Print message with information about updating the boot code if a new

vdev is attached to a root pool (e.g. when creating a mirrored boot pool).

Reviewed by:	pav
Approved by:	delphij (mentor)
MFC after:	3 days

cddl/contrib/opensolaris/lib/libzfs/common/libzfs_pool.c

@@ -1890,18 +1890,17 @@ zpool_vdev_attach(zpool_handle_t *zhp,
 	zcmd_free_nvlists(&zc);
 
 	if (ret == 0) {
-#ifdef sun
 		if (rootpool) {
-			/*
-			 * XXX - This should be removed once we can
-			 * automatically install the bootblocks on the
-			 * newly attached disk.
-			 */
-			(void) fprintf(stderr, dgettext(TEXT_DOMAIN, "Please "
-			    "be sure to invoke %s to make '%s' bootable.\n"),
-			    BOOTCMD, new_disk);
+			(void) fprintf(stderr, dgettext(TEXT_DOMAIN, "If "
+			    "you boot from pool '%s', you may need to update\n"
+			    "boot code on newly attached disk '%s'.\n\n"
+			    "Assuming you use GPT partitioning and 'da0' is "
+			    "your new boot disk\n"
+			    "you may use the following command:\n\n"
+			    "\tgpart bootcode -b /boot/pmbr -p "
+			    "/boot/gptzfsboot -i 1 da0\n\n"),
+			    zhp->zpool_name, new_disk);
 		}
-#endif	/* sun */
 		return (0);
 	}