Index: usr.sbin/config/config.h
===================================================================
--- usr.sbin/config/config.h
+++ usr.sbin/config/config.h
@@ -58,6 +58,7 @@
 	char	*f_warn;		/* warning message */
 	const char *f_objprefix;	/* prefix string for object name */
 	const char *f_srcprefix;	/* source prefix such as $S/ */
+	char	*f_requires;		/* which other options does this require */
 };
 
 struct files_name {
Index: usr.sbin/config/configvers.h
===================================================================
--- usr.sbin/config/configvers.h
+++ usr.sbin/config/configvers.h
@@ -49,7 +49,7 @@
  *
  * $FreeBSD$
  */
-#define	CONFIGVERS	600018
+#define	CONFIGVERS	600019
 #define	MAJOR_VERS(x)	((x) / 100000)
 
 /* Last config(8) version to require envmode/hintmode */
Index: usr.sbin/config/mkmakefile.c
===================================================================
--- usr.sbin/config/mkmakefile.c
+++ usr.sbin/config/mkmakefile.c
@@ -129,6 +129,36 @@
 	return (ifp);
 }
 
+/*
+ * Make sure that we have all the required options.
+ */
+static void
+check_required_devices(void)
+{
+	struct file_list *tp;
+	struct device *dp;
+	bool found;
+	const char *name;
+
+	STAILQ_FOREACH(tp, &ftab, f_next) {
+		if (tp->f_requires == NULL)
+			continue;
+		name = tp->f_requires;
+		found = false;
+		STAILQ_FOREACH(dp, &dtab, d_next) {
+			if (eq(dp->d_name, name)) {
+				found = true;
+				break;
+			}
+		}
+		if (!found) {
+			printf("File %s requires device %s, which is not present\n",
+			    tp->f_fn, tp->f_requires);
+			exit(1);
+		}
+	}
+}
+
 /*
  * Build the makefile from the skeleton
  */
@@ -140,6 +170,7 @@
 	struct opt *op, *t;
 
 	read_files();
+	check_required_devices();
 	ifp = open_makefile_template();
 	ofp = fopen(path("Makefile.new"), "w");
 	if (ofp == NULL)
@@ -392,7 +423,7 @@
 	struct file_list *tp;
 	struct device *dp;
 	struct opt *op;
-	char *wd, *this, *compilewith, *depends, *clean, *warning;
+	char *wd, *this, *compilewith, *depends, *clean, *warning, *requires;
 	const char *objprefix;
 	int compile, match, nreqs, std, filetype, not,
 	    imp_rule, no_ctfconvert, no_obj, before_depend, nowerror;
@@ -409,6 +440,7 @@
 	 *      [ dependency "dependency-list"] [ before-depend ]
 	 *	[ clean "file-list"] [ warning "text warning" ]
 	 *	[ obj-prefix "file prefix"]
+	 *	[ requires "requires-list" ]
 	 *	[ nowerror ] [ local ]
 	 */
 	wd = get_word(fp);
@@ -448,6 +480,7 @@
 	depends = NULL;
 	clean = NULL;
 	warning = NULL;
+	requires = NULL;
 	std = 0;
 	imp_rule = 0;
 	no_ctfconvert = 0;
@@ -507,6 +540,14 @@
 			depends = ns(wd);
 			continue;
 		}
+		if (eq(wd, "requires")) {
+			wd = get_quoted_word(fp);
+			if (wd == (char *)EOF || wd == NULL)
+				errout("%s: %s missing dependency string.\n",
+				       fname, this);
+			requires = ns(wd);
+			continue;
+		}
 		if (eq(wd, "clean")) {
 			wd = get_quoted_word(fp);
 			if (wd == (char *)EOF || wd == NULL)
@@ -597,6 +638,7 @@
 		if (nowerror)
 			tp->f_flags |= NOWERROR;
 		tp->f_compilewith = compilewith;
+		tp->f_requires = requires;
 		tp->f_depends = depends;
 		tp->f_clean = clean;
 		tp->f_warn = warning;