[Qemu-devel] pcm.c:7843:(snd_pcm_recover) underrun occurred

[Qemu-devel] pcm.c:7843:(snd_pcm_recover) underrun occurred

[Francesco Turco]

Hello.

I'm not sure if asking in qemu-devel is the right thing to do, as I'm 
not a QEMU developer, but stefanha in the #qemu IRC channel told me to 
do so. :-)

I'm running QEMU 1.6.1 on a 64-bit Gentoo Linux system. The guest 
operating system is Windows 7 32-bit. I get multiple identical warning 
messages when using the ac97 or hda sound cards:

 > ALSA lib 
/var/tmp/portage/media-libs/alsa-lib-1.0.27.2/work/alsa-lib-1.0.27.2/src/pcm/pcm.c:7843:(snd_pcm_recover) 
underrun occurred

The difference between ac97 and hda is that the former works well, while 
the latter causes the sound to be garbled.

/var/tmp/portage is the directory where Portage, the Gentoo package 
manager, builds programs. I don't know why it is mentioned in the error 
message.

I also don't know if this is an ALSA problem or a QEMU problem.

The command I use is:

 > qemu-system-i386 -cpu host -m 1G -k it -drive 
file=~/QEMU/windows-7.img,media=disk,index=0 -vga std -net nic -net user 
-enable-kvm -display sdl -soundhw ac97

My real sound card is an Intel HD Audio:

 > lspci | grep "Audio device"
 > 00:1b.0 Audio device: Intel Corporation 82801I (ICH9 Family) HD Audio 
Controller (rev 02)

How can I debug this problem further?

Thank you.

Re: [Qemu-devel] pcm.c:7843:(snd_pcm_recover) underrun occurred

[Stefan Hajnoczi]

On Wed, Nov 20, 2013 at 09:39:26PM +0100, Francesco Turco wrote:
> I'm not sure if asking in qemu-devel is the right thing to do, as
> I'm not a QEMU developer, but stefanha in the #qemu IRC channel told
> me to do so. :-)
> 
> I'm running QEMU 1.6.1 on a 64-bit Gentoo Linux system. The guest
> operating system is Windows 7 32-bit. I get multiple identical
> warning messages when using the ac97 or hda sound cards:
> 
> > ALSA lib /var/tmp/portage/media-libs/alsa-lib-1.0.27.2/work/alsa-lib-1.0.27.2/src/pcm/pcm.c:7843:(snd_pcm_recover)
> underrun occurred
> 
> The difference between ac97 and hda is that the former works well,
> while the latter causes the sound to be garbled.
> 
> /var/tmp/portage is the directory where Portage, the Gentoo package
> manager, builds programs. I don't know why it is mentioned in the
> error message.
> 
> I also don't know if this is an ALSA problem or a QEMU problem.
> 
> The command I use is:
> 
> > qemu-system-i386 -cpu host -m 1G -k it -drive
> file=~/QEMU/windows-7.img,media=disk,index=0 -vga std -net nic -net
> user -enable-kvm -display sdl -soundhw ac97
> 
> My real sound card is an Intel HD Audio:
> 
> > lspci | grep "Audio device"
> > 00:1b.0 Audio device: Intel Corporation 82801I (ICH9 Family) HD
> Audio Controller (rev 02)

Extra info from IRC discussion:

The guest is just playing system sounds.  This is *not* a real-time
audio app with low-latency settings that easily hits underruns.

Stefan