* Prasad Joshi (P.G.Joshi@xxxxxxxxxxxxxxxxxxxxx) wrote:
> 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)
A PCI bridge has config space that states what busses are behind it.
The bridge at 00:14.4 is a bridge between bus 0 and bus 1, you can tell
from this line:
Bus: primary=00, secondary=01, subordinate=01, sec-latency=64
There are no other devices behind that bridge (so theoretically you could
safely use it for device assignment).
> If you can explain this, I will try to find if the other network card
> also sits behind the bridge or not.
The other network interface card you have (03:00.0) is a PCIe device,
it's upstream is the PCIe port. It should not have the aliasing issue,
and should work.
00:06.0 PCI bridge: ATI Technologies Inc RD890 PCI to PCI bridge (PCI express gpp port F)
Bus: primary=00, secondary=03, subordinate=03, sec-latency=0
03:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168B PCI Express Gigabit Ethernet controller
> 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. :(
The GPU is also in a PCIe port, here:
00:02.0 PCI bridge: ATI Technologies Inc RD890 PCI to PCI bridge (PCI express gpp port B)
Bus: primary=00, secondary=06, subordinate=06, sec-latency=0
06:00.0 VGA compatible controller: nVidia Corporation G86 [Quadro NVS 290]
> Please explain how to find out this information.
Using lspci -t you can see the topology pretty easily. Otherwise you
can sift through lspci output to find the topology.
thanks,
-chris
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