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SubjectRe: New resources - pls, explain :-(
Hello,

> > This can be easily handled by having my pci_request_device() request
> > all the regions the device has. This way usual PCI drivers won't need to
> > bother with resource allocation and the other ones will be able to do
> > their magic tricks directly. Okay?
>
> Why?
>
> We have IO regions, and that's really all the driver cares about. The
> "struct pci_dev" is useful for device identification, but it is not the
> device. The device is really the IO port accesses you make in the driver,
> and as such it makes sense to just allocate those resources.
>
> Marking the actual "struct pci_dev" busy buys you nothing over marking the
> IO range busy, and as has been shown it has problems.

Please read the text I've written and you've quoted a bit more carefully.
It says that I propose pci_request_device() allocating _the_resources_, so that
the problems we were speaking about some mails ago will be solved and usual
drivers still won't need to do any resource magic -- they'll just say
"grab this device and anything that comes with it".

> Oh, they are there. They just don't announce their PCI IO ranges, exactly
> because they implement legacy stuff that doesn't expect them to be
> announced.

> For example, take the PIIX4 which exists in probably 90% of modern PCI
> machines. It has _tons_ of devices on it, and some are announced as PCI IO
> regions while others are not. Even when it announces that it has a IDE
> subfunction, it doesn't actually announce the IO range it listens on (it
> announces the extended IO range, but not the traditional one).

> Now, imagine that you have a modularized system, and you by mistake load a
> PIIX4-aware IDE module after you already loaded a "classical" IDE module.
> The PIIX4-aware IDE module _should_ notice that the IO range is already in
> use, and should abort.

Well, in this case my old "just allocate the whole PCI device and
don't care about resources" would still work since a driver for such a device
would of course need to request the legacy ports explicitly as they are
not a part of any PCI regions.

But anyway, I feel that making pci_request_device() allocating all
the resources is a better solution.

Have a nice fortnight
--
Martin `MJ' Mares <mj@ucw.cz> http://atrey.karlin.mff.cuni.cz/~mj/
Faculty of Math and Physics, Charles University, Prague, Czech Rep., Earth
"A LISP programmer knows value of everything, but cost of nothing."

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