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Message-ID: <44AD0C2B.7060204@innova-card.com>
Date:	Thu, 06 Jul 2006 15:12:11 +0200
Reply-To: Franck <vagabon.xyz@gmail.com>
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To:	Atsushi Nemoto <anemo@mba.ocn.ne.jp>
CC:	vagabon.xyz@gmail.com, linux-mips@linux-mips.org,
	ralf@linux-mips.org
Subject: Re: [PATCH] do not count pages in holes with sparsemem
References: <20060705.221354.74751389.anemo@mba.ocn.ne.jp>	<44ABC59C.6070607@innova-card.com> <20060705.231737.59032119.anemo@mba.ocn.ne.jp>
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From:	Franck Bui-Huu <vagabon.xyz@gmail.com>
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Atsushi Nemoto wrote:
> On Wed, 05 Jul 2006 15:58:52 +0200, Franck Bui-Huu <vagabon.xyz@gmail.com> wrote:
>> BTW why using __pa(OFFSET) ? isn't it going to yield always into 0 ?
>> At least on MIPS, it's defined as
>>
>> #define __pa(x)	((unsigned long) (x) - PAGE_OFFSET)
>>
>> why not using ARCH_PFN_OFFSET instead ?
> 
> Indeed.  I copied the code from free_area_init().  I think 0 is enough
> for MIPS.  Patch revised.  Thank you for comments.
> 
> 

Ok thinking more about it, some platforms may have physical memory
that doesn't start at 0. MIPS doesn't support such platform though it
should be fairly easy. In that case __pa should be defined as:

	#define __pa(x)	((unsigned long) (x) - PAGE_OFFSET + PFN_PHYS(ARCH_PFN_OFFSET))

and use in your patch:

	free_area_init_node(0, NODE_DATA(0), zones_size, ARCH_PFN_OFFSET, zholes_size);

So I would recommend to use ARCH_PFN_OFFSET.

		Franck