Messages in this thread | | | Date | Sun, 13 Jan 2008 00:49:11 +0300 | From | Ivan Kokshaysky <> | Subject | Re: [Patch v2] Make PCI extended config space (MMCONFIG) a driver opt-in |
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On Sat, Jan 12, 2008 at 09:45:57AM -0800, Arjan van de Ven wrote: > btw this is my main objection to your patch; it intertwines the conf1 > and mmconfig code even more.
There is nothing wrong with it; please realize that mmconf and conf1 are just different cpu-side interfaces. Both produce precisely the *same* bus cycles as far as the lower 256-byte space is concerned.
> When (and I'm saying "when" not "if") systems arrive that only have > MMCONFIG for some of the devices, we'll have to detangle this again, > and I'm really not looking forward to that.
MMCONFIG for *some* of the devices? This doesn't sound realistic from technical point of view. MMCONFIG-only systems? Sure. I really hope to see these. But it won't be PC-AT architecture anymore. It has to be something like alpha, for instance, fully utilizing the 64-bit address space, and we'll have to have the whole low-level PCI infrastructure completely different for these future platforms anyway. Right now, each and every x86 chipset *does* require working conf1 just in order to set up the mmconf aperture. It's the very fundamental thing, sort of design philosophy.
Ivan.
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