diff --git a/qemu/scripts/qapi-event.py b/qemu/scripts/qapi-event.py
index abec6289..30e64584 100644
--- a/qemu/scripts/qapi-event.py
+++ b/qemu/scripts/qapi-event.py
@@ -79,7 +79,10 @@ def gen_event_send(name, arg_type, boxed):
     QObject *obj;
     Visitor *v;
 ''')
-        ret += gen_param_var(arg_type)
+        if not boxed:
+            ret += gen_param_var(arg_type)
+    else:
+        assert not boxed
 
     ret += mcgen('''
 
diff --git a/qemu/scripts/qapi.py b/qemu/scripts/qapi.py
index 3b8703a5..570a74ec 100644
--- a/qemu/scripts/qapi.py
+++ b/qemu/scripts/qapi.py
@@ -526,10 +526,14 @@ def check_type(expr_info, source, value, allow_array=False,
 
 def check_command(expr, expr_info):
     name = expr['command']
+    boxed = expr.get('boxed', False)
 
+    args_meta = ['struct']
+    if boxed:
+        args_meta += ['union', 'alternate']
     check_type(expr_info, "'data' for command '%s'" % name,
-               expr.get('data'), allow_dict=True, allow_optional=True,
-               allow_metas=['struct'])
+               expr.get('data'), allow_dict=not boxed, allow_optional=True,
+               allow_metas=args_meta)
     returns_meta = ['union', 'struct']
     if name in returns_whitelist:
         returns_meta += ['built-in', 'alternate', 'enum']
@@ -541,11 +545,15 @@ def check_command(expr, expr_info):
 def check_event(expr, expr_info):
     global events
     name = expr['event']
+    boxed = expr.get('boxed', False)
 
+    meta = ['struct']
+    if boxed:
+        meta += ['union', 'alternate']
     events.append(name)
     check_type(expr_info, "'data' for event '%s'" % name,
-               expr.get('data'), allow_dict=True, allow_optional=True,
-               allow_metas=['struct'])
+               expr.get('data'), allow_dict=not boxed, allow_optional=True,
+               allow_metas=meta)
 
 
 def check_union(expr, expr_info):
@@ -699,6 +707,10 @@ def check_keys(expr_elem, meta, required, optional=[]):
             raise QAPIExprError(info,
                                 "'%s' of %s '%s' should only use false value"
                                 % (key, meta, name))
+        if key == 'boxed' and value is not True:
+            raise QAPIExprError(info,
+                                "'%s' of %s '%s' should only use true value"
+                                % (key, meta, name))
     for key in required:
         if key not in expr:
             raise QAPIExprError(info,
@@ -730,10 +742,10 @@ def check_exprs(exprs):
             add_struct(expr, info)
         elif 'command' in expr:
             check_keys(expr_elem, 'command', [],
-                       ['data', 'returns', 'gen', 'success-response'])
+                       ['data', 'returns', 'gen', 'success-response', 'boxed'])
             add_name(expr['command'], info, 'command')
         elif 'event' in expr:
-            check_keys(expr_elem, 'event', [], ['data'])
+            check_keys(expr_elem, 'event', [], ['data', 'boxed'])
             add_name(expr['event'], info, 'event')
         else:
             raise QAPIExprError(expr_elem['info'],
@@ -1177,6 +1189,9 @@ class QAPISchemaAlternateType(QAPISchemaType):
     def visit(self, visitor):
         visitor.visit_alternate_type(self.name, self.info, self.variants)
 
+    def is_empty(self):
+        return False
+
 
 class QAPISchemaCommand(QAPISchemaEntity):
     def __init__(self, name, info, arg_type, ret_type, gen, success_response,
@@ -1195,9 +1210,19 @@ class QAPISchemaCommand(QAPISchemaEntity):
     def check(self, schema):
         if self._arg_type_name:
             self.arg_type = schema.lookup_type(self._arg_type_name)
-            assert isinstance(self.arg_type, QAPISchemaObjectType)
-            assert not self.arg_type.variants   # not implemented
-            assert not self.boxed               # not implemented
+            assert (isinstance(self.arg_type, QAPISchemaObjectType) or
+                    isinstance(self.arg_type, QAPISchemaAlternateType))
+            self.arg_type.check(schema)
+            if self.boxed:
+                if self.arg_type.is_empty():
+                    raise QAPIExprError(self.info,
+                                        "Cannot use 'boxed' with empty type")
+            else:
+                assert not isinstance(self.arg_type, QAPISchemaAlternateType)
+                assert not self.arg_type.variants
+        elif self.boxed:
+            raise QAPIExprError(self.info,
+                                "Use of 'boxed' requires 'data'")
         if self._ret_type_name:
             self.ret_type = schema.lookup_type(self._ret_type_name)
             assert isinstance(self.ret_type, QAPISchemaType)
@@ -1219,9 +1244,19 @@ class QAPISchemaEvent(QAPISchemaEntity):
     def check(self, schema):
         if self._arg_type_name:
             self.arg_type = schema.lookup_type(self._arg_type_name)
-            assert isinstance(self.arg_type, QAPISchemaObjectType)
-            assert not self.arg_type.variants   # not implemented
-            assert not self.boxed               # not implemented
+            assert (isinstance(self.arg_type, QAPISchemaObjectType) or
+                    isinstance(self.arg_type, QAPISchemaAlternateType))
+            self.arg_type.check(schema)
+            if self.boxed:
+                if self.arg_type.is_empty():
+                    raise QAPIExprError(self.info,
+                                        "Cannot use 'boxed' with empty type")
+            else:
+                assert not isinstance(self.arg_type, QAPISchemaAlternateType)
+                assert not self.arg_type.variants
+        elif self.boxed:
+            raise QAPIExprError(self.info,
+                                "Use of 'boxed' requires 'data'")
 
     def visit(self, visitor):
         visitor.visit_event(self.name, self.info, self.arg_type, self.boxed)
@@ -1661,9 +1696,11 @@ extern const char *const %(c_name)s_lookup[];
 
 def gen_params(arg_type, boxed, extra):
     if not arg_type:
+        assert not boxed
         return extra
     if boxed:
-        assert False     # not implemented
+        ret += '%s arg' % arg_type.c_param_type()
+        sep = ', '
     else:
         assert not arg_type.variants
         for memb in arg_type.members: