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From: Marcel Apfelbaum <marcel@redhat.com>
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Date: Sun, 8 Jan 2017 10:17:12 +0200
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Subject: Re: [Qemu-devel] [RFC] pxb: Restrict to x86
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To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: David Gibson <david@gibson.dropbear.id.au>, ehabkost@redhat.com, thuth@redhat.com, lvivier@redhat.com, qemu-ppc@nongnu.org, qemu-devel@nongnu.org

On 01/06/2017 09:41 PM, Michael S. Tsirkin wrote:
> On Fri, Jan 06, 2017 at 08:13:11AM +0200, Marcel Apfelbaum wrote:
>> On 01/06/2017 07:04 AM, David Gibson wrote:
>>> The PCI Expander Bridge (PXB) device is essentially a hack to allow
>>> different PCIe devices to be assigned to different NUMA nodes on x86.  Each
>>> PXB is sort-of a separate PCI host bridge, except that its config space
>>> is shared with the config space of the main PCI host bridge, rather than
>>> being independent.
>>>
>>
>> Hi David,
>>
>>> This is only necessary if the platform doesn't (easily) allow truly
>>> independent PCI host bridges.  AFAIK that's just x86.
>>>
>>
>> Indeed, it is possible to support independent PCI host bridges on x86 by
>> using a separate MMCONFIG space for each one and enable separate PCI domains.
>> We simply didn't need this until now, but maybe will be implemented it in the future.
>
> In fact I would say that's the cleanest way to do this on q35.
>

Message received :)

Thanks,
Marcel


>>> This patch makes it possible to configure PXB out of the build, and adjusts
>>> the default configs so it's only included on x86 targets.
>>>
>>

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