Re: [PATCH] x86/pci: try to detect host_bridge pci_cfg_space

Ingo Molnar
2009-03-08T11:05:01Z

* Yinghai Lu <yinghai@kernel.org> wrote:

> H. Peter Anvin wrote:
> > H. Peter Anvin wrote:
> >> Yinghai Lu wrote:
> >>> Impact: get correct pci_cfg_size for host_bridge
> >>>
> >>> more host bridges support 4k cfg, so check them directly
> >>> instead of quirks.
> >>>
> >>> Signed-off-by: Yinghai Lu <yinghai@kernel.org>
> >>
> >> I'm utterly confused by this. This is basically saying we should try
> >> to probe for an extended device space for every host bridge.
> >> Logically speaking, this is valid: if there is a valid path by which
> >> we can probe for byte 256 then it should succeed.
> >>
> >> HOWEVER, the same argument applies for *every single device*. So if
> >> this does indeed work, why should we limit it to host bridges?
> >>
> >
> > Looking at the code (as opposed to just the patch) made it a bit
> > clearer. The argument you're making here is that only host bridges are
> > known to have extended address space without also having a PCI-X
> > extension header, right?
>
>
> Yes.

This too should go into the v2 patch description.

I'd also suggest to flip around the subject line from x86/pci to
pci/x86 - it's more of a PCI patch than a pure x86 patch. The
same problem could affect other platforms too i suspect.

Ingo