Initial import, 0.1 + pk 0.2.4-B1

24 files changed, 5106 insertions, 0 deletions

diff --git a/sys/ddb/db_access.c b/sys/ddb/db_access.c
new file mode 100644
index 000000000000..63368c0cbc0c
--- /dev/null
+++ b/sys/ddb/db_access.c
@@ -0,0 +1,116 @@
+/* 
+ * Mach Operating System
+ * Copyright (c) 1991,1990 Carnegie Mellon University
+ * All Rights Reserved.
+ * 
+ * Permission to use, copy, modify and distribute this software and its
+ * documentation is hereby granted, provided that both the copyright
+ * notice and this permission notice appear in all copies of the
+ * software, derivative works or modified versions, and any portions
+ * thereof, and that both notices appear in supporting documentation.
+ * 
+ * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS 
+ * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
+ * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ * 
+ * Carnegie Mellon requests users of this software to return to
+ * 
+ *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
+ *  School of Computer Science
+ *  Carnegie Mellon University
+ *  Pittsburgh PA 15213-3890
+ * 
+ * any improvements or extensions that they make and grant Carnegie the
+ * rights to redistribute these changes.
+ */
+/*
+ * HISTORY
+ * $Log: db_access.c,v $
+ * Revision 1.1  1992/03/25  21:44:50  pace
+ * Initial revision
+ *
+ * Revision 2.3  91/02/05  17:05:44  mrt
+ * 	Changed to new Mach copyright
+ * 	[91/01/31  16:16:22  mrt]
+ * 
+ * Revision 2.2  90/08/27  21:48:20  dbg
+ * 	Fix type declarations.
+ * 	[90/08/07            dbg]
+ * 	Created.
+ * 	[90/07/25            dbg]
+ * 
+ */
+/*
+ *	Author: David B. Golub, Carnegie Mellon University
+ *	Date:	7/90
+ */
+#include "param.h"
+#include "proc.h"
+#include <machine/db_machdep.h>		/* type definitions */
+
+/*
+ * Access unaligned data items on aligned (longword)
+ * boundaries.
+ */
+
+extern void	db_read_bytes();	/* machine-dependent */
+extern void	db_write_bytes();	/* machine-dependent */
+
+int db_extend[] = {	/* table for sign-extending */
+	0,
+	0xFFFFFF80,
+	0xFFFF8000,
+	0xFF800000
+};
+
+db_expr_t
+db_get_value(addr, size, is_signed)
+	db_addr_t	addr;
+	register int	size;
+	boolean_t	is_signed;
+{
+	char		data[sizeof(int)];
+	register db_expr_t value;
+	register int	i;
+
+	db_read_bytes(addr, size, data);
+
+	value = 0;
+#if	BYTE_MSF
+	for (i = 0; i < size; i++)
+#else	/* BYTE_LSF */
+	for (i = size - 1; i >= 0; i--)
+#endif
+	{
+	    value = (value << 8) + (data[i] & 0xFF);
+	}
+	    
+	if (size < 4) {
+	    if (is_signed && (value & db_extend[size]) != 0)
+		value |= db_extend[size];
+	}
+	return (value);
+}
+
+void
+db_put_value(addr, size, value)
+	db_addr_t	addr;
+	register int	size;
+	register db_expr_t value;
+{
+	char		data[sizeof(int)];
+	register int	i;
+
+#if	BYTE_MSF
+	for (i = size - 1; i >= 0; i--)
+#else	/* BYTE_LSF */
+	for (i = 0; i < size; i++)
+#endif
+	{
+	    data[i] = value & 0xFF;
+	    value >>= 8;
+	}
+
+	db_write_bytes(addr, size, data);
+}
+
diff --git a/sys/ddb/db_access.h b/sys/ddb/db_access.h
new file mode 100644
index 000000000000..ddc5349148fa
--- /dev/null
+++ b/sys/ddb/db_access.h
@@ -0,0 +1,55 @@
+/* 
+ * Mach Operating System
+ * Copyright (c) 1991,1990 Carnegie Mellon University
+ * All Rights Reserved.
+ * 
+ * Permission to use, copy, modify and distribute this software and its
+ * documentation is hereby granted, provided that both the copyright
+ * notice and this permission notice appear in all copies of the
+ * software, derivative works or modified versions, and any portions
+ * thereof, and that both notices appear in supporting documentation.
+ * 
+ * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS 
+ * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
+ * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ * 
+ * Carnegie Mellon requests users of this software to return to
+ * 
+ *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
+ *  School of Computer Science
+ *  Carnegie Mellon University
+ *  Pittsburgh PA 15213-3890
+ * 
+ * any improvements or extensions that they make and grant Carnegie the
+ * rights to redistribute these changes.
+ */
+/*
+ * HISTORY
+ * $Log: db_access.h,v $
+ * Revision 1.1  1992/03/25  21:44:53  pace
+ * Initial revision
+ *
+ * Revision 2.3  91/02/05  17:05:49  mrt
+ * 	Changed to new Mach copyright
+ * 	[91/01/31  16:16:37  mrt]
+ * 
+ * Revision 2.2  90/08/27  21:48:27  dbg
+ * 	Created.
+ * 	[90/08/07            dbg]
+ * 
+ */
+/*
+ *	Author: David B. Golub, Carnegie Mellon University
+ *	Date:	7/90
+ */
+/*
+ * Data access functions for debugger.
+ */
+#include <machine/db_machdep.h>		/* expression types */
+
+extern db_expr_t db_get_value(/* db_addr_t addr,
+				 int size,
+				 boolean_t is_signed */);
+extern void	 db_put_value(/* db_addr_t addr,
+				 int size,
+				 db_expr_t value */);
diff --git a/sys/ddb/db_aout.c b/sys/ddb/db_aout.c
new file mode 100644
index 000000000000..88f4b03e1858
--- /dev/null
+++ b/sys/ddb/db_aout.c
@@ -0,0 +1,309 @@
+/* 
+ * Mach Operating System
+ * Copyright (c) 1991,1990 Carnegie Mellon University
+ * All Rights Reserved.
+ * 
+ * Permission to use, copy, modify and distribute this software and its
+ * documentation is hereby granted, provided that both the copyright
+ * notice and this permission notice appear in all copies of the
+ * software, derivative works or modified versions, and any portions
+ * thereof, and that both notices appear in supporting documentation.
+ * 
+ * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS 
+ * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
+ * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ * 
+ * Carnegie Mellon requests users of this software to return to
+ * 
+ *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
+ *  School of Computer Science
+ *  Carnegie Mellon University
+ *  Pittsburgh PA 15213-3890
+ * 
+ * any improvements or extensions that they make and grant Carnegie the
+ * rights to redistribute these changes.
+ */
+/*
+ * HISTORY
+ * $Log: db_aout.c,v $
+ * Revision 1.1  1992/03/25  21:44:55  pace
+ * Initial revision
+ *
+ * Revision 2.3  91/02/05  17:05:55  mrt
+ * 	Changed to new Mach copyright
+ * 	[91/01/31  16:16:44  mrt]
+ * 
+ * Revision 2.2  90/08/27  21:48:35  dbg
+ * 	Created.
+ * 	[90/08/17            dbg]
+ * 
+ */
+/*
+ *	Author: David B. Golub, Carnegie Mellon University
+ *	Date:	7/90
+ */
+/*
+ * Symbol table routines for a.out format files.
+ */
+
+#include "param.h"
+#include "proc.h"
+#include <machine/db_machdep.h>		/* data types */
+#include <ddb/db_sym.h>
+
+#ifndef	DB_NO_AOUT
+
+#define _AOUT_INCLUDE_
+#include "nlist.h"
+
+/*
+ * An a.out symbol table as loaded into the kernel debugger:
+ *
+ * symtab	-> size of symbol entries, in bytes
+ * sp		-> first symbol entry
+ *		   ...
+ * ep		-> last symbol entry + 1
+ * strtab	== start of string table
+ *		   size of string table in bytes,
+ *		   including this word
+ *		-> strings
+ */
+
+/*
+ * Find pointers to the start and end of the symbol entries,
+ * given a pointer to the start of the symbol table.
+ */
+#define	db_get_aout_symtab(symtab, sp, ep) \
+	(sp = (struct nlist *)((symtab) + 1), \
+	 ep = (struct nlist *)((char *)sp + *(symtab)))
+
+#define SYMTAB_SPACE 63000
+int db_symtabsize = SYMTAB_SPACE;
+char db_symtab[SYMTAB_SPACE] = { 1 };
+
+X_db_sym_init(symtab, esymtab, name)
+	int *	symtab;		/* pointer to start of symbol table */
+	char *	esymtab;	/* pointer to end of string table,
+				   for checking - rounded up to integer
+				   boundary */
+	char *	name;
+{
+	register struct nlist	*sym_start, *sym_end;
+	register struct nlist	*sp;
+	register char *	strtab;
+	register int	strlen;
+
+	if (*symtab < 4) {
+		printf ("DDB: no symbols\n");
+		return;
+	}
+
+	db_get_aout_symtab(symtab, sym_start, sym_end);
+
+	strtab = (char *)sym_end;
+	strlen = *(int *)strtab;
+
+#if 0
+	if (strtab + ((strlen + sizeof(int) - 1) & ~(sizeof(int)-1))
+	    != esymtab)
+	{
+	    db_printf("[ %s symbol table not valid ]\n", name);
+	    return;
+	}
+
+	db_printf("[ preserving %#x bytes of %s symbol table ]\n",
+		esymtab - (char *)symtab, name);
+#endif
+
+	for (sp = sym_start; sp < sym_end; sp++) {
+	    register int strx;
+	    strx = sp->n_un.n_strx;
+	    if (strx != 0) {
+		if (strx > strlen) {
+		    db_printf("Bad string table index (%#x)\n", strx);
+		    sp->n_un.n_name = 0;
+		    continue;
+		}
+		sp->n_un.n_name = strtab + strx;
+	    }
+	}
+
+	db_add_symbol_table(sym_start, sym_end, name, (char *)symtab);
+}
+
+db_sym_t
+X_db_lookup(stab, symstr)
+	db_symtab_t	*stab;
+	char *		symstr;
+{
+	register struct nlist *sp, *ep;
+
+	sp = (struct nlist *)stab->start;
+	ep = (struct nlist *)stab->end;
+
+	for (; sp < ep; sp++) {
+	    if (sp->n_un.n_name == 0)
+		continue;
+	    if ((sp->n_type & N_STAB) == 0 &&
+		sp->n_un.n_name != 0 &&
+		db_eqname(sp->n_un.n_name, symstr, '_'))
+	    {
+		return ((db_sym_t)sp);
+	    }
+	}
+	return ((db_sym_t)0);
+}
+
+db_sym_t
+X_db_search_symbol(symtab, off, strategy, diffp)
+	db_symtab_t *	symtab;
+	register
+	db_addr_t	off;
+	db_strategy_t	strategy;
+	db_expr_t	*diffp;		/* in/out */
+{
+	register unsigned int	diff = *diffp;
+	register struct nlist	*symp = 0;
+	register struct nlist	*sp, *ep;
+
+	sp = (struct nlist *)symtab->start;
+	ep = (struct nlist *)symtab->end;
+
+	for (; sp < ep; sp++) {
+	    if (sp->n_un.n_name == 0)
+		continue;
+	    if ((sp->n_type & N_STAB) != 0)
+		continue;
+	    if (off >= sp->n_value) {
+		if (off - sp->n_value < diff) {
+		    diff = off - sp->n_value;
+		    symp = sp;
+		    if (diff == 0)
+			break;
+		}
+		else if (off - sp->n_value == diff) {
+		    if (symp == 0)
+			symp = sp;
+		    else if ((symp->n_type & N_EXT) == 0 &&
+				(sp->n_type & N_EXT) != 0)
+			symp = sp;	/* pick the external symbol */
+		}
+	    }
+	}
+	if (symp == 0) {
+	    *diffp = off;
+	}
+	else {
+	    *diffp = diff;
+	}
+	return ((db_sym_t)symp);
+}
+
+/*
+ * Return the name and value for a symbol.
+ */
+void
+X_db_symbol_values(sym, namep, valuep)
+	db_sym_t	sym;
+	char		**namep;
+	db_expr_t	*valuep;
+{
+	register struct nlist *sp;
+
+	sp = (struct nlist *)sym;
+	if (namep)
+	    *namep = sp->n_un.n_name;
+	if (valuep)
+	    *valuep = sp->n_value;
+}
+
+boolean_t
+X_db_line_at_pc()
+{
+	return (FALSE);
+}
+
+/*
+ * Initialization routine for a.out files.
+ */
+kdb_init()
+{
+#if 0
+	extern char	*esym;
+	extern int	end;
+
+	if (esym > (char *)&end) {
+	    X_db_sym_init((int *)&end, esym, "mach");
+	}
+#endif
+
+	X_db_sym_init (db_symtab, 0, "mach");
+}
+
+#if 0
+/*
+ * Read symbol table from file.
+ * (should be somewhere else)
+ */
+#include <boot_ufs/file_io.h>
+#include <vm/vm_kern.h>
+
+read_symtab_from_file(fp, symtab_name)
+	struct file	*fp;
+	char *		symtab_name;
+{
+	vm_size_t	resid;
+	kern_return_t	result;
+	vm_offset_t	symoff;
+	vm_size_t	symsize;
+	vm_offset_t	stroff;
+	vm_size_t	strsize;
+	vm_size_t	table_size;
+	vm_offset_t	symtab;
+
+	if (!get_symtab(fp, &symoff, &symsize)) {
+	    boot_printf("[ error %d reading %s file header ]\n",
+			result, symtab_name);
+	    return;
+	}
+
+	stroff = symoff + symsize;
+	result = read_file(fp, (vm_offset_t)stroff,
+			(vm_offset_t)&strsize, sizeof(strsize), &resid);
+	if (result || resid) {
+	    boot_printf("[ no valid symbol table present for %s ]\n",
+		symtab_name);
+		return;
+	}
+
+	table_size = sizeof(int) + symsize + strsize;
+	table_size = (table_size + sizeof(int)-1) & ~(sizeof(int)-1);
+
+	symtab = kmem_alloc_wired(kernel_map, table_size);
+
+	*(int *)symtab = symsize;
+
+	result = read_file(fp, symoff,
+			symtab + sizeof(int), symsize, &resid);
+	if (result || resid) {
+	    boot_printf("[ error %d reading %s symbol table ]\n",
+			result, symtab_name);
+	    return;
+	}
+
+	result = read_file(fp, stroff,
+			symtab + sizeof(int) + symsize, strsize, &resid);
+	if (result || resid) {
+	    boot_printf("[ error %d reading %s string table ]\n",
+			result, symtab_name);
+	    return;
+	}
+
+	X_db_sym_init((int *)symtab,
+			(char *)(symtab + table_size),
+			symtab_name);
+	
+}
+#endif
+
+#endif	/* DB_NO_AOUT */
diff --git a/sys/ddb/db_break.c b/sys/ddb/db_break.c
new file mode 100644
index 000000000000..9db7a041a111
--- /dev/null
+++ b/sys/ddb/db_break.c
@@ -0,0 +1,387 @@
+/* 
+ * Mach Operating System
+ * Copyright (c) 1991,1990 Carnegie Mellon University
+ * All Rights Reserved.
+ * 
+ * Permission to use, copy, modify and distribute this software and its
+ * documentation is hereby granted, provided that both the copyright
+ * notice and this permission notice appear in all copies of the
+ * software, derivative works or modified versions, and any portions
+ * thereof, and that both notices appear in supporting documentation.
+ * 
+ * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS 
+ * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
+ * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ * 
+ * Carnegie Mellon requests users of this software to return to
+ * 
+ *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
+ *  School of Computer Science
+ *  Carnegie Mellon University
+ *  Pittsburgh PA 15213-3890
+ * 
+ * any improvements or extensions that they make and grant Carnegie the
+ * rights to redistribute these changes.
+ */
+/*
+ * HISTORY
+ * $Log: db_break.c,v $
+ * Revision 1.1  1992/03/25  21:44:57  pace
+ * Initial revision
+ *
+ * Revision 2.7  91/02/05  17:06:00  mrt
+ * 	Changed to new Mach copyright
+ * 	[91/01/31  16:17:01  mrt]
+ * 
+ * Revision 2.6  91/01/08  15:09:03  rpd
+ * 	Added db_map_equal, db_map_current, db_map_addr.
+ * 	[90/11/10            rpd]
+ * 
+ * Revision 2.5  90/11/05  14:26:32  rpd
+ * 	Initialize db_breakpoints_inserted to TRUE.
+ * 	[90/11/04            rpd]
+ * 
+ * Revision 2.4  90/10/25  14:43:33  rwd
+ * 	Added map field to breakpoints.
+ * 	Added map argument to db_set_breakpoint, db_delete_breakpoint,
+ * 	db_find_breakpoint.  Added db_find_breakpoint_here.
+ * 	[90/10/18            rpd]
+ * 
+ * Revision 2.3  90/09/28  16:57:07  jsb
+ * 	Fixed db_breakpoint_free.
+ * 	[90/09/18            rpd]
+ * 
+ * Revision 2.2  90/08/27  21:49:53  dbg
+ * 	Reflected changes in db_printsym()'s calling seq.
+ * 	[90/08/20            af]
+ * 	Clear breakpoints only if inserted.
+ * 	Reduce lint.
+ * 	[90/08/07            dbg]
+ * 	Created.
+ * 	[90/07/25            dbg]
+ * 
+ */
+/*
+ *	Author: David B. Golub, Carnegie Mellon University
+ *	Date:	7/90
+ */
+/*
+ * Breakpoints.
+ */
+#include "param.h"
+#include "proc.h"
+#include <machine/db_machdep.h>		/* type definitions */
+
+#include <ddb/db_lex.h>
+#include <ddb/db_break.h>
+#include <ddb/db_access.h>
+#include <ddb/db_sym.h>
+#include <ddb/db_break.h>
+
+extern boolean_t db_map_equal();
+extern boolean_t db_map_current();
+extern vm_map_t db_map_addr();
+
+#define	NBREAKPOINTS	100
+struct db_breakpoint	db_break_table[NBREAKPOINTS];
+db_breakpoint_t		db_next_free_breakpoint = &db_break_table[0];
+db_breakpoint_t		db_free_breakpoints = 0;
+db_breakpoint_t		db_breakpoint_list = 0;
+
+db_breakpoint_t
+db_breakpoint_alloc()
+{
+	register db_breakpoint_t	bkpt;
+
+	if ((bkpt = db_free_breakpoints) != 0) {
+	    db_free_breakpoints = bkpt->link;
+	    return (bkpt);
+	}
+	if (db_next_free_breakpoint == &db_break_table[NBREAKPOINTS]) {
+	    db_printf("All breakpoints used.\n");
+	    return (0);
+	}
+	bkpt = db_next_free_breakpoint;
+	db_next_free_breakpoint++;
+
+	return (bkpt);
+}
+
+void
+db_breakpoint_free(bkpt)
+	register db_breakpoint_t	bkpt;
+{
+	bkpt->link = db_free_breakpoints;
+	db_free_breakpoints = bkpt;
+}
+
+void
+db_set_breakpoint(map, addr, count)
+	vm_map_t	map;
+	db_addr_t	addr;
+	int		count;
+{
+	register db_breakpoint_t	bkpt;
+
+	if (db_find_breakpoint(map, addr)) {
+	    db_printf("Already set.\n");
+	    return;
+	}
+
+	bkpt = db_breakpoint_alloc();
+	if (bkpt == 0) {
+	    db_printf("Too many breakpoints.\n");
+	    return;
+	}
+
+	bkpt->map = map;
+	bkpt->address = addr;
+	bkpt->flags = 0;
+	bkpt->init_count = count;
+	bkpt->count = count;
+
+	bkpt->link = db_breakpoint_list;
+	db_breakpoint_list = bkpt;
+}
+
+void
+db_delete_breakpoint(map, addr)
+	vm_map_t	map;
+	db_addr_t	addr;
+{
+	register db_breakpoint_t	bkpt;
+	register db_breakpoint_t	*prev;
+
+	for (prev = &db_breakpoint_list;
+	     (bkpt = *prev) != 0;
+	     prev = &bkpt->link) {
+	    if (db_map_equal(bkpt->map, map) &&
+		(bkpt->address == addr)) {
+		*prev = bkpt->link;
+		break;
+	    }
+	}
+	if (bkpt == 0) {
+	    db_printf("Not set.\n");
+	    return;
+	}
+
+	db_breakpoint_free(bkpt);
+}
+
+db_breakpoint_t
+db_find_breakpoint(map, addr)
+	vm_map_t	map;
+	db_addr_t	addr;
+{
+	register db_breakpoint_t	bkpt;
+
+	for (bkpt = db_breakpoint_list;
+	     bkpt != 0;
+	     bkpt = bkpt->link)
+	{
+	    if (db_map_equal(bkpt->map, map) &&
+		(bkpt->address == addr))
+		return (bkpt);
+	}
+	return (0);
+}
+
+db_breakpoint_t
+db_find_breakpoint_here(addr)
+	db_addr_t	addr;
+{
+    return db_find_breakpoint(db_map_addr(addr), addr);
+}
+
+boolean_t	db_breakpoints_inserted = TRUE;
+
+void
+db_set_breakpoints()
+{
+	register db_breakpoint_t	bkpt;
+
+	if (!db_breakpoints_inserted) {
+
+	    for (bkpt = db_breakpoint_list;
+	         bkpt != 0;
+	         bkpt = bkpt->link)
+		if (db_map_current(bkpt->map)) {
+		    bkpt->bkpt_inst = db_get_value(bkpt->address,
+						   BKPT_SIZE,
+						   FALSE);
+		    db_put_value(bkpt->address,
+				 BKPT_SIZE,
+				 BKPT_SET(bkpt->bkpt_inst));
+		}
+	    db_breakpoints_inserted = TRUE;
+	}
+}
+
+void
+db_clear_breakpoints()
+{
+	register db_breakpoint_t	bkpt;
+
+	if (db_breakpoints_inserted) {
+
+	    for (bkpt = db_breakpoint_list;
+	         bkpt != 0;
+		 bkpt = bkpt->link)
+		if (db_map_current(bkpt->map)) {
+		    db_put_value(bkpt->address, BKPT_SIZE, bkpt->bkpt_inst);
+		}
+	    db_breakpoints_inserted = FALSE;
+	}
+}
+
+/*
+ * Set a temporary breakpoint.
+ * The instruction is changed immediately,
+ * so the breakpoint does not have to be on the breakpoint list.
+ */
+db_breakpoint_t
+db_set_temp_breakpoint(addr)
+	db_addr_t	addr;
+{
+	register db_breakpoint_t	bkpt;
+
+	bkpt = db_breakpoint_alloc();
+	if (bkpt == 0) {
+	    db_printf("Too many breakpoints.\n");
+	    return 0;
+	}
+
+	bkpt->map = NULL;
+	bkpt->address = addr;
+	bkpt->flags = BKPT_TEMP;
+	bkpt->init_count = 1;
+	bkpt->count = 1;
+
+	bkpt->bkpt_inst = db_get_value(bkpt->address, BKPT_SIZE, FALSE);
+	db_put_value(bkpt->address, BKPT_SIZE, BKPT_SET(bkpt->bkpt_inst));
+	return bkpt;
+}
+
+void
+db_delete_temp_breakpoint(bkpt)
+	db_breakpoint_t	bkpt;
+{
+	db_put_value(bkpt->address, BKPT_SIZE, bkpt->bkpt_inst);
+	db_breakpoint_free(bkpt);
+}
+
+/*
+ * List breakpoints.
+ */
+void
+db_list_breakpoints()
+{
+	register db_breakpoint_t	bkpt;
+
+	if (db_breakpoint_list == 0) {
+	    db_printf("No breakpoints set\n");
+	    return;
+	}
+
+	db_printf(" Map      Count    Address\n");
+	for (bkpt = db_breakpoint_list;
+	     bkpt != 0;
+	     bkpt = bkpt->link)
+	{
+	    db_printf("%s%8x %5d    ",
+		      db_map_current(bkpt->map) ? "*" : " ",
+		      bkpt->map, bkpt->init_count);
+	    db_printsym(bkpt->address, DB_STGY_PROC);
+	    db_printf("\n");
+	}
+}
+
+/* Delete breakpoint */
+/*ARGSUSED*/
+void
+db_delete_cmd(addr, have_addr, count, modif)
+	db_expr_t	addr;
+	int		have_addr;
+	db_expr_t	count;
+	char *		modif;
+{
+	db_delete_breakpoint(db_map_addr(addr), (db_addr_t)addr);
+}
+
+/* Set breakpoint with skip count */
+/*ARGSUSED*/
+void
+db_breakpoint_cmd(addr, have_addr, count, modif)
+	db_expr_t	addr;
+	int		have_addr;
+	db_expr_t	count;
+	char *		modif;
+{
+	if (count == -1)
+	    count = 1;
+
+	db_set_breakpoint(db_map_addr(addr), (db_addr_t)addr, count);
+}
+
+/* list breakpoints */
+void
+db_listbreak_cmd()
+{
+	db_list_breakpoints();
+}
+
+#include <vm/vm_kern.h>
+
+/*
+ *	We want ddb to be usable before most of the kernel has been
+ *	initialized.  In particular, current_thread() or kernel_map
+ *	(or both) may be null.
+ */
+
+boolean_t
+db_map_equal(map1, map2)
+	vm_map_t	map1, map2;
+{
+	return ((map1 == map2) ||
+		((map1 == NULL) && (map2 == kernel_map)) ||
+		((map1 == kernel_map) && (map2 == NULL)));
+}
+
+boolean_t
+db_map_current(map)
+	vm_map_t	map;
+{
+#if 0
+	thread_t	thread;
+
+	return ((map == NULL) ||
+		(map == kernel_map) ||
+		(((thread = current_thread()) != NULL) &&
+		 (map == thread->task->map)));
+#else
+	return (1);
+#endif
+}
+
+vm_map_t
+db_map_addr(addr)
+	vm_offset_t addr;
+{
+#if 0
+	thread_t	thread;
+
+	/*
+	 *	We want to return kernel_map for all
+	 *	non-user addresses, even when debugging
+	 *	kernel tasks with their own maps.
+	 */
+
+	if ((VM_MIN_ADDRESS <= addr) &&
+	    (addr < VM_MAX_ADDRESS) &&
+	    ((thread = current_thread()) != NULL))
+	    return thread->task->map;
+	else
+#endif
+	    return kernel_map;
+}
diff --git a/sys/ddb/db_break.h b/sys/ddb/db_break.h
new file mode 100644
index 000000000000..874cbcb5c349
--- /dev/null
+++ b/sys/ddb/db_break.h
@@ -0,0 +1,84 @@
+/* 
+ * Mach Operating System
+ * Copyright (c) 1991,1990 Carnegie Mellon University
+ * All Rights Reserved.
+ * 
+ * Permission to use, copy, modify and distribute this software and its
+ * documentation is hereby granted, provided that both the copyright
+ * notice and this permission notice appear in all copies of the
+ * software, derivative works or modified versions, and any portions
+ * thereof, and that both notices appear in supporting documentation.
+ * 
+ * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS 
+ * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
+ * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ * 
+ * Carnegie Mellon requests users of this software to return to
+ * 
+ *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
+ *  School of Computer Science
+ *  Carnegie Mellon University
+ *  Pittsburgh PA 15213-3890
+ * 
+ * any improvements or extensions that they make and grant Carnegie the
+ * rights to redistribute these changes.
+ */
+/*
+ * HISTORY
+ * $Log: db_break.h,v $
+ * Revision 1.1  1992/03/25  21:44:59  pace
+ * Initial revision
+ *
+ * Revision 2.4  91/02/05  17:06:06  mrt
+ * 	Changed to new Mach copyright
+ * 	[91/01/31  16:17:10  mrt]
+ * 
+ * Revision 2.3  90/10/25  14:43:40  rwd
+ * 	Added map field to breakpoints.
+ * 	[90/10/18            rpd]
+ * 
+ * Revision 2.2  90/08/27  21:50:00  dbg
+ * 	Modularized typedef names.
+ * 	[90/08/20            af]
+ * 	Add external defintions.
+ * 	[90/08/07            dbg]
+ * 	Created.
+ * 	[90/07/25            dbg]
+ * 
+ */
+/*
+ *	Author: David B. Golub, Carnegie Mellon University
+ *	Date:	7/90
+ */
+#ifndef	_DDB_DB_BREAK_H_
+#define	_DDB_DB_BREAK_H_
+
+#include <vm/vm_map.h>
+#include <machine/db_machdep.h>
+
+/*
+ * Breakpoint.
+ */
+
+struct db_breakpoint {
+	vm_map_t map;			/* in this map */
+	db_addr_t address;		/* set here */
+	int	init_count;		/* number of times to skip bkpt */
+	int	count;			/* current count */
+	int	flags;			/* flags: */
+#define	BKPT_SINGLE_STEP	0x2	    /* to simulate single step */
+#define	BKPT_TEMP		0x4	    /* temporary */
+	int	bkpt_inst;		/* saved instruction at bkpt */
+	struct db_breakpoint *link;	/* link in in-use or free chain */
+};
+typedef struct db_breakpoint *db_breakpoint_t;
+
+extern db_breakpoint_t	db_find_breakpoint();
+extern db_breakpoint_t	db_find_breakpoint_here();
+extern void		db_set_breakpoints();
+extern void		db_clear_breakpoints();
+
+extern db_breakpoint_t	db_set_temp_breakpoint(/* db_addr_t addr */);
+extern void		db_delete_temp_breakpoint(/* db_breakpoint_t bkpt */);
+
+#endif	_DDB_DB_BREAK_H_
diff --git a/sys/ddb/db_command.c b/sys/ddb/db_command.c
new file mode 100644
index 000000000000..e660e183bd05
--- /dev/null
+++ b/sys/ddb/db_command.c
@@ -0,0 +1,526 @@
+/* 
+ * Mach Operating System
+ * Copyright (c) 1991,1990 Carnegie Mellon University
+ * All Rights Reserved.
+ * 
+ * Permission to use, copy, modify and distribute this software and its
+ * documentation is hereby granted, provided that both the copyright
+ * notice and this permission notice appear in all copies of the
+ * software, derivative works or modified versions, and any portions
+ * thereof, and that both notices appear in supporting documentation.
+ * 
+ * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS 
+ * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
+ * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ * 
+ * Carnegie Mellon requests users of this software to return to
+ * 
+ *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
+ *  School of Computer Science
+ *  Carnegie Mellon University
+ *  Pittsburgh PA 15213-3890
+ * 
+ * any improvements or extensions that they make and grant Carnegie the
+ * rights to redistribute these changes.
+ */
+/*
+ * HISTORY
+ * $Log: db_command.c,v $
+ *
+ * PATCHES MAGIC                LEVEL   PATCH THAT GOT US HERE
+ * --------------------         -----   ----------------------
+ * CURRENT PATCH LEVEL:         1       00081
+ * --------------------         -----   ----------------------
+ *
+ * 01 Feb 93	Julian Elischer		move strcmp to a more general
+ *					part of the kernel.
+ *
+ * Revision 1.1  1992/03/25  21:45:02  pace
+ * Initial revision
+ *
+ * Revision 2.6  91/02/05  17:06:10  mrt
+ * 	Changed to new Mach copyright
+ * 	[91/01/31  16:17:18  mrt]
+ * 
+ * Revision 2.5  91/01/08  17:31:54  rpd
+ * 	Forward reference for db_fncall();
+ * 	[91/01/04  12:35:17  rvb]
+ * 
+ * 	Add call as a synonym for ! and match for next
+ * 	[91/01/04  12:14:48  rvb]
+ * 
+ * Revision 2.4  90/11/07  16:49:15  rpd
+ * 	Added search.
+ * 	[90/11/06            rpd]
+ * 
+ * Revision 2.3  90/10/25  14:43:45  rwd
+ * 	Changed db_fncall to print the result unsigned.
+ * 	[90/10/19            rpd]
+ * 
+ * 	Added CS_MORE to db_watchpoint_cmd.
+ * 	[90/10/17            rpd]
+ * 	Added watchpoint commands: watch, dwatch, show watches.
+ * 	[90/10/16            rpd]
+ * 
+ * Revision 2.2  90/08/27  21:50:10  dbg
+ * 	Remove 'listbreaks' - use 'show breaks' instead.  Change 'show
+ * 	threads' to 'show all threads' to avoid clash with 'show thread'.
+ * 	Set 'dot' here from db_prev or db_next, depending on 'db_ed_style'
+ * 	flag and syntax table.
+ * 	[90/08/22            dbg]
+ * 	Reduce lint.
+ * 	[90/08/07            dbg]
+ * 	Created.
+ * 	[90/07/25            dbg]
+ * 
+ */
+/*
+ *	Author: David B. Golub, Carnegie Mellon University
+ *	Date:	7/90
+ */
+/*
+ * Command dispatcher.
+ */
+#include "param.h"
+#include "proc.h"
+#include <machine/db_machdep.h>		/* type definitions */
+
+#include <ddb/db_lex.h>
+#include <ddb/db_output.h>
+
+#include <setjmp.h>
+
+/*
+ * Exported global variables
+ */
+boolean_t	db_cmd_loop_done;
+jmp_buf		db_jmpbuf;
+db_addr_t	db_dot;
+db_addr_t	db_last_addr;
+db_addr_t	db_prev;
+db_addr_t	db_next;
+
+/*
+ * if 'ed' style: 'dot' is set at start of last item printed,
+ * and '+' points to next line.
+ * Otherwise: 'dot' points to next item, '..' points to last.
+ */
+boolean_t	db_ed_style = TRUE;
+
+
+/*
+ * Utility routine - discard tokens through end-of-line.
+ */
+void
+db_skip_to_eol()
+{
+	int	t;
+	do {
+	    t = db_read_token();
+	} while (t != tEOL);
+}
+
+/*
+ * Command table
+ */
+struct command {
+	char *	name;		/* command name */
+	void	(*fcn)();	/* function to call */
+	int	flag;		/* extra info: */
+#define	CS_OWN		0x1	    /* non-standard syntax */
+#define	CS_MORE		0x2	    /* standard syntax, but may have other
+				       words at end */
+#define	CS_SET_DOT	0x100	    /* set dot after command */
+	struct command *more;	/* another level of command */
+};
+
+/*
+ * Results of command search.
+ */
+#define	CMD_UNIQUE	0
+#define	CMD_FOUND	1
+#define	CMD_NONE	2
+#define	CMD_AMBIGUOUS	3
+#define	CMD_HELP	4
+
+/*
+ * Search for command prefix.
+ */
+int
+db_cmd_search(name, table, cmdp)
+	char *		name;
+	struct command	*table;
+	struct command	**cmdp;	/* out */
+{
+	struct command	*cmd;
+	int		result = CMD_NONE;
+
+	for (cmd = table; cmd->name != 0; cmd++) {
+	    register char *lp;
+	    register char *rp;
+	    register int  c;
+
+	    lp = name;
+	    rp = cmd->name;
+	    while ((c = *lp) == *rp) {
+		if (c == 0) {
+		    /* complete match */
+		    *cmdp = cmd;
+		    return (CMD_UNIQUE);
+		}
+		lp++;
+		rp++;
+	    }
+	    if (c == 0) {
+		/* end of name, not end of command -
+		   partial match */
+		if (result == CMD_FOUND) {
+		    result = CMD_AMBIGUOUS;
+		    /* but keep looking for a full match -
+		       this lets us match single letters */
+		}
+		else {
+		    *cmdp = cmd;
+		    result = CMD_FOUND;
+		}
+	    }
+	}
+	if (result == CMD_NONE) {
+	    /* check for 'help' */
+		if (name[0] == 'h' && name[1] == 'e'
+		    && name[2] == 'l' && name[3] == 'p')
+			result = CMD_HELP;
+	}
+	return (result);
+}
+
+void
+db_cmd_list(table)
+	struct command *table;
+{
+	register struct command *cmd;
+
+	for (cmd = table; cmd->name != 0; cmd++) {
+	    db_printf("%-12s", cmd->name);
+	    db_end_line();
+	}
+}
+
+void
+db_command(last_cmdp, cmd_table)
+	struct command	**last_cmdp;	/* IN_OUT */
+	struct command	*cmd_table;
+{
+	struct command	*cmd;
+	int		t;
+	char		modif[TOK_STRING_SIZE];
+	db_expr_t	addr, count;
+	boolean_t	have_addr;
+	int		result;
+
+	t = db_read_token();
+	if (t == tEOL) {
+	    /* empty line repeats last command, at 'next' */
+	    cmd = *last_cmdp;
+	    addr = (db_expr_t)db_next;
+	    have_addr = FALSE;
+	    count = 1;
+	    modif[0] = '\0';
+	}
+	else if (t == tEXCL) {
+	    void db_fncall();
+	    db_fncall();
+	    return;
+	}
+	else if (t != tIDENT) {
+	    db_printf("?\n");
+	    db_flush_lex();
+	    return;
+	}
+	else {
+	    /*
+	     * Search for command
+	     */
+	    while (cmd_table) {
+		result = db_cmd_search(db_tok_string,
+				       cmd_table,
+				       &cmd);
+		switch (result) {
+		    case CMD_NONE:
+			db_printf("No such command\n");
+			db_flush_lex();
+			return;
+		    case CMD_AMBIGUOUS:
+			db_printf("Ambiguous\n");
+			db_flush_lex();
+			return;
+		    case CMD_HELP:
+			db_cmd_list(cmd_table);
+			db_flush_lex();
+			return;
+		    default:
+			break;
+		}
+		if ((cmd_table = cmd->more) != 0) {
+		    t = db_read_token();
+		    if (t != tIDENT) {
+			db_cmd_list(cmd_table);
+			db_flush_lex();
+			return;
+		    }
+		}
+	    }
+
+	    if ((cmd->flag & CS_OWN) == 0) {
+		/*
+		 * Standard syntax:
+		 * command [/modifier] [addr] [,count]
+		 */
+		t = db_read_token();
+		if (t == tSLASH) {
+		    t = db_read_token();
+		    if (t != tIDENT) {
+			db_printf("Bad modifier\n");
+			db_flush_lex();
+			return;
+		    }
+		    db_strcpy(modif, db_tok_string);
+		}
+		else {
+		    db_unread_token(t);
+		    modif[0] = '\0';
+		}
+
+		if (db_expression(&addr)) {
+		    db_dot = (db_addr_t) addr;
+		    db_last_addr = db_dot;
+		    have_addr = TRUE;
+		}
+		else {
+		    addr = (db_expr_t) db_dot;
+		    have_addr = FALSE;
+		}
+		t = db_read_token();
+		if (t == tCOMMA) {
+		    if (!db_expression(&count)) {
+			db_printf("Count missing\n");
+			db_flush_lex();
+			return;
+		    }
+		}
+		else {
+		    db_unread_token(t);
+		    count = -1;
+		}
+		if ((cmd->flag & CS_MORE) == 0) {
+		    db_skip_to_eol();
+		}
+	    }
+	}
+	*last_cmdp = cmd;
+	if (cmd != 0) {
+	    /*
+	     * Execute the command.
+	     */
+	    (*cmd->fcn)(addr, have_addr, count, modif);
+
+	    if (cmd->flag & CS_SET_DOT) {
+		/*
+		 * If command changes dot, set dot to
+		 * previous address displayed (if 'ed' style).
+		 */
+		if (db_ed_style) {
+		    db_dot = db_prev;
+		}
+		else {
+		    db_dot = db_next;
+		}
+	    }
+	    else {
+		/*
+		 * If command does not change dot,
+		 * set 'next' location to be the same.
+		 */
+		db_next = db_dot;
+	    }
+	}
+}
+
+/*
+ * 'show' commands
+ */
+extern void	db_listbreak_cmd();
+extern void	db_listwatch_cmd();
+extern void	db_show_regs(), db_show_one_thread(), db_show_all_threads();
+extern void	vm_map_print(), vm_object_print(), vm_page_print();
+extern void	ipc_port_print();
+void		db_show_help();
+
+struct command db_show_all_cmds[] = {
+#if 0
+	{ "threads",	db_show_all_threads,0,	0 },
+#endif
+	{ (char *)0 }
+};
+
+struct command db_show_cmds[] = {
+	{ "all",	0,			0,	db_show_all_cmds },
+	{ "registers",	db_show_regs,		0,	0 },
+	{ "breaks",	db_listbreak_cmd, 	0,	0 },
+	{ "watches",	db_listwatch_cmd, 	0,	0 },
+#if 0
+	{ "thread",	db_show_one_thread,	0,	0 },
+#endif
+	{ "map",	vm_map_print,		0,	0 },
+	{ "object",	vm_object_print,	0,	0 },
+#if 0
+	{ "page",	vm_page_print,		0,	0 },
+#endif
+#if 0
+	{ "port",	ipc_port_print,		0,	0 },
+#endif
+	{ (char *)0, }
+};
+
+extern void	db_print_cmd(), db_examine_cmd(), db_set_cmd();
+extern void	db_search_cmd();
+extern void	db_write_cmd();
+extern void	db_delete_cmd(), db_breakpoint_cmd();
+extern void	db_deletewatch_cmd(), db_watchpoint_cmd();
+extern void	db_single_step_cmd(), db_trace_until_call_cmd(),
+		db_trace_until_matching_cmd(), db_continue_cmd();
+extern void	db_stack_trace_cmd();
+void		db_help_cmd();
+void		db_fncall();
+
+struct command db_command_table[] = {
+	{ "print",	db_print_cmd,		0,	0 },
+	{ "examine",	db_examine_cmd,		CS_SET_DOT, 0 },
+	{ "x",		db_examine_cmd,		CS_SET_DOT, 0 },
+	{ "search",	db_search_cmd,		CS_OWN|CS_SET_DOT, 0 },
+	{ "set",	db_set_cmd,		CS_OWN,	0 },
+	{ "write",	db_write_cmd,		CS_MORE|CS_SET_DOT, 0 },
+	{ "w",		db_write_cmd,		CS_MORE|CS_SET_DOT, 0 },
+	{ "delete",	db_delete_cmd,		0,	0 },
+	{ "d",		db_delete_cmd,		0,	0 },
+	{ "break",	db_breakpoint_cmd,	0,	0 },
+	{ "dwatch",	db_deletewatch_cmd,	0,	0 },
+	{ "watch",	db_watchpoint_cmd,	CS_MORE,0 },
+	{ "step",	db_single_step_cmd,	0,	0 },
+	{ "s",		db_single_step_cmd,	0,	0 },
+	{ "continue",	db_continue_cmd,	0,	0 },
+	{ "c",		db_continue_cmd,	0,	0 },
+	{ "until",	db_trace_until_call_cmd,0,	0 },
+	{ "next",	db_trace_until_matching_cmd,0,	0 },
+	{ "match",	db_trace_until_matching_cmd,0,	0 },
+	{ "trace",	db_stack_trace_cmd,	0,	0 },
+	{ "call",	db_fncall,		CS_OWN,	0 },
+	{ "show",	0,			0,	db_show_cmds },
+	{ (char *)0, }
+};
+
+struct command	*db_last_command = 0;
+
+void
+db_help_cmd()
+{
+	struct command *cmd = db_command_table;
+
+	while (cmd->name != 0) {
+	    db_printf("%-12s", cmd->name);
+	    db_end_line();
+	    cmd++;
+	}
+}
+
+void
+db_command_loop()
+{
+	/*
+	 * Initialize 'prev' and 'next' to dot.
+	 */
+	db_prev = db_dot;
+	db_next = db_dot;
+
+	db_cmd_loop_done = 0;
+	while (!db_cmd_loop_done) {
+
+	    (void) setjmp(db_jmpbuf);
+	    if (db_print_position() != 0)
+		db_printf("\n");
+
+	    db_printf("db> ");
+	    (void) db_read_line();
+
+	    db_command(&db_last_command, db_command_table);
+	}
+}
+
+void
+db_error(s)
+	char *s;
+{
+	if (s)
+	    db_printf(s);
+	db_flush_lex();
+	longjmp(db_jmpbuf, 1);
+}
+
+
+/*
+ * Call random function:
+ * !expr(arg,arg,arg)
+ */
+void
+db_fncall()
+{
+	db_expr_t	fn_addr;
+#define	MAXARGS		11
+	db_expr_t	args[MAXARGS];
+	int		nargs = 0;
+	db_expr_t	retval;
+	db_expr_t	(*func)();
+	int		t;
+
+	if (!db_expression(&fn_addr)) {
+	    db_printf("Bad function\n");
+	    db_flush_lex();
+	    return;
+	}
+	func = (db_expr_t (*) ()) fn_addr;
+
+	t = db_read_token();
+	if (t == tLPAREN) {
+	    if (db_expression(&args[0])) {
+		nargs++;
+		while ((t = db_read_token()) == tCOMMA) {
+		    if (nargs == MAXARGS) {
+			db_printf("Too many arguments\n");
+			db_flush_lex();
+			return;
+		    }
+		    if (!db_expression(&args[nargs])) {
+			db_printf("Argument missing\n");
+			db_flush_lex();
+			return;
+		    }
+		    nargs++;
+		}
+		db_unread_token(t);
+	    }
+	    if (db_read_token() != tRPAREN) {
+		db_printf("?\n");
+		db_flush_lex();
+		return;
+	    }
+	}
+	db_skip_to_eol();
+
+	while (nargs < MAXARGS) {
+	    args[nargs++] = 0;
+	}
+
+	retval = (*func)(args[0], args[1], args[2], args[3], args[4],
+			 args[5], args[6], args[7], args[8], args[9] );
+	db_printf("%#n\n", retval);
+}
diff --git a/sys/ddb/db_command.h b/sys/ddb/db_command.h
new file mode 100644
index 000000000000..938a3d6a28a1
--- /dev/null
+++ b/sys/ddb/db_command.h
@@ -0,0 +1,67 @@
+/* 
+ * Mach Operating System
+ * Copyright (c) 1991,1990 Carnegie Mellon University
+ * All Rights Reserved.
+ * 
+ * Permission to use, copy, modify and distribute this software and its
+ * documentation is hereby granted, provided that both the copyright
+ * notice and this permission notice appear in all copies of the
+ * software, derivative works or modified versions, and any portions
+ * thereof, and that both notices appear in supporting documentation.
+ * 
+ * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS 
+ * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
+ * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ * 
+ * Carnegie Mellon requests users of this software to return to
+ * 
+ *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
+ *  School of Computer Science
+ *  Carnegie Mellon University
+ *  Pittsburgh PA 15213-3890
+ * 
+ * any improvements or extensions that they make and grant Carnegie the
+ * rights to redistribute these changes.
+ */
+/*
+ * HISTORY
+ * $Log: db_command.h,v $
+ * Revision 1.1  1992/03/25  21:45:05  pace
+ * Initial revision
+ *
+ * Revision 2.3  91/02/05  17:06:15  mrt
+ * 	Changed to new Mach copyright
+ * 	[91/01/31  16:17:28  mrt]
+ * 
+ * Revision 2.2  90/08/27  21:50:19  dbg
+ * 	Replace db_last_address_examined with db_prev, db_next.
+ * 	[90/08/22            dbg]
+ * 	Created.
+ * 	[90/08/07            dbg]
+ * 
+ */
+/*
+ *	Author: David B. Golub, Carnegie Mellon University
+ *	Date:	7/90
+ */
+/*
+ * Command loop declarations.
+ */
+
+#include "param.h"
+#include "proc.h"
+#include <machine/db_machdep.h>
+
+extern void	db_command_loop();
+extern void	db_skip_to_eol();
+
+extern void	db_error(/* char * */);	/* report error */
+
+extern db_addr_t	db_dot;		/* current location */
+extern db_addr_t	db_last_addr;	/* last explicit address typed */
+extern db_addr_t	db_prev;	/* last address examined
+					   or written */
+extern db_addr_t	db_next;	/* next address to be examined
+					   or written */
+
+
diff --git a/sys/ddb/db_examine.c b/sys/ddb/db_examine.c
new file mode 100644
index 000000000000..66f5f6858c0e
--- /dev/null
+++ b/sys/ddb/db_examine.c
@@ -0,0 +1,364 @@
+/* 
+ * Mach Operating System
+ * Copyright (c) 1991,1990 Carnegie Mellon University
+ * All Rights Reserved.
+ * 
+ * Permission to use, copy, modify and distribute this software and its
+ * documentation is hereby granted, provided that both the copyright
+ * notice and this permission notice appear in all copies of the
+ * software, derivative works or modified versions, and any portions
+ * thereof, and that both notices appear in supporting documentation.
+ * 
+ * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS 
+ * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
+ * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ * 
+ * Carnegie Mellon requests users of this software to return to
+ * 
+ *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
+ *  School of Computer Science
+ *  Carnegie Mellon University
+ *  Pittsburgh PA 15213-3890
+ * 
+ * any improvements or extensions that they make and grant Carnegie the
+ * rights to redistribute these changes.
+ */
+/*
+ * HISTORY
+ * $Log: db_examine.c,v $
+ * Revision 1.1  1992/03/25  21:45:07  pace
+ * Initial revision
+ *
+ * Revision 2.4  91/02/05  17:06:20  mrt
+ * 	Changed to new Mach copyright
+ * 	[91/01/31  16:17:37  mrt]
+ * 
+ * Revision 2.3  90/11/07  16:49:23  rpd
+ * 	Added db_search_cmd, db_search.
+ * 	[90/11/06            rpd]
+ * 
+ * Revision 2.2  90/08/27  21:50:38  dbg
+ * 	Add 'r', 'z' to print and examine formats.
+ * 	Change calling sequence of db_disasm.
+ * 	db_examine sets db_prev and db_next instead of explicitly
+ * 	advancing dot.
+ * 	[90/08/20            dbg]
+ * 	Reflected changes in db_printsym()'s calling seq.
+ * 	[90/08/20            af]
+ * 	Reduce lint.
+ * 	[90/08/07            dbg]
+ * 	Created.
+ * 	[90/07/25            dbg]
+ * 
+ */
+/*
+ *	Author: David B. Golub, Carnegie Mellon University
+ *	Date:	7/90
+ */
+#include "param.h"
+#include "proc.h"
+#include <machine/db_machdep.h>		/* type definitions */
+
+#include <ddb/db_lex.h>
+#include <ddb/db_output.h>
+#include <ddb/db_command.h>
+#include <ddb/db_sym.h>
+
+char	db_examine_format[TOK_STRING_SIZE] = "x";
+
+extern	db_addr_t db_disasm(/* db_addr_t, boolean_t */);
+			/* instruction disassembler */
+
+/*
+ * Examine (print) data.
+ */
+/*ARGSUSED*/
+void
+db_examine_cmd(addr, have_addr, count, modif)
+	db_expr_t	addr;
+	int		have_addr;
+	db_expr_t	count;
+	char *		modif;
+{
+	if (modif[0] != '\0')
+	    db_strcpy(db_examine_format, modif);
+
+	if (count == -1)
+	    count = 1;
+
+	db_examine((db_addr_t) addr, db_examine_format, count);
+}
+
+db_examine(addr, fmt, count)
+	register
+	db_addr_t	addr;
+	char *		fmt;	/* format string */
+	int		count;	/* repeat count */
+{
+	int		c;
+	db_expr_t	value;
+	int		size;
+	int		width;
+	char *		fp;
+
+	while (--count >= 0) {
+	    fp = fmt;
+	    size = 4;
+	    width = 16;
+	    while ((c = *fp++) != 0) {
+		switch (c) {
+		    case 'b':
+			size = 1;
+			width = 4;
+			break;
+		    case 'h':
+			size = 2;
+			width = 8;
+			break;
+		    case 'l':
+			size = 4;
+			width = 16;
+			break;
+		    case 'a':	/* address */
+			/* always forces a new line */
+			if (db_print_position() != 0)
+			    db_printf("\n");
+			db_prev = addr;
+			db_printsym(addr, DB_STGY_ANY);
+			db_printf(":\t");
+			break;
+		    default:
+			if (db_print_position() == 0) {
+			    /* If we hit a new symbol, print it */
+			    char *	name;
+			    db_expr_t	off;
+
+			    db_find_sym_and_offset(addr, &name, &off);
+			    if (off == 0)
+				db_printf("%s:\t", name);
+			    else
+				db_printf("\t\t");
+
+			    db_prev = addr;
+			}
+
+			switch (c) {
+			    case 'r':	/* signed, current radix */
+				value = db_get_value(addr, size, TRUE);
+				addr += size;
+				db_printf("%-*r", width, value);
+				break;
+			    case 'x':	/* unsigned hex */
+				value = db_get_value(addr, size, FALSE);
+				addr += size;
+				db_printf("%-*x", width, value);
+				break;
+			    case 'z':	/* signed hex */
+				value = db_get_value(addr, size, TRUE);
+				addr += size;
+				db_printf("%-*z", width, value);
+				break;
+			    case 'd':	/* signed decimal */
+				value = db_get_value(addr, size, TRUE);
+				addr += size;
+				db_printf("%-*d", width, value);
+				break;
+			    case 'u':	/* unsigned decimal */
+				value = db_get_value(addr, size, FALSE);
+				addr += size;
+				db_printf("%-*u", width, value);
+				break;
+			    case 'o':	/* unsigned octal */
+				value = db_get_value(addr, size, FALSE);
+				addr += size;
+				db_printf("%-*o", width, value);
+				break;
+			    case 'c':	/* character */
+				value = db_get_value(addr, 1, FALSE);
+				addr += 1;
+				if (value >= ' ' && value <= '~')
+				    db_printf("%c", value);
+				else
+				    db_printf("\\%03o", value);
+				break;
+			    case 's':	/* null-terminated string */
+				for (;;) {
+				    value = db_get_value(addr, 1, FALSE);
+				    addr += 1;
+				    if (value == 0)
+					break;
+				    if (value >= ' ' && value <= '~')
+					db_printf("%c", value);
+				    else
+					db_printf("\\%03o", value);
+				}
+				break;
+			    case 'i':	/* instruction */
+				addr = db_disasm(addr, FALSE);
+				break;
+			    case 'I':	/* instruction, alternate form */
+				addr = db_disasm(addr, TRUE);
+				break;
+			    default:
+				break;
+			}
+			if (db_print_position() != 0)
+			    db_end_line();
+			break;
+		}
+	    }
+	}
+	db_next = addr;
+}
+
+/*
+ * Print value.
+ */
+char	db_print_format = 'x';
+
+/*ARGSUSED*/
+void
+db_print_cmd(addr, have_addr, count, modif)
+	db_expr_t	addr;
+	int		have_addr;
+	db_expr_t	count;
+	char *		modif;
+{
+	db_expr_t	value;
+
+	if (modif[0] != '\0')
+	    db_print_format = modif[0];
+
+	switch (db_print_format) {
+	    case 'a':
+		db_printsym((db_addr_t)addr, DB_STGY_ANY);
+		break;
+	    case 'r':
+		db_printf("%11r", addr);
+		break;
+	    case 'x':
+		db_printf("%8x", addr);
+		break;
+	    case 'z':
+		db_printf("%8z", addr);
+		break;
+	    case 'd':
+		db_printf("%11d", addr);
+		break;
+	    case 'u':
+		db_printf("%11u", addr);
+		break;
+	    case 'o':
+		db_printf("%16o", addr);
+		break;
+	    case 'c':
+		value = addr & 0xFF;
+		if (value >= ' ' && value <= '~')
+		    db_printf("%c", value);
+		else
+		    db_printf("\\%03o", value);
+		break;
+	}
+	db_printf("\n");
+}
+
+db_print_loc_and_inst(loc)
+	db_addr_t	loc;
+{
+	db_printsym(loc, DB_STGY_PROC);
+	db_printf(":\t");
+	(void) db_disasm(loc, TRUE);
+}
+
+db_strcpy(dst, src)
+	register char *dst;
+	register char *src;
+{
+	while (*dst++ = *src++)
+	    ;
+}
+
+/*
+ * Search for a value in memory.
+ * Syntax: search [/bhl] addr value [mask] [,count]
+ */
+void
+db_search_cmd()
+{
+	int		t;
+	db_addr_t	addr;
+	int		size;
+	db_expr_t	value;
+	db_expr_t	mask;
+	unsigned int	count;
+
+	t = db_read_token();
+	if (t == tSLASH) {
+	    t = db_read_token();
+	    if (t != tIDENT) {
+	      bad_modifier:
+		db_printf("Bad modifier\n");
+		db_flush_lex();
+		return;
+	    }
+
+	    if (!strcmp(db_tok_string, "b"))
+		size = 1;
+	    else if (!strcmp(db_tok_string, "h"))
+		size = 2;
+	    else if (!strcmp(db_tok_string, "l"))
+		size = 4;
+	    else
+		goto bad_modifier;
+	} else {
+	    db_unread_token(t);
+	    size = 4;
+	}
+
+	if (!db_expression(&addr)) {
+	    db_printf("Address missing\n");
+	    db_flush_lex();
+	    return;
+	}
+
+	if (!db_expression(&value)) {
+	    db_printf("Value missing\n");
+	    db_flush_lex();
+	    return;
+	}
+
+	if (!db_expression(&mask))
+	    mask = 0xffffffff;
+
+	t = db_read_token();
+	if (t == tCOMMA) {
+	    if (!db_expression(&count)) {
+		db_printf("Count missing\n");
+		db_flush_lex();
+		return;
+	    }
+	} else {
+	    db_unread_token(t);
+	    count = -1;		/* effectively forever */
+	}
+	db_skip_to_eol();
+
+	db_search(addr, size, value, mask, count);
+}
+
+db_search(addr, size, value, mask, count)
+	register
+	db_addr_t	addr;
+	int		size;
+	db_expr_t	value;
+	db_expr_t	mask;
+	unsigned int	count;
+{
+	while (count-- != 0) {
+		db_prev = addr;
+		if ((db_get_value(addr, size, FALSE) & mask) == value)
+			break;
+		addr += size;
+	}
+	db_next = addr;
+}
diff --git a/sys/ddb/db_expr.c b/sys/ddb/db_expr.c
new file mode 100644
index 000000000000..062662c48e8d
--- /dev/null
+++ b/sys/ddb/db_expr.c
@@ -0,0 +1,248 @@
+/* 
+ * Mach Operating System
+ * Copyright (c) 1991,1990 Carnegie Mellon University
+ * All Rights Reserved.
+ * 
+ * Permission to use, copy, modify and distribute this software and its
+ * documentation is hereby granted, provided that both the copyright
+ * notice and this permission notice appear in all copies of the
+ * software, derivative works or modified versions, and any portions
+ * thereof, and that both notices appear in supporting documentation.
+ * 
+ * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS 
+ * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
+ * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ * 
+ * Carnegie Mellon requests users of this software to return to
+ * 
+ *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
+ *  School of Computer Science
+ *  Carnegie Mellon University
+ *  Pittsburgh PA 15213-3890
+ * 
+ * any improvements or extensions that they make and grant Carnegie the
+ * rights to redistribute these changes.
+ */
+/*
+ * HISTORY
+ * $Log: db_expr.c,v $
+ * Revision 1.1  1992/03/25  21:45:09  pace
+ * Initial revision
+ *
+ * Revision 2.3  91/02/05  17:06:25  mrt
+ * 	Changed to new Mach copyright
+ * 	[91/01/31  16:17:46  mrt]
+ * 
+ * Revision 2.2  90/08/27  21:50:57  dbg
+ * 	Use '..' instead of '$$' for db_prev.
+ * 	Use '+' for db_next.
+ * 	[90/08/22            dbg]
+ * 
+ * 	Allow repeated unary operators.
+ * 	[90/08/20            dbg]
+ * 
+ * 	Reflected back rename of db_symbol_value->db_value_of_name
+ * 	[90/08/20            af]
+ * 	Reduce lint.
+ * 	[90/08/07            dbg]
+ * 	Created.
+ * 	[90/07/25            dbg]
+ * 
+ */
+/*
+ *	Author: David B. Golub, Carnegie Mellon University
+ *	Date:	7/90
+ */
+#include "param.h"
+#include "proc.h"
+#include <machine/db_machdep.h>
+#include <ddb/db_lex.h>
+#include <ddb/db_access.h>
+#include <ddb/db_command.h>
+
+boolean_t
+db_term(valuep)
+	db_expr_t *valuep;
+{
+	int	t;
+
+	t = db_read_token();
+	if (t == tIDENT) {
+	    if (!db_value_of_name(db_tok_string, valuep)) {
+		db_error("Symbol not found\n");
+		/*NOTREACHED*/
+	    }
+	    return (TRUE);
+	}
+	if (t == tNUMBER) {
+	    *valuep = (db_expr_t)db_tok_number;
+	    return (TRUE);
+	}
+	if (t == tDOT) {
+	    *valuep = (db_expr_t)db_dot;
+	    return (TRUE);
+	}
+	if (t == tDOTDOT) {
+	    *valuep = (db_expr_t)db_prev;
+	    return (TRUE);
+	}
+	if (t == tPLUS) {
+	    *valuep = (db_expr_t) db_next;
+	    return (TRUE);
+	}
+	if (t == tDITTO) {
+	    *valuep = (db_expr_t)db_last_addr;
+	    return (TRUE);
+	}
+	if (t == tDOLLAR) {
+	    if (!db_get_variable(valuep))
+		return (FALSE);
+	    return (TRUE);
+	}
+	if (t == tLPAREN) {
+	    if (!db_expression(valuep)) {
+		db_error("Syntax error\n");
+		/*NOTREACHED*/
+	    }
+	    t = db_read_token();
+	    if (t != tRPAREN) {
+		db_error("Syntax error\n");
+		/*NOTREACHED*/
+	    }
+	    return (TRUE);
+	}
+	db_unread_token(t);
+	return (FALSE);
+}
+
+boolean_t
+db_unary(valuep)
+	db_expr_t *valuep;
+{
+	int	t;
+
+	t = db_read_token();
+	if (t == tMINUS) {
+	    if (!db_unary(valuep)) {
+		db_error("Syntax error\n");
+		/*NOTREACHED*/
+	    }
+	    *valuep = -*valuep;
+	    return (TRUE);
+	}
+	if (t == tSTAR) {
+	    /* indirection */
+	    if (!db_unary(valuep)) {
+		db_error("Syntax error\n");
+		/*NOTREACHED*/
+	    }
+	    *valuep = db_get_value((db_addr_t)*valuep, sizeof(int), FALSE);
+	    return (TRUE);
+	}
+	db_unread_token(t);
+	return (db_term(valuep));
+}
+
+boolean_t
+db_mult_expr(valuep)
+	db_expr_t *valuep;
+{
+	db_expr_t	lhs, rhs;
+	int		t;
+
+	if (!db_unary(&lhs))
+	    return (FALSE);
+
+	t = db_read_token();
+	while (t == tSTAR || t == tSLASH || t == tPCT || t == tHASH) {
+	    if (!db_term(&rhs)) {
+		db_error("Syntax error\n");
+		/*NOTREACHED*/
+	    }
+	    if (t == tSTAR)
+		lhs *= rhs;
+	    else {
+		if (rhs == 0) {
+		    db_error("Divide by 0\n");
+		    /*NOTREACHED*/
+		}
+		if (t == tSLASH)
+		    lhs /= rhs;
+		else if (t == tPCT)
+		    lhs %= rhs;
+		else
+		    lhs = ((lhs+rhs-1)/rhs)*rhs;
+	    }
+	    t = db_read_token();
+	}
+	db_unread_token(t);
+	*valuep = lhs;
+	return (TRUE);
+}
+
+boolean_t
+db_add_expr(valuep)
+	db_expr_t *valuep;
+{
+	db_expr_t	lhs, rhs;
+	int		t;
+
+	if (!db_mult_expr(&lhs))
+	    return (FALSE);
+
+	t = db_read_token();
+	while (t == tPLUS || t == tMINUS) {
+	    if (!db_mult_expr(&rhs)) {
+		db_error("Syntax error\n");
+		/*NOTREACHED*/
+	    }
+	    if (t == tPLUS)
+		lhs += rhs;
+	    else
+		lhs -= rhs;
+	    t = db_read_token();
+	}
+	db_unread_token(t);
+	*valuep = lhs;
+	return (TRUE);
+}
+
+boolean_t
+db_shift_expr(valuep)
+	db_expr_t *valuep;
+{
+	db_expr_t	lhs, rhs;
+	int		t;
+
+	if (!db_add_expr(&lhs))
+	    return (FALSE);
+
+	t = db_read_token();
+	while (t == tSHIFT_L || t == tSHIFT_R) {
+	    if (!db_add_expr(&rhs)) {
+		db_error("Syntax error\n");
+		/*NOTREACHED*/
+	    }
+	    if (rhs < 0) {
+		db_error("Negative shift amount\n");
+		/*NOTREACHED*/
+	    }
+	    if (t == tSHIFT_L)
+		lhs <<= rhs;
+	    else {
+		/* Shift right is unsigned */
+		lhs = (unsigned) lhs >> rhs;
+	    }
+	    t = db_read_token();
+	}
+	db_unread_token(t);
+	*valuep = lhs;
+	return (TRUE);
+}
+
+int
+db_expression(valuep)
+	db_expr_t *valuep;
+{
+	return (db_shift_expr(valuep));
+}
diff --git a/sys/ddb/db_input.c b/sys/ddb/db_input.c
new file mode 100644
index 000000000000..5ec7824c51d5
--- /dev/null
+++ b/sys/ddb/db_input.c
@@ -0,0 +1,268 @@
+/* 
+ * Mach Operating System
+ * Copyright (c) 1991,1990 Carnegie Mellon University
+ * All Rights Reserved.
+ * 
+ * Permission to use, copy, modify and distribute this software and its
+ * documentation is hereby granted, provided that both the copyright
+ * notice and this permission notice appear in all copies of the
+ * software, derivative works or modified versions, and any portions
+ * thereof, and that both notices appear in supporting documentation.
+ * 
+ * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS 
+ * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
+ * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ * 
+ * Carnegie Mellon requests users of this software to return to
+ * 
+ *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
+ *  School of Computer Science
+ *  Carnegie Mellon University
+ *  Pittsburgh PA 15213-3890
+ * 
+ * any improvements or extensions that they make and grant Carnegie the
+ * rights to redistribute these changes.
+ */
+/*
+ * HISTORY
+ * $Log: db_input.c,v $
+ * Revision 1.1  1992/03/25  21:45:10  pace
+ * Initial revision
+ *
+ * Revision 2.4  91/02/14  14:41:53  mrt
+ * 	Add input line editing.
+ * 	[90/11/11            dbg]
+ * 
+ * Revision 2.3  91/02/05  17:06:32  mrt
+ * 	Changed to new Mach copyright
+ * 	[91/01/31  16:18:13  mrt]
+ * 
+ * Revision 2.2  90/08/27  21:51:03  dbg
+ * 	Reduce lint.
+ * 	[90/08/07            dbg]
+ * 	Created.
+ * 	[90/07/25            dbg]
+ * 
+ */
+/*
+ *	Author: David B. Golub, Carnegie Mellon University
+ *	Date:	7/90
+ */
+
+#include "param.h"
+#include "proc.h"
+#include <ddb/db_output.h>
+
+/*
+ * Character input and editing.
+ */
+
+/*
+ * We don't track output position while editing input,
+ * since input always ends with a new-line.  We just
+ * reset the line position at the end.
+ */
+char *	db_lbuf_start;	/* start of input line buffer */
+char *	db_lbuf_end;	/* end of input line buffer */
+char *	db_lc;		/* current character */
+char *	db_le;		/* one past last character */
+
+#define	CTRL(c)		((c) & 0x1f)
+#define	isspace(c)	((c) == ' ' || (c) == '\t')
+#define	BLANK		' '
+#define	BACKUP		'\b'
+
+void
+db_putstring(s, count)
+	char	*s;
+	int	count;
+{
+	while (--count >= 0)
+	    cnputc(*s++);
+}
+
+void
+db_putnchars(c, count)
+	int	c;
+	int	count;
+{
+	while (--count >= 0)
+	    cnputc(c);
+}
+
+/*
+ * Delete N characters, forward or backward
+ */
+#define	DEL_FWD		0
+#define	DEL_BWD		1
+void
+db_delete(n, bwd)
+	int	n;
+	int	bwd;
+{
+	register char *p;
+
+	if (bwd) {
+	    db_lc -= n;
+	    db_putnchars(BACKUP, n);
+	}
+	for (p = db_lc; p < db_le-n; p++) {
+	    *p = *(p+n);
+	    cnputc(*p);
+	}
+	db_putnchars(BLANK, n);
+	db_putnchars(BACKUP, db_le - db_lc);
+	db_le -= n;
+}
+
+/* returns TRUE at end-of-line */
+int
+db_inputchar(c)
+	int	c;
+{
+	switch (c) {
+	    case CTRL('b'):
+		/* back up one character */
+		if (db_lc > db_lbuf_start) {
+		    cnputc(BACKUP);
+		    db_lc--;
+		}
+		break;
+	    case CTRL('f'):
+		/* forward one character */
+		if (db_lc < db_le) {
+		    cnputc(*db_lc);
+		    db_lc++;
+		}
+		break;
+	    case CTRL('a'):
+		/* beginning of line */
+		while (db_lc > db_lbuf_start) {
+		    cnputc(BACKUP);
+		    db_lc--;
+		}
+		break;
+	    case CTRL('e'):
+		/* end of line */
+		while (db_lc < db_le) {
+		    cnputc(*db_lc);
+		    db_lc++;
+		}
+		break;
+	    case CTRL('h'):
+	    case 0177:
+		/* erase previous character */
+		if (db_lc > db_lbuf_start)
+		    db_delete(1, DEL_BWD);
+		break;
+	    case CTRL('d'):
+		/* erase next character */
+		if (db_lc < db_le)
+		    db_delete(1, DEL_FWD);
+		break;
+	    case CTRL('k'):
+		/* delete to end of line */
+		if (db_lc < db_le)
+		    db_delete(db_le - db_lc, DEL_FWD);
+		break;
+	    case CTRL('t'):
+		/* twiddle last 2 characters */
+		if (db_lc >= db_lbuf_start + 2) {
+		    c = db_lc[-2];
+		    db_lc[-2] = db_lc[-1];
+		    db_lc[-1] = c;
+		    cnputc(BACKUP);
+		    cnputc(BACKUP);
+		    cnputc(db_lc[-2]);
+		    cnputc(db_lc[-1]);
+		}
+		break;
+	    case CTRL('r'):
+		db_putstring("^R\n", 3);
+		if (db_le > db_lbuf_start) {
+		    db_putstring(db_lbuf_start, db_le - db_lbuf_start);
+		    db_putnchars(BACKUP, db_le - db_lc);
+		}
+		break;
+	    case '\n':
+	    case '\r':
+		*db_le++ = c;
+		return (1);
+	    default:
+		if (db_le == db_lbuf_end) {
+		    cnputc('\007');
+		}
+		else if (c >= ' ' && c <= '~') {
+		    register char *p;
+
+		    for (p = db_le; p > db_lc; p--)
+			*p = *(p-1);
+		    *db_lc++ = c;
+		    db_le++;
+		    cnputc(c);
+		    db_putstring(db_lc, db_le - db_lc);
+		    db_putnchars(BACKUP, db_le - db_lc);
+		}
+		break;
+	}
+	return (0);
+}
+
+int
+db_readline(lstart, lsize)
+	char *	lstart;
+	int	lsize;
+{
+	db_force_whitespace();	/* synch output position */
+
+	db_lbuf_start = lstart;
+	db_lbuf_end   = lstart + lsize;
+	db_lc = lstart;
+	db_le = lstart;
+
+	while (!db_inputchar(cngetc()))
+	    continue;
+
+	db_putchar('\n');	/* synch output position */
+
+	*db_le = 0;
+	return (db_le - db_lbuf_start);
+}
+
+void
+db_check_interrupt()
+{
+	register int	c;
+
+	c = cnmaygetc();
+	switch (c) {
+	    case -1:		/* no character */
+		return;
+
+	    case CTRL('c'):
+		db_error((char *)0);
+		/*NOTREACHED*/
+
+	    case CTRL('s'):
+		do {
+		    c = cnmaygetc();
+		    if (c == CTRL('c'))
+			db_error((char *)0);
+		} while (c != CTRL('q'));
+		break;
+
+	    default:
+		/* drop on floor */
+		break;
+	}
+}
+
+cnmaygetc ()
+{
+	return (-1);
+}
+
+/* called from kdb_trap in db_interface.c */
+cnpollc (flag)
+{
+}	
diff --git a/sys/ddb/db_lex.c b/sys/ddb/db_lex.c
new file mode 100644
index 000000000000..dcfd90038a82
--- /dev/null
+++ b/sys/ddb/db_lex.c
@@ -0,0 +1,295 @@
+/* 
+ * Mach Operating System
+ * Copyright (c) 1991,1990 Carnegie Mellon University
+ * All Rights Reserved.
+ * 
+ * Permission to use, copy, modify and distribute this software and its
+ * documentation is hereby granted, provided that both the copyright
+ * notice and this permission notice appear in all copies of the
+ * software, derivative works or modified versions, and any portions
+ * thereof, and that both notices appear in supporting documentation.
+ * 
+ * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS 
+ * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
+ * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ * 
+ * Carnegie Mellon requests users of this software to return to
+ * 
+ *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
+ *  School of Computer Science
+ *  Carnegie Mellon University
+ *  Pittsburgh PA 15213-3890
+ * 
+ * any improvements or extensions that they make and grant Carnegie the
+ * rights to redistribute these changes.
+ */
+/*
+ * HISTORY
+ * $Log: db_lex.c,v $
+ * Revision 1.1  1992/03/25  21:45:13  pace
+ * Initial revision
+ *
+ * Revision 2.3  91/02/05  17:06:36  mrt
+ * 	Changed to new Mach copyright
+ * 	[91/01/31  16:18:20  mrt]
+ * 
+ * Revision 2.2  90/08/27  21:51:10  dbg
+ * 	Add 'dotdot' token.
+ * 	[90/08/22            dbg]
+ * 
+ * 	Allow backslash to quote any character into an identifier.
+ * 	Allow colon in identifier for symbol table qualification.
+ * 	[90/08/16            dbg]
+ * 	Reduce lint.
+ * 	[90/08/07            dbg]
+ * 	Created.
+ * 	[90/07/25            dbg]
+ * 
+ */
+/*
+ *	Author: David B. Golub, Carnegie Mellon University
+ *	Date:	7/90
+ */
+/*
+ * Lexical analyzer.
+ */
+#include <ddb/db_lex.h>
+
+char	db_line[120];
+char *	db_lp, *db_endlp;
+
+int
+db_read_line()
+{
+	int	i;
+
+	i = db_readline(db_line, sizeof(db_line));
+	if (i == 0)
+	    return (0);	/* EOI */
+	db_lp = db_line;
+	db_endlp = db_lp + i;
+	return (i);
+}
+
+void
+db_flush_line()
+{
+	db_lp = db_line;
+	db_endlp = db_line;
+}
+
+int	db_look_char = 0;
+
+int
+db_read_char()
+{
+	int	c;
+
+	if (db_look_char != 0) {
+	    c = db_look_char;
+	    db_look_char = 0;
+	}
+	else if (db_lp >= db_endlp)
+	    c = -1;
+	else 
+	    c = *db_lp++;
+	return (c);
+}
+
+void
+db_unread_char(c)
+{
+	db_look_char = c;
+}
+
+int	db_look_token = 0;
+
+void
+db_unread_token(t)
+	int	t;
+{
+	db_look_token = t;
+}
+
+int
+db_read_token()
+{
+	int	t;
+
+	if (db_look_token) {
+	    t = db_look_token;
+	    db_look_token = 0;
+	}
+	else
+	    t = db_lex();
+	return (t);
+}
+
+int	db_tok_number;
+char	db_tok_string[TOK_STRING_SIZE];
+
+int	db_radix = 16;
+
+void
+db_flush_lex()
+{
+	db_flush_line();
+	db_look_char = 0;
+	db_look_token = 0;
+}
+
+int
+db_lex()
+{
+	int	c;
+
+	c = db_read_char();
+	while (c <= ' ' || c > '~') {
+	    if (c == '\n' || c == -1)
+		return (tEOL);
+	    c = db_read_char();
+	}
+
+	if (c >= '0' && c <= '9') {
+	    /* number */
+	    int	r, digit;
+
+	    if (c > '0')
+		r = db_radix;
+	    else {
+		c = db_read_char();
+		if (c == 'O' || c == 'o')
+		    r = 8;
+		else if (c == 'T' || c == 't')
+		    r = 10;
+		else if (c == 'X' || c == 'x')
+		    r = 16;
+		else {
+		    r = db_radix;
+		    db_unread_char(c);
+		}
+		c = db_read_char();
+	    }
+	    db_tok_number = 0;
+	    for (;;) {
+		if (c >= '0' && c <= ((r == 8) ? '7' : '9'))
+		    digit = c - '0';
+		else if (r == 16 && ((c >= 'A' && c <= 'F') ||
+				     (c >= 'a' && c <= 'f'))) {
+		    if (c >= 'a')
+			digit = c - 'a' + 10;
+		    else if (c >= 'A')
+			digit = c - 'A' + 10;
+		}
+		else
+		    break;
+		db_tok_number = db_tok_number * r + digit;
+		c = db_read_char();
+	    }
+	    if ((c >= '0' && c <= '9') ||
+		(c >= 'A' && c <= 'Z') ||
+		(c >= 'a' && c <= 'z') ||
+		(c == '_'))
+	    {
+		db_error("Bad character in number\n");
+		db_flush_lex();
+		return (tEOF);
+	    }
+	    db_unread_char(c);
+	    return (tNUMBER);
+	}
+	if ((c >= 'A' && c <= 'Z') ||
+	    (c >= 'a' && c <= 'z') ||
+	    c == '_' || c == '\\')
+	{
+	    /* string */
+	    char *cp;
+
+	    cp = db_tok_string;
+	    if (c == '\\') {
+		c = db_read_char();
+		if (c == '\n' || c == -1)
+		    db_error("Bad escape\n");
+	    }
+	    *cp++ = c;
+	    while (1) {
+		c = db_read_char();
+		if ((c >= 'A' && c <= 'Z') ||
+		    (c >= 'a' && c <= 'z') ||
+		    (c >= '0' && c <= '9') ||
+		    c == '_' || c == '\\' || c == ':')
+		{
+		    if (c == '\\') {
+			c = db_read_char();
+			if (c == '\n' || c == -1)
+			    db_error("Bad escape\n");
+		    }
+		    *cp++ = c;
+		    if (cp == db_tok_string+sizeof(db_tok_string)) {
+			db_error("String too long\n");
+			db_flush_lex();
+			return (tEOF);
+		    }
+		    continue;
+		}
+		else {
+		    *cp = '\0';
+		    break;
+		}
+	    }
+	    db_unread_char(c);
+	    return (tIDENT);
+	}
+
+	switch (c) {
+	    case '+':
+		return (tPLUS);
+	    case '-':
+		return (tMINUS);
+	    case '.':
+		c = db_read_char();
+		if (c == '.')
+		    return (tDOTDOT);
+		db_unread_char(c);
+		return (tDOT);
+	    case '*':
+		return (tSTAR);
+	    case '/':
+		return (tSLASH);
+	    case '=':
+		return (tEQ);
+	    case '%':
+		return (tPCT);
+	    case '#':
+		return (tHASH);
+	    case '(':
+		return (tLPAREN);
+	    case ')':
+		return (tRPAREN);
+	    case ',':
+		return (tCOMMA);
+	    case '"':
+		return (tDITTO);
+	    case '$':
+		return (tDOLLAR);
+	    case '!':
+		return (tEXCL);
+	    case '<':
+		c = db_read_char();
+		if (c == '<')
+		    return (tSHIFT_L);
+		db_unread_char(c);
+		break;
+	    case '>':
+		c = db_read_char();
+		if (c == '>')
+		    return (tSHIFT_R);
+		db_unread_char(c);
+		break;
+	    case -1:
+		return (tEOF);
+	}
+	db_printf("Bad character\n");
+	db_flush_lex();
+	return (tEOF);
+}
diff --git a/sys/ddb/db_lex.h b/sys/ddb/db_lex.h
new file mode 100644
index 000000000000..56c55694994c
--- /dev/null
+++ b/sys/ddb/db_lex.h
@@ -0,0 +1,89 @@
+/* 
+ * Mach Operating System
+ * Copyright (c) 1991,1990 Carnegie Mellon University
+ * All Rights Reserved.
+ * 
+ * Permission to use, copy, modify and distribute this software and its
+ * documentation is hereby granted, provided that both the copyright
+ * notice and this permission notice appear in all copies of the
+ * software, derivative works or modified versions, and any portions
+ * thereof, and that both notices appear in supporting documentation.
+ * 
+ * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS 
+ * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
+ * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ * 
+ * Carnegie Mellon requests users of this software to return to
+ * 
+ *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
+ *  School of Computer Science
+ *  Carnegie Mellon University
+ *  Pittsburgh PA 15213-3890
+ * 
+ * any improvements or extensions that they make and grant Carnegie the
+ * rights to redistribute these changes.
+ */
+/*
+ * HISTORY
+ * $Log: db_lex.h,v $
+ * Revision 1.1  1992/03/25  21:45:15  pace
+ * Initial revision
+ *
+ * Revision 2.3  91/02/05  17:06:41  mrt
+ * 	Changed to new Mach copyright
+ * 	[91/01/31  16:18:28  mrt]
+ * 
+ * Revision 2.2  90/08/27  21:51:16  dbg
+ * 	Add 'dotdot' token.
+ * 	[90/08/22            dbg]
+ * 	Export db_flush_lex.
+ * 	[90/08/07            dbg]
+ * 	Created.
+ * 	[90/07/25            dbg]
+ * 
+ */
+/*
+ *	Author: David B. Golub, Carnegie Mellon University
+ *	Date:	7/90
+ */
+/*
+ * Lexical analyzer.
+ */
+extern int	db_read_line();
+extern void	db_flush_line();
+extern int	db_read_char();
+extern void	db_unread_char(/* char c */);
+extern int	db_read_token();
+extern void	db_unread_token(/* int t */);
+extern void	db_flush_lex();
+
+extern int	db_tok_number;
+#define	TOK_STRING_SIZE		120 
+extern char	db_tok_string[TOK_STRING_SIZE];
+extern int	db_radix;
+
+#define	tEOF		(-1)
+#define	tEOL		1
+#define	tNUMBER		2
+#define	tIDENT		3
+#define	tPLUS		4
+#define	tMINUS		5
+#define	tDOT		6
+#define	tSTAR		7
+#define	tSLASH		8
+#define	tEQ		9
+#define	tLPAREN		10
+#define	tRPAREN		11
+#define	tPCT		12
+#define	tHASH		13
+#define	tCOMMA		14
+#define	tDITTO		15
+#define	tDOLLAR		16
+#define	tEXCL		17
+#define	tSHIFT_L	18
+#define	tSHIFT_R	19
+#define	tDOTDOT		20
+
+
+
+
diff --git a/sys/ddb/db_output.c b/sys/ddb/db_output.c
new file mode 100644
index 000000000000..fc8fca776693
--- /dev/null
+++ b/sys/ddb/db_output.c
@@ -0,0 +1,389 @@
+/* 
+ * Mach Operating System
+ * Copyright (c) 1991,1990 Carnegie Mellon University
+ * All Rights Reserved.
+ * 
+ * Permission to use, copy, modify and distribute this software and its
+ * documentation is hereby granted, provided that both the copyright
+ * notice and this permission notice appear in all copies of the
+ * software, derivative works or modified versions, and any portions
+ * thereof, and that both notices appear in supporting documentation.
+ * 
+ * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS 
+ * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
+ * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ * 
+ * Carnegie Mellon requests users of this software to return to
+ * 
+ *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
+ *  School of Computer Science
+ *  Carnegie Mellon University
+ *  Pittsburgh PA 15213-3890
+ * 
+ * any improvements or extensions that they make and grant Carnegie the
+ * rights to redistribute these changes.
+ *
+ * PATCHES MAGIC                LEVEL   PATCH THAT GOT US HERE
+ * --------------------         -----   ----------------------
+ * CURRENT PATCH LEVEL:         4       00083
+ * --------------------         -----   ----------------------
+ *
+ * 14 Mar 93	Chris G. Demetriou	Fixed so that tab is not output,
+ *					use spaces instead.
+ */
+/*
+ * HISTORY
+ * $Log: db_output.c,v $
+ * Revision 1.1  1992/03/25  21:45:18  pace
+ * Initial revision
+ *
+ * Revision 2.3  91/02/05  17:06:45  mrt
+ * 	Changed to new Mach copyright
+ * 	[91/01/31  16:18:41  mrt]
+ * 
+ * Revision 2.2  90/08/27  21:51:25  dbg
+ * 	Put extra features of db_doprnt in _doprnt.
+ * 	[90/08/20            dbg]
+ * 	Reduce lint.
+ * 	[90/08/07            dbg]
+ * 	Created.
+ * 	[90/07/25            dbg]
+ * 
+ */
+/*
+ * 	Author: David B. Golub, Carnegie Mellon University
+ *	Date:	7/90
+ */
+
+/*
+ * Printf and character output for debugger.
+ */
+
+#include "param.h"
+#include <machine/stdarg.h>
+
+/*
+ *	Character output - tracks position in line.
+ *	To do this correctly, we should know how wide
+ *	the output device is - then we could zero
+ *	the line position when the output device wraps
+ *	around to the start of the next line.
+ *
+ *	Instead, we count the number of spaces printed
+ *	since the last printing character so that we
+ *	don't print trailing spaces.  This avoids most
+ *	of the wraparounds.
+ */
+int	db_output_position = 0;		/* output column */
+int	db_last_non_space = 0;		/* last non-space character */
+int	db_tab_stop_width = 8;		/* how wide are tab stops? */
+#define	NEXT_TAB(i) \
+	((((i) + db_tab_stop_width) / db_tab_stop_width) * db_tab_stop_width)
+int	db_max_width = 80;		/* output line width */
+
+extern void	db_check_interrupt();
+
+/*
+ * Force pending whitespace.
+ */
+void
+db_force_whitespace()
+{
+	register int last_print, next_tab;
+
+	last_print = db_last_non_space;
+	while (last_print < db_output_position) {
+	    next_tab = NEXT_TAB(last_print);
+	    if (next_tab <= db_output_position) {
+		while (last_print < next_tab) { /* DON'T send a tab!!! */
+			cnputc(' ');
+			last_print++;
+		}
+	    }
+	    else {
+		cnputc(' ');
+		last_print++;
+	    }
+	}
+	db_last_non_space = db_output_position;
+}
+
+/*
+ * Output character.  Buffer whitespace.
+ */
+db_putchar(c)
+	int	c;		/* character to output */
+{
+	if (c > ' ' && c <= '~') {
+	    /*
+	     * Printing character.
+	     * If we have spaces to print, print them first.
+	     * Use tabs if possible.
+	     */
+	    db_force_whitespace();
+	    cnputc(c);
+	    db_output_position++;
+	    db_last_non_space = db_output_position;
+	}
+	else if (c == '\n') {
+	    /* Return */
+	    cnputc(c);
+	    db_output_position = 0;
+	    db_last_non_space = 0;
+	    db_check_interrupt();
+	}
+	else if (c == '\t') {
+	    /* assume tabs every 8 positions */
+	    db_output_position = NEXT_TAB(db_output_position);
+	}
+	else if (c == ' ') {
+	    /* space */
+	    db_output_position++;
+	}
+	else if (c == '\007') {
+	    /* bell */
+	    cnputc(c);
+	}
+	/* other characters are assumed non-printing */
+}
+
+/*
+ * Return output position
+ */
+int
+db_print_position()
+{
+	return (db_output_position);
+}
+
+/*
+ * End line if too long.
+ */
+void
+db_end_line()
+{
+	if (db_output_position >= db_max_width)
+	    db_printf("\n");
+}
+
+/*
+ * Printing
+ */
+extern int	db_radix;
+
+/*VARARGS1*/
+db_printf(char *fmt, ...)
+{
+	va_list	listp;
+	va_start(listp, fmt);
+	db_printf_guts (fmt, listp);
+	va_end(listp);
+}
+
+/* alternate name */
+
+/*VARARGS1*/
+kdbprintf(char *fmt, ...)
+{
+	va_list	listp;
+	va_start(listp, fmt);
+	db_printf_guts (fmt, listp);
+	va_end(listp);
+}
+
+/*
+ * Put a number (base <= 16) in a buffer in reverse order; return an
+ * optional length and a pointer to the NULL terminated (preceded?)
+ * buffer.
+ */
+static char *
+db_ksprintn(ul, base, lenp)
+	register u_long ul;
+	register int base, *lenp;
+{					/* A long in base 8, plus NULL. */
+	static char buf[sizeof(long) * NBBY / 3 + 2];
+	register char *p;
+
+	p = buf;
+	do {
+		*++p = "0123456789abcdef"[ul % base];
+	} while (ul /= base);
+	if (lenp)
+		*lenp = p - buf;
+	return (p);
+}
+
+db_printf_guts(fmt, ap)
+	register const char *fmt;
+	va_list ap;
+{
+	register char *p;
+	register int ch, n;
+	u_long ul;
+	int base, lflag, tmp, width;
+	char padc;
+	int ladjust;
+	int sharpflag;
+	int neg;
+
+	for (;;) {
+		padc = ' ';
+		width = 0;
+		while ((ch = *(u_char *)fmt++) != '%') {
+			if (ch == '\0')
+				return;
+			db_putchar(ch);
+		}
+		lflag = 0;
+		ladjust = 0;
+		sharpflag = 0;
+		neg = 0;
+reswitch:	switch (ch = *(u_char *)fmt++) {
+		case '0':
+			padc = '0';
+			goto reswitch;
+		case '1': case '2': case '3': case '4':
+		case '5': case '6': case '7': case '8': case '9':
+			for (width = 0;; ++fmt) {
+				width = width * 10 + ch - '0';
+				ch = *fmt;
+				if (ch < '0' || ch > '9')
+					break;
+			}
+			goto reswitch;
+		case 'l':
+			lflag = 1;
+			goto reswitch;
+		case '-':
+			ladjust = 1;
+			goto reswitch;
+		case '#':
+			sharpflag = 1;
+			goto reswitch;
+		case 'b':
+			ul = va_arg(ap, int);
+			p = va_arg(ap, char *);
+			for (p = db_ksprintn(ul, *p++, NULL); ch = *p--;)
+				db_putchar(ch);
+
+			if (!ul)
+				break;
+
+			for (tmp = 0; n = *p++;) {
+				if (ul & (1 << (n - 1))) {
+					db_putchar(tmp ? ',' : '<');
+					for (; (n = *p) > ' '; ++p)
+						db_putchar(n);
+					tmp = 1;
+				} else
+					for (; *p > ' '; ++p);
+			}
+			if (tmp)
+				db_putchar('>');
+			break;
+		case '*':
+			width = va_arg (ap, int);
+			if (width < 0) {
+				ladjust = !ladjust;
+				width = -width;
+			}
+			goto reswitch;
+		case 'c':
+			db_putchar(va_arg(ap, int));
+			break;
+		case 's':
+			p = va_arg(ap, char *);
+			width -= strlen (p);
+			if (!ladjust && width > 0)
+				while (width--)
+					db_putchar (padc);
+			while (ch = *p++)
+				db_putchar(ch);
+			if (ladjust && width > 0)
+				while (width--)
+					db_putchar (padc);
+			break;
+		case 'r':
+			ul = lflag ? va_arg(ap, u_long) : va_arg(ap, u_int);
+			if ((long)ul < 0) {
+				neg = 1;
+				ul = -(long)ul;
+			}
+			base = db_radix;
+			if (base < 8 || base > 16)
+				base = 10;
+			goto number;
+		case 'n':
+			ul = lflag ? va_arg(ap, u_long) : va_arg(ap, u_int);
+			base = db_radix;
+			if (base < 8 || base > 16)
+				base = 10;
+			goto number;
+		case 'd':
+			ul = lflag ? va_arg(ap, long) : va_arg(ap, int);
+			if ((long)ul < 0) {
+				neg = 1;
+				ul = -(long)ul;
+			}
+			base = 10;
+			goto number;
+		case 'o':
+			ul = lflag ? va_arg(ap, u_long) : va_arg(ap, u_int);
+			base = 8;
+			goto number;
+		case 'u':
+			ul = lflag ? va_arg(ap, u_long) : va_arg(ap, u_int);
+			base = 10;
+			goto number;
+		case 'z':
+			ul = lflag ? va_arg(ap, u_long) : va_arg(ap, u_int);
+			if ((long)ul < 0) {
+				neg = 1;
+				ul = -(long)ul;
+			}
+			base = 16;
+			goto number;
+		case 'x':
+			ul = lflag ? va_arg(ap, u_long) : va_arg(ap, u_int);
+			base = 16;
+number:			p = (char *)db_ksprintn(ul, base, &tmp);
+			if (sharpflag && ul != 0) {
+				if (base == 8)
+					tmp++;
+				else if (base == 16)
+					tmp += 2;
+			}
+			if (neg)
+				tmp++;
+
+			if (!ladjust && width && (width -= tmp) > 0)
+				while (width--)
+					db_putchar(padc);
+			if (neg)
+				db_putchar ('-');
+			if (sharpflag && ul != 0) {
+				if (base == 8) {
+					db_putchar ('0');
+				} else if (base == 16) {
+					db_putchar ('0');
+					db_putchar ('x');
+				}
+			}
+			if (ladjust && width && (width -= tmp) > 0)
+				while (width--)
+					db_putchar(padc);
+
+			while (ch = *p--)
+				db_putchar(ch);
+			break;
+		default:
+			db_putchar('%');
+			if (lflag)
+				db_putchar('l');
+			/* FALLTHROUGH */
+		case '%':
+			db_putchar(ch);
+		}
+	}
+}
+
diff --git a/sys/ddb/db_output.h b/sys/ddb/db_output.h
new file mode 100644
index 000000000000..3ad599d8cc3e
--- /dev/null
+++ b/sys/ddb/db_output.h
@@ -0,0 +1,53 @@
+/* 
+ * Mach Operating System
+ * Copyright (c) 1991,1990 Carnegie Mellon University
+ * All Rights Reserved.
+ * 
+ * Permission to use, copy, modify and distribute this software and its
+ * documentation is hereby granted, provided that both the copyright
+ * notice and this permission notice appear in all copies of the
+ * software, derivative works or modified versions, and any portions
+ * thereof, and that both notices appear in supporting documentation.
+ * 
+ * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS 
+ * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
+ * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ * 
+ * Carnegie Mellon requests users of this software to return to
+ * 
+ *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
+ *  School of Computer Science
+ *  Carnegie Mellon University
+ *  Pittsburgh PA 15213-3890
+ * 
+ * any improvements or extensions that they make and grant Carnegie the
+ * rights to redistribute these changes.
+ */
+/*
+ * HISTORY
+ * $Log: db_output.h,v $
+ * Revision 1.1  1992/03/25  21:45:20  pace
+ * Initial revision
+ *
+ * Revision 2.3  91/02/05  17:06:49  mrt
+ * 	Changed to new Mach copyright
+ * 	[91/01/31  16:18:48  mrt]
+ * 
+ * Revision 2.2  90/08/27  21:51:32  dbg
+ * 	Created.
+ * 	[90/08/07            dbg]
+ * 
+ */
+/*
+ * 	Author: David B. Golub, Carnegie Mellon University
+ *	Date:	8/90
+ */
+
+/*
+ * Printing routines for kernel debugger.
+ */
+
+extern void	db_force_whitespace();
+extern int	db_print_position();
+extern void	db_end_line();
+extern int	db_printf();
diff --git a/sys/ddb/db_print.c b/sys/ddb/db_print.c
new file mode 100644
index 000000000000..48eef38c6aa1
--- /dev/null
+++ b/sys/ddb/db_print.c
@@ -0,0 +1,104 @@
+/* 
+ * Mach Operating System
+ * Copyright (c) 1991,1990 Carnegie Mellon University
+ * All Rights Reserved.
+ * 
+ * Permission to use, copy, modify and distribute this software and its
+ * documentation is hereby granted, provided that both the copyright
+ * notice and this permission notice appear in all copies of the
+ * software, derivative works or modified versions, and any portions
+ * thereof, and that both notices appear in supporting documentation.
+ * 
+ * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS 
+ * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
+ * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ * 
+ * Carnegie Mellon requests users of this software to return to
+ * 
+ *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
+ *  School of Computer Science
+ *  Carnegie Mellon University
+ *  Pittsburgh PA 15213-3890
+ * 
+ * any improvements or extensions that they make and grant Carnegie the
+ * rights to redistribute these changes.
+ */
+/*
+ * HISTORY
+ * $Log: db_print.c,v $
+ * Revision 1.1  1992/03/25  21:45:22  pace
+ * Initial revision
+ *
+ * Revision 2.5  91/02/05  17:06:53  mrt
+ * 	Changed to new Mach copyright
+ * 	[91/01/31  16:18:56  mrt]
+ * 
+ * Revision 2.4  90/10/25  14:43:54  rwd
+ * 	Changed db_show_regs to print unsigned.
+ * 	[90/10/19            rpd]
+ * 	Generalized the watchpoint support.
+ * 	[90/10/16            rwd]
+ * 
+ * Revision 2.3  90/09/09  23:19:52  rpd
+ * 	Avoid totally incorrect guesses of symbol names for small values.
+ * 	[90/08/30  17:39:08  af]
+ * 
+ * Revision 2.2  90/08/27  21:51:49  dbg
+ * 	Insist that 'show thread' be called with an explicit address.
+ * 	[90/08/22            dbg]
+ * 
+ * 	Fix type for db_maxoff.
+ * 	[90/08/20            dbg]
+ * 
+ * 	Do not dereference the "valuep" field of a variable directly,
+ * 	call the new db_read/write_variable functions instead.
+ * 	Reflected changes in symbol lookup functions.
+ * 	[90/08/20            af]
+ * 	Reduce lint.
+ * 	[90/08/10  14:33:44  dbg]
+ * 
+ * 	Created.
+ * 	[90/07/25            dbg]
+ * 
+ */
+/*
+ * 	Author: David B. Golub, Carnegie Mellon University
+ *	Date:	7/90
+ */
+
+/*
+ * Miscellaneous printing.
+ */
+#include "param.h"
+#include "proc.h"
+
+#include <machine/db_machdep.h>
+
+#include <ddb/db_lex.h>
+#include <ddb/db_variables.h>
+#include <ddb/db_sym.h>
+
+extern unsigned int	db_maxoff;
+
+void
+db_show_regs()
+{
+	int	(*func)();
+	register struct db_variable *regp;
+	db_expr_t	value, offset;
+	char *		name;
+
+	for (regp = db_regs; regp < db_eregs; regp++) {
+	    db_read_variable(regp, &value);
+	    db_printf("%-12s%#10n", regp->name, value);
+	    db_find_xtrn_sym_and_offset((db_addr_t)value, &name, &offset);
+	    if (name != 0 && offset <= db_maxoff && offset != value) {
+		db_printf("\t%s", name);
+		if (offset != 0)
+		    db_printf("+%#r", offset);
+	    }
+	    db_printf("\n");
+	}
+	db_print_loc_and_inst(PC_REGS(DDB_REGS));
+}
+
diff --git a/sys/ddb/db_run.c b/sys/ddb/db_run.c
new file mode 100644
index 000000000000..b8e33aa75ec9
--- /dev/null
+++ b/sys/ddb/db_run.c
@@ -0,0 +1,426 @@
+/* 
+ * Mach Operating System
+ * Copyright (c) 1991,1990 Carnegie Mellon University
+ * All Rights Reserved.
+ * 
+ * Permission to use, copy, modify and distribute this software and its
+ * documentation is hereby granted, provided that both the copyright
+ * notice and this permission notice appear in all copies of the
+ * software, derivative works or modified versions, and any portions
+ * thereof, and that both notices appear in supporting documentation.
+ * 
+ * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS 
+ * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
+ * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ * 
+ * Carnegie Mellon requests users of this software to return to
+ * 
+ *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
+ *  School of Computer Science
+ *  Carnegie Mellon University
+ *  Pittsburgh PA 15213-3890
+ * 
+ * any improvements or extensions that they make and grant Carnegie the
+ * rights to redistribute these changes.
+ */
+/*
+ * HISTORY
+ * $Log: db_run.c,v $
+ * Revision 1.1  1992/03/25  21:45:24  pace
+ * Initial revision
+ *
+ * Revision 2.5  91/02/05  17:06:58  mrt
+ * 	Changed to new Mach copyright
+ * 	[91/01/31  16:19:05  mrt]
+ * 
+ * Revision 2.4  91/01/08  15:09:10  rpd
+ * 	Fixed bug in db_restart_at_pc.
+ * 	[90/12/07            rpd]
+ * 	Added STEP_COUNT and count option to db_continue_cmd.
+ * 	Changed db_stop_at_pc to return (modified) is_breakpoint.
+ * 	Fixed db_stop_at_pc to print newlines in the right places.
+ * 	[90/11/27            rpd]
+ * 
+ * Revision 2.3  90/10/25  14:43:59  rwd
+ * 	Changed db_find_breakpoint to db_find_breakpoint_here.
+ * 	[90/10/18            rpd]
+ * 
+ * 	Fixed db_set_single_step to pass regs to branch_taken.
+ * 	Added watchpoint argument to db_restart_at_pc.
+ * 	[90/10/17            rpd]
+ * 	Generalized the watchpoint support.
+ * 	[90/10/16            rwd]
+ * 	Added watchpoint support.
+ * 	[90/10/16            rpd]
+ * 
+ * Revision 2.2  90/08/27  21:51:59  dbg
+ * 	Fixed names for single-step functions.
+ * 	[90/08/20            af]
+ * 	Reduce lint.
+ * 	[90/08/07            dbg]
+ * 	Created.
+ * 	[90/07/25            dbg]
+ * 
+ */
+/*
+ * 	Author: David B. Golub, Carnegie Mellon University
+ *	Date:	7/90
+ */
+
+/*
+ * Commands to run process.
+ */
+#include "param.h"
+#include "proc.h"
+#include <machine/db_machdep.h>
+
+#include <ddb/db_lex.h>
+#include <ddb/db_break.h>
+#include <ddb/db_access.h>
+
+int	db_run_mode;
+#define	STEP_NONE	0
+#define	STEP_ONCE	1
+#define	STEP_RETURN	2
+#define	STEP_CALLT	3
+#define	STEP_CONTINUE	4
+#define STEP_INVISIBLE	5
+#define	STEP_COUNT	6
+
+boolean_t	db_sstep_print;
+int		db_loop_count;
+int		db_call_depth;
+
+int		db_inst_count;
+int		db_load_count;
+int		db_store_count;
+
+#ifndef db_set_single_step
+void		db_set_single_step(/* db_regs_t *regs */);	/* forward */
+#endif
+#ifndef db_clear_single_step
+void		db_clear_single_step(/* db_regs_t *regs */);
+#endif
+
+boolean_t
+db_stop_at_pc(is_breakpoint)
+	boolean_t	*is_breakpoint;
+{
+	register db_addr_t	pc;
+	register db_breakpoint_t bkpt;
+
+	db_clear_single_step(DDB_REGS);
+	db_clear_breakpoints();
+	db_clear_watchpoints();
+	pc = PC_REGS(DDB_REGS);
+
+#ifdef	FIXUP_PC_AFTER_BREAK
+	if (*is_breakpoint) {
+	    /*
+	     * Breakpoint trap.  Fix up the PC if the
+	     * machine requires it.
+	     */
+	    FIXUP_PC_AFTER_BREAK
+	    pc = PC_REGS(DDB_REGS);
+	}
+#endif
+
+	/*
+	 * Now check for a breakpoint at this address.
+	 */
+	bkpt = db_find_breakpoint_here(pc);
+	if (bkpt) {
+	    if (--bkpt->count == 0) {
+		bkpt->count = bkpt->init_count;
+		*is_breakpoint = TRUE;
+		return (TRUE);	/* stop here */
+	    }
+	} else if (*is_breakpoint) {
+		ddb_regs.tf_eip += 1;
+	}
+		
+	*is_breakpoint = FALSE;
+
+	if (db_run_mode == STEP_INVISIBLE) {
+	    db_run_mode = STEP_CONTINUE;
+	    return (FALSE);	/* continue */
+	}
+	if (db_run_mode == STEP_COUNT) {
+	    return (FALSE); /* continue */
+	}
+	if (db_run_mode == STEP_ONCE) {
+	    if (--db_loop_count > 0) {
+		if (db_sstep_print) {
+		    db_printf("\t\t");
+		    db_print_loc_and_inst(pc);
+		    db_printf("\n");
+		}
+		return (FALSE);	/* continue */
+	    }
+	}
+	if (db_run_mode == STEP_RETURN) {
+	    db_expr_t ins = db_get_value(pc, sizeof(int), FALSE);
+
+	    /* continue until matching return */
+
+	    if (!inst_trap_return(ins) &&
+		(!inst_return(ins) || --db_call_depth != 0)) {
+		if (db_sstep_print) {
+		    if (inst_call(ins) || inst_return(ins)) {
+			register int i;
+
+			db_printf("[after %6d]     ", db_inst_count);
+			for (i = db_call_depth; --i > 0; )
+			    db_printf("  ");
+			db_print_loc_and_inst(pc);
+			db_printf("\n");
+		    }
+		}
+		if (inst_call(ins))
+		    db_call_depth++;
+		return (FALSE);	/* continue */
+	    }
+	}
+	if (db_run_mode == STEP_CALLT) {
+	    db_expr_t ins = db_get_value(pc, sizeof(int), FALSE);
+
+	    /* continue until call or return */
+
+	    if (!inst_call(ins) &&
+		!inst_return(ins) &&
+		!inst_trap_return(ins)) {
+		return (FALSE);	/* continue */
+	    }
+	}
+	db_run_mode = STEP_NONE;
+	return (TRUE);
+}
+
+void
+db_restart_at_pc(watchpt)
+	boolean_t watchpt;
+{
+	register db_addr_t	pc = PC_REGS(DDB_REGS);
+
+	if ((db_run_mode == STEP_COUNT) ||
+	    (db_run_mode == STEP_RETURN) ||
+	    (db_run_mode == STEP_CALLT)) {
+	    db_expr_t		ins;
+
+	    /*
+	     * We are about to execute this instruction,
+	     * so count it now.
+	     */
+
+	    ins = db_get_value(pc, sizeof(int), FALSE);
+	    db_inst_count++;
+	    db_load_count += inst_load(ins);
+	    db_store_count += inst_store(ins);
+#ifdef	SOFTWARE_SSTEP
+	    /* XXX works on mips, but... */
+	    if (inst_branch(ins) || inst_call(ins)) {
+		ins = db_get_value(next_instr_address(pc,1),
+				   sizeof(int), FALSE);
+		db_inst_count++;
+		db_load_count += inst_load(ins);
+		db_store_count += inst_store(ins);
+	    }
+#endif	SOFTWARE_SSTEP
+	}
+
+	if (db_run_mode == STEP_CONTINUE) {
+	    if (watchpt || db_find_breakpoint_here(pc)) {
+		/*
+		 * Step over breakpoint/watchpoint.
+		 */
+		db_run_mode = STEP_INVISIBLE;
+		db_set_single_step(DDB_REGS);
+	    } else {
+		db_set_breakpoints();
+		db_set_watchpoints();
+	    }
+	} else {
+	    db_set_single_step(DDB_REGS);
+	}
+}
+
+void
+db_single_step(regs)
+	db_regs_t *regs;
+{
+	if (db_run_mode == STEP_CONTINUE) {
+	    db_run_mode = STEP_INVISIBLE;
+	    db_set_single_step(regs);
+	}
+}
+
+#ifdef	SOFTWARE_SSTEP
+/*
+ *	Software implementation of single-stepping.
+ *	If your machine does not have a trace mode
+ *	similar to the vax or sun ones you can use
+ *	this implementation, done for the mips.
+ *	Just define the above conditional and provide
+ *	the functions/macros defined below.
+ *
+ * extern boolean_t
+ *	inst_branch(),		returns true if the instruction might branch
+ * extern unsigned
+ *	branch_taken(),		return the address the instruction might
+ *				branch to
+ *	db_getreg_val();	return the value of a user register,
+ *				as indicated in the hardware instruction
+ *				encoding, e.g. 8 for r8
+ *			
+ * next_instr_address(pc,bd)	returns the address of the first
+ *				instruction following the one at "pc",
+ *				which is either in the taken path of
+ *				the branch (bd==1) or not.  This is
+ *				for machines (mips) with branch delays.
+ *
+ *	A single-step may involve at most 2 breakpoints -
+ *	one for branch-not-taken and one for branch taken.
+ *	If one of these addresses does not already have a breakpoint,
+ *	we allocate a breakpoint and save it here.
+ *	These breakpoints are deleted on return.
+ */			
+db_breakpoint_t	db_not_taken_bkpt = 0;
+db_breakpoint_t	db_taken_bkpt = 0;
+
+void
+db_set_single_step(regs)
+	register db_regs_t *regs;
+{
+	db_addr_t pc = PC_REGS(regs);
+	register unsigned	 inst, brpc;
+
+	/*
+	 *	User was stopped at pc, e.g. the instruction
+	 *	at pc was not executed.
+	 */
+	inst = db_get_value(pc, sizeof(int), FALSE);
+	if (inst_branch(inst) || inst_call(inst)) {
+	    extern unsigned getreg_val();
+
+	    brpc = branch_taken(inst, pc, getreg_val, regs);
+	    if (brpc != pc) {	/* self-branches are hopeless */
+		db_taken_bkpt = db_set_temp_breakpoint(brpc);
+	    }
+	    pc = next_instr_address(pc,1);
+	}
+	pc = next_instr_address(pc,0);
+	db_not_taken_bkpt = db_set_temp_breakpoint(pc);
+}
+
+void
+db_clear_single_step(regs)
+	db_regs_t *regs;
+{
+	register db_breakpoint_t	bkpt;
+
+	if (db_taken_bkpt != 0) {
+	    db_delete_temp_breakpoint(db_taken_bkpt);
+	    db_taken_bkpt = 0;
+	}
+	if (db_not_taken_bkpt != 0) {
+	    db_delete_temp_breakpoint(db_not_taken_bkpt);
+	    db_not_taken_bkpt = 0;
+	}
+}
+
+#endif	SOFTWARE_SSTEP
+
+extern int	db_cmd_loop_done;
+
+/* single-step */
+/*ARGSUSED*/
+void
+db_single_step_cmd(addr, have_addr, count, modif)
+	db_expr_t	addr;
+	int		have_addr;
+	db_expr_t	count;
+	char *		modif;
+{
+	boolean_t	print = FALSE;
+
+	if (count == -1)
+	    count = 1;
+
+	if (modif[0] == 'p')
+	    print = TRUE;
+
+	db_run_mode = STEP_ONCE;
+	db_loop_count = count;
+	db_sstep_print = print;
+	db_inst_count = 0;
+	db_load_count = 0;
+	db_store_count = 0;
+
+	db_cmd_loop_done = 1;
+}
+
+/* trace and print until call/return */
+/*ARGSUSED*/
+void
+db_trace_until_call_cmd(addr, have_addr, count, modif)
+	db_expr_t	addr;
+	int		have_addr;
+	db_expr_t	count;
+	char *		modif;
+{
+	boolean_t	print = FALSE;
+
+	if (modif[0] == 'p')
+	    print = TRUE;
+
+	db_run_mode = STEP_CALLT;
+	db_sstep_print = print;
+	db_inst_count = 0;
+	db_load_count = 0;
+	db_store_count = 0;
+
+	db_cmd_loop_done = 1;
+}
+
+/*ARGSUSED*/
+void
+db_trace_until_matching_cmd(addr, have_addr, count, modif)
+	db_expr_t	addr;
+	int		have_addr;
+	db_expr_t	count;
+	char *		modif;
+{
+	boolean_t	print = FALSE;
+
+	if (modif[0] == 'p')
+	    print = TRUE;
+
+	db_run_mode = STEP_RETURN;
+	db_call_depth = 1;
+	db_sstep_print = print;
+	db_inst_count = 0;
+	db_load_count = 0;
+	db_store_count = 0;
+
+	db_cmd_loop_done = 1;
+}
+
+/* continue */
+/*ARGSUSED*/
+void
+db_continue_cmd(addr, have_addr, count, modif)
+	db_expr_t	addr;
+	int		have_addr;
+	db_expr_t	count;
+	char *		modif;
+{
+	if (modif[0] == 'c')
+	    db_run_mode = STEP_COUNT;
+	else
+	    db_run_mode = STEP_CONTINUE;
+	db_inst_count = 0;
+	db_load_count = 0;
+	db_store_count = 0;
+
+	db_cmd_loop_done = 1;
+}
diff --git a/sys/ddb/db_sym.c b/sys/ddb/db_sym.c
new file mode 100644
index 000000000000..0517c68521ee
--- /dev/null
+++ b/sys/ddb/db_sym.c
@@ -0,0 +1,360 @@
+/* 
+ * Mach Operating System
+ * Copyright (c) 1991,1990 Carnegie Mellon University
+ * All Rights Reserved.
+ * 
+ * Permission to use, copy, modify and distribute this software and its
+ * documentation is hereby granted, provided that both the copyright
+ * notice and this permission notice appear in all copies of the
+ * software, derivative works or modified versions, and any portions
+ * thereof, and that both notices appear in supporting documentation.
+ * 
+ * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS 
+ * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
+ * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ * 
+ * Carnegie Mellon requests users of this software to return to
+ * 
+ *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
+ *  School of Computer Science
+ *  Carnegie Mellon University
+ *  Pittsburgh PA 15213-3890
+ * 
+ * any improvements or extensions that they make and grant Carnegie the
+ * rights to redistribute these changes.
+ */
+/*
+ * HISTORY
+ * $Log: db_sym.c,v $
+ * Revision 1.1  1992/03/25  21:45:27  pace
+ * Initial revision
+ *
+ * Revision 2.5  91/02/05  17:07:07  mrt
+ * 	Changed to new Mach copyright
+ * 	[91/01/31  16:19:17  mrt]
+ * 
+ * Revision 2.4  90/10/25  14:44:05  rwd
+ * 	Changed db_printsym to print unsigned.
+ * 	[90/10/19            rpd]
+ * 
+ * Revision 2.3  90/09/09  23:19:56  rpd
+ * 	Avoid totally incorrect guesses of symbol names for small values.
+ * 	[90/08/30  17:39:48  af]
+ * 
+ * Revision 2.2  90/08/27  21:52:18  dbg
+ * 	Removed nlist.h.  Fixed some type declarations.
+ * 	Qualifier character is ':'.
+ * 	[90/08/20            dbg]
+ * 	Modularized symtab info into a new db_symtab_t type.
+ * 	Modified db_add_symbol_table  and others accordingly.
+ * 	Defined db_sym_t, a new (opaque) type used to represent
+ * 	symbols.  This should support all sort of future symtable
+ * 	formats. Functions like db_qualify take a db_sym_t now.
+ * 	New db_symbol_values() function to explode the content
+ * 	of a db_sym_t.
+ * 	db_search_symbol() replaces db_find_sym_and_offset(), which is
+ * 	now a macro defined in our (new) header file.  This new
+ * 	function accepts more restrictive searches, which are
+ * 	entirely delegated to the symtab-specific code.
+ * 	Accordingly, db_printsym() accepts a strategy parameter.
+ * 	New db_line_at_pc() function.
+ * 	Renamed misleading db_eqsym into db_eqname.
+ * 	[90/08/20  10:47:06  af]
+ * 
+ * 	Created.
+ * 	[90/07/25            dbg]
+ * 
+ * Revision 2.1  90/07/26  16:43:52  dbg
+ * Created.
+ * 
+ */
+/*
+ * 	Author: David B. Golub, Carnegie Mellon University
+ *	Date:	7/90
+ */
+#include "param.h"
+#include "proc.h"
+#include <machine/db_machdep.h>
+#include <ddb/db_sym.h>
+
+/*
+ * We import from the symbol-table dependent routines:
+ */
+extern db_sym_t	X_db_lookup();
+extern db_sym_t	X_db_search_symbol();
+extern boolean_t X_db_line_at_pc();
+extern void	X_db_symbol_values();
+
+/*
+ * Multiple symbol tables
+ */
+#define	MAXNOSYMTABS	3	/* mach, ux, emulator */
+
+db_symtab_t	db_symtabs[MAXNOSYMTABS] = {{0,},};
+int db_nsymtab = 0;
+
+db_symtab_t	*db_last_symtab;
+
+db_sym_t	db_lookup();	/* forward */
+
+/*
+ * Add symbol table, with given name, to list of symbol tables.
+ */
+void
+db_add_symbol_table(start, end, name, ref)
+	char *start;
+	char *end;
+	char *name;
+	char *ref;
+{
+	if (db_nsymtab >= MAXNOSYMTABS) {
+		printf ("No slots left for %s symbol table", name);
+		panic ("db_sym.c: db_add_symbol_table");
+	}
+
+	db_symtabs[db_nsymtab].start = start;
+	db_symtabs[db_nsymtab].end = end;
+	db_symtabs[db_nsymtab].name = name;
+	db_symtabs[db_nsymtab].private = ref;
+	db_nsymtab++;
+}
+
+/*
+ *  db_qualify("vm_map", "ux") returns "unix:vm_map".
+ *
+ *  Note: return value points to static data whose content is
+ *  overwritten by each call... but in practice this seems okay.
+ */
+static char *
+db_qualify(sym, symtabname)
+	db_sym_t	sym;
+	register char	*symtabname;
+{
+	char		*symname;
+	static char     tmp[256];
+	register char	*s;
+
+	db_symbol_values(sym, &symname, 0);
+	s = tmp;
+	while (*s++ = *symtabname++) {
+	}
+	s[-1] = ':';
+	while (*s++ = *symname++) {
+	}
+	return tmp;
+}
+
+
+boolean_t
+db_eqname(src, dst, c)
+	char *src;
+	char *dst;
+	char c;
+{
+	if (!strcmp(src, dst))
+	    return (TRUE);
+	if (src[0] == c)
+	    return (!strcmp(src+1,dst));
+	return (FALSE);
+}
+
+boolean_t
+db_value_of_name(name, valuep)
+	char		*name;
+	db_expr_t	*valuep;
+{
+	db_sym_t	sym;
+
+	sym = db_lookup(name);
+	if (sym == DB_SYM_NULL)
+	    return (FALSE);
+	db_symbol_values(sym, &name, valuep);
+	return (TRUE);
+}
+
+
+/*
+ * Lookup a symbol.
+ * If the symbol has a qualifier (e.g., ux:vm_map),
+ * then only the specified symbol table will be searched;
+ * otherwise, all symbol tables will be searched.
+ */
+db_sym_t
+db_lookup(symstr)
+	char *symstr;
+{
+	db_sym_t sp;
+	register int i;
+	int symtab_start = 0;
+	int symtab_end = db_nsymtab;
+	register char *cp;
+
+	/*
+	 * Look for, remove, and remember any symbol table specifier.
+	 */
+	for (cp = symstr; *cp; cp++) {
+		if (*cp == ':') {
+			*cp = '\0';
+			for (i = 0; i < db_nsymtab; i++) {
+				if (! strcmp(symstr, db_symtabs[i].name)) {
+					symtab_start = i;
+					symtab_end = i + 1;
+					break;
+				}
+			}
+			*cp = ':';
+			if (i == db_nsymtab) {
+				db_error("invalid symbol table name");
+			}
+			symstr = cp+1;
+		}
+	}
+
+	/*
+	 * Look in the specified set of symbol tables.
+	 * Return on first match.
+	 */
+	for (i = symtab_start; i < symtab_end; i++) {
+		if (sp = X_db_lookup(&db_symtabs[i], symstr)) {
+			db_last_symtab = &db_symtabs[i];
+			return sp;
+		}
+	}
+	return 0;
+}
+
+/*
+ * Does this symbol name appear in more than one symbol table?
+ * Used by db_symbol_values to decide whether to qualify a symbol.
+ */
+boolean_t db_qualify_ambiguous_names = FALSE;
+
+boolean_t
+db_symbol_is_ambiguous(sym)
+	db_sym_t	sym;
+{
+	char		*sym_name;
+	register int	i;
+	register
+	boolean_t	found_once = FALSE;
+
+	if (!db_qualify_ambiguous_names)
+		return FALSE;
+
+	db_symbol_values(sym, &sym_name, 0);
+	for (i = 0; i < db_nsymtab; i++) {
+		if (X_db_lookup(&db_symtabs[i], sym_name)) {
+			if (found_once)
+				return TRUE;
+			found_once = TRUE;
+		}
+	}
+	return FALSE;
+}
+
+/*
+ * Find the closest symbol to val, and return its name
+ * and the difference between val and the symbol found.
+ */
+db_sym_t
+db_search_symbol( val, strategy, offp)
+	register db_addr_t	val;
+	db_strategy_t		strategy;
+	db_expr_t		*offp;
+{
+	register
+	unsigned int	diff;
+	unsigned int	newdiff;
+	register int	i;
+	db_sym_t	ret = DB_SYM_NULL, sym;
+
+	newdiff = diff = ~0;
+	db_last_symtab = 0;
+	for (i = 0; i < db_nsymtab; i++) {
+	    sym = X_db_search_symbol(&db_symtabs[i], val, strategy, &newdiff);
+	    if (newdiff < diff) {
+		db_last_symtab = &db_symtabs[i];
+		diff = newdiff;
+		ret = sym;
+	    }
+	}
+	*offp = diff;
+	return ret;
+}
+
+/*
+ * Return name and value of a symbol
+ */
+void
+db_symbol_values(sym, namep, valuep)
+	db_sym_t	sym;
+	char		**namep;
+	db_expr_t	*valuep;
+{
+	db_expr_t	value;
+
+	if (sym == DB_SYM_NULL) {
+		*namep = 0;
+		return;
+	}
+
+	X_db_symbol_values(sym, namep, &value);
+
+	if (db_symbol_is_ambiguous(sym))
+		*namep = db_qualify(sym, db_last_symtab->name);
+	if (valuep)
+		*valuep = value;
+}
+
+
+/*
+ * Print a the closest symbol to value
+ *
+ * After matching the symbol according to the given strategy
+ * we print it in the name+offset format, provided the symbol's
+ * value is close enough (eg smaller than db_maxoff).
+ * We also attempt to print [filename:linenum] when applicable
+ * (eg for procedure names).
+ *
+ * If we could not find a reasonable name+offset representation,
+ * then we just print the value in hex.  Small values might get
+ * bogus symbol associations, e.g. 3 might get some absolute
+ * value like _INCLUDE_VERSION or something, therefore we do
+ * not accept symbols whose value is zero (and use plain hex).
+ */
+
+unsigned int	db_maxoff = 0x10000000;
+
+void
+db_printsym(off, strategy)
+	db_expr_t	off;
+	db_strategy_t	strategy;
+{
+	db_expr_t	d;
+	char 		*filename;
+	char		*name;
+	db_expr_t	value;
+	int 		linenum;
+	db_sym_t	cursym;
+
+	cursym = db_search_symbol(off, strategy, &d);
+	db_symbol_values(cursym, &name, &value);
+	if (name == 0 || d >= db_maxoff || value == 0) {
+		db_printf("%#n", off);
+		return;
+	}
+	db_printf("%s", name);
+	if (d)
+		db_printf("+%#r", d);
+	if (strategy == DB_STGY_PROC) {
+		if (db_line_at_pc(cursym, &filename, &linenum, off))
+			db_printf(" [%s:%d]", filename, linenum);
+	}
+}
+
+
+boolean_t
+db_line_at_pc( sym, filename, linenum, pc)
+{
+	return X_db_line_at_pc( db_last_symtab, sym, filename, linenum, pc);
+}
diff --git a/sys/ddb/db_sym.h b/sys/ddb/db_sym.h
new file mode 100644
index 000000000000..663f1cd4201a
--- /dev/null
+++ b/sys/ddb/db_sym.h
@@ -0,0 +1,114 @@
+/* 
+ * Mach Operating System
+ * Copyright (c) 1991,1990 Carnegie Mellon University
+ * All Rights Reserved.
+ * 
+ * Permission to use, copy, modify and distribute this software and its
+ * documentation is hereby granted, provided that both the copyright
+ * notice and this permission notice appear in all copies of the
+ * software, derivative works or modified versions, and any portions
+ * thereof, and that both notices appear in supporting documentation.
+ * 
+ * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS 
+ * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
+ * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ * 
+ * Carnegie Mellon requests users of this software to return to
+ * 
+ *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
+ *  School of Computer Science
+ *  Carnegie Mellon University
+ *  Pittsburgh PA 15213-3890
+ * 
+ * any improvements or extensions that they make and grant Carnegie the
+ * rights to redistribute these changes.
+ */
+/*
+ * HISTORY
+ * $Log: db_sym.h,v $
+ * Revision 1.1  1992/03/25  21:45:29  pace
+ * Initial revision
+ *
+ * Revision 2.3  91/02/05  17:07:12  mrt
+ * 	Changed to new Mach copyright
+ * 	[91/01/31  16:19:27  mrt]
+ * 
+ * Revision 2.2  90/08/27  21:52:39  dbg
+ * 	Changed type of db_sym_t to char * - it's a better type for an
+ * 	opaque pointer.
+ * 	[90/08/22            dbg]
+ * 
+ * 	Created.
+ * 	[90/08/19            af]
+ * 
+ */
+/*
+ * 	Author: Alessandro Forin, Carnegie Mellon University
+ *	Date:	8/90
+ */
+
+/*
+ * This module can handle multiple symbol tables
+ */
+typedef struct {
+	char		*name;		/* symtab name */
+	char		*start;		/* symtab location */
+	char		*end;
+	char		*private;	/* optional machdep pointer */
+} db_symtab_t;
+
+extern db_symtab_t	*db_last_symtab; /* where last symbol was found */
+
+/*
+ * Symbol representation is specific to the symtab style:
+ * BSD compilers use dbx' nlist, other compilers might use
+ * a different one
+ */
+typedef	char *		db_sym_t;	/* opaque handle on symbols */
+#define	DB_SYM_NULL	((db_sym_t)0)
+
+/*
+ * Non-stripped symbol tables will have duplicates, for instance
+ * the same string could match a parameter name, a local var, a
+ * global var, etc.
+ * We are most concern with the following matches.
+ */
+typedef int		db_strategy_t;	/* search strategy */
+
+#define	DB_STGY_ANY	0			/* anything goes */
+#define DB_STGY_XTRN	1			/* only external symbols */
+#define DB_STGY_PROC	2			/* only procedures */
+
+extern boolean_t	db_qualify_ambiguous_names;
+					/* if TRUE, check across symbol tables
+					 * for multiple occurrences of a name.
+					 * Might slow down quite a bit */
+
+/*
+ * Functions exported by the symtable module
+ */
+extern void	db_add_symbol_table();
+					/* extend the list of symbol tables */
+
+extern int	db_value_of_name(/* char*, db_expr_t* */);
+					/* find symbol value given name */
+
+extern db_sym_t	db_search_symbol(/* db_expr_t, db_strategy_t, int* */);
+					/* find symbol given value */
+
+extern void	db_symbol_values(/* db_sym_t, char**, db_expr_t* */);
+					/* return name and value of symbol */
+
+#define db_find_sym_and_offset(val,namep,offp)	\
+	db_symbol_values(db_search_symbol(val,DB_STGY_ANY,offp),namep,0)
+					/* find name&value given approx val */
+
+#define db_find_xtrn_sym_and_offset(val,namep,offp)	\
+	db_symbol_values(db_search_symbol(val,DB_STGY_XTRN,offp),namep,0)
+					/* ditto, but no locals */
+
+extern int	db_eqname(/* char*, char*, char */);
+					/* strcmp, modulo leading char */
+
+extern void	db_printsym(/* db_expr_t, db_strategy_t */);
+					/* print closest symbol to a value */
diff --git a/sys/ddb/db_trap.c b/sys/ddb/db_trap.c
new file mode 100644
index 000000000000..099fab143961
--- /dev/null
+++ b/sys/ddb/db_trap.c
@@ -0,0 +1,106 @@
+/* 
+ * Mach Operating System
+ * Copyright (c) 1991,1990 Carnegie Mellon University
+ * All Rights Reserved.
+ * 
+ * Permission to use, copy, modify and distribute this software and its
+ * documentation is hereby granted, provided that both the copyright
+ * notice and this permission notice appear in all copies of the
+ * software, derivative works or modified versions, and any portions
+ * thereof, and that both notices appear in supporting documentation.
+ * 
+ * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS 
+ * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
+ * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ * 
+ * Carnegie Mellon requests users of this software to return to
+ * 
+ *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
+ *  School of Computer Science
+ *  Carnegie Mellon University
+ *  Pittsburgh PA 15213-3890
+ * 
+ * any improvements or extensions that they make and grant Carnegie the
+ * rights to redistribute these changes.
+ */
+/*
+ * HISTORY
+ * $Log: db_trap.c,v $
+ * Revision 1.1  1992/03/25  21:45:31  pace
+ * Initial revision
+ *
+ * Revision 2.5  91/02/05  17:07:16  mrt
+ * 	Changed to new Mach copyright
+ * 	[91/01/31  16:19:35  mrt]
+ * 
+ * Revision 2.4  91/01/08  15:09:17  rpd
+ * 	Changed db_stop_at_pc's arguments.
+ * 	Print db_inst_count, db_load_count, db_store_count.
+ * 	[90/11/27            rpd]
+ * 
+ * Revision 2.3  90/10/25  14:44:11  rwd
+ * 	From rpd.
+ * 	[90/10/19  17:03:17  rwd]
+ * 
+ * 	Generalized the watchpoint support.
+ * 	[90/10/16            rwd]
+ * 	Added watchpoint support.
+ * 	[90/10/16            rpd]
+ * 
+ * Revision 2.2  90/08/27  21:52:52  dbg
+ * 	Assign to db_dot before calling the print function.
+ * 	[90/08/20            af]
+ * 	Reduce lint.
+ * 	[90/08/07            dbg]
+ * 	Created.
+ * 	[90/07/25            dbg]
+ * 
+ */
+/*
+ * 	Author: David B. Golub, Carnegie Mellon University
+ *	Date:	7/90
+ */
+
+/*
+ * Trap entry point to kernel debugger.
+ */
+#include "param.h"
+#include "proc.h"
+#include <ddb/db_command.h>
+#include <ddb/db_break.h>
+
+extern void		db_restart_at_pc();
+extern boolean_t	db_stop_at_pc();
+
+extern int		db_inst_count;
+extern int		db_load_count;
+extern int		db_store_count;
+
+db_trap(type, code)
+	int	type, code;
+{
+	boolean_t	bkpt;
+	boolean_t	watchpt;
+
+	bkpt = IS_BREAKPOINT_TRAP(type, code);
+	watchpt = IS_WATCHPOINT_TRAP(type, code);
+
+	if (db_stop_at_pc(&bkpt)) {
+	    if (db_inst_count) {
+		db_printf("After %d instructions (%d loads, %d stores),\n",
+			  db_inst_count, db_load_count, db_store_count);
+	    }
+	    if (bkpt)
+		db_printf("Breakpoint at\t");
+	    else if (watchpt)
+		db_printf("Watchpoint at\t");
+	    else
+		db_printf("Stopped at\t");
+	    db_dot = PC_REGS(DDB_REGS);
+	    db_print_loc_and_inst(db_dot);
+
+	    db_command_loop();
+	}
+
+	db_restart_at_pc(watchpt);
+}
diff --git a/sys/ddb/db_variables.c b/sys/ddb/db_variables.c
new file mode 100644
index 000000000000..ed9512df5221
--- /dev/null
+++ b/sys/ddb/db_variables.c
@@ -0,0 +1,186 @@
+/* 
+ * Mach Operating System
+ * Copyright (c) 1991,1990 Carnegie Mellon University
+ * All Rights Reserved.
+ * 
+ * Permission to use, copy, modify and distribute this software and its
+ * documentation is hereby granted, provided that both the copyright
+ * notice and this permission notice appear in all copies of the
+ * software, derivative works or modified versions, and any portions
+ * thereof, and that both notices appear in supporting documentation.
+ * 
+ * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS 
+ * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
+ * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ * 
+ * Carnegie Mellon requests users of this software to return to
+ * 
+ *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
+ *  School of Computer Science
+ *  Carnegie Mellon University
+ *  Pittsburgh PA 15213-3890
+ * 
+ * any improvements or extensions that they make and grant Carnegie the
+ * rights to redistribute these changes.
+ */
+/*
+ * HISTORY
+ * $Log: db_variables.c,v $
+ * Revision 1.1  1992/03/25  21:45:33  pace
+ * Initial revision
+ *
+ * Revision 2.3  91/02/05  17:07:19  mrt
+ * 	Changed to new Mach copyright
+ * 	[91/01/31  16:19:46  mrt]
+ * 
+ * Revision 2.2  90/08/27  21:53:24  dbg
+ * 	New db_read/write_variable functions.  Should be used instead
+ * 	of dereferencing valuep directly, which might not be a true
+ * 	pointer if there is an fcn() access function.
+ * 	[90/08/20            af]
+ * 
+ * 	Fix declarations.
+ * 	Check for trailing garbage after last expression on command line.
+ * 	[90/08/10  14:34:54  dbg]
+ * 
+ * 	Created.
+ * 	[90/07/25            dbg]
+ * 
+ */
+/*
+ * 	Author: David B. Golub, Carnegie Mellon University
+ *	Date:	7/90
+ */
+
+#include "param.h"
+#include "proc.h"
+#include <machine/db_machdep.h>
+
+#include <ddb/db_lex.h>
+#include <ddb/db_variables.h>
+
+extern unsigned int	db_maxoff;
+
+extern int	db_radix;
+extern int	db_max_width;
+extern int	db_tab_stop_width;
+
+struct db_variable db_vars[] = {
+	{ "radix",	&db_radix, FCN_NULL },
+	{ "maxoff",	(int *)&db_maxoff, FCN_NULL },
+	{ "maxwidth",	&db_max_width, FCN_NULL },
+	{ "tabstops",	&db_tab_stop_width, FCN_NULL },
+};
+struct db_variable *db_evars = db_vars + sizeof(db_vars)/sizeof(db_vars[0]);
+
+int
+db_find_variable(varp)
+	struct db_variable	**varp;
+{
+	int	t;
+	struct db_variable *vp;
+
+	t = db_read_token();
+	if (t == tIDENT) {
+	    for (vp = db_vars; vp < db_evars; vp++) {
+		if (!strcmp(db_tok_string, vp->name)) {
+		    *varp = vp;
+		    return (1);
+		}
+	    }
+	    for (vp = db_regs; vp < db_eregs; vp++) {
+		if (!strcmp(db_tok_string, vp->name)) {
+		    *varp = vp;
+		    return (1);
+		}
+	    }
+	}
+	db_error("Unknown variable\n");
+	return (0);
+}
+
+int
+db_get_variable(valuep)
+	db_expr_t	*valuep;
+{
+	struct db_variable *vp;
+
+	if (!db_find_variable(&vp))
+	    return (0);
+
+	db_read_variable(vp, valuep);
+
+	return (1);
+}
+
+int
+db_set_variable(value)
+	db_expr_t	value;
+{
+	struct db_variable *vp;
+
+	if (!db_find_variable(&vp))
+	    return (0);
+
+	db_write_variable(vp, &value);
+
+	return (1);
+}
+
+
+db_read_variable(vp, valuep)
+	struct db_variable *vp;
+	db_expr_t	*valuep;
+{
+	int	(*func)() = vp->fcn;
+
+	if (func == FCN_NULL)
+	    *valuep = *(vp->valuep);
+	else
+	    (*func)(vp, valuep, DB_VAR_GET);
+}
+
+db_write_variable(vp, valuep)
+	struct db_variable *vp;
+	db_expr_t	*valuep;
+{
+	int	(*func)() = vp->fcn;
+
+	if (func == FCN_NULL)
+	    *(vp->valuep) = *valuep;
+	else
+	    (*func)(vp, valuep, DB_VAR_SET);
+}
+
+void
+db_set_cmd()
+{
+	db_expr_t	value;
+	int	(*func)();
+	struct db_variable *vp;
+	int	t;
+
+	t = db_read_token();
+	if (t != tDOLLAR) {
+	    db_error("Unknown variable\n");
+	    return;
+	}
+	if (!db_find_variable(&vp)) {
+	    db_error("Unknown variable\n");
+	    return;
+	}
+
+	t = db_read_token();
+	if (t != tEQ)
+	    db_unread_token(t);
+
+	if (!db_expression(&value)) {
+	    db_error("No value\n");
+	    return;
+	}
+	if (db_read_token() != tEOL) {
+	    db_error("?\n");
+	}
+
+	db_write_variable(vp, &value);
+}
diff --git a/sys/ddb/db_variables.h b/sys/ddb/db_variables.h
new file mode 100644
index 000000000000..f958d2c38349
--- /dev/null
+++ b/sys/ddb/db_variables.h
@@ -0,0 +1,72 @@
+/* 
+ * Mach Operating System
+ * Copyright (c) 1991,1990 Carnegie Mellon University
+ * All Rights Reserved.
+ * 
+ * Permission to use, copy, modify and distribute this software and its
+ * documentation is hereby granted, provided that both the copyright
+ * notice and this permission notice appear in all copies of the
+ * software, derivative works or modified versions, and any portions
+ * thereof, and that both notices appear in supporting documentation.
+ * 
+ * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS 
+ * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
+ * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ * 
+ * Carnegie Mellon requests users of this software to return to
+ * 
+ *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
+ *  School of Computer Science
+ *  Carnegie Mellon University
+ *  Pittsburgh PA 15213-3890
+ * 
+ * any improvements or extensions that they make and grant Carnegie the
+ * rights to redistribute these changes.
+ */
+/*
+ * HISTORY
+ * $Log: db_variables.h,v $
+ * Revision 1.1  1992/03/25  21:45:35  pace
+ * Initial revision
+ *
+ * Revision 2.3  91/02/05  17:07:23  mrt
+ * 	Changed to new Mach copyright
+ * 	[91/01/31  16:19:54  mrt]
+ * 
+ * Revision 2.2  90/08/27  21:53:40  dbg
+ * 	Modularized typedef name.  Documented the calling sequence of
+ * 	the (optional) access function of a variable.  Now the valuep
+ * 	field can be made opaque, eg be an offset that fcn() resolves.
+ * 	[90/08/20            af]
+ * 
+ * 	Created.
+ * 	[90/07/25            dbg]
+ * 
+ */
+/*
+ * 	Author: David B. Golub, Carnegie Mellon University
+ *	Date:	7/90
+ */
+
+#ifndef	_DB_VARIABLES_H_
+#define	_DB_VARIABLES_H_
+
+/*
+ * Debugger variables.
+ */
+struct db_variable {
+	char	*name;		/* Name of variable */
+	int	*valuep;	/* value of variable */
+				/* function to call when reading/writing */
+	int	(*fcn)(/* db_variable *vp, db_expr_t *valuep, int op */);
+#define DB_VAR_GET	0
+#define DB_VAR_SET	1
+};
+#define	FCN_NULL	((int (*)())0)
+
+extern struct db_variable	db_vars[];	/* debugger variables */
+extern struct db_variable	*db_evars;
+extern struct db_variable	db_regs[];	/* machine registers */
+extern struct db_variable	*db_eregs;
+
+#endif	/* _DB_VARIABLES_H_ */
diff --git a/sys/ddb/db_watch.c b/sys/ddb/db_watch.c
new file mode 100644
index 000000000000..e69d906d93e7
--- /dev/null
+++ b/sys/ddb/db_watch.c
@@ -0,0 +1,294 @@
+/* 
+ * Mach Operating System
+ * Copyright (c) 1991,1990 Carnegie Mellon University
+ * All Rights Reserved.
+ * 
+ * Permission to use, copy, modify and distribute this software and its
+ * documentation is hereby granted, provided that both the copyright
+ * notice and this permission notice appear in all copies of the
+ * software, derivative works or modified versions, and any portions
+ * thereof, and that both notices appear in supporting documentation.
+ * 
+ * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS 
+ * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
+ * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ * 
+ * Carnegie Mellon requests users of this software to return to
+ * 
+ *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
+ *  School of Computer Science
+ *  Carnegie Mellon University
+ *  Pittsburgh PA 15213-3890
+ * 
+ * any improvements or extensions that they make and grant Carnegie the
+ * rights to redistribute these changes.
+ */
+/*
+ * HISTORY
+ * $Log: db_watch.c,v $
+ * Revision 1.1  1992/03/25  21:45:37  pace
+ * Initial revision
+ *
+ * Revision 2.5  91/02/05  17:07:27  mrt
+ * 	Changed to new Mach copyright
+ * 	[91/01/31  16:20:02  mrt]
+ * 
+ * Revision 2.4  91/01/08  15:09:24  rpd
+ * 	Use db_map_equal, db_map_current, db_map_addr.
+ * 	[90/11/10            rpd]
+ * 
+ * Revision 2.3  90/11/05  14:26:39  rpd
+ * 	Initialize db_watchpoints_inserted to TRUE.
+ * 	[90/11/04            rpd]
+ * 
+ * Revision 2.2  90/10/25  14:44:16  rwd
+ * 	Made db_watchpoint_cmd parse a size argument.
+ * 	[90/10/17            rpd]
+ * 	Generalized the watchpoint support.
+ * 	[90/10/16            rwd]
+ * 	Created.
+ * 	[90/10/16            rpd]
+ * 
+ */
+/*
+ * 	Author: Richard P. Draves, Carnegie Mellon University
+ *	Date:	10/90
+ */
+
+#include "param.h"
+#include "proc.h"
+#include <machine/db_machdep.h>
+
+#include <vm/vm_map.h>
+#include <ddb/db_lex.h>
+#include <ddb/db_watch.h>
+#include <ddb/db_access.h>
+#include <ddb/db_sym.h>
+#include <machine/db_machdep.h>
+
+/*
+ * Watchpoints.
+ */
+
+extern boolean_t db_map_equal();
+extern boolean_t db_map_current();
+extern vm_map_t db_map_addr();
+
+boolean_t	db_watchpoints_inserted = TRUE;
+
+#define	NWATCHPOINTS	100
+struct db_watchpoint	db_watch_table[NWATCHPOINTS];
+db_watchpoint_t		db_next_free_watchpoint = &db_watch_table[0];
+db_watchpoint_t		db_free_watchpoints = 0;
+db_watchpoint_t		db_watchpoint_list = 0;
+
+db_watchpoint_t
+db_watchpoint_alloc()
+{
+	register db_watchpoint_t	watch;
+
+	if ((watch = db_free_watchpoints) != 0) {
+	    db_free_watchpoints = watch->link;
+	    return (watch);
+	}
+	if (db_next_free_watchpoint == &db_watch_table[NWATCHPOINTS]) {
+	    db_printf("All watchpoints used.\n");
+	    return (0);
+	}
+	watch = db_next_free_watchpoint;
+	db_next_free_watchpoint++;
+
+	return (watch);
+}
+
+void
+db_watchpoint_free(watch)
+	register db_watchpoint_t	watch;
+{
+	watch->link = db_free_watchpoints;
+	db_free_watchpoints = watch;
+}
+
+void
+db_set_watchpoint(map, addr, size)
+	vm_map_t	map;
+	db_addr_t	addr;
+	vm_size_t	size;
+{
+	register db_watchpoint_t	watch;
+
+	if (map == NULL) {
+	    db_printf("No map.\n");
+	    return;
+	}
+
+	/*
+	 *	Should we do anything fancy with overlapping regions?
+	 */
+
+	for (watch = db_watchpoint_list;
+	     watch != 0;
+	     watch = watch->link)
+	    if (db_map_equal(watch->map, map) &&
+		(watch->loaddr == addr) &&
+		(watch->hiaddr == addr+size)) {
+		db_printf("Already set.\n");
+		return;
+	    }
+
+	watch = db_watchpoint_alloc();
+	if (watch == 0) {
+	    db_printf("Too many watchpoints.\n");
+	    return;
+	}
+
+	watch->map = map;
+	watch->loaddr = addr;
+	watch->hiaddr = addr+size;
+
+	watch->link = db_watchpoint_list;
+	db_watchpoint_list = watch;
+
+	db_watchpoints_inserted = FALSE;
+}
+
+void
+db_delete_watchpoint(map, addr)
+	vm_map_t	map;
+	db_addr_t	addr;
+{
+	register db_watchpoint_t	watch;
+	register db_watchpoint_t	*prev;
+
+	for (prev = &db_watchpoint_list;
+	     (watch = *prev) != 0;
+	     prev = &watch->link)
+	    if (db_map_equal(watch->map, map) &&
+		(watch->loaddr <= addr) &&
+		(addr < watch->hiaddr)) {
+		*prev = watch->link;
+		db_watchpoint_free(watch);
+		return;
+	    }
+
+	db_printf("Not set.\n");
+}
+
+void
+db_list_watchpoints()
+{
+	register db_watchpoint_t	watch;
+
+	if (db_watchpoint_list == 0) {
+	    db_printf("No watchpoints set\n");
+	    return;
+	}
+
+	db_printf(" Map        Address  Size\n");
+	for (watch = db_watchpoint_list;
+	     watch != 0;
+	     watch = watch->link)
+	    db_printf("%s%8x  %8x  %x\n",
+		      db_map_current(watch->map) ? "*" : " ",
+		      watch->map, watch->loaddr,
+		      watch->hiaddr - watch->loaddr);
+}
+
+/* Delete watchpoint */
+/*ARGSUSED*/
+void
+db_deletewatch_cmd(addr, have_addr, count, modif)
+	db_expr_t	addr;
+	int		have_addr;
+	db_expr_t	count;
+	char *		modif;
+{
+	db_delete_watchpoint(db_map_addr(addr), addr);
+}
+
+/* Set watchpoint */
+/*ARGSUSED*/
+void
+db_watchpoint_cmd(addr, have_addr, count, modif)
+	db_expr_t	addr;
+	int		have_addr;
+	db_expr_t	count;
+	char *		modif;
+{
+	vm_size_t	size;
+	db_expr_t	value;
+
+	if (db_expression(&value))
+	    size = (vm_size_t) value;
+	else
+	    size = 4;
+	db_skip_to_eol();
+
+	db_set_watchpoint(db_map_addr(addr), addr, size);
+}
+
+/* list watchpoints */
+void
+db_listwatch_cmd()
+{
+	db_list_watchpoints();
+}
+
+void
+db_set_watchpoints()
+{
+	register db_watchpoint_t	watch;
+
+	if (!db_watchpoints_inserted) {
+	    for (watch = db_watchpoint_list;
+	         watch != 0;
+	         watch = watch->link)
+		pmap_protect(watch->map->pmap,
+			     trunc_page(watch->loaddr),
+			     round_page(watch->hiaddr),
+			     VM_PROT_READ);
+
+	    db_watchpoints_inserted = TRUE;
+	}
+}
+
+void
+db_clear_watchpoints()
+{
+	db_watchpoints_inserted = FALSE;
+}
+
+boolean_t
+db_find_watchpoint(map, addr, regs)
+	vm_map_t	map;
+	db_addr_t	addr;
+	db_regs_t	*regs;
+{
+	register db_watchpoint_t watch;
+	db_watchpoint_t found = 0;
+
+	for (watch = db_watchpoint_list;
+	     watch != 0;
+	     watch = watch->link)
+	    if (db_map_equal(watch->map, map)) {
+		if ((watch->loaddr <= addr) &&
+		    (addr < watch->hiaddr))
+		    return (TRUE);
+		else if ((trunc_page(watch->loaddr) <= addr) &&
+			 (addr < round_page(watch->hiaddr)))
+		    found = watch;
+	    }
+
+	/*
+	 *	We didn't hit exactly on a watchpoint, but we are
+	 *	in a protected region.  We want to single-step
+	 *	and then re-protect.
+	 */
+
+	if (found) {
+	    db_watchpoints_inserted = FALSE;
+	    db_single_step(regs);
+	}
+
+	return (FALSE);
+}
diff --git a/sys/ddb/db_watch.h b/sys/ddb/db_watch.h
new file mode 100644
index 000000000000..9795755bfdcc
--- /dev/null
+++ b/sys/ddb/db_watch.h
@@ -0,0 +1,74 @@
+/* 
+ * Mach Operating System
+ * Copyright (c) 1991,1990 Carnegie Mellon University
+ * All Rights Reserved.
+ * 
+ * Permission to use, copy, modify and distribute this software and its
+ * documentation is hereby granted, provided that both the copyright
+ * notice and this permission notice appear in all copies of the
+ * software, derivative works or modified versions, and any portions
+ * thereof, and that both notices appear in supporting documentation.
+ * 
+ * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS 
+ * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
+ * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ * 
+ * Carnegie Mellon requests users of this software to return to
+ * 
+ *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
+ *  School of Computer Science
+ *  Carnegie Mellon University
+ *  Pittsburgh PA 15213-3890
+ * 
+ * any improvements or extensions that they make and grant Carnegie the
+ * rights to redistribute these changes.
+ */
+/*
+ * HISTORY
+ * $Log: db_watch.h,v $
+ * Revision 1.1  1992/03/25  21:45:40  pace
+ * Initial revision
+ *
+ * Revision 2.3  91/02/05  17:07:31  mrt
+ * 	Changed to new Mach copyright
+ * 	[91/01/31  16:20:09  mrt]
+ * 
+ * Revision 2.2  90/10/25  14:44:21  rwd
+ * 	Generalized the watchpoint support.
+ * 	[90/10/16            rwd]
+ * 	Created.
+ * 	[90/10/16            rpd]
+ * 
+ */
+/*
+ * 	Author: David B. Golub, Carnegie Mellon University
+ *	Date:	10/90
+ */
+
+#ifndef	_DDB_DB_WATCH_
+#define	_DDB_DB_WATCH_
+
+#include <vm/vm_map.h>
+#include <machine/db_machdep.h>
+
+/*
+ * Watchpoint.
+ */
+
+typedef struct db_watchpoint {
+	vm_map_t map;			/* in this map */
+	db_addr_t loaddr;		/* from this address */
+	db_addr_t hiaddr;		/* to this address */
+	struct db_watchpoint *link;	/* link in in-use or free chain */
+} *db_watchpoint_t;
+
+extern boolean_t db_find_watchpoint(/* vm_map_t map, db_addr_t addr,
+				     db_regs_t *regs */);
+extern void db_set_watchpoints();
+extern void db_clear_watchpoints();
+
+extern void db_set_watchpoint(/* vm_map_t map, db_addr_t addr, vm_size_t size */);
+extern void db_delete_watchpoint(/* vm_map_t map, db_addr_t addr */);
+extern void db_list_watchpoints();
+
+#endif	_DDB_DB_WATCH_
diff --git a/sys/ddb/db_write_cmd.c b/sys/ddb/db_write_cmd.c
new file mode 100644
index 000000000000..dce22a915c78
--- /dev/null
+++ b/sys/ddb/db_write_cmd.c
@@ -0,0 +1,120 @@
+/* 
+ * Mach Operating System
+ * Copyright (c) 1991,1990 Carnegie Mellon University
+ * All Rights Reserved.
+ * 
+ * Permission to use, copy, modify and distribute this software and its
+ * documentation is hereby granted, provided that both the copyright
+ * notice and this permission notice appear in all copies of the
+ * software, derivative works or modified versions, and any portions
+ * thereof, and that both notices appear in supporting documentation.
+ * 
+ * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS 
+ * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
+ * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ * 
+ * Carnegie Mellon requests users of this software to return to
+ * 
+ *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
+ *  School of Computer Science
+ *  Carnegie Mellon University
+ *  Pittsburgh PA 15213-3890
+ * 
+ * any improvements or extensions that they make and grant Carnegie the
+ * rights to redistribute these changes.
+ */
+/*
+ * HISTORY
+ * $Log: db_write_cmd.c,v $
+ * Revision 1.1  1992/03/25  21:45:42  pace
+ * Initial revision
+ *
+ * Revision 2.4  91/02/05  17:07:35  mrt
+ * 	Changed to new Mach copyright
+ * 	[91/01/31  16:20:19  mrt]
+ * 
+ * Revision 2.3  90/10/25  14:44:26  rwd
+ * 	Changed db_write_cmd to print unsigned.
+ * 	[90/10/19            rpd]
+ * 
+ * Revision 2.2  90/08/27  21:53:54  dbg
+ * 	Set db_prev and db_next instead of explicitly advancing dot.
+ * 	[90/08/22            dbg]
+ * 	Reflected changes in db_printsym()'s calling seq.
+ * 	[90/08/20            af]
+ * 	Warn user if nothing was written.
+ * 	[90/08/07            dbg]
+ * 	Created.
+ * 	[90/07/25            dbg]
+ * 
+ */
+/*
+ *	Author: David B. Golub,  Carnegie Mellon University
+ *	Date:	7/90
+ */
+
+#include "param.h"
+#include "proc.h"
+#include <machine/db_machdep.h>
+
+#include <ddb/db_lex.h>
+#include <ddb/db_access.h>
+#include <ddb/db_command.h>
+#include <ddb/db_sym.h>
+
+/*
+ * Write to file.
+ */
+/*ARGSUSED*/
+void
+db_write_cmd(address, have_addr, count, modif)
+	db_expr_t	address;
+	boolean_t	have_addr;
+	db_expr_t	count;
+	char *		modif;
+{
+	register
+	db_addr_t	addr;
+	register
+	db_expr_t	old_value;
+	db_expr_t	new_value;
+	register int	size;
+	boolean_t	wrote_one = FALSE;
+
+	addr = (db_addr_t) address;
+
+	switch (modif[0]) {
+	    case 'b':
+		size = 1;
+		break;
+	    case 'h':
+		size = 2;
+		break;
+	    case 'l':
+	    case '\0':
+		size = 4;
+		break;
+	    default:
+		db_error("Unknown size\n");
+		return;
+	}
+
+	while (db_expression(&new_value)) {
+	    old_value = db_get_value(addr, size, FALSE);
+	    db_printsym(addr, DB_STGY_ANY);
+	    db_printf("\t\t%#8n\t=\t%#8n\n", old_value, new_value);
+	    db_put_value(addr, size, new_value);
+	    addr += size;
+
+	    wrote_one = TRUE;
+	}
+
+	if (!wrote_one)
+	    db_error("Nothing written.\n");
+
+	db_next = addr;
+	db_prev = addr - size;
+
+	db_skip_to_eol();
+}
+