Is the answer
"All PCI buses located behind a PCI-PCI bridge must reside between the seondary bus number and the subordinate bus number (inclusive)."
00:14.4 PCI bridge: ATI Technologies Inc SBx00 PCI to PCI Bridge
Bus: primary=00, secondary=01, subordinate=01, sec-latency=64
So all the PCI devices between secondary (01) and subordinate (01) (in this case same) are behind the PCI Bridge. Correct me if I am wrong.
01:05.0 Ethernet controller: Intel Corporation 82557/8/9/0/1 Ethernet Pro 100 (rev 0c)
As Bus ID is 01 this ethernet controller is behind the PCI Bridge
03:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168B PCI Express Gigabit Ethernet controller (rev 06)
As Bus: 03, I can assume this is not behind the PCI Bridge
But if subordinate would have been, say 03 or 04, then even this ethernet card (03:00:0) would be behind the PCI Bridge.
Am I correct?
Thanks and Regards,
Prasad
________________________________________
From: Prasad Joshi
Sent: 22 December 2010 13:16
To: Chris Wright
Cc: kvm@xxxxxxxxxxxxxxx
Subject: RE: Query on IOMMU
I have few (may be stupid) questions on this
> From: Chris Wright [chrisw@xxxxxxxxxxxx]
> That's the issue. The IOMMU has a set of page tables for each DeviceID.
> For most devices, the DeviceID is the same as the Bus:Dev.Func (the PCI
> address) of the device. But this does not always work. One example is
> when a device is behind a PCI-to-PCI Bridge. In that case, the device
> memory read/write requests (attempts to DMA) will appear as if they came
> from the bridge.
Oh I see, I can understand this part.
>
> 00:14.4 PCI bridge: ATI Technologies Inc SBx00 PCI to PCI Bridge
> Bus: primary=00, secondary=01, subordinate=01, sec-latency=64
>
> That's the bridge that sits between your e100 and the IOMMU.
Can you please explain how did you make out the device 01:05:0 is behind the bridge?
01:05.0 Ethernet controller: Intel Corporation 82557/8/9/0/1 Ethernet Pro 100 (rev 0c)
If you can explain this, I will try to find if the other network card also sits behind the bridge or not. I would like to know the same thing for the PCIe GPU card connected to my machine. If GPU card is also sitting behind the bridge then the hardware may be useless for the project. :(
Please explain how to find out this information.
> thanks,
> -chris
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