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

[Jesse Barnes]

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

> On Wed, 27 Jan 2010 12:50:12 -0800 (PST)
> Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> 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
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