Re: [PATCH v2 09/12] qapi: make most CPU commands unconditionally available

[Pierrick Bouvier <pierrick.bouvier@linaro.org>]

On 5/18/25 11:29 PM, Markus Armbruster wrote:
> Pierrick Bouvier <pierrick.bouvier@linaro.org> writes:
> 
>> From: Daniel P. Berrangé <berrange@redhat.com>
>>
>> This removes the TARGET_* conditions from all the CPU commands
>> that are conceptually target independent. Top level stubs are
>> provided to cope with targets which do not currently implement
>> all of the commands.
>>
>> Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
>> Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
>> Signed-off-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
> 
> [...]
> 
>> diff --git a/qapi/machine-target.json b/qapi/machine-target.json
>> deleted file mode 100644
>> index e153291a7fc..00000000000
>> --- a/qapi/machine-target.json
>> +++ /dev/null
> 
> [...]
> 
>> -##
>> -# @query-cpu-model-comparison:
>> -#
>> -# Compares two CPU models, @modela and @modelb, returning how they
>> -# compare in a specific configuration.  The results indicates how
>> -# both models compare regarding runnability.  This result can be
>> -# used by tooling to make decisions if a certain CPU model will
>> -# run in a certain configuration or if a compatible CPU model has
>> -# to be created by baselining.
>> -#
>> -# Usually, a CPU model is compared against the maximum possible CPU
>> -# model of a certain configuration (e.g. the "host" model for KVM).
>> -# If that CPU model is identical or a subset, it will run in that
>> -# configuration.
>> -#
>> -# The result returned by this command may be affected by:
>> -#
>> -# * QEMU version: CPU models may look different depending on the QEMU
>> -#   version.  (Except for CPU models reported as "static" in
>> -#   query-cpu-definitions.)
>> -# * machine-type: CPU model may look different depending on the
>> -#   machine-type.  (Except for CPU models reported as "static" in
>> -#   query-cpu-definitions.)
>> -# * machine options (including accelerator): in some architectures,
>> -#   CPU models may look different depending on machine and accelerator
>> -#   options.  (Except for CPU models reported as "static" in
>> -#   query-cpu-definitions.)
>> -# * "-cpu" arguments and global properties: arguments to the -cpu
>> -#   option and global properties may affect expansion of CPU models.
>> -#   Using query-cpu-model-expansion while using these is not advised.
>> -#
>> -# Some architectures may not support comparing CPU models.  s390x
>> -# supports comparing CPU models.
>> -#
>> -# @modela: description of the first CPU model to compare, referred to
>> -#     as "model A" in CpuModelCompareResult
>> -#
>> -# @modelb: description of the second CPU model to compare, referred to
>> -#     as "model B" in CpuModelCompareResult
>> -#
>> -# Returns: a CpuModelCompareInfo describing how both CPU models
>> -#     compare
>> -#
>> -# Errors:
>> -#     - if comparing CPU models is not supported
>> -#     - if a model cannot be used
>> -#     - if a model contains an unknown cpu definition name, unknown
>> -#       properties or properties with wrong types.
>> -#
>> -# .. note:: This command isn't specific to s390x, but is only
>> -#    implemented on this architecture currently.
> 
> We lose this note.  Intentional?
> 
> Perhaps because we also have the "Some architectures ..." paragraph
> above?
> 
>> -#
>> -# Since: 2.8
>> -##
>> -{ 'command': 'query-cpu-model-comparison',
>> -  'data': { 'modela': 'CpuModelInfo', 'modelb': 'CpuModelInfo' },
>> -  'returns': 'CpuModelCompareInfo',
>> -  'if': 'TARGET_S390X' }
>> -
>> -##
>> -# @query-cpu-model-baseline:
>> -#
>> -# Baseline two CPU models, @modela and @modelb, creating a compatible
>> -# third model.  The created model will always be a static,
>> -# migration-safe CPU model (see "static" CPU model expansion for
>> -# details).
>> -#
>> -# This interface can be used by tooling to create a compatible CPU
>> -# model out two CPU models.  The created CPU model will be identical
>> -# to or a subset of both CPU models when comparing them.  Therefore,
>> -# the created CPU model is guaranteed to run where the given CPU
>> -# models run.
>> -#
>> -# The result returned by this command may be affected by:
>> -#
>> -# * QEMU version: CPU models may look different depending on the QEMU
>> -#   version.  (Except for CPU models reported as "static" in
>> -#   query-cpu-definitions.)
>> -# * machine-type: CPU model may look different depending on the
>> -#   machine-type.  (Except for CPU models reported as "static" in
>> -#   query-cpu-definitions.)
>> -# * machine options (including accelerator): in some architectures,
>> -#   CPU models may look different depending on machine and accelerator
>> -#   options.  (Except for CPU models reported as "static" in
>> -#   query-cpu-definitions.)
>> -# * "-cpu" arguments and global properties: arguments to the -cpu
>> -#   option and global properties may affect expansion of CPU models.
>> -#   Using query-cpu-model-expansion while using these is not advised.
>> -#
>> -# Some architectures may not support baselining CPU models.  s390x
>> -# supports baselining CPU models.
>> -#
>> -# @modela: description of the first CPU model to baseline
>> -#
>> -# @modelb: description of the second CPU model to baseline
>> -#
>> -# Returns: a CpuModelBaselineInfo describing the baselined CPU model
>> -#
>> -# Errors:
>> -#     - if baselining CPU models is not supported
>> -#     - if a model cannot be used
>> -#     - if a model contains an unknown cpu definition name, unknown
>> -#       properties or properties with wrong types.
>> -#
>> -# .. note:: This command isn't specific to s390x, but is only
>> -#    implemented on this architecture currently.
> 
> We lose this note.  Intentional?
> 
> Perhaps because we also have the "Some architectures ..." paragraph
> above?
> 
>> -#
>> -# Since: 2.8
>> -##
>> -{ 'command': 'query-cpu-model-baseline',
>> -  'data': { 'modela': 'CpuModelInfo',
>> -            'modelb': 'CpuModelInfo' },
>> -  'returns': 'CpuModelBaselineInfo',
>> -  'if': 'TARGET_S390X' }
> 
> [...]
> 

Yes, those notes don't have any reason to be present anymore, and the 
new "Some architectures..." paragraph replaces them.