Re: [PATCH v4 3/3] target/i386: Restrict X86CPUFeatureWord to X86 targets

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

On 10/1/20 5:29 PM, Eduardo Habkost wrote:
> On Thu, Oct 01, 2020 at 04:41:52PM +0200, Philippe Mathieu-Daudé wrote:
>> Only qemu-system-FOO and qemu-storage-daemon provide QMP
>> monitors, therefore such declarations and definitions are
>> irrelevant for user-mode emulation.
>>
>> Restricting the x86-specific commands to machine-target.json
>> pulls less QAPI-generated code into user-mode.
> 
> Is this still true without "qapi: Restrict code generated for
> user-mode"?

The correct description so far is:

"Restricting the x86-specific commands to machine-target.json
pulls less QAPI-generated code into non-x86 targets.", as of
this commit the X86CPURegister32 definitions are not built in
the other ARM/S390/PPC/... targets.

I still have some hope "qapi: Restrict code generated for user-mode"
get merged some day.

> 
> Markus, Eric: what's the difference between machine.json and
> machine-target.json? commit 7f7b4e7abef4 ("qapi: Split
> machine-target.json off target.json and misc.json") explains what
> but not why.
> 
>>
>> Acked-by: Richard Henderson <richard.henderson@linaro.org>
>> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> 
> Why the visit_type_X86CPUFeatureWordInfoList() stub was required
> in v3, but not in this version?

Because it is ifdef'ed out in the previous (new) patch:
"target/i386/cpu: Restrict some of feature-words uses to system-mode".

> 
> 
>> ---
>>  qapi/machine-target.json | 45 ++++++++++++++++++++++++++++++++++++++++
>>  qapi/machine.json        | 42 -------------------------------------
>>  target/i386/cpu.c        |  2 +-
>>  3 files changed, 46 insertions(+), 43 deletions(-)
>>
>> diff --git a/qapi/machine-target.json b/qapi/machine-target.json
>> index 698850cc78..b4d769a53b 100644
>> --- a/qapi/machine-target.json
>> +++ b/qapi/machine-target.json
>> @@ -4,6 +4,51 @@
>>  # This work is licensed under the terms of the GNU GPL, version 2 or later.
>>  # See the COPYING file in the top-level directory.
>>  
>> +##
>> +# @X86CPURegister32:
>> +#
>> +# A X86 32-bit register
>> +#
>> +# Since: 1.5
>> +##
>> +{ 'enum': 'X86CPURegister32',
>> +  'data': [ 'EAX', 'EBX', 'ECX', 'EDX', 'ESP', 'EBP', 'ESI', 'EDI' ],
>> +  'if': 'defined(TARGET_I386)' }
>> +
>> +##
>> +# @X86CPUFeatureWordInfo:
>> +#
>> +# Information about a X86 CPU feature word
>> +#
>> +# @cpuid-input-eax: Input EAX value for CPUID instruction for that feature word
>> +#
>> +# @cpuid-input-ecx: Input ECX value for CPUID instruction for that
>> +#                   feature word
>> +#
>> +# @cpuid-register: Output register containing the feature bits
>> +#
>> +# @features: value of output register, containing the feature bits
>> +#
>> +# Since: 1.5
>> +##
>> +{ 'struct': 'X86CPUFeatureWordInfo',
>> +  'data': { 'cpuid-input-eax': 'int',
>> +            '*cpuid-input-ecx': 'int',
>> +            'cpuid-register': 'X86CPURegister32',
>> +            'features': 'int' },
>> +  'if': 'defined(TARGET_I386)' }
>> +
>> +##
>> +# @DummyForceArrays:
>> +#
>> +# Not used by QMP; hack to let us use X86CPUFeatureWordInfoList internally
>> +#
>> +# Since: 2.5
>> +##
>> +{ 'struct': 'DummyForceArrays',
>> +  'data': { 'unused': ['X86CPUFeatureWordInfo'] },
>> +  'if': 'defined(TARGET_I386)' }
>> +
>>  ##
>>  # @CpuModelInfo:
>>  #
>> diff --git a/qapi/machine.json b/qapi/machine.json
>> index 756dacb06f..995e972858 100644
>> --- a/qapi/machine.json
>> +++ b/qapi/machine.json
>> @@ -574,48 +574,6 @@
>>     'dst': 'uint16',
>>     'val': 'uint8' }}
>>  
>> -##
>> -# @X86CPURegister32:
>> -#
>> -# A X86 32-bit register
>> -#
>> -# Since: 1.5
>> -##
>> -{ 'enum': 'X86CPURegister32',
>> -  'data': [ 'EAX', 'EBX', 'ECX', 'EDX', 'ESP', 'EBP', 'ESI', 'EDI' ] }
>> -
>> -##
>> -# @X86CPUFeatureWordInfo:
>> -#
>> -# Information about a X86 CPU feature word
>> -#
>> -# @cpuid-input-eax: Input EAX value for CPUID instruction for that feature word
>> -#
>> -# @cpuid-input-ecx: Input ECX value for CPUID instruction for that
>> -#                   feature word
>> -#
>> -# @cpuid-register: Output register containing the feature bits
>> -#
>> -# @features: value of output register, containing the feature bits
>> -#
>> -# Since: 1.5
>> -##
>> -{ 'struct': 'X86CPUFeatureWordInfo',
>> -  'data': { 'cpuid-input-eax': 'int',
>> -            '*cpuid-input-ecx': 'int',
>> -            'cpuid-register': 'X86CPURegister32',
>> -            'features': 'int' } }
>> -
>> -##
>> -# @DummyForceArrays:
>> -#
>> -# Not used by QMP; hack to let us use X86CPUFeatureWordInfoList internally
>> -#
>> -# Since: 2.5
>> -##
>> -{ 'struct': 'DummyForceArrays',
>> -  'data': { 'unused': ['X86CPUFeatureWordInfo'] } }
>> -
>>  ##
>>  # @NumaCpuOptions:
>>  #
>> diff --git a/target/i386/cpu.c b/target/i386/cpu.c
>> index 9f72342506..848a65ded2 100644
>> --- a/target/i386/cpu.c
>> +++ b/target/i386/cpu.c
>> @@ -38,7 +38,7 @@
>>  #include "qemu/option.h"
>>  #include "qemu/config-file.h"
>>  #include "qapi/error.h"
>> -#include "qapi/qapi-visit-machine.h"
>> +#include "qapi/qapi-visit-machine-target.h"
>>  #include "qapi/qapi-visit-run-state.h"
>>  #include "qapi/qmp/qdict.h"
>>  #include "qapi/qmp/qerror.h"
>> -- 
>> 2.26.2
>>
>