12071 clarify implementation of single_instance in SMF services
Reviewed by: Robert Mustacchi <rm@fingolfin.org>

@@ -19,11 +19,11 @@
  * CDDL HEADER END
  */
 
 /*
  * Copyright (c) 2004, 2010, Oracle and/or its affiliates. All rights reserved.
- * Copyright 2015 Joyent, Inc.
+ * Copyright 2019 Joyent, Inc.
  * Copyright 2012 Milan Jurik. All rights reserved.
  * Copyright 2017 RackTop Systems.
  * Copyright 2018 OmniOS Community Edition (OmniOSce) Association.
  */
 

@@ -9741,10 +9741,14 @@
         while ((ret = scf_iter_next_property(exp_prop_iter, exp_prop)) == 1) {
                 if (scf_property_get_name(exp_prop, exp_str, exp_str_sz) < 0)
                         scfdie();
 
                 if (strcmp(exp_str, SCF_PROPERTY_SINGLE_INSTANCE) == 0) {
+                        /*
+                         * Unimplemented and obsolete, but we still process it
+                         * for compatibility purposes.
+                         */
                         if (prop_check_type(exp_prop, SCF_TYPE_BOOLEAN) == 0 &&
                             prop_get_val(exp_prop, exp_val) == 0) {
                                 uint8_t b;
 
                                 if (scf_value_get_boolean(exp_val, &b) !=