Re: qemu 4.2.0 audiodev soundhw

[Jakob Bohm]

As someone who doesn't always keep libvirt and qemu in sync (if using 
libvirt
at all), keeping forward and backwards compatibility for command lines and
other interfaces becomes quite critical.  For example doing a quick site
compile of a more recent qemu needs to work with whatever a distribution
libvirt or local script invokes, even if later upgrading libvirt without
recompiling qemu.

In that light, option 2 is not just preferable, but necessary.

It can however be simplified to silently assume a hard coded audiodev 
value,
with the qemu-system man page explicitly stating that value, along with the
version dependency of both syntax generations.

In fact, over the years, I have found it excruciatingly difficult to find
valid qemu documentation, as each feature effort tends to leave behind
half-updated pages and a bunch of uncoordinated messages about what may or
may not have been implemented in unspecified versions.

On 20/04/2020 19:54, Idar Lund wrote:
> Hi,
>
> Thanks for your response!
>
> Yes, I agree with you on the options. If you guys decide on (3), I 
> would suggest to make it dynamically like this; "-soundhw 
> hda,audiodev=sound1". This would then copy the 'audiodev' (and 
> possible other) parameter(s) to the '-device' option.
>
> My personal preference would be to recommend option number 1.
> The reason for this is that maintaining a shortcut like this makes it 
> hard to maintain for developers when adding features and fixes bugs on 
> other options. And of course documentation maintainers :)
> The second reason as I see it is that people tend to create a .sh 
> script or similar to start their qemu virtual machines if they don't 
> use libvirt/xml schema. And for that, a more verbose command would 
> actually be easier to maintain for users since we then know where to 
> put parameters like this.
>
> -Idar
>
> On Mon, Apr 20, 2020 at 4:44 PM Gerd Hoffmann <address@hidden 
> <mailto:address@hidden>> wrote:
>
>     On Fri, Apr 17, 2020 at 12:15:30PM +0100, Peter Maydell wrote:
>     > On Fri, 17 Apr 2020 at 12:08, Idar Lund <address@hidden
>     <mailto:address@hidden>> wrote:
>     > > I'm using qemu-system-x86_64 with the following options:
>     > > -audiodev pa,id=sound1,server=/run/user/1000/pulse/native \
>     > > -soundhw hda
>     > >
>     > > After upgrade to 4.2.0 (qemu-4.2.0-7.fc32) I get the following
>     warning:
>     > > (qemu) audio: Device hda: audiodev default parameter is
>     deprecated, please specify audiodev=sound1
>     > >
>     > > The documentation `man qemu-system-x86_64` seems to not
>     reflect this.
>     > > How am I supposed to use audiodev and soundhw?
>     >
>     > This looks like another question for you, Gerd...
>
>     Hmm, good question how to proceed here best ...
>
>     "-soundhw hda" is a shortcut for "-device intel-hda -device
>     hda-duplex"
>
>     You can use "-device intel-hda -device hda-duplex,audiodev=sound1" to
>     make the warning go away.  That is pretty verbose when compared to
>     "-soundhw hda" though ...
>
>     So the options I see are:
>
>       (1) deprecate the -soundhw shortcut, expect users to use -device
>           instead.
>       (2) have -soundhw lookup the audiodev and add it automatically. 
>     Works
>           only with a single audiodev, but that isn't different from what
>           we have today.  If you want do more complicated things you
>           already have to use the more verbose -device command line.
>       (3) add audiodev option to -soundhw.
>
>     I don't like (3) much, our command line is already messy enough. 
>     So my
>     personal preference would be (1) or (2) ...

Enjoy

Jakob
--
Jakob Bohm, CIO, Partner, WiseMo A/S.  http://www.wisemo.com
Transformervej 29, 2860 Soborg, Denmark.  Direct +45 31 13 16 10
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