Re: [Qemu-devel] [PATCH RFC] docs: add PCIe devices placement guidelines

[Marcel Apfelbaum <marcel@redhat.com>]

On 10/04/2016 08:54 PM, Laine Stump wrote:
> On 10/04/2016 12:10 PM, Laine Stump wrote:
>> On 10/04/2016 11:40 AM, Laszlo Ersek wrote:
>
>>> Small correction to your wording though: you don't want to attach the
>>> DMI-PCI bridge to the PXB device, but to the extra root bus provided by
>>> the PXB.
>>
>> This made me realize something - the root bus on a pxb-pcie controller
>> has a single slot and that slot can accept either a pcie-root-port
>> (ioh3420) or a dmi-to-pci-bridge. If you want to have both express and
>> legacy PCI devices on the same NUMA node, then you would either need to
>> create one pxb-pcie for the pcie-root-port and another for the
>> dmi-to-pci-bridge, or you would need to put the pcie-root-port and
>> dmi-to-pci-bridge onto different functions of the single slot. Should
>> the latter work properly?
>

Hi,

> We were discussing pxb-pcie today while Dan was trying to get a particular configuration working, and there was some disagreement about two points that I stated above as fact (but which may just be
> misunderstanding again):
>
> 1) Does pxb-pcie only provide a single slot (0)? Or does it provide 32 slots (0-31) just like the pcie root complex?
>

It provides 32 slots behaving like a PCI Express Root Complex.

> 2) can you really only plug a pcie-root-port (ioh3420) into a pxb-pcie? Or will it accept anything that pcie.0 accepts?

It supports only PCI Express Root Ports. It does not support Integrated Devices.

Thanks,
Marcel