[PATCH 10/13] migration: Improve example and documentation of vmstate_register()

[Juan Quintela]

Signed-off-by: Juan Quintela <quintela@redhat.com>
---
 docs/devel/migration.rst | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/docs/devel/migration.rst b/docs/devel/migration.rst
index c3e1400c0c..a9fde75862 100644
--- a/docs/devel/migration.rst
+++ b/docs/devel/migration.rst
@@ -165,13 +165,17 @@ An example (from hw/input/pckbd.c)
       }
   };
 
-We are declaring the state with name "pckbd".
-The ``version_id`` is 3, and the fields are 4 uint8_t in a KBDState structure.
-We registered this with:
+We are declaring the state with name "pckbd".  The ``version_id`` is
+3, and the fields are 4 uint8_t in a KBDState structure.  We
+registered this with one of those.  The first one will generate a
+device ``instance_id`` different for each registration.  Use the
+second one if you already have an id different for each instance of
+the device:
 
 .. code:: c
 
-    vmstate_register(NULL, 0, &vmstate_kbd, s);
+    vmstate_register_any(NULL, &vmstate_kbd, s);
+    vmstate_register(NULL, instance_id, &vmstate_kbd, s);
 
 For devices that are ``qdev`` based, we can register the device in the class
 init function:
-- 
2.41.0