Date: Sun, 28 Feb 2010 00:16:28 -0800 (PST)
Message-Id: <20100228.001628.48507956.davem@davemloft.net>
To: fujita.tomonori@lab.ntt.co.jp
Cc: hancockrwd@gmail.com, bzolnier@gmail.com, linux-kernel@vger.kernel.org,
       netdev@vger.kernel.org, linux-usb@vger.kernel.org
Subject: Re: [RFC PATCH] fix problems with NETIF_F_HIGHDMA in networking
 drivers
From: David Miller <davem@davemloft.net>
In-Reply-To: <20100228033706G.fujita.tomonori@lab.ntt.co.jp>
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	<51f3faa71002271015i7c9ec45j18381b1269bfd799@mail.gmail.com>
	<20100228033706G.fujita.tomonori@lab.ntt.co.jp>
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From: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Date: Sun, 28 Feb 2010 03:38:19 +0900

> When I proposed such approach (always use swiotlb) before, IIRC,
> the objections were:
> 
> - better to make allocation respect dma_mask. (I don't think that this
>   approach is possible since we don't know which device handles data
>   later when we allocate memory).

And such objects might end up being processed by multiple devices with
different DMA restrictions.

> - swiotlb is not good for small systems since it allocates too much
>   memory (we can fix this though).

Indeed.
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