Re: [Bug #15124] PCI host bridge windows ignored (works with pci=use_crs)

Jesse Barnes
2010-01-27T21:02:10Z

On Wed, 27 Jan 2010 12:59:05 -0800
Jesse Barnes <jbarnes@virtuousgeek.org> wrote:

> On Wed, 27 Jan 2010 12:50:12 -0800 (PST)
> Linus Torvalds <torvalds@linux-foundation.org> wrote:
>
> >
> >
> > On Wed, 27 Jan 2010, Bjorn Helgaas wrote:
> > >
> > > Without intel_bus.c, we essentially assume config 1 all the time.
> > > If we keep intel_bus.c and this patch for .33, things should work
> > > for configs 1 and 4. Adding support for config 4 is good.
> >
> > Quite frankly, is there any major downside to just disabling/removing
> > intel_bus.c for 2.6.33? If we're not planning on having it in the long run
> > anyway - or even if we are, but we can't be really happy about the state
> > of it as it would be in 2.6.33, not using it at all seems to be the
> > smaller headache.
> >
> > The machines that it helps are also the machines where you can fix things
> > up with 'use_csr', no? And they are pretty rare, and they didn't use to
> > work without that use_csr in 2.6.32 either, so it's not even a regression.
> >
> > Am I missing something?
>
> No that's the plan. intel_bus.c was a good effort, but it's just too
> different from what Windows does, and it'll always be behind. We'll
> disable it for 2.6.33 and try again to move to _CRS in 2.6.34 (but
> fixing the problem with large numbers of _CRS resources this time).

Should say "disable it for 2.6.33 for all but multi-IOH configs", which
seem to be fairly rare anyway, and were what intel_bus.c was designed
to accommodate. On the one machine that motivated it, use_crs was
broken (though it likely isn't now), so it seems the safest route.

--
Jesse Barnes, Intel Open Source Technology Center