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From: Marcel Apfelbaum <marcel@redhat.com>
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Date: Mon, 16 Nov 2015 11:52:48 +0200
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Subject: Re: [Qemu-devel] [PATCH V2 0/4] hw/pcie: Multi-root support for Q35
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To: Paolo Bonzini <pbonzini@redhat.com>, qemu-devel@nongnu.org
Cc: imammedo@redhat.com, rth@twiddle.net, kraxel@redhat.com, ehabkost@redhat.com, mst@redhat.com

On 11/16/2015 10:40 AM, Paolo Bonzini wrote:
>
>
> On 15/11/2015 16:39, Marcel Apfelbaum wrote:
>>   Addressed Gerd Hoffmann comments:
>>   - Added x-enable-internal-bridge compat property to keep the PCI
>>     bridge for older machine to avoid breaking migration.
>
> This will break PXB command lines written for "-M pc" in QEMU <= 2.5.
> Technically there's no prohibition against doing so, but we've never
> done it; I'm not sure why we should start doing so now.

Hi Paolo,

Can you please explain how does it break the command line?

For QEMU < 2.5 we automatically have the  x-enable-internal-bridge compat property "on"
so the command line remains the same.

For QEMU >= 2.5 is "off" by default and the bridge disappear, without command line changes.

>
> Can we have two devices, on for a PCI expander bridge and one for a PCIe
> expander bridge?

Gerd also asked for this, OK, I am going for it.

Thanks,
Marcel

>
> Paolo
>