On Thu, Aug 25, 2016 at 5:17 PM, Jakub Niedermertl <jniederm@redhat.com> wrote:
Hi Gianluca,

QEMU_AUDIO_DRV=none is most probably the problem. Libvirt is supposed to set "QEMU_AUDIO_DRV" to "spice" for VMs with graphics. Please make sure that the "Optimize for" attribute is set to "Desktop" (in Edit VM dialog) and try to shutdown and start the VM again. If the QEMU process will still have QEMU_AUDIO_DRV=none set, you can try to set the variable in /etc/sysconfig/libvirtd by adding line "QEMU_AUDIO_DRV=spice" and restart the libvirtd service.

Jakub

So, some revamping of information as some time has passed and new guests have been nstalled on the same system:

Engine version (self hosted) : oVirt Engine Version: 3.6.6.2-1.el7.centos

Host OS : CentOS 7.2 with kernel 3.10.0-327.18.2.el7.x86_64

Host oVirt version is 3.6.6 as in ovirt-release36-3.6.6-1.noarch

Host libvirt/vdsmd components:
[g.cecchi@ovirt01 ~]$ rpm -qa|grep -E "libvirt|vdsm"
libvirt-daemon-driver-network-1.2.17-13.el7_2.4.x86_64
libvirt-python-1.2.17-2.el7.x86_64
vdsm-cli-4.17.28-0.el7.centos.noarch
libvirt-lock-sanlock-1.2.17-13.el7_2.4.x86_64
libvirt-daemon-driver-secret-1.2.17-13.el7_2.4.x86_64
libvirt-daemon-config-network-1.2.17-13.el7_2.4.x86_64
vdsm-xmlrpc-4.17.28-0.el7.centos.noarch
libvirt-glib-0.1.9-1.el7.x86_64
libvirt-daemon-driver-qemu-1.2.17-13.el7_2.4.x86_64
libvirt-daemon-kvm-1.2.17-13.el7_2.4.x86_64
libvirt-client-1.2.17-13.el7_2.4.x86_64
vdsm-hook-vmfex-dev-4.17.28-0.el7.centos.noarch
libvirt-daemon-driver-storage-1.2.17-13.el7_2.4.x86_64
vdsm-infra-4.17.28-0.el7.centos.noarch
vdsm-jsonrpc-4.17.28-0.el7.centos.noarch
libvirt-daemon-config-nwfilter-1.2.17-13.el7_2.4.x86_64
vdsm-python-4.17.28-0.el7.centos.noarch
libvirt-gobject-0.1.9-1.el7.x86_64
libvirt-daemon-driver-interface-1.2.17-13.el7_2.4.x86_64
vdsm-yajsonrpc-4.17.28-0.el7.centos.noarch
libvirt-daemon-driver-nodedev-1.2.17-13.el7_2.4.x86_64
libvirt-gconfig-0.1.9-1.el7.x86_64
libvirt-daemon-driver-nwfilter-1.2.17-13.el7_2.4.x86_64
vdsm-4.17.28-0.el7.centos.noarch
libvirt-daemon-1.2.17-13.el7_2.4.x86_64

Host hw : intel NUC6i5SYH

Client is Fedora 23 with virt-viewer-3.0-1.fc23.x86_64

With a Fedora 24 guest accessed using firefox, user portal and remote-viewer, sounds are ok (test speakers).
The Fedora 24 guest is configured as "Optimized for Desktop", in its console options, advanced parameters, I have "soundcard enabled"

And in web admin portal I see this line in f24 VM bottom pane, label "Vm devices":
https://drive.google.com/file/d/0BwoPbcrMv8mvU0tQZTNBVmZVcTg/view?usp=sharing

Also for a CentOS 7.2 guest, with same config, sound is ok (test speakers)
Instead for a CentOS 6.8 guest with same config I see the device inside the OS, but no sound:

https://drive.google.com/file/d/0BwoPbcrMv8mvbHRLSDBueVZObTA/view?usp=sharing

In CentOS 6.8 the audio device is seen as:
00:08.0 Audio device: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) High Definition Audio Controller (rev 01)

and it seems the same in CentOS 7.2 guest OS:
00:08.0 Audio device: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) High Definition Audio Controller (rev 01)

Under /var/log/libvirt/qemu of host I indeed see

C6 c6desktop.log:

2016-08-25 23:00:37.668+0000: starting up libvirt version: 1.2.17, package: 13.el7_2.4 (CentOS Build
System <http://bugs.centos.org>, 2016-03-31-16:56:26, worker1.bsys.centos.org), qemu version: 2.3.0
(qemu-kvm-ev-2.3.0-31.el7_2.10.1)
LC_ALL=C PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin QEMU_AUDIO_DRV=none /usr/libexec/qem
u-kvm -name c6desktop ...

C7 c7desktop.log :

2016-08-25 22:59:02.531+0000: starting up libvirt version: 1.2.17, package: 13.el7_2.4 (CentOS Build
System <http://bugs.centos.org>, 2016-03-31-16:56:26, worker1.bsys.centos.org), qemu version: 2.3.0
(qemu-kvm-ev-2.3.0-31.el7_2.10.1)
LC_ALL=C PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin QEMU_AUDIO_DRV=spice /usr/libexec/qe
mu-kvm -name c7desktop ...

Apparently all is the same in qemu-kvm command lines, comparing c6 with c7 one, but I don't understand who drives instead the QEMU_AUDIO_DRV=XXX in log file that is different between the two guests (none vs spice) and btw also in f24 it is spice:

2016-07-31 23:00:44.778+0000: starting up libvirt version: 1.2.17, package: 13.el7_2.4 (CentOS Build
System <http://bugs.centos.org>, 2016-03-31-16:56:26, worker1.bsys.centos.org), qemu version: 2.3.0
(qemu-kvm-ev-2.3.0-31.el7_2.10.1)
LC_ALL=C PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin QEMU_AUDIO_DRV=spice /usr/libexec/qe
mu-kvm -name f24 ...

Could it be that initially c6 was created as optimized for server and then even if changing it to optimized for desktop, it doesn't get actually some parts of the change?

Or something related to ich6 drivers in CentOS 6?

In messages of C6 guest I see:
Aug 26 01:00:58 localhost kernel: snd_hda_intel 0000:00:08.0: PCI INT A -> Link[LNKD] -> GSI 10 (level, high) -> IRQ 10
Aug 26 01:00:58 localhost kernel: sr 1:0:0:0: Attached scsi generic sg0 type 5
Aug 26 01:00:58 localhost kernel: sound hdaudioC0D0: autoconfig for ID 22: line_outs=1 (0x3/0x0/0x0/0x0/0x0) type:line
Aug 26 01:00:58 localhost kernel: sound hdaudioC0D0:    speaker_outs=0 (0x0/0x0/0x0/0x0/0x0)
Aug 26 01:00:58 localhost kernel: sound hdaudioC0D0:    hp_outs=0 (0x0/0x0/0x0/0x0/0x0)
Aug 26 01:00:58 localhost kernel: sound hdaudioC0D0:    mono: mono_out=0x0
Aug 26 01:00:58 localhost kernel: sound hdaudioC0D0:    inputs:
Aug 26 01:00:58 localhost kernel: sound hdaudioC0D0:      Line=0x5

and related to kernel modules:
[g.cecchi@localhost ~]$ sudo lsmod | grep  snd
snd_hda_codec_generic    64356  1
snd_hda_intel          56602  1
snd_hda_codec         144814  2 snd_hda_codec_generic,snd_hda_intel
snd_hwdep               6972  1 snd_hda_codec
snd_seq                60769  0
snd_seq_device          7277  1 snd_seq
snd_pcm                93697  2 snd_hda_intel,snd_hda_codec
snd_timer              22747  2 snd_seq,snd_pcm
snd                    73783  10 snd_hda_codec_generic,snd_hda_intel,snd_hda_codec,snd_hwdep,snd_seq,snd_seq_device,snd_pcm,snd_timer
soundcore               7958  2 snd_hda_codec,snd
snd_page_alloc          8856  2 snd_hda_intel,snd_pcm


In dmesg for C7 guest (messages is less verbose):
[    3.406940] snd_hda_intel 0000:00:08.0: irq 35 for MSI/MSI-X
[    3.451694] snd_hda_codec_generic hdaudioC0D0: autoconfig for ID 22: line_outs=1 (0x3/0x0/0x0/0x0/0x0) type:line
[    3.451697] snd_hda_codec_generic hdaudioC0D0:    speaker_outs=0 (0x0/0x0/0x0/0x0/0x0)
[    3.451699] snd_hda_codec_generic hdaudioC0D0:    hp_outs=0 (0x0/0x0/0x0/0x0/0x0)
[    3.451700] snd_hda_codec_generic hdaudioC0D0:    mono: mono_out=0x0
[    3.451701] snd_hda_codec_generic hdaudioC0D0:    inputs:
[    3.451703] snd_hda_codec_generic hdaudioC0D0:      Line=0x5

and related to kernel modules:

[g.cecchi@c7plone ~]$ sudo lsmod|grep snd
snd_hda_codec_generic    74126  1
snd_hda_intel          35779  4
snd_hda_codec         137386  2 snd_hda_codec_generic,snd_hda_intel
snd_hda_core           57760  3 snd_hda_codec_generic,snd_hda_codec,snd_hda_intel
snd_hwdep              13608  1 snd_hda_codec
snd_seq                66691  0
snd_seq_device         14356  1 snd_seq
snd_pcm               105835  3 snd_hda_codec,snd_hda_intel,snd_hda_core
snd_timer              29639  2 snd_pcm,snd_seq
snd                    83425  16 snd_hwdep,snd_timer,snd_pcm,snd_seq,snd_hda_codec_generic,snd_hda_codec,snd_hda_intel,snd_seq_device
soundcore              15047  1 snd

Thanks in advance

Gianluca