need help with lspci output

[bodisha]

Hello and thanks in advance for any help anyone can offer!

I'm trying to understand how to tell what hardware cards are install into what slot on a Centos machine. I believe I understand the lspci output is formatted as bus:slot:function... and that in a hypothetical bare metal machine the bus & slot would correspond to physical bus/slot. If I've misunderstood that could someone please correct me.

My confusion is about the function field. I understand it ranges from 0-7 but do the fields correspond to any particular function? or are the functions vendor specific? Could someone set me straight on this?

Once again thanks in advanced for any help

[aks]

Physical in this sense means where the solder tracks run, not necessarily what seems to be the obvious physical layout.

All devices have at least 1 function, function 0. As you say, there are 8 possible functions per device, numbered 0-7. Any device that has more than 1 function is a multi-function device. Multi-function devices, such as a combination modem+soundcard will usually have 2 uniquely addressable functions, numbered 0 and 1. It's about addressing *that* function. Additionally, every function has 256 eight-bit registers. Registers 0-3F are defined by the PCI specification and provide a wealth of information about the particular function. Registers 40-FF are vendor defined and control the properties of the function itself.

[bodisha]

Thanks for the reply. It sounds like I might be a bit more unclear on the subject of bus/slot than I might have thought. Your reply confused me a bit more than I already was.

"Physical in this sense means where the solder tracks run, not necessarily what seems to be the obvious physical layout."

Could I ask you to clarify a bit please? I'm unsure how solder tracks would differ from the physical layout. In my head they'd pretty much be one in the same. Thanks!

[aks]

Your reply confused me a bit more than I already was

Glad to be of help

What I meant was that a physical slot (let's say from left to right) could actually be physically connected in the order 3 1 2 4. To trace, you would have to trace the tracks. The tracks are the physical layout from the computers viewpoint.

[TrevorH]

I'm not sure that there is necessarily any relationship between the physical position of a slot on the motherboard and the slot number as reported by lspci. Yes, there probably should be if everything was logical but real life interferes!

[MartinR]

The only reliable way I've found is to put a unique board in a slot, boot, lspci, look for the board (record it), shutdown and move to the next slot. It's a right royal PITA with IBM/Lenovo xServers - they have a 5 minute boot time from cold.

Tip: use lspci -tv to see a map of the kernel's view including bridges.