Re: HELP: Need to determine physical slot number of card in PCIe slot

[linux-os (Dick Johnson)]

On Fri, 21 Apr 2006, Timothy Miller wrote:

> I apologize if this is not the right place to ask this question.  I
> have done some googling around, and I have not found an answer to
> this, although I suspect I'm just not using the right search terms.
> Also, I'm not a member of this list, so please CC me if you reply.
>
> I have put together a diagnostic system for my employer using a
> stripped-down Gentoo system (2.6.15 kernel).  We're testing some PCIe
> cards on an ABIT IL8, which has four PCIe slots.  Since this is a test
> rig, when a card fails a test, we need to know which of the four slots
> the card is in.  When developing this, I had assumed that the PCI bus
> ID would be a function of the slot number, but apparently, it is not.
> We can put one card into any of the four slots, and we get the same
> bus ID.  If we put in four cards, we get a set of ID numbers that
> isn't sequential.
>
> I've poked around in /proc, without finding anything.  I found
> /sys/bus/pci_express, but it's really weird what I see, because it
> shows what appears to be some slots repeated and some missing, and
> also, there doesn't seem to be a way to associate the slot with the
> bus ID  (I assume pcie00 is slot zero).  Under /sys/bus/pci/devices, I
> do see the PCI bus ID of the cards in question, but I cannot figure
> out how to associate that with the slot number.  The directory
> /sys/bus/pci/slots is empty.
>
> Is there some reasonable way for me to be able to determine, given a
> bus ID, which physical slot the PCIe card is in?
>
> Note:  I am not using a kernel driver for these cards.  I'm using
> /dev/mem to map mmio, and I'm using libpci to access PCI config space.
> Everything works great (besides the slot number issue here).
>
> Thank you very much in advance for your help.
>
>
> --- Timothy Miller

PCI_SLOT(struct pci_dev *) is a macro defined in one of the headers.
Unfortunately, it will not uniquely define a board. Also, the slot number
itself has nothing to do with the physical machine because, upon
startup, the BIOS assigns "slots" in the order devices are found.

But, for a particular configuration, it is possible to uniquely
define a board as long as they don't get moved around! In one
of our devices, I do something like this and it has been good enough
for the service people to find a malfunctioning board.

slot = dev->bus->number << 8) | PCI_SLOT(dev->devfn);


Cheers,
Dick Johnson
Penguin : Linux version 2.6.16.4 on an i686 machine (5592.89 BogoMips).
Warning : 98.36% of all statistics are fiction, book release in April.
_


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