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

Arjan van de Ven
2008-01-29T15:31:18Z

On Tue, 29 Jan 2008 10:15:45 -0500
Tony Camuso <tcamuso@redhat.com> wrote:

> Arjan van de Ven wrote:
> > On Tue, 29 Jan 2008 09:15:02 -0500
> > Tony Camuso <tcamuso@redhat.com> wrote:
> >
> >> Greg,
> >>
> >> The problem with Arjan's patch, if I understand it correctly, is
> >> that it requires drivers to make a call to access extended PCI
> >> config space.
> >>
> >> And, IIRC, Arjan's patch encumbers drivers for all arch's, even
> >> those that have no MMCONFIG problems.
> >>
> >> The patches proposed by Loic, Ivan, Matthew, and myself, all
> >> address the problem in an x86-specific manner that is transparent
> >> to the drivers.
> >
> > this is not quite correct; the patches from Loic, Ivan, Matthew and
> > you are for a different problem statement.
> >
> > Your patch problem statement is "need to fix mmconfig", my patch
> > problem statement is "need to not make users who don't need it
> > suffer". These are orthogonal problems.
> >
> >
>
> Yes, but your patch also makes users who need extended PCI config
> space suffer.
>
> Right now, that isn't a lot of people in x86 land, but your patch
> encumbers drivers for non-x86 archs with an additional call to access
> space that they've never had a problem with.

lets say s/x86/x86, IA64 and architectures that use intel, amd or via chipsets/

> As more PCI express drivers start to take advantage of AER and other
> advanced express capabilities, the extra call to address a condition
> specific to legacy x86 hardware is, IMNSHO, a kludge.

in addition to pci_enable(), pci_enable_msi(), pci_enable_busmaster() they already need to do
to enable various features?

--
If you want to reach me at my work email, use arjan@linux.intel.com
For development, discussion and tips for power savings,
visit http://www.lesswatts.org