Index: head/sys/kern/subr_unit.c
===================================================================
--- head/sys/kern/subr_unit.c
+++ head/sys/kern/subr_unit.c
@@ -68,11 +68,11 @@
  */
 
 #include <sys/types.h>
-#include <sys/bitstring.h>
 #include <sys/_unrhdr.h>
 
 #ifdef _KERNEL
 
+#include <sys/bitstring.h>
 #include <sys/param.h>
 #include <sys/malloc.h>
 #include <sys/kernel.h>
@@ -98,6 +98,11 @@
 
 #else /* ...USERLAND */
 
+#include <bitstring.h>
+#include <err.h>
+#include <errno.h>
+#include <getopt.h>
+#include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -880,9 +885,13 @@
 #ifndef _KERNEL	/* USERLAND test driver */
 
 /*
- * Simple stochastic test driver for the above functions
+ * Simple stochastic test driver for the above functions.  The code resides
+ * here so that it can access static functions and structures.
  */
 
+static bool verbose;
+#define VPRINTF(...)	{if (verbose) printf(__VA_ARGS__);}
+
 static void
 print_unr(struct unrhdr *uh, struct unr *up)
 {
@@ -933,7 +942,7 @@
 	int j;
 
 	if (a[i]) {
-		printf("F %u\n", i);
+		VPRINTF("F %u\n", i);
 		free_unr(uh, i);
 		a[i] = 0;
 	} else {
@@ -941,7 +950,7 @@
 		j = alloc_unr(uh);
 		if (j != -1) {
 			a[j] = 1;
-			printf("A %d\n", j);
+			VPRINTF("A %d\n", j);
 		}
 		no_alloc = 0;
 	}
@@ -954,40 +963,73 @@
 
 	j = alloc_unr_specific(uh, i);
 	if (j == -1) {
-		printf("F %u\n", i);
+		VPRINTF("F %u\n", i);
 		a[i] = 0;
 		free_unr(uh, i);
 	} else {
 		a[i] = 1;
-		printf("A %d\n", j);
+		VPRINTF("A %d\n", j);
 	}
 }
 
-/* Number of unrs to test */
-#define NN	10000
+static void
+usage(char** argv)
+{
+	printf("%s [-h] [-r REPETITIONS] [-v]\n", argv[0]);
+}
 
 int
-main(int argc __unused, const char **argv __unused)
+main(int argc, char **argv)
 {
 	struct unrhdr *uh;
+	char *a;
+	long count = 10000;	/* Number of unrs to test */
+	long reps = 1;
+	int ch;
 	u_int i, x, m, j;
-	char a[NN];
+
+	verbose = false;
+
+	while ((ch = getopt(argc, argv, "hr:v")) != -1) {
+		switch (ch) {
+		case 'r':
+			errno = 0;
+			reps = strtol(optarg, NULL, 0);
+			if (errno == ERANGE || errno == EINVAL) {
+				usage(argv);
+				exit(2);
+			}
+			
+			break;
+		case 'v':
+			verbose = true;
+			break;
+		case 'h':
+		default:
+			usage(argv);
+			exit(2);
+		}
+
+
+	}
 
 	setbuf(stdout, NULL);
-	uh = new_unrhdr(0, NN - 1, NULL);
+	uh = new_unrhdr(0, count - 1, NULL);
 	print_unrhdr(uh);
 
-	memset(a, 0, sizeof a);
+	a = calloc(count, sizeof(char));
+	if (a == NULL)
+		err(1, "calloc failed");
 	srandomdev();
 
-	fprintf(stderr, "sizeof(struct unr) %zu\n", sizeof(struct unr));
-	fprintf(stderr, "sizeof(struct unrb) %zu\n", sizeof(struct unrb));
-	fprintf(stderr, "sizeof(struct unrhdr) %zu\n", sizeof(struct unrhdr));
-	fprintf(stderr, "NBITS %d\n", NBITS);
+	printf("sizeof(struct unr) %zu\n", sizeof(struct unr));
+	printf("sizeof(struct unrb) %zu\n", sizeof(struct unrb));
+	printf("sizeof(struct unrhdr) %zu\n", sizeof(struct unrhdr));
+	printf("NBITS %d\n", NBITS);
 	x = 1;
-	for (m = 0; m < NN * 100; m++) {
+	for (m = 0; m < count * reps; m++) {
 		j = random();
-		i = (j >> 1) % NN;
+		i = (j >> 1) % count;
 #if 0
 		if (a[i] && (j & 1))
 			continue;
@@ -997,19 +1039,22 @@
 		else
 			test_alloc_unr_specific(uh, i, a);
 
-		if (1)	/* XXX: change this for detailed debug printout */
+		if (verbose)
 			print_unrhdr(uh);
 		check_unrhdr(uh, __LINE__);
 	}
-	for (i = 0; i < NN; i++) {
+	for (i = 0; i < count; i++) {
 		if (a[i]) {
-			printf("C %u\n", i);
+			if (verbose) {
+				printf("C %u\n", i);
+				print_unrhdr(uh);
+			}
 			free_unr(uh, i);
-			print_unrhdr(uh);
 		}
 	}
 	print_unrhdr(uh);
 	delete_unrhdr(uh);
+	free(a);
 	return (0);
 }
 #endif
Index: head/tests/sys/kern/Makefile
===================================================================
--- head/tests/sys/kern/Makefile
+++ head/tests/sys/kern/Makefile
@@ -4,12 +4,14 @@
 FILESGROUPS=	TESTS
 TESTSPACKAGE=	${PACKAGE}
 TESTSRC=	${SRCTOP}/contrib/netbsd-tests/kernel
+.PATH:		${SRCTOP}/sys/kern
 
 TESTSDIR=	${TESTSBASE}/sys/kern
 
 ATF_TESTS_C+=	kern_copyin
 ATF_TESTS_C+=	kern_descrip_test
 ATF_TESTS_C+=	ptrace_test
+PLAIN_TESTS_C+=	subr_unit_test
 ATF_TESTS_C+=	unix_seqpacket_test
 ATF_TESTS_C+=	unix_passfd_test
 TEST_METADATA.unix_seqpacket_test+=	timeout="15"
@@ -23,6 +25,14 @@
 CFLAGS.mqueue_test+=	-I${SRCTOP}/tests
 LIBADD.mqueue_test+=	rt
 
+# subr_unit.c contains functions whose prototypes lie in headers that cannot be
+# included in userland.  But as far as subr_unit_test goes, they're effectively
+# static.  So it's ok to disable -Wmissing-prototypes for this program.
+CFLAGS.subr_unit.c+=	-Wno-missing-prototypes
+# XXX: -Wno-sign-compare will be eliminated as part of D6004
+CFLAGS.subr_unit.c+=	-Wno-sign-compare
+SRCS.subr_unit_test+=	subr_unit.c
+
 WARNS?=	5
 
 TESTS_SUBDIRS+=	acct