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Date: Mon, 13 Jun 2016 09:00:41 -0700
From: Christoph Hellwig <hch@infradead.org>
To: "Luis R. Rodriguez" <mcgrof@kernel.org>
Cc: Krzysztof Kozlowski <k.kozlowski@samsung.com>,
        Andrew Morton <akpm@linux-foundation.org>, hch@infradead.org,
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        "Michael S. Tsirkin" <mst@redhat.com>,
        Andy Lutomirski <luto@kernel.org>, linux-doc@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4 01/44] dma-mapping: Use unsigned long for dma_attrs
Message-ID: <20160613160041.GA23851@infradead.org>
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On Fri, Jun 10, 2016 at 04:49:47PM +0200, Luis R. Rodriguez wrote:
> Do we not expect the number of argument to grow ? This "cleanup" would
> do away with such possibilities, and then require adding the API later,
> and this requiring a full set of collateral evolutions again when this
> is needed. What was the original motivation for using this instead of
> the approach you are suggesting ?

We still got plenty of space for attrs.  If you're worried about running
out of 32 flags we could do a dma_attrs_t typedef that we could swich
to a u64.  That would have another advantage in that we could add a
__bitwise sparse annotation to avoid people passing the wrong kind of
flags.