Re: [Qemu-devel] [PATCH] libxl: change default QEMU machine to pc-i440fx-1.6

[Fabio Fantoni <fabio.fantoni@m2r.biz>]

Il 03/06/2014 15:38, Stefano Stabellini ha scritto:
> On Wed, 28 May 2014, Paolo Bonzini wrote:
>> Il 28/05/2014 18:41, Stefano Stabellini ha scritto:
>>> However it would still place xen-platform at slot 3 instead of slot 2 if
>>> soundhw is specified. It seems to me that there is not a perfect
>>> solution to this problem.  We can either:
>>>
>>> - Switch to -machine pc-i440fx-1.6 by default and use consistently the
>>> same -machine option no matter the value of xen_platform_pci. Nice, but
>>> we break compatibility with existing guests if soundhw is specified.
>>>
>>> - Switch to -machine pc-i440fx-1.6 only when xen_platform_pci=0 is
>>> specified and keep xenfv if xen_platform_pci=1. We still break
>>> compatibility when soundhw is specified together with xen_platform_pci=0.
>> - change the implementation of the soundhw option to use -device instead.
> Thanks, this sounds like the best option by far.
>
> I noticed that "-soundhw hda" becomes "-device intel-hda".
>
> Given that the VM config file exports a soundhw paramter, we would need
> a programmatic way to get the -device command line option from the
> soundhw paramter. Is there a way to do that?
Not only -device intel-hda, if I remember good there is also -device 
hda-duplex
soundhw now in libxl is only a string passed to qemu without check, 
probably is good add another parameter with a selectable options 
supported, similar to vga, for example audio=ac97|intelhda and libxl 
will check if exist and give to qemu the correct -device parameters.
The only problem is that audio device as many and not all qemu build 
support all (howevercurrently libxl does not care and isthe user having 
to make sure of the features support in qemu and view the log if qemu 
fails).
In addition there are also the disks to convert in -device.
I tried last year but with -device the automatic selection of bus and 
slot (unit now used in xen is not supported in -device if I remember 
good) was not working properly and the manual I did not know if I could 
do it working with cd/disk hot-plug working.

Thanks for any reply and sorry for my bad english.