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

Greg KH
2007-11-13T20:30:33Z

On Tue, Nov 13, 2007 at 01:21:54PM -0700, Alex Chiang wrote:
> * Greg KH <greg@kroah.com>:
> > On Mon, Nov 12, 2007 at 05:08:53PM -0700, Alex Chiang wrote:
> > >
> > > Recently, Matthew Wilcox sent out the following mail about
> > > PCI slots:
> > >
> > > http://marc.info/?l=linux-pci&m=119432330418980&w=2
> > >
> > > The following patch series is a rough first cut at
> > > implementing the ideas he outlined, namely, that PCI slots
> > > are physical objects that we care about, independent of their
> > > hotplug capabilities.
> >
> > 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?
>
> On HP ia64 systems, that information is locked away in ACPI, and
> there's no easy way to get at it. Alex Williamson tried providing
> a generic dev_acpi driver, so that userspace could do whatever
> they wanted to with the information:
>
> http://lkml.org/lkml/2004/8/3/106
>
> And that effort kinda died. I'm of mixed feelings on that driver,
> since it would be really nice to get unfettered access to the
> ACPI namespace, but it's pretty dangerous, since any interesting
> thing you might want to do is actually a method (aka, it calls
> into firmware) and who knows what side effects there might be.
>
> So from my point of view, if ia64 customers want to know about
> the slots they have in their systems, we're gonna have to do
> something kernel-intrusive anyhow.

Doesn't /sys/firmware/acpi give you raw access to the correct tables
already?

And isn't there some other tool that dumps the raw ACPI tables? I
thought the acpi developers used it all the time when debugging things
with users.

thanks,

greg k-h