Re: [PATCH v2 08/12] qapi: Make CpuModelExpansionInfo::deprecated-props optional and generic

[Pierrick Bouvier]

On 5/18/25 11:18 PM, Markus Armbruster wrote:

Pierrick Bouvier <pierrick.bouv...@linaro.org> writes:

From: Philippe Mathieu-Daudé <phi...@linaro.org>

We'd like to have some unified QAPI schema. Having a structure field
conditional to a target being built in is not very practical.

While @deprecated-props is only used by s390x target, it is generic
enough and could be used by other targets (assuming we expand
CpuModelExpansionType enum values).

Let's always include this field, regardless of the target, but
make it optional.

Let's add:

   This is not a compatibility break only because the field remains
   present always on S390x.

Reviewed-by: Richard Henderson <richard.hender...@linaro.org>
Signed-off-by: Philippe Mathieu-Daudé <phi...@linaro.org>
Signed-off-by: Pierrick Bouvier <pierrick.bouv...@linaro.org>
---
  qapi/machine-target.json | 7 +++----
  1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/qapi/machine-target.json b/qapi/machine-target.json
index 426ce4ee82d..e153291a7fc 100644
--- a/qapi/machine-target.json
+++ b/qapi/machine-target.json
@@ -244,19 +244,18 @@
  #
  # @model: the expanded CpuModelInfo.
  #
-# @deprecated-props: a list of properties that are flagged as
+# @deprecated-props: an optional list of properties that are flagged as
  #     deprecated by the CPU vendor.  The list depends on the
  #     CpuModelExpansionType: "static" properties are a subset of the
  #     enabled-properties for the expanded model; "full" properties are
  #     a set of properties that are deprecated across all models for
-#     the architecture.  (since: 9.1).
+#     the architecture.  (since: 10.1 -- since 9.1 on s390x --).
  #
  # Since: 2.8
  ##
  { 'struct': 'CpuModelExpansionInfo',
    'data': { 'model': 'CpuModelInfo',
-            'deprecated-props' : { 'type': ['str'],
-                                   'if': 'TARGET_S390X' } },
+            '*deprecated-props' : { 'type': ['str'] } },

[Copied from review of prior posts]

Make this

                '*deprecated-props' : ['str'] },

please.

When I see "optional array", I wonder about the difference between
"absent" and "present and empty".  The doc comment doesn't quite explain
it.  I figure "present and empty" means empty, while "absent" means we
don't know / not implemented.

Is the difference useful?

Daniel doubts it is.

Philippe is happy to implement either variant.

    'if': { 'any': [ 'TARGET_S390X',
                     'TARGET_I386',
                     'TARGET_ARM',

Note the patch doesn't touch any of the qmp_query_cpu_model_expansion().
The S390x version continues to set @deprecated_props always.  The others
continue not to set it.

Changed to "'*deprecated-props' : ['str'] }", as requested.