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Date: Thu, 2 Aug 2007 14:26:21 +0100
From: Christoph Hellwig <hch@infradead.org>
Subject: Re: [PATCH 3/4] vmemmap: pull out the vmemmap code into its own file
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To: Andy Whitcroft <apw@shadowen.org>
Cc: Andrew Morton <akpm@linux-foundation.org>, linux-mm@kvack.org, linux-arch@vger.kernel.org, Christoph Hellwig <hch@infradead.org>, Nick Piggin <npiggin@suse.de>, Christoph Lameter <clameter@sgi.com>, Mel Gorman <mel@csn.ul.ie>
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On Thu, Aug 02, 2007 at 10:25:35AM +0100, Andy Whitcroft wrote:
> + * Special Kconfig settings:
> + *
> + * CONFIG_ARCH_POPULATES_SPARSEMEM_VMEMMAP
> + *
> + * 	The architecture has its own functions to populate the memory
> + * 	map and provides a vmemmap_populate function.
> + *
> + * CONFIG_ARCH_POPULATES_SPARSEMEM_VMEMMAP_PMD
> + *
> + * 	The architecture provides functions to populate the pmd level
> + * 	of the vmemmap mappings.  Allowing mappings using large pages
> + * 	where available.
> + *
> + * 	If neither are set then PAGE_SIZE mappings are generated which
> + * 	require one PTE/TLB per PAGE_SIZE chunk of the virtual memory map.
> + */

This is the kinda of mess I mean.  Which architecturs set either of these
and why?  This code would be a lot more acceptable if we hadn't three
different variants of the arch interface.