Re: [PATCH 0/5][RFC] Physical PCI slot objects

Alex Chiang
2007-11-13T20:59:51Z

* Linas Vepstas <linas@austin.ibm.com>:
> On Tue, Nov 13, 2007 at 09:01:29AM -0800, Greg KH wrote:
> >
> > Also, some companies already provide userspace tools to get
> > all of this information about the different slots in a system
> > and what is where, from userspace, no kernel changes are
> > needed. So, why add all this extra complexity to the kernel
> > if it is not needed?
>
> Second that motion.... I don't get it. What are the goals of
> this patch, really? Just to get a "slot geographical location"
> from the kernel?

Yes, plus some general cleanups in the PCI hotplug space (more
patches queued up, pending the results of this series ;)

But to use the word "just" kinda implies that this is a trivial
feature that no one really cares about, which I'm not really sure
I agree with. Slot geographical location is important for
managability folks, who want to know which slot out of 192 (on a
big HP ia64 system, e.g.) that their failing network card might
be sitting in.

And again, we (HP ia64) need to get this information from the
kernel.

> I'm balancing the intellectual appeal of having a kernel struct
> for representing physical objects, against the headache of
> reading (debugging, modifying) code that has yet another struct
> doing yet another thing. So far, the dread of future headaches
> is winning.

Well, hopefully, the future is cleaner, rather than messier. ;)

> On pseries systems, I deal with something called the
> "partitionable endpoint", which I think probably usually
> corresponds to physical slots, but I don't really know.
>
> So, naively, the physical slot concept doesn't really map to
> what I have to work with; it just adds one more appendix to it
> all, one more thing to get confused about.

Sorry, I'm a bit ignorant about pseries -- what kind of name does
your PCI hotplug driver give to those slots? What shows up in
/sys/bus/pci/slots/?

> To be clear: above remarks are for the PowerPC boxes. I have no
> clue about how things work on the IBM Intel-based boxes. And
> Greg's original "get IBM to agree" remark is about the
> Intel-based boxes.

A split house. I have no idea how Proliants work either. :)

Thanks.

/ac