dynamic addition of OF property to /proc/device-tree

Dave Hansen haveblue at us.ibm.com
Sat Aug 28 11:10:20 EST 2004

On Fri, 2004-08-27 at 16:50, Paul Mackerras wrote:
> John Rose writes:
> > > Is this a good time to talk Martin into updating his tools to lookup the
> > > pci domain somewhere other than /proc/device-tree?
> >
> > Yes, Martin, how about that? :)
> What precisely do you mean?  What are you suggesting he does instead
> of what?

It think it was established (from an earlier patch) that Martin's tools
are currently the only user of the linux,pci-domain property in the
OpenFirmware tree.  From what I understand, this is how Martin's tool
found out which PCI domain a particular adapter is in.

So, John Rose noted that he couldn't create the necessary properties at
runtime with /proc/ppc64/ofdt because it lacked the capacity "add a
property (as opposed to a node) dynamically" and asked for suggestions.

So, I thought that, instead of adding more functionality to the kernel
to support exporting the linux,pci-domain (which someone was already
trying to remove) in a hotplug situation, this might be an opportunity
to modify the tools instead.  The tools could, instead, use the driver
model and sysfs to determine the PCI domain of a particular adapter.

If that happened, not only would we be able to avoid addming more
functionality to the OpenFirmware /proc code, but we'd also make John
Rose happy because he could completely remove linux,pci-domain, like he
tried here: http://ozlabs.org/ppc64-patches/patch.pl?id=184

I just wondered if it was feasible, and if this was a good time to
update those tools.

-- Dave

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