Re: [Patch v2] Make PCI extended config space (MMCONFIG) a driver opt-in

Ivan Kokshaysky
2007-12-28T21:12:01Z

On Fri, Dec 28, 2007 at 12:40:53PM -0500, Loic Prylli wrote:
> The only quirk I see removed is a bitmap with an arbitrary size (that we
> don't really know is sufficient for every system), and that is only
> built using comparison between mmconf and type1 accesses. IMHO, there
> is zero knowledge in that removed code (no knowledge about specific
> chipsets that work or don't work, or misleading BIOSes).

Precisely.

As a side note: that code also has zero knowledge about what the generic
PCI probe code can do later, like it fails to detect this ATI/CRS breakage.

> One thing that could be changed in pci_cfg_space_size() is to avoid
> making a special case for PCI-X 266MHz/533Mhz (assume cfg_size == 256
> for such devices too, reserve extended cfg-space for pci-express
> devices). There is good reasons to think no such PCI-X 266Mhz/533 device
> will ever have an extended-space (no capability IDs was ever defined in
> the PCI-X 2.0 spec, no new revision is planned). Such a check would
> avoid the possibility of trying extended-conf-space access for PCI-X 2.0
> devices behind a amd-8132 or similar (such accesses would just returnd
> -1, but there was some objections raised about doing anything like that
> other than at initialization time, even if there is ample reasons to
> argue it would be harmless).

I agree, we should remove it. IIRC, this PCI-X check was written
long ago with some draft (not a final spec) in hands. Matthew?

Ivan.