diff --git a/include/qapi/compat-policy.h b/include/qapi/compat-policy.h
new file mode 100644
index 0000000000..b8c6638156
--- /dev/null
+++ b/include/qapi/compat-policy.h
@@ -0,0 +1,20 @@
+/*
+ * Policy for handling "funny" management interfaces
+ *
+ * Copyright (C) 2020 Red Hat, Inc.
+ *
+ * Authors:
+ *  Markus Armbruster <armbru@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or
+ * later.  See the COPYING file in the top-level directory.
+ */
+
+#ifndef QAPI_COMPAT_POLICY_H
+#define QAPI_COMPAT_POLICY_H
+
+#include "qapi/qapi-types-compat.h"
+
+extern CompatPolicy compat_policy;
+
+#endif
diff --git a/qapi/compat.json b/qapi/compat.json
new file mode 100644
index 0000000000..fc24a58a9e
--- /dev/null
+++ b/qapi/compat.json
@@ -0,0 +1,51 @@
+# -*- Mode: Python -*-
+
+##
+# = Compatibility policy
+##
+
+##
+# @CompatPolicyInput:
+#
+# Policy for handling "funny" input.
+#
+# @accept: Accept silently
+# @reject: Reject with an error
+#
+# Since: 6.0
+##
+{ 'enum': 'CompatPolicyInput',
+  'data': [ 'accept', 'reject' ] }
+
+##
+# @CompatPolicyOutput:
+#
+# Policy for handling "funny" output.
+#
+# @accept: Pass on unchanged
+# @hide: Filter out
+#
+# Since: 6.0
+##
+{ 'enum': 'CompatPolicyOutput',
+  'data': [ 'accept', 'hide' ] }
+
+##
+# @CompatPolicy:
+#
+# Policy for handling deprecated management interfaces.
+#
+# This is intended for testing users of the management interfaces.
+#
+# Limitation: covers only syntactic aspects of QMP, i.e. stuff tagged
+# with feature 'deprecated'.  We may want to extend it to cover
+# semantic aspects, CLI, and experimental features.
+#
+# @deprecated-input: how to handle deprecated input (default 'accept')
+# @deprecated-output: how to handle deprecated output (default 'accept')
+#
+# Since: 6.0
+##
+{ 'struct': 'CompatPolicy',
+  'data': { '*deprecated-input': 'CompatPolicyInput',
+            '*deprecated-output': 'CompatPolicyOutput' } }
diff --git a/qapi/meson.build b/qapi/meson.build
index d4424ae6e7..0d20226fa3 100644
--- a/qapi/meson.build
+++ b/qapi/meson.build
@@ -25,6 +25,7 @@ qapi_all_modules = [
   'block-export',
   'char',
   'common',
+  'compat',
   'control',
   'crypto',
   'dump',
diff --git a/qapi/qapi-schema.json b/qapi/qapi-schema.json
index 3441c9a9ae..4912b9744e 100644
--- a/qapi/qapi-schema.json
+++ b/qapi/qapi-schema.json
@@ -79,6 +79,7 @@
 { 'include': 'migration.json' }
 { 'include': 'transaction.json' }
 { 'include': 'trace.json' }
+{ 'include': 'compat.json' }
 { 'include': 'control.json' }
 { 'include': 'introspect.json' }
 { 'include': 'qom.json' }
diff --git a/qapi/qmp-dispatch.c b/qapi/qmp-dispatch.c
index 5e597c76f7..f6a65f502d 100644
--- a/qapi/qmp-dispatch.c
+++ b/qapi/qmp-dispatch.c
@@ -14,6 +14,7 @@
 #include "qemu/osdep.h"
 
 #include "block/aio.h"
+#include "qapi/compat-policy.h"
 #include "qapi/error.h"
 #include "qapi/qmp/dispatch.h"
 #include "qapi/qmp/qdict.h"
@@ -23,6 +24,8 @@
 #include "qemu/coroutine.h"
 #include "qemu/main-loop.h"
 
+CompatPolicy compat_policy;
+
 static QDict *qmp_dispatch_check_obj(QDict *dict, bool allow_oob,
                                      Error **errp)
 {
diff --git a/qemu-options.hx b/qemu-options.hx
index 671b310ab8..6b5a244b33 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -3507,6 +3507,26 @@ DEFHEADING()
 
 DEFHEADING(Debug/Expert options:)
 
+DEF("compat", HAS_ARG, QEMU_OPTION_compat,
+    "-compat [deprecated-input=accept|reject][,deprecated-output=accept|hide]\n"
+    "                Policy for handling deprecated management interfaces\n",
+    QEMU_ARCH_ALL)
+SRST
+``-compat [deprecated-input=@var{input-policy}][,deprecated-output=@var{output-policy}]``
+    Set policy for handling deprecated management interfaces (experimental):
+
+    ``deprecated-input=accept`` (default)
+        Accept deprecated commands and arguments
+    ``deprecated-input=reject``
+        Reject deprecated commands and arguments
+    ``deprecated-output=accept`` (default)
+        Emit deprecated command results and events
+    ``deprecated-output=hide``
+        Suppress deprecated command results and events
+
+    Limitation: covers only syntactic aspects of QMP.
+ERST
+
 DEF("fw_cfg", HAS_ARG, QEMU_OPTION_fwcfg,
     "-fw_cfg [name=]<name>,file=<file>\n"
     "                add named fw_cfg entry with contents from file\n"
diff --git a/softmmu/vl.c b/softmmu/vl.c
index cba7ab3441..4cbbdd81e0 100644
--- a/softmmu/vl.c
+++ b/softmmu/vl.c
@@ -29,6 +29,7 @@
 #include "exec/cpu-common.h"
 #include "hw/boards.h"
 #include "hw/qdev-properties.h"
+#include "qapi/compat-policy.h"
 #include "qapi/error.h"
 #include "qapi/qmp/qdict.h"
 #include "qapi/qmp/qjson.h"
@@ -114,6 +115,7 @@
 #include "sysemu/replay.h"
 #include "qapi/qapi-events-run-state.h"
 #include "qapi/qapi-visit-block-core.h"
+#include "qapi/qapi-visit-compat.h"
 #include "qapi/qapi-visit-ui.h"
 #include "qapi/qapi-commands-block-core.h"
 #include "qapi/qapi-commands-migration.h"
@@ -3458,6 +3460,21 @@ void qemu_init(int argc, char **argv, char **envp)
                 enable_mlock = qemu_opt_get_bool(opts, "mem-lock", false);
                 enable_cpu_pm = qemu_opt_get_bool(opts, "cpu-pm", false);
                 break;
+            case QEMU_OPTION_compat:
+                {
+                    CompatPolicy *opts;
+                    Visitor *v;
+
+                    v = qobject_input_visitor_new_str(optarg, NULL,
+                                                      &error_fatal);
+
+                    visit_type_CompatPolicy(v, NULL, &opts, &error_fatal);
+                    QAPI_CLONE_MEMBERS(CompatPolicy, &compat_policy, opts);
+
+                    qapi_free_CompatPolicy(opts);
+                    visit_free(v);
+                    break;
+                }
             case QEMU_OPTION_msg:
                 opts = qemu_opts_parse_noisily(qemu_find_opts("msg"), optarg,
                                                false);