Messages in this thread | | | Date | Tue, 29 Jan 2008 10:15:45 -0500 | From | Tony Camuso <> | Subject | Re: [Patch v2] Make PCI extended config space (MMCONFIG) a driver opt-in |
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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.
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.
The patches submitted by the others fix the problems with MMCONFIG without encumbering the drivers to be aware of any difference between legacy config space and extended config space.
I have tested these patches on a number of systems exhibiting various MMCONFIG- related pathologies, and they work.
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