Re: [PATCH v7 02/12] accel: Introduce 'query-accels' QMP command

[Philippe Mathieu-Daudé]

On 5/5/21 9:41 PM, Eduardo Habkost wrote:
> On Wed, May 05, 2021 at 02:57:56PM +0200, Philippe Mathieu-Daudé wrote:
>> Introduce the 'query-accels' QMP command which returns a list
>> of built-in accelerator names.
>>
>> - Accelerator is a QAPI enum of all existing accelerators,
>>
>> - AcceleratorInfo is a QAPI structure providing accelerator
>>   specific information. Currently the common structure base
>>   provides the name of the accelerator, while the specific
>>   part is empty, but each accelerator can expand it.
>>
>> - 'query-accels' QMP command returns a list of @AcceleratorInfo
>>
>> For example on a KVM-only build we get:
>>
>>     { "execute": "query-accels" }
>>     {
>>         "return": [
>>             {
>>                 "name": "qtest"
>>             },
>>             {
>>                 "name": "kvm"
>>             }
>>         ]
>>     }
>>
>> Note that we can't make the enum values or union branches conditional
>> because of target-specific poisoning of accelerator definitions.
> 
> I assume this will be clarified in v8, based on your reply to v5.
> I don't understand what "target-specific poisoning of accelerator
> definitions" means.

$ git grep poison
...
include/exec/poison.h:88:#pragma GCC poison CONFIG_HAX
include/exec/poison.h:89:#pragma GCC poison CONFIG_HVF
include/exec/poison.h:90:#pragma GCC poison CONFIG_LINUX_USER
include/exec/poison.h:91:#pragma GCC poison CONFIG_KVM
include/exec/poison.h:92:#pragma GCC poison CONFIG_SOFTMMU
include/exec/poison.h:93:#pragma GCC poison CONFIG_WHPX
include/exec/poison.h:94:#pragma GCC poison CONFIG_XEN

I thought QAPI was target agnostic, but I just found:

  if module.endswith('-target')
    qapi_specific_outputs += qapi_module_outputs

  specific_ss.add(when: 'CONFIG_SOFTMMU', if_true: qapi_files[i])

So instead of adding this to qapi/machine.json I'll see
if I can add it to qapi/machine-target.json and use
conditionals.