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Date: Tue, 18 Oct 2011 06:59:28 -0500
Message-ID: <CAN_cFWNKeD8sf-nmv9ZtVxKu1XMf3caNRKHtkzdq9zfSMig6-w@mail.gmail.com>
Subject: Re: [PATCH 34/49] gma500: the GEM and GTT code is device independant
From: Rob Clark <rob.clark@linaro.org>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Hugh Dickins <hughd@google.com>,
        Patrik Jakobsson <patrik.r.jakobsson@gmail.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Christoph Hellwig <hch@infradead.org>, greg@kroah.com,
        linux-kernel@vger.kernel.org
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On Tue, Oct 18, 2011 at 5:45 AM, Alan Cox <alan@lxorguk.ukuu.org.uk> wrote:
>> What troubles could you see for swap+uncached (or more likely,
>> writecombine) pages?
>
> That should never occur. I would argue the driver is responsible for
> putting the cache state of the page back sensibly before it unpins it.
> That's a simple enough rule and one I think all the drivers follow at
> this point.

no, what I'm trying to avoid is having two virtual mappings to the
same physical page with different cache attributes.  This is not
allowed on some architectures (like ARM)

BR,
-R