Re: [PATCH 2/3] qapi, audio: respect build time conditions in audio schema

[Markus Armbruster <armbru@redhat.com>]

Daniel P. Berrangé <berrange@redhat.com> writes:

> Currently the -audiodev accepts any audiodev type regardless of what is
> built in to QEMU. An error only occurs later at runtime when a sound
> device tries to use the audio backend.
>
> With this change QEMU will immediately reject -audiodev args that are
> not compiled into the binary. The QMP schema will also be introspectable
> to identify what is compiled in.
>
> Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

Subject "qapi, audio: respect build time conditions in audio schema"
feels too narrow.  The patch goes beyond the schema, because it has to:
guarding QAPI schema parts with 'if' requires guarding use of C code
generated for it with #if.

An easy way out is perhaps stating just the aim:

    audio: Make introspection reflect build configuration

This assumes the patch does a complete job.  If there's more audio build
configuration to reflect, add a suitable qualifier like "more closely".

Fun: before the patch, the CONFIG_AUDIO_ conditionals are effectively
applied just to output of -help.

[...]
> diff --git a/qapi/audio.json b/qapi/audio.json
> index d7b91230d7..9af1b8140c 100644
> --- a/qapi/audio.json
> +++ b/qapi/audio.json
> @@ -386,8 +386,24 @@
>  # Since: 4.0
>  ##
>  { 'enum': 'AudiodevDriver',
> -  'data': [ 'none', 'alsa', 'coreaudio', 'dsound', 'jack', 'oss', 'pa',
> -            'sdl', 'spice', 'wav' ] }
> +  'data': [ 'none',
> +            { 'name': 'alsa',
> +              'if': 'defined(CONFIG_AUDIO_ALSA)' },
> +            { 'name': 'coreaudio',
> +              'if': 'defined(CONFIG_AUDIO_COREAUDIO)' },
> +            { 'name': 'dsound',
> +              'if': 'defined(CONFIG_AUDIO_DSOUND)' },
> +            { 'name': 'jack',
> +              'if': 'defined(CONFIG_AUDIO_JACK)' },
> +            { 'name': 'oss',
> +              'if': 'defined(CONFIG_AUDIO_OSS)' },
> +            { 'name': 'pa',
> +              'if': 'defined(CONFIG_AUDIO_PA)' },
> +            { 'name': 'sdl',
> +              'if': 'defined(CONFIG_AUDIO_SDL)' },
> +            { 'name': 'spice',
> +              'if': 'defined(CONFIG_SPICE)' },
> +            'wav' ] }
>  
>  ##
>  # @Audiodev:
> @@ -410,14 +426,22 @@
>    'discriminator': 'driver',
>    'data': {
>      'none':      'AudiodevGenericOptions',
> -    'alsa':      'AudiodevAlsaOptions',
> -    'coreaudio': 'AudiodevCoreaudioOptions',
> -    'dsound':    'AudiodevDsoundOptions',
> -    'jack':      'AudiodevJackOptions',
> -    'oss':       'AudiodevOssOptions',
> -    'pa':        'AudiodevPaOptions',
> -    'sdl':       'AudiodevSdlOptions',
> -    'spice':     'AudiodevGenericOptions',
> +    'alsa':      { 'type': 'AudiodevAlsaOptions',
> +                   'if': 'defined(CONFIG_AUDIO_ALSA)' },
> +    'coreaudio': { 'type': 'AudiodevCoreaudioOptions',
> +                   'if': 'defined(CONFIG_AUDIO_COREAUDIO)' },
> +    'dsound':    { 'type': 'AudiodevDsoundOptions',
> +                   'if': 'defined(CONFIG_AUDIO_DSOUND)' },
> +    'jack':      { 'type': 'AudiodevJackOptions',
> +                   'if': 'defined(CONFIG_AUDIO_JACK)' },
> +    'oss':       { 'type': 'AudiodevOssOptions',
> +                   'if': 'defined(CONFIG_AUDIO_OSS)' },
> +    'pa':        { 'type': 'AudiodevPaOptions',
> +                   'if': 'defined(CONFIG_AUDIO_PA)' },
> +    'sdl':       { 'type': 'AudiodevSdlOptions',
> +                   'if': 'defined(CONFIG_AUDIO_SDL)' },
> +    'spice':     { 'type': 'AudiodevGenericOptions',
> +                   'if': 'defined(CONFIG_SPICE)' },
>      'wav':       'AudiodevWavOptions' } }
>  
>  ##

For the QAPI schema part:
Acked-by: Markus Armbruster <armbru@redhat.com>