << 0)
+#define BREAKPOINT_FLAG_RW_EXEC		(0 << 0)
+#define BREAKPOINT_FLAG_RW_WRITE	(1 << 0)
+#define BREAKPOINT_FLAG_RW_RW		(2 << 0)
+#define BREAKPOINT_FLAG_LEN_MASK	(3 << 2)
+#define BREAKPOINT_FLAG_LEN_1		(0 << 2)
+#define BREAKPOINT_FLAG_LEN_2		(1 << 2)
+#define BREAKPOINT_FLAG_LEN_4		(2 << 2)
+#define BREAKPOINT_FLAG_MODE_MASK	(3 << 4)
+#define BREAKPOINT_FLAG_MODE_OFF	(0 << 4)
+#define BREAKPOINT_FLAG_MODE_LOCAL	(1 << 4)
+#define BREAKPOINT_FLAG_MODE_GLOBAL	(2 << 4)
+
+_PROTOTYPE(int breakpoint_set, (phys_bytes linaddr, int index, int flags));
+
 /* functions defined in architecture-independent kernel source. */
 #include "../../proto.h"