[+cc Martin, pciutils maintainer] On Thu, Jun 28, 2012 at 4:02 AM, Holger Eitzenberger <holger@xxxxxxxxxxxxxxxx> wrote: > Hi, > > I have a problem identifying PCI devices (NICs in this case) on some > hardware. > > In case the questions I have are too stupid please just ignore this > email. > > While I usually use the bus:device.function to identify the hardware > this is not possible on some hardware, because the bus numbers are > changing. And this is all because the box has 4 slots, and each slot > can possibly hold one of 3 different types of modules, differing in > the number of NICs they hold. > > I found out that this is a well known problem, which is due to the > fact that the different modules have a different number of PCI bridges > on them. In my case from 2 to 7 PCI bridges per module. > > And then I came across the Chassis Capability (id 04). On first read > this sounded as it would solve the problem, making the ID unique again > if configured properly, irrespective of the actual slot module used. > Has anyone experience with the Chassis Capability? I think you're referring to the "Slot Identification" capability. As far as I can tell, the kernel ignores it. I don't see spec details about it; the PCI spec v3 says it's fully documented in the PCI to PCI Bridge spec, but I don't see anything in the P2P bridge spec v1.2. But I suppose if pciutils knows how to decode it, it must be documented *somewhere*. > In my understanding the Chassis Capability is transparent to the OS, > the devices can still be identified by bus:device.function, correct? Yes. The kernel uses segment/bus/device/function to identify a PCI device. I'm not sure exactly what your objective is, but maybe this is related: https://fedoraproject.org/wiki/Features/ConsistentNetworkDeviceNaming > According to the lspci source it should show something like: > > Capabilities: [04] Slot ID: 8 slots, First1, chassis 42 > > I was unable to find some sample lspci output when googling, a sample > output would be helpfull as well. > > What I found helpfull, without the Chassis Capability, was a small tool > I wrote (derived from pciutils/examle.c), which is able to identify > the devices with a "path walk" from the PCI Root Port to the actual > device. So e. g. when specifying: > > ./example -s '/00:02.0/:05.0/:01.1/:05.1' > > In this case '00:02.0' is the Root Port, the other device except the > last are PCI bridges, specified with a wildcard for the bus number. > > Would this be a feature of interest for pciutils in general? > > Thanks! > > /Holger -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
