[Qemu-devel] [PATCH v2 1/1] qmp: marking qmp_cpu as deprecated

[Daniel Henrique Barboza <danielhb@linux.vnet.ibm.com>]

qmp_cpu is a nop that was created a while ago in commit 755f196898
("qapi: Convert the cpu command") for the sake of compatibility,
due to the existence of hmp_cpu.

Today, there is no need or requirement to keep it as is. QMP is
meant to be as stateless as possible, thus any QMP command that
needs a specific monitor CPU setup should provide it in its
arguments, instead of relying in the current QMP monitor state.

This patch flags qmp_cpu as deprecated in qemu-doc.texi,
qapi-schema.json and changes qmp_cpu body to show a deprecation
message if used.

Signed-off-by: Daniel Henrique Barboza <danielhb@linux.vnet.ibm.com>
---
 qapi-schema.json |  5 ++++-
 qemu-doc.texi    | 10 ++++++++++
 qmp.c            |  2 +-
 3 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/qapi-schema.json b/qapi-schema.json
index 18457954a8..b51b89e19b 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -1052,7 +1052,10 @@
 #
 # Since: 0.14.0
 #
-# Notes: Do not use this command.
+# Notes: Do not use this command. It was deprecated in release 2.12.0 and will
+#        be removed, with no replacement, at any time in the future. QMP
+#        commands that rely on the current CPU monitor should specify it as a
+#        parameter.
 ##
 { 'command': 'cpu', 'data': {'index': 'int'} }
 
diff --git a/qemu-doc.texi b/qemu-doc.texi
index f7317dfc66..09e6c5046a 100644
--- a/qemu-doc.texi
+++ b/qemu-doc.texi
@@ -2516,6 +2516,16 @@ subsystem image.
 The ``convert -s snapshot_id_or_name'' argument is obsoleted
 by the ``convert -l snapshot_param'' argument instead.
 
+@section System emulator machine protocol commands
+
+@subsection qmp_cpu (since 2.12.0)
+
+The ``qmp_cpu'' command was implemented in release 0.14.0 as a functional
+no-op, remaining as such up to release 2.12.0 when it was deprecated and
+flagged for future removal. No replacement will be provided: any QMP command
+that uses the current CPU monitor should, instead, specify the CPU in its
+parameters.
+
 @section System emulator human monitor commands
 
 @subsection host_net_add (since 2.10.0)
diff --git a/qmp.c b/qmp.c
index e8c303116a..d8543d713d 100644
--- a/qmp.c
+++ b/qmp.c
@@ -115,7 +115,7 @@ void qmp_system_powerdown(Error **erp)
 
 void qmp_cpu(int64_t index, Error **errp)
 {
-    /* Just do nothing */
+    error_setg(errp, "qmp_cpu is deprecated, do not use this command");
 }
 
 void qmp_cpu_add(int64_t id, Error **errp)
-- 
2.13.6