On Sunday, December 18, 2022 6:15:29 PM CET Volker Rümelin wrote: > Some emulated audio devices allow guests to select very low > sample rates that the audio subsystem doesn't support. The lowest > supported sample rate depends on the audio backend used and in > most cases can be changed with various -audiodev arguments. Until > now, the audio_bug function emits an error message similar to the > following error message > > A bug was just triggered in audio_calloc > Save all your work and restart without audio > I am sorry > Context: > audio_pcm_sw_alloc_resources_out passed invalid arguments to > audio_calloc > nmemb=0 size=16 (len=0) > audio: Could not allocate buffer for `ac97.po' (0 samples) > > and the audio subsystem continues without sound for the affected > device. > > The fact that the selected sample rate is not supported is not a > guest error. Instead of displaying an error message, the missing > audio support is now logged. Simply continuing without sound is > correct, since the audio stream won't transport anything > reasonable at such high resample ratios anyway. > > The AUD_open_* functions return NULL like before. The opened > audio device will not be registered in the audio subsystem and > consequently the audio frontend callback functions will not be > called. The AUD_read and AUD_write functions return early in this > case. This is necessary because, for example, the Sound Blaster 16 > emulation calls AUD_write from the DMA callback function. > > Signed-off-by: Volker Rümelin <vr_q...@t-online.de> > --- > audio/audio.c | 1 + > audio/audio_template.h | 13 +++++++++++++ > 2 files changed, 14 insertions(+) > > diff --git a/audio/audio.c b/audio/audio.c > index d849a94a81..f6b420688d 100644 > --- a/audio/audio.c > +++ b/audio/audio.c > @@ -31,6 +31,7 @@ > #include "qapi/qobject-input-visitor.h" > #include "qapi/qapi-visit-audio.h" > #include "qemu/cutils.h" > +#include "qemu/log.h" > #include "qemu/module.h" > #include "qemu/help_option.h" > #include "sysemu/sysemu.h" > diff --git a/audio/audio_template.h b/audio/audio_template.h > index 720a32e57e..bfa94b4d22 100644 > --- a/audio/audio_template.h > +++ b/audio/audio_template.h > @@ -115,6 +115,19 @@ static int glue (audio_pcm_sw_alloc_resources_, TYPE) > (SW *sw) > #else > samples = (int64_t)sw->HWBUF->size * sw->ratio >> 32; > #endif > + if (samples == 0) { > + HW *hw = sw->hw; > + size_t f_fe_min; > + > + /* f_fe_min = ceil(1 [frames] * f_be [Hz] / size_be [frames]) */ > + f_fe_min = (hw->info.freq + HWBUF->size - 1) / HWBUF->size; > + qemu_log_mask(LOG_UNIMP, > + AUDIO_CAP ": The guest selected a " NAME " sample rate" > + " of %d Hz for %s. Only sample rates >= %zu Hz are" > + " supported.\n", > + sw->info.freq, sw->name, f_fe_min); > + return -1;
You probably want to `sw->buf = NULL;` before returning here, or adjust the condition for the error message below. The other thing that puzzles me, in error case these template functions return -1, which would then be feed to g_malloc*()? > + } > > sw->buf = audio_calloc(__func__, samples, sizeof(struct st_sample)); > if (!sw->buf) { >