[libvirt] [PATCH] Allow control over QEMU audio backend

[Daniel P. Berrange]

On Wed, Sep 23, 2009 at 04:27:30PM +0200, Daniel Veillard wrote:
> On Tue, Sep 22, 2009 at 11:45:02AM +0100, Daniel P. Berrange wrote:
> > When using VNC for graphics + keyboard + mouse, we shouldn't
> > then use the host OS for audio. Audio should go back over
> > VNC.
> > 
> > When using SDL for graphics, we should use the host OS for
> > audio since that's where the display is. We need to allow
> > certain QEMU env variables to be passed through to guest
> > too to allow choice of QEMU audio backend.
> 
>  All this makes sense !
> 
> > * qemud/libvirtd.sysconf: Mention QEMU/SDL audio env vars
> > * src/qemu_conf.c: Passthrough QEMU/SDL audio env for SDL display,
> >   disable host audio for VNC display
> > ---
> >  daemon/libvirtd.sysconf |    8 ++++++++
> >  src/qemu/qemu_conf.c    |   14 ++++++++++++++
> >  2 files changed, 22 insertions(+), 0 deletions(-)
> > 
> > diff --git a/daemon/libvirtd.sysconf b/daemon/libvirtd.sysconf
> > index fe4596a..28080a0 100644
> > --- a/daemon/libvirtd.sysconf
> > +++ b/daemon/libvirtd.sysconf
> > @@ -7,3 +7,11 @@
> >  
> >  # Override Kerberos service keytab for SASL/GSSAPI
> >  #KRB5_KTNAME=/etc/libvirt/krb5.tab
> > +
> > +# Override the QEMU/SDL default audio driver probing when
> > +# starting virtual machines using SDL graphics
> > +#
> > +# NB these have no effect for VMs using VNC
> > +#QEMU_AUDIO_DRV=sdl
> > +#
> > +#SDL_AUDIODRIVER=pulse
> > diff --git a/src/qemu/qemu_conf.c b/src/qemu/qemu_conf.c
> > index 273aeca..74ca52b 100644
> > --- a/src/qemu/qemu_conf.c
> > +++ b/src/qemu/qemu_conf.c
> > @@ -2109,6 +2109,13 @@ int qemudBuildCommandLine(virConnectPtr conn,
> >              ADD_ARG_LIT("-k");
> >              ADD_ARG_LIT(def->graphics[0]->data.vnc.keymap);
> >          }
> > +
> > +        /* QEMU implements a VNC extension for providing audio, so we
> > +         * set the audio backend to none, to prevent it opening the
> > +         * host OS audio devices since that causes security issues
> > +         * and is non-sensical when using VNC.
> > +         */
> > +        ADD_ENV_LIT("QEMU_AUDIO_DRV=none");
> >      } else if ((def->ngraphics == 1) &&
> >                 def->graphics[0]->type == VIR_DOMAIN_GRAPHICS_TYPE_SDL) {
> >          char *xauth = NULL;
> > @@ -2131,6 +2138,13 @@ int qemudBuildCommandLine(virConnectPtr conn,
> >              ADD_ENV(display);
> >          if (def->graphics[0]->data.sdl.fullscreen)
> >              ADD_ARG_LIT("-full-screen");
> > +
> > +        /* If using SDL for video, then we should just let it
> > +         * use QEMU's host audio drivers, possibly SDL too
> > +         * User can set these two before starting libvirtd
> > +         */
> > +        ADD_ENV_COPY("QEMU_AUDIO_DRV");
> > +        ADD_ENV_COPY("SDL_AUDIODRIVER");
> >      }
> >  
> >      if (def->nvideos) {
> 
>  ACK,
> 
> I wonder if that would be sufficient to drop the
> libvirt-0.6.4-svirt-sound.patch that we carry in Fedora, not sure
> because we still may use the local audio in some cases. Opinion ?

Yes, it is intended that this patch obsolete that one we're carrying
in Fedora.


Daniel
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