Re: Understanding lspci output

From: John Sigler
Date: Wed Oct 17 2007 - 07:58:07 EST


Hello Martin,

Martin Mares wrote:

I ran lspci -vvv on a system:
http://linux.kernel.free.fr/halt/lspci.txt

(I used lspci version 2.2.5 in case it matters.)

But I'm having a hard time making sense of the output.

1. How many PCI buses are there in the system?

Two, just see the bus numbers of the devices. (However, there might be
additional buses with no devices present and in case these are connected
to a separate host bridge, they need not be visible.)

4. Does the system have a PCI-X bus?

Yes, the devices on bus 01 are PCI-X devices, so there is a PCI-X bus.

I thought PCI-X devices could operate on a PCI bus? If that is true, then the presence of a PCI-X device would not necessarily imply the presence of a PCI-X bus, right?

There are no external PCI-X slots in the system, only 2 PCI slots.
The 4 NICs are integrated to the motherboard.
http://advantech.com/products/1U-Rackmount-Intel-Pentium-4Processor-based-Platform-with-4PCI-LAN-Ports-2-PCI-Expansion-Slots/mod_1-23A2W4.aspx

2. Do any of the PCI buses support 66 MHz operation?

Yes, PCI-X does.

So the 01:0f.0 device (Multimedia video controller) is on the same bus as the 4 PCI-X devices and will have to share the bus bandwidth?

Does 66MHz+ in the Status line means this device is running at 66 MHz?

3. Do any of the PCI slots support 64-bit data path?

This cannot be inferred from the lspci output -- there is no way how to
tell if a bus has physical slots or it exists only internally.

Can I use lspci to see whether a specific PCI device is using a 64-bit data path? (e.g. the 01:0f.0 device)

Regards.
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