Re: DMA in PCI chipset -- module vs. compiled-in

[Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>]

On 2/6/06, Lee Revell <rlrevell@joe-job.com> wrote:
> On Mon, 2006-02-06 at 19:49 +0000, Alan Cox wrote:
> > On Sul, 2006-02-05 at 23:32 -0500, Lee Revell wrote:
> > > Generic and chipset specific support are not complementary, they are
> > > mutually exclusive.  Having generic PCI IDE support enabled will prevent
> > > the chipset specific support from working properly.
> >
> > Untrue.
> >
> > The PCI generic driver by default grabs only hardware with PCI IDS it
> > knows can be driven generically. That list purposefully has no overlaps
> > with chipset drivers.
>
> OK.  But wasn't this a problem in previous kernels?

It wasn't.  The issue is more complicated, you can have
three host drivers driving the same hardware:

* ide-generic driver
  - ISA like support
  - also works for PCI in legacy mode

* IDE PCI generic (the one Alan refers to)
  - generic IDE PCI support
  - by default doesn't grab IDs for which we have other drivers
    (can be forced by using kernel parameter)

* chipset specific driver

The most common mistake is to built-in ide-generic driver
and compile chipset specific driver as module...

To William:
CONFIG_IDE_GENERIC=n is a likely solution for your problem.

Bartlomiej
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