Re: [Qemu-devel] [PATCH 1/4] hw/pxb: remove the built-in pci bridge

[Marcel Apfelbaum <marcel@redhat.com>]

On 11/13/2015 11:13 AM, Gerd Hoffmann wrote:
> On Do, 2015-11-12 at 17:11 +0200, Marcel Apfelbaum wrote:
>> As part of porting the pxb device to Q35 remove the internal pci-2-pci
>> bridge. The only way to hot-pug devices on the extra PCI root buses
>> is by adding a pci-2-pci to the pxb before the firmware assign the
>> IO/mem resources.
>
> I think this breaks live migration and is guest-visible too.  So not
> going to fly without backward-compatibility mode for old machine
> types ...
>
> Possibly it is easier to just have have pci and pcie pxb devices look
> differenty rather than adding all the compatibility fluff.
>

Hi Gerd,

Thank you for the review.

Yes, you are right about migration, but I prefer to add a compat-prop rather
than different devices because I do want to remove the internal pci-bridge
even for pxb PCI.
The reason is the feedback I got from libvirt that "composed" device are not recommended.

In conclusion, since I am going to get rid of the pci-bridge, the devices will be exactly
the same (except for the internal bus).

I want to use the same concept as virtio-pci devices that get to be "express" on PCIe,
but remain PCI on PCI buses.

Thanks,
Marcel


> cheers,
>    Gerd
>
>