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Date: Sat, 14 Apr 2012 13:38:59 +0200
From: Ingo Molnar <mingo@kernel.org>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: Alessandro Rubini <rubini@gnudd.com>, mingo@elte.hu,
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        giancarlo.asnaghi@st.com, alan@linux.intel.com
Subject: Re: [PATCH V4 1/3] x86: introduce CONFIG_X86_DEV_DMA_OPS
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* H. Peter Anvin <hpa@zytor.com> wrote:

> On 04/12/2012 01:32 PM, Alessandro Rubini wrote:
> >>
> >> Not as a compile-time patch.
> > 
> > Why not? CONFIG_ISA is a compile-time choice. I thought that if you
> > compile for non-ISA systems you may reuse the zone mechanism with a
> > different split.
> > 
> > But if not a compile-time thing, would you accept it at run time?
> > I feel it's not a beautiful approach, because it must clearly be
> > masked by #ifndef CONFIG_ISA or such. Worse, you must know the zone
> > split at the beginning, before you scan the PCI bus and find your
> > devices.
> > 
> 
> Compile-time is unacceptable, because it breaks the "one 
> kernel image" policy we have on x86.  So it should be done at 
> runtime.

Agreed. CONFIG_ISA is an old mistake - we try not to repeat old 
mistakes.

Thanks,

	Ingo