Subject: Re: [PATCH] x86: Fix CONFIG_PCI=n compile failure
From: James Bottomley <James.Bottomley@HansenPartnership.com>
To: Arjan van de Ven <arjan@infradead.org>
Cc: Ingo Molnar <mingo@elte.hu>,
       Linus Torvalds <torvalds@linux-foundation.org>,
       Glauber Costa <gcosta@redhat.com>,
       linux-kernel <linux-kernel@vger.kernel.org>,
       Thomas Gleixner <tglx@linutronix.de>
In-Reply-To: <20081029070824.10c19a57@infradead.org>
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Date: Wed, 29 Oct 2008 09:18:03 -0500
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On Wed, 2008-10-29 at 07:08 -0700, Arjan van de Ven wrote:
> On Wed, 29 Oct 2008 09:01:46 -0500
> James Bottomley <James.Bottomley@HansenPartnership.com> wrote:
> 
> > This is obviously some strange definition of the word "right" of
> > which I was previously unaware.  That patch moves forbid_dac plus a
> > load of quirk processing (also for a PCI bus) out from under
> > CONFIG_PCI only ... which will fix the compile error, sure.
> > 
> > However, if you'd be so kind, please explain how a DAC (meaning Dual
> > Addressing Cycle on the PCI bus) is useful (or even can be effected)
> > without a PCI bus?
> > 
> > All its really doing is contaminating pci-dma.c with clutter that only
> > needs to be there because someone can't get the separation right.o
> >
> 
> why do you even want that file for CONFIG_PCI=n ??

Um, my fault from long ago.  It's contaminated with the dma_ API pieces
that are bus generic.

The correct solution, I think, is to split it out into a bus generic
piece and a PCI specific piece.  I think all the intel/amd IOMMU stuff
should be in the PCI specific piece ... although I know there's a
theoretical case where the AMD iommu can be ht bus only with no PCI bus,
I don't think anyone's built such a beast, in which case it's safe to
condition iommu presence on CONFIG_PCI?

James


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