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SubjectRe: [PATCH] x86: Bypass legacy PIC and PIT on ACPI hardware reduced platform
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On Wednesday, March 04, 2015 08:21:01 PM Alan Cox wrote:
> On Wed, 2015-03-04 at 15:05 +0100, Borislav Petkov wrote:
> > On Wed, Mar 04, 2015 at 03:16:07PM +0100, Rafael J. Wysocki wrote:
> > > Sort of. What we need is a "do not touch PIC/PIT" bit for the code that
> > > tries to fall back to them in some cases (which may appear to work if
> > > the hardware is physically there, but it may confuse the platform).
> >
> > Can "some cases" detection be nicely put into a x86_platform
> > platform-specific method?
>
> In some cases they don't belong in x86, ACPI is also used for ARM64.
>
> However
>
> if ( has_8259_pic() )
>
> is trivally 0, 1 or some platform or acpi provided method.

And which is how that should have been implemented to start with IMO.

Besides, the "ACPI reduced hardware" case is kind of a red herring here,
because it most likely is not the only case when we'll want has_8259_pic()
to return 0 (quite likely, we'll want that on all BayTrail-based systems,
for example).


--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.


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