Re: [Xen-devel] Multi-bridged PCIe devices (Was: Re: iommuu/vt-d issues with LSI MegaSAS (PERC5i))

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 11.09.13 at 14:45, Gordan Bobic <gordan@xxxxxxxxxx> wrote:
>  dmesg, xl dmesg, lspci -vvvnn and lspci -tvnn output is attached.
> 
>  I'll try adding one of my LSI cards and see the comparative
>  behaviour. Right now I don't even know if the phantom device
>  is on the SAS card or the motherboard.

The Adaptec card being the only thing on bus 0f makes it pretty
likely that this other device also is on that card.

I guess the issue is mainly because the device itself is a PCI one,
while the immediately upstream bridge (where I mean only the
visible one) is PCIe. There _must_ be a PCIe-PCI bridge between
them. And as long as firmware doesn't know about that bridge
and the bridge doesn't properly handle config space accesses to
it, such a device just can't be used with an IOMMU (without some
yet to be invented workaround).

Jan


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