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Message-Id: <1195520101.6970.28.camel@pasglop>
Date: Tue, 20 Nov 2007 11:55:01 +1100
From: Benjamin Herrenschmidt <benh@...nel.crashing.org>
To: David Miller <davem@...emloft.net>
Cc: James.Bottomley@...senPartnership.com,
linux-kernel@...r.kernel.org, linux-scsi@...r.kernel.org,
rmk@....linux.org.uk
Subject: Re: SCSI breakage on non-cache coherent architectures
On Mon, 2007-11-19 at 16:46 -0800, David Miller wrote:
>
> 1) Require that entire buffers are commited by call sites,
> and thus "embedding" DMA'd within non-DMA stuff isn't allowed
>
> 2) Add the __dma_cacheline_aligned tag.
>
> But note that with #2 it could get quite ugly because the
> alignment and size both have a minimum that needs to be
> enforced, not just the alignment alone. So either:
Yup.
> struct foo {
> unsigned int other_unrelated_stuff;
>
> struct object dma_thing __dma_cacheline_aligned;
>
> unsigned int more_nondma_stuff __dma_cacheline_aligned;
> };
In my tests, I had used a "fuckton_t" object defined to be an empty
thing with alignment constraint, seemed to work :-) But I'd rather
require #1.
BTW. What is the status nowadays with skb's ?
Cheers,
Ben.
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