linux-kernel - Re: [PATCH] NVMe: Fix compilation on architecturs without readq/writeq

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Date:	Mon, 23 Jan 2012 15:04:27 -0800
From:	"H. Peter Anvin" <hpa@...ux.intel.com>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
CC:	Hitoshi Mitake <h.mitake@...il.com>, Ingo Molnar <mingo@...e.hu>,
	Matthew Wilcox <matthew.r.wilcox@...el.com>,
	Roland Dreier <roland@...estorage.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	James Bottomley <James.Bottomley@...allels.com>,
	linux-kernel@...r.kernel.org, linux-nvme@...radead.org
Subject: Re: [PATCH] NVMe: Fix compilation on architecturs without readq/writeq

On 01/23/2012 08:57 AM, Linus Torvalds wrote:
> On Mon, Jan 23, 2012 at 8:05 AM, Hitoshi Mitake<h.mitake@...il.com>  wrote:
>>
>> I wrote the patch which adds the new file include/asm-generic/io-nonatomic.h.
>> io-nonatomic.h provides non-atomic version readq()/writeq().
>
> I do wonder if we should do "little-endian" and "big-endian" variations?
>
> Quoting Willy:
>
>    "For this particular hardware, it's defined to work if you read the
> low order bits first"
>
> so I think we need make that explicit, and make two include files:
>
>     include/asm-generic/io-64b-lo-hi.h
>     include/asm-generic/io-64b-hi-lo.h
>
> or something like that. And thus indirectly document these kinds of
> requirements.
>

I would concur with this (and I have suggested exactly this in the past.)

	-hpa

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