Re: [PATCH V4 1/3] x86: introduce CONFIG_X86_DEV_DMA_OPS

From: H. Peter Anvin
Date: Thu Apr 12 2012 - 16:48:24 EST


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.

-hpa

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