Understanding lspci output

Understanding lspci output

[John Sigler]

Hello everyone,

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?

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

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

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

Regards.

Re: Understanding lspci output

[Martin Mares]

Hello!

> 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.

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

Yes, PCI-X does.

> 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.

				Have a nice fortnight
-- 
Martin `MJ' Mares                          <mj@ucw.cz>   http://mj.ucw.cz/
Faculty of Math and Physics, Charles University, Prague, Czech Rep., Earth
hAS ANYONE SEEN MY cAPSLOCK KEY?

Re: Understanding lspci output

[John Sigler]

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.

Re: Understanding lspci output

[Robert Hancock]

John Sigler wrote:
>>> 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 

The NICs are all PCI-X devices and they report "64bit+" so they will be 
running on a PCI-X bus internally.

> 
> 
>>> 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?

I believe so.

> 
>>> 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)

The "Multimedia video controller: DekTec Digital Video B.V. DTA-105" 
doesn't report PCI-X capabilities. And looking at the card on their web 
site, it does not have a 64-bit extension, so it doesn't support 64-bit.

-- 
Robert Hancock      Saskatoon, SK, Canada
To email, remove "nospam" from hancockr@nospamshaw.ca
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