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Date: Thu, 21 Jan 2010 01:32:05 +0000
From: Jamie Lokier <jamie@shareable.org>
To: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: anfei <anfei.zhou@gmail.com>, linux-kernel@vger.kernel.org,
       linux-mm@kvack.org, linux@arm.linux.org.uk
Subject: Re: cache alias in mmap + write
Message-ID: <20100121013205.GA29808@shareable.org>
References: <20100120174630.4071.A69D9226@jp.fujitsu.com> <20100120095242.GA5672@desktop> <20100121094733.3778.A69D9226@jp.fujitsu.com>
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KOSAKI Motohiro wrote:
>  2. Add some commnet. almost developer only have x86 machine. so, arm
>     specific trick need additional explicit explanation. otherwise anybody
>     might break this code in the future.

That's Documentation/cachetlb.txt.

What's being discussed here is not ARM-specific, although it appears
maintainers of different architecture (ARM and MIPS for a start) may
have different ideas about what they are guaranteeing to userspace.
It sounds like MIPS expects userspace to use msync() sometimes (even
though Linux msync(MS_INVALIDATE) is quite broken), and ARM expects to
to keep mappings coherent automatically (which is sometimes slower
than necessary, but usually very helpful).

>  3. Resend the patch. original mail isn't good patch format. please
>  consider to reduce akpm suffer.

This type of change in generic code would need review from a number of
architecture maintainers, I'd expect.

-- Jamie