Re: [Xen-devel] [PATCH v2] libxl: change default QEMU machine to pc-i440fx-1.6

[Don Slutz <dslutz@xxxxxxxxxxx>]

On 07/11/14 11:08, Ian Campbell wrote:
> On Fri, 2014-07-11 at 15:54 +0100, Stefano Stabellini wrote:
> > On Fri, 11 Jul 2014, Ian Campbell wrote:
> > > On Fri, 2014-07-11 at 12:14 +0100, Stefano Stabellini wrote:
> > > > On Thu, 10 Jul 2014, Ian Jackson wrote:
> > > > > Stefano Stabellini writes ("Re: [PATCH v2] libxl: change default QEMU machine to 
> > > > > pc-i440fx-1.6"):
> > If we use -M pc or -M pc-i440fx-1.6, the xen-platform-pci device is
> > created slightly later in the QEMU boot sequence. The Intel HDA device
> > is able to "steal" its slot on the PCI bus.
> >
> > On the other hand it is worth pointing out that currently libxl switches
> > from -M xenfv to -M pc silently depending on whether the
> > xen_platform_pci option is enabled or disabled. If it is disabled we get
> > pc, that is a moving target and not guaranteed to be compatible with
> > anything.
> Changing that option is a guest reboot scenario, which is completely
> different to a migration. I think it is (just about) OK for the PCI id
> to change on a reboot, but it certainly isn't OK on migrate.
>
> If you can't get the platform device created earlier then perhaps you
> can find a way to influence the slot used by the hda device?
>
> Ian.
I see 2 options:

1) change only the -M pc to -M pc-i440fx-1.6 (I.E. continue to use xenfv)

2) Add ",addr=0x1.0x0" to the xen platform device.  (Which will cause
    QEMU to abort in this case.)  Also fix soundhw handling to stop using
    "-soundhw", and switch to "--device intel-hda,addr=0x12.0x0 -device
    hda-duplex" etc.


As a side note on #1, I do have a hack to allow adjusting the placement
of the xen platform device (adding a new xl.cfg option for it), but is not
ready to be a patch.  It would allow still using "-soundhw" "hda" but would
require a config change.

   -Don Slutz


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