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Date: Fri, 1 May 2009 13:46:18 -0400
From: Christoph Hellwig <hch@infradead.org>
To: Dave Hansen <dave@linux.vnet.ibm.com>
Cc: linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC][PATCH 34/35] powerpc use generic ptemap.h
Message-ID: <20090501174617.GB8104@infradead.org>
References: <20090501144201.D31EF417@kernel> <20090501144254.52127677@kernel>
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On Fri, May 01, 2009 at 07:42:54AM -0700, Dave Hansen wrote:
> 
> powerpc is a bid of an oddball here.  It seems to have CONFIG_HIGHPTE
> behavior at all times when compiled as 32-bit.  There's even an
> #ifdef CONFIG_HIGHPTE in arch/powerpc/mm/pgtable_32.c, but there's no
> trace of HIGHPTE in Kconfig anywhere.
> 
> This gives ppc32 an explicit HIGHPTE in Kconfig so that we can use
> the #ifdef in asm-generic/ptemap.h and let ppc use the generic code
> with x86 and frv.

But if you enabled HIGHPTE you need to remove that ifdef in pgtable_32.c
because it didn't get triggered before.

>  #define _POWERPC_ASM_PTEMAP_H
>  
>  #ifndef __powerpc64__
> +/*
> + * This lets us use the x86 implementation
> + * in the generic ptemap.h
> + */
> +#define kmap_atomic_pte(page, type) kmap_atomic(page, type)
> +#endif

That comment doesn't make any sense to me, x86 should have nothing to do
with it.  Also the comment would comfortably fit into a single line
instead of two.