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Date: Tue, 14 Apr 2015 11:26:13 +0200
From: Laurent Dufour <ldufour@linux.vnet.ibm.com>
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To: Andrew Morton <akpm@linux-foundation.org>, Ingo Molnar <mingo@kernel.org>
Subject: Re: [RESEND PATCH v3 1/2] mm: Introducing arch_remap hook
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Cc: Rik van Riel <riel@redhat.com>, Pavel Emelyanov <xemul@parallels.com>,
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On 13/04/2015 22:59, Andrew Morton wrote:
> On Mon, 13 Apr 2015 17:02:19 +0300 "Kirill A. Shutemov" <kirill@shutemov.name> wrote:
> 
>>> Kirill, if I'm right with it, can you suggest the header where to put
>>> the "generic" mremap hook's (empty) body?
>>
>> I initially thought it would be enough to put it into
>> <asm-generic/mmu_context.h>, expecting it works as
>> <asm-generic/pgtable.h>. But that's not the case.
>>
>> It probably worth at some point rework all <asm/mmu_context.h> to include
>> <asm-generic/mmu_context.h> at the end as we do for <asm/pgtable.h>.
>> But that's outside the scope of the patchset, I guess.
>>
>> I don't see any better candidate for such dummy header. :-/
> 
> Do away with __HAVE_ARCH_REMAP and do it like this:
> 
> arch/x/include/asm/y.h:
> 
> 	extern void arch_remap(...);
> 	#define arch_remap arch_remap
> 
> include/linux/z.h:
> 
> 	#include <asm/y.h>
> 
> 	#ifndef arch_remap
> 	static inline void arch_remap(...) { }
> 	#define arch_remap arch_remap
> 	#endif

Hi Andrew,

I like your idea, but I can't find any good candidate for <asm/y.h> and
<linux/z.h>.

I tried with <linux/mm.h> and <asm/mmu_context.h> but
<asm/mmu_context.h> is already including <linux/mm.h>.

Do you have any suggestion ?

Another option could be to do it like the actual arch_unmap() in
<asm-generic/mm_hooks.h> but this is the opposite of your idea, and Ingo
was not comfortable with this idea due to the impact of the other
architectures.

Cheers,
Laurent.