diff --git a/usr.sbin/config/config.h b/usr.sbin/config/config.h
index 1887c2238c65..6974b86a6faf 100644
--- a/usr.sbin/config/config.h
+++ b/usr.sbin/config/config.h
@@ -1,4 +1,4 @@
-/*	$NetBSD: config.h,v 1.38 1998/06/10 04:33:31 scottr Exp $	*/
+/*	$NetBSD: config.h,v 1.39 1998/06/24 11:20:54 jonathan Exp $	*/
 
 /*
  * Copyright (c) 1992, 1993
@@ -309,6 +309,8 @@ struct	hashtab *needcnttab;	/* retains names marked "needs-count" */
 struct	hashtab *opttab;	/* table of configured options */
 struct	hashtab *fsopttab;	/* table of configured file systems */
 struct	hashtab *defopttab;	/* options that have been "defopt"'d */
+struct	hashtab *defflagtab;	/* options that have been "defflag"'d */
+struct	hashtab *defparamtab;	/* options that have been "defparam"'d */
 struct	hashtab *deffstab;	/* defined file systems */
 struct	hashtab *optfiletab;	/* "defopt"'d option .h files */
 struct	hashtab *attrtab;	/* attributes (locators, etc.) */
@@ -362,6 +364,10 @@ void	addmkoption __P((const char *name, const char *value));
 void	deffilesystem __P((const char *fname, struct nvlist *fses));
 void	defoption __P((const char *fname, struct nvlist *opts,
 	    struct nvlist *deps));
+void	defflag __P((const char *fname, struct nvlist *opts,
+	    struct nvlist *deps));
+void	defparam __P((const char *fname, struct nvlist *opts,
+	    struct nvlist *deps));
 int	devbase_has_instances __P((struct devbase *, int));
 int	deva_has_instances __P((struct deva *, int));
 void	setupdirs __P((void));
@@ -393,6 +399,7 @@ void	initsem __P((void));
 void	*emalloc __P((size_t));
 void	*erealloc __P((void *, size_t));
 char	*sourcepath __P((const char *));
+void	warn __P((const char *, ...));			/* immediate warns */
 void	error __P((const char *, ...));			/* immediate errs */
 void	xerror __P((const char *, int, const char *, ...)); /* delayed errs */
 __dead void panic __P((const char *, ...));
diff --git a/usr.sbin/config/gram.y b/usr.sbin/config/gram.y
index f3e1a2fa0204..de476a9b2c31 100644
--- a/usr.sbin/config/gram.y
+++ b/usr.sbin/config/gram.y
@@ -1,5 +1,5 @@
 %{
-/*	$NetBSD: gram.y,v 1.23 1998/06/10 04:33:31 scottr Exp $	*/
+/*	$NetBSD: gram.y,v 1.24 1998/06/24 11:20:54 jonathan Exp $	*/
 
 /*
  * Copyright (c) 1992, 1993
@@ -97,9 +97,9 @@ static	void	check_maxpart __P((void));
 	int	val;
 }
 
-%token	AND AT ATTACH BUILD COMPILE_WITH CONFIG DEFFS DEFINE DEFOPT DEVICE
-%token	DEVCLASS DUMPS ENDFILE XFILE XOBJECT FILE_SYSTEM FLAGS INCLUDE
-%token	XMACHINE MAJOR MAKEOPTIONS
+%token	AND AT ATTACH BUILD COMPILE_WITH CONFIG DEFFS DEFINE DEFOPT 
+%token	DEFPARAM DEFFLAG DEVICE DEVCLASS DUMPS ENDFILE XFILE XOBJECT
+%token	FILE_SYSTEM FLAGS INCLUDE XMACHINE MAJOR MAKEOPTIONS
 %token	MAXUSERS MAXPARTITIONS MINOR ON OPTIONS PSEUDO_DEVICE ROOT SOURCE
 %token	TYPE WITH NEEDS_COUNT NEEDS_FLAG
 %token	<val> NUMBER
@@ -241,6 +241,10 @@ one_def:
 	DEFINE WORD interface_opt	{ (void)defattr($2, $3, 0); } |
 	DEFOPT optfile_opt defopts defoptdeps
 					{ defoption($2, $3, $4); } |
+	DEFFLAG optfile_opt defopts defoptdeps
+					{ defflag($2, $3, $4); } |
+	DEFPARAM optfile_opt defopts defoptdeps
+					{ defparam($2, $3, $4); } |
 	DEVICE devbase interface_opt attrs_opt
 					{ defdev($2, $3, $4, 0); } |
 	ATTACH devbase AT atlist devattach_opt attrs_opt
diff --git a/usr.sbin/config/main.c b/usr.sbin/config/main.c
index fc13570afc95..28eadd771b84 100644
--- a/usr.sbin/config/main.c
+++ b/usr.sbin/config/main.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: main.c,v 1.33 1998/06/10 04:33:31 scottr Exp $	*/
+/*	$NetBSD: main.c,v 1.34 1998/06/24 11:20:54 jonathan Exp $	*/
 
 /*
  * Copyright (c) 1992, 1993
@@ -88,6 +88,10 @@ static	int	mksymlinks __P((void));
 static	int	hasparent __P((struct devi *));
 static	int	cfcrosscheck __P((struct config *, const char *,
 		    struct nvlist *));
+void	defopt __P((struct hashtab *ht, const char *fname,
+	     struct nvlist *opts, struct nvlist *deps));
+
+int badfilename __P((const char *fname));
 
 int
 main(argc, argv)
@@ -177,6 +181,8 @@ usage:
 	fsopttab = ht_new();
 	deffstab = ht_new();
 	defopttab = ht_new();
+	defparamtab = ht_new();
+	defflagtab = ht_new();
 	optfiletab = ht_new();
 	nextopt = &options;
 	nextmkopt = &mkoptions;
@@ -390,13 +396,40 @@ deffilesystem(fname, fses)
 	}
 }
 
+/*
+ * Sanity check a file name.
+ */
+int
+badfilename(fname)
+	const char *fname;
+{
+	const char *n;
+
+	/*
+	 * We're putting multiple options into one file.  Sanity
+	 * check the file name.
+	 */
+	if (strchr(fname, '/') != NULL) {
+		error("option file name contains a `/'");
+		return 1;
+	}
+	if ((n = strrchr(fname, '.')) == NULL || strcmp(n, ".h") != 0) {
+		error("option file name does not end in `.h'");
+		return 1;
+	}
+	return 0;
+}
+
+
 /*
  * Define one or more standard options.  If an option file name is specified,
  * place all options in one file with the specified name.  Otherwise, create
  * an option file for each option.
+ * record the option information in the specified table.
  */
 void
-defoption(fname, opts, deps)
+defopt(ht, fname, opts, deps)
+	struct hashtab *ht;
 	const char *fname;
 	struct nvlist *opts, *deps;
 {
@@ -405,19 +438,8 @@ defoption(fname, opts, deps)
 	char *p, c;
 	char low[500];
 
-	if (fname != NULL) {
-		/*
-		 * We're putting multiple options into one file.  Sanity
-		 * check the file name.
-		 */
-		if (strchr(fname, '/') != NULL) {
-			error("option file name contains a `/'");
-			return;
-		}
-		if ((n = strrchr(fname, '.')) == NULL || strcmp(n, ".h") != 0) {
-			error("option file name does not end in `.h'");
-			return;
-		}
+	if (fname != NULL && badfilename(fname)) {
+		return;
 	}
 
 	/*
@@ -425,7 +447,7 @@ defoption(fname, opts, deps)
 	 */
 	for (nv = opts; nv != NULL; nv = nextnv) {
 		nextnv = nv->nv_next;
-		if (ht_insert(defopttab, nv->nv_name, nv)) {
+		if (ht_insert(ht, nv->nv_name, nv)) {
 			error("file system or option `%s' already defined",
 			    nv->nv_name);
 			return;
@@ -474,6 +496,44 @@ defoption(fname, opts, deps)
 	}
 }
 
+/*
+ * Define one or more standard options.  If an option file name is specified,
+ * place all options in one file with the specified name.  Otherwise, create
+ * an option file for each option.
+ */
+void
+defoption(fname, opts, deps)
+	const char *fname;
+	struct nvlist *opts, *deps;
+{
+	defopt(defopttab, fname, opts, deps);
+}
+
+
+/*
+ * Define an option for which a value is required. 
+ */
+void
+defparam(fname, opts, deps)
+	const char *fname;
+	struct nvlist *opts, *deps;
+{
+	defopt(defparamtab, fname, opts, deps);
+}
+
+/*
+ * Define an option which must have a value, and which
+ * emits  a "needs-flag" style output.
+ */
+void
+defflag(fname, opts, deps)
+	const char *fname;
+	struct nvlist *opts, *deps;
+{
+	defopt(defflagtab, fname, opts, deps);
+}
+
+
 /*
  * Add an option from "options FOO".  Note that this selects things that
  * are "optional foo".
@@ -485,12 +545,38 @@ addoption(name, value)
 	const char *n;
 	char *p, c;
 	char low[500];
+	int is_fs, is_param, is_flag, is_opt, is_undecl;
+
+	/* 
+	 * Figure out how this option was declared (if at all.)
+	 * XXX should use "params" and "flags" in config.
+	 * XXX crying out for a type field in a unified hashtab.
+	 */
+	is_fs = ht_lookup(deffstab, name) != NULL;
+	is_param = ht_lookup(defparamtab, name) != NULL;
+	is_opt = ht_lookup(defopttab, name) != NULL;
+	is_flag = ht_lookup(defflagtab, name) != NULL;
+	is_undecl = (!is_param && !is_flag && !is_fs && !is_opt);
 
 	/* Make sure this is not a defined file system. */
-	if (ht_lookup(deffstab, name) != NULL) {
+	if (is_fs) {
 		error("`%s' is a defined file system", name);
 		return;
 	}
+	/* A defparam must have a value */
+	if (is_param && value == NULL) {
+		error("option `%s' must have a value", name);
+		return;
+	}
+	/* A defflag must not have a value */
+	if (is_flag && value != NULL) {
+		error("option `%s' must not have a value", name);
+		return;
+	}
+
+	if (is_undecl) {
+		warn("undeclared option `%s' added to IDENT", name);
+	}
 
 	if (do_option(opttab, &nextopt, name, value, "options"))
 		return;
diff --git a/usr.sbin/config/mkheaders.c b/usr.sbin/config/mkheaders.c
index 885610bd370d..dc708001bcee 100644
--- a/usr.sbin/config/mkheaders.c
+++ b/usr.sbin/config/mkheaders.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: mkheaders.c,v 1.18 1998/02/19 06:13:51 thorpej Exp $	*/
+/*	$NetBSD: mkheaders.c,v 1.19 1998/06/24 11:20:55 jonathan Exp $	*/
 
 /*
  * Copyright (c) 1992, 1993
@@ -61,6 +61,7 @@ static int locators_print __P((const char *, void *, void *));
 static int defopts_print __P((const char *, void *, void *));
 static char *cntname __P((const char *));
 static int cmphdr __P((const char *, const char *));
+static int fprintcnt(FILE *fp, struct nvlist *nv);
 
 
 /*
@@ -88,6 +89,16 @@ mkheaders()
 	return (0);
 }
 
+
+static int
+fprintcnt(fp, nv)
+	FILE *fp;
+	struct nvlist *nv;
+{
+	return (fprintf(fp, "#define\t%s\t%d\n",
+	     cntname(nv->nv_name), nv->nv_int));
+}
+
 static int
 emitcnt(head)
 	struct nvlist *head;
@@ -106,8 +117,7 @@ emitcnt(head)
 	}
 
 	for (nv = head; nv != NULL; nv = nv->nv_next)
-		if (fprintf(fp, "#define\t%s\t%d\n",
-		    cntname(nv->nv_name), nv->nv_int) < 0)
+		if (fprintcnt(fp, nv) < 0)
 			return (err("writ", tfname, fp));
 
 	if (fclose(fp) == EOF)
@@ -128,6 +138,8 @@ defopts_print(name, value, arg)
 	char tfname[BUFSIZ];
 	struct nvlist *nv, *option;
 	int isfsoption;
+	int isparam;
+	int isflag;
 	FILE *fp;
 
 	(void)sprintf(tfname, "tmp_%s", name);
@@ -139,6 +151,8 @@ defopts_print(name, value, arg)
 
 	for (nv = value; nv != NULL; nv = nv->nv_next) {
 		isfsoption = (ht_lookup(deffstab, nv->nv_name) != NULL);
+		isparam  = (ht_lookup(defparamtab, nv->nv_name) != NULL);
+		isflag  = (ht_lookup(defflagtab, nv->nv_name) != NULL);
 
 		if ((option = ht_lookup(opttab, nv->nv_name)) == NULL &&
 		    (option = ht_lookup(fsopttab, nv->nv_name)) == NULL) {
@@ -155,6 +169,9 @@ defopts_print(name, value, arg)
 			if (fputc('\n', fp) < 0)
 				goto bad;
 		}
+		if (isflag)
+			fprintcnt(fp, nv);
+
 	}
 
 	if (fclose(fp) == EOF)
diff --git a/usr.sbin/config/scan.l b/usr.sbin/config/scan.l
index a8b4177442a3..2520fc8d0135 100644
--- a/usr.sbin/config/scan.l
+++ b/usr.sbin/config/scan.l
@@ -1,5 +1,5 @@
 %{
-/*	$NetBSD: scan.l,v 1.21 1998/04/09 00:32:39 tv Exp $	*/
+/*	$NetBSD: scan.l,v 1.22 1998/06/24 11:20:55 jonathan Exp $	*/
 
 /*
  * Copyright (c) 1992, 1993
@@ -90,7 +90,9 @@ compile-with	return COMPILE_WITH;
 config		return CONFIG;
 deffs		return DEFFS;
 define		return DEFINE;
+defflag		return DEFFLAG;
 defopt		return DEFOPT;
+defparam	return DEFPARAM;
 devclass	return DEVCLASS;
 device		return DEVICE;
 dumps		return DUMPS;
diff --git a/usr.sbin/config/util.c b/usr.sbin/config/util.c
index 434895562401..62f49f0a0a07 100644
--- a/usr.sbin/config/util.c
+++ b/usr.sbin/config/util.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: util.c,v 1.6 1997/10/18 07:59:38 lukem Exp $	*/
+/*	$NetBSD: util.c,v 1.7 1998/06/24 11:20:55 jonathan Exp $	*/
 
 /*
  * Copyright (c) 1992, 1993
@@ -58,6 +58,9 @@
 
 static void nomem __P((void));
 static void vxerror __P((const char *, int, const char *, va_list));
+static void vxwarn __P((const char *, int, const char *, va_list));
+static void vxmsg __P((const char *fname, int line, const char *class, 
+		       const char *fmt, va_list));
 
 /*
  * Malloc, with abort on error.
@@ -165,6 +168,38 @@ nvfreel(nv)
 	}
 }
 
+void
+#if __STDC__
+warn(const char *fmt, ...)
+#else
+warn(fmt, va_alist)
+	const char *fmt;
+	va_dcl
+#endif
+{
+	va_list ap;
+	extern const char *yyfile;
+
+#if __STDC__
+	va_start(ap, fmt);
+#else
+	va_start(ap);
+#endif
+	vxwarn(yyfile, currentline(), fmt, ap);
+	va_end(ap);
+}
+
+
+static void
+vxwarn(file, line, fmt, ap)
+	const char *file;
+	int line;
+	const char *fmt;
+	va_list ap;
+{
+	vxmsg(file, line, "warning: ", fmt, ap);
+}
+
 /*
  * External (config file) error.  Complain, using current file
  * and line number.
@@ -176,7 +211,7 @@ error(const char *fmt, ...)
 error(fmt, va_alist)
 	const char *fmt;
 	va_dcl
-#endif
+#endif	/* __STDC__ */
 {
 	va_list ap;
 	extern const char *yyfile;
@@ -226,13 +261,11 @@ vxerror(file, line, fmt, ap)
 	const char *fmt;
 	va_list ap;
 {
-
-	(void)fprintf(stderr, "%s:%d: ", file, line);
-	(void)vfprintf(stderr, fmt, ap);
-	(void)putc('\n', stderr);
+	vxmsg(file, line, "", fmt, ap);
 	errors++;
 }
 
+
 /*
  * Internal error, abort.
  */
@@ -258,3 +291,20 @@ panic(fmt, va_alist)
 	va_end(ap);
 	exit(2);
 }
+
+/*
+ * Internal form of error() and xerror().
+ */
+static void
+vxmsg(file, line, msgclass, fmt, ap)
+	const char *file;
+	int line;
+	const char *msgclass;
+	const char *fmt;
+	va_list ap;
+{
+
+	(void)fprintf(stderr, "%s:%d: %s", file, line, msgclass);
+	(void)vfprintf(stderr, fmt, ap);
+	(void)putc('\n', stderr);
+}