Index: head/sbin/fsck_ffs/pass5.c
===================================================================
--- head/sbin/fsck_ffs/pass5.c
+++ head/sbin/fsck_ffs/pass5.c
@@ -35,6 +35,7 @@
 #include <sys/cdefs.h>
 __FBSDID("$FreeBSD$");
 
+#define	IN_RTLD			/* So we pickup the P_OSREL defines */
 #include <sys/param.h>
 #include <sys/sysctl.h>
 
@@ -73,6 +74,7 @@
 	newcg->cg_niblk = fs->fs_ipg;
 	if (preen == 0 && yflag == 0 && fs->fs_magic == FS_UFS2_MAGIC &&
 	    fswritefd != -1 && (fs->fs_metackhash & CK_CYLGRP) == 0 &&
+	    getosreldate() >= P_OSREL_CK_CLYGRP &&
 	    reply("ADD CYLINDER GROUP CHECKSUM PROTECTION") != 0) {
 		fs->fs_metackhash |= CK_CYLGRP;
 		rewritecg = 1;
Index: head/sbin/newfs/mkfs.c
===================================================================
--- head/sbin/newfs/mkfs.c
+++ head/sbin/newfs/mkfs.c
@@ -44,6 +44,7 @@
 #include <sys/cdefs.h>
 __FBSDID("$FreeBSD$");
 
+#define	IN_RTLD			/* So we pickup the P_OSREL defines */
 #include <sys/param.h>
 #include <sys/disklabel.h>
 #include <sys/file.h>
@@ -495,7 +496,7 @@
 	/*
 	 * Set flags for metadata that is being check-hashed.
 	 */
-	if (Oflag > 1)
+	if (Oflag > 1 && getosreldate() >= P_OSREL_CK_CLYGRP)
 		sblock.fs_metackhash = CK_CYLGRP;
 
 	/*
Index: head/sbin/newfs/newfs.c
===================================================================
--- head/sbin/newfs/newfs.c
+++ head/sbin/newfs/newfs.c
@@ -398,10 +398,6 @@
 		if (pp != NULL)
 			pp->p_size *= secperblk;
 	}
-	if (getosreldate() < __FreeBSD_version) {
-		warnx("%s is newer than the running kernel and may not be compatible",
-		    getprogname());
-	}
 	mkfs(pp, special);
 	ufs_disk_close(&disk);
 	if (!jflag)
Index: head/sys/sys/param.h
===================================================================
--- head/sys/sys/param.h
+++ head/sys/sys/param.h
@@ -84,6 +84,7 @@
 #define	P_OSREL_SHUTDOWN_ENOTCONN	1100077
 #define	P_OSREL_MAP_GUARD		1200035
 #define	P_OSREL_WRFSBASE		1200041
+#define	P_OSREL_CK_CLYGRP		1200046
 #define	P_OSREL_VMTOTAL64		1200054
 
 #define	P_OSREL_MAJOR(x)		((x) / 100000)