Re: [PATCH 1/9] audio: Add easy dummy audio initialiser

[Marc-André Lureau]

Hi

On Fri, Sep 22, 2023 at 1:46 PM Paolo Bonzini <pbonzini@redhat.com> wrote:
>
> From: Martin Kletzander <mkletzan@redhat.com>
>
> In case of sound devices which are created by default (some of them even with
> -nodefaults) it would not be nice to users if qemu required explicit:
>
>   -audiodev driver=none,id=audio0 -machine audiodev=audio0
>
> when they just want to run a VM and not care about any audio output.  Instead
> this little helper makes it easy to create a dummy audiodev (driver=none) in
> case there is no audiodev specified for the machine.  To make sure users
> are not surprised by no sound output a helping message is also printed out.
>
> Signed-off-by: Martin Kletzander <mkletzan@redhat.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  audio/audio.c | 34 ++++++++++++++++++++++++++++++++++
>  audio/audio.h |  2 ++
>  2 files changed, 36 insertions(+)
>
> diff --git a/audio/audio.c b/audio/audio.c
> index d72e7db7fb9..8c74bc6b88c 100644
> --- a/audio/audio.c
> +++ b/audio/audio.c
> @@ -41,6 +41,7 @@
>  #include "sysemu/runstate.h"
>  #include "ui/qemu-spice.h"
>  #include "trace.h"
> +#include "hw/boards.h"
>
>  #define AUDIO_CAP "audio"
>  #include "audio_int.h"
> @@ -2174,6 +2175,39 @@ bool audio_init_audiodevs(void)
>      return true;
>  }
>
> +static void audio_init_dummy(const char *id)
> +{
> +    Audiodev *dev = g_new0(Audiodev, 1);
> +    AudiodevListEntry *e = g_new0(AudiodevListEntry, 1);
> +
> +    dev->driver = AUDIODEV_DRIVER_NONE;
> +    dev->id = g_strdup(id);
> +
> +    audio_validate_opts(dev, &error_abort);
> +    audio_init(dev, NULL);
> +
> +    e->dev = dev;
> +    QSIMPLEQ_INSERT_TAIL(&audiodevs, e, next);
> +}
> +
> +const char *audio_maybe_init_dummy(const char *default_id)
> +{
> +    MachineState *ms = MACHINE(qdev_get_machine());
> +
> +    if (ms->default_audiodev) {
> +        return ms->default_audiodev;
> +    }

../audio/audio.c:2197:11: error: ‘MachineState’ {aka ‘struct
MachineState’} has no member named ‘default_audiodev’
 2197 |     if (ms->default_audiodev) {

introduced in next patch

> +
> +    dolog("warning: No audiodev specified for implicit machine devices, "
> +          "no audio output will be available for these. "
> +          "For setting a backend audiodev for such devices try using "
> +          "the audiodev machine option.\n");
> +
> +    audio_init_dummy(default_id);
> +
> +    return default_id;
> +}
> +
>  audsettings audiodev_to_audsettings(AudiodevPerDirectionOptions *pdo)
>  {
>      return (audsettings) {
> diff --git a/audio/audio.h b/audio/audio.h
> index a276ec13eba..81d39526625 100644
> --- a/audio/audio.h
> +++ b/audio/audio.h
> @@ -176,6 +176,8 @@ void audio_help(void);
>  AudioState *audio_state_by_name(const char *name);
>  const char *audio_get_id(QEMUSoundCard *card);
>
> +const char *audio_maybe_init_dummy(const char *default_id);
> +
>  #define DEFINE_AUDIO_PROPERTIES(_s, _f)         \
>      DEFINE_PROP_AUDIODEV("audiodev", _s, _f)
>
> --
> 2.41.0
>
>


-- 
Marc-André Lureau