diff -ur on17/usr/src/uts/common/fs/ufs/ufs_vfsops.c bc-on17/usr/src/uts/common/fs/ufs/ufs_vfsops.c
--- on17/usr/src/uts/common/fs/ufs/ufs_vfsops.c	Tue Jun 14 02:45:19 2005
+++ bc-on17/usr/src/uts/common/fs/ufs/ufs_vfsops.c	Sun Jul 10 23:38:01 2005
@@ -551,7 +551,7 @@
 
 	/* cannot remount to RDONLY */
 	if (vfsp->vfs_flag & VFS_RDONLY)
-		return (EINVAL);
+		return (ENOTSUP);
 
 	/* whoops, wrong dev */
 	if (vfsp->vfs_dev != dev)