It turns out, after building 14 different commits between v5.8 and v5.9,
that a three line change in drivers/pci/controller/pci-xgene.c breaks PCI
on this machine. If I revert this file and build the commit that changed
it, PCI works properly. No config options changed between these commits.

I suppose now it's just a matter of figuring out why this change breaks it,
and how it can be fixed and applied to 5.9+.

On Tue, Feb 9, 2021 at 4:03 AM Valdis Klētnieks <valdis.kletnieks@vt.edu>
wrote:

> On Mon, 08 Feb 2021 09:00:27 -0500, Evan T Mesterhazy said:
>
> > Thanks, Greg - good suggestion regarding `git bisect`. I was able to
> narrow
> > it down to a change between 5.8 and 5.9, so maybe that's the next logical
> > thing to do. None of the config options added between those releases
> seemed
> > relevant to the issue, but perhaps one of them is and I just don't
> realize
> > it.
>
> You're probably looking for a config option that was *removed* between
> those releases.
>


-- 
Evan Mesterhazy
etm2131@columbia.edu