Date: Sat, 22 Mar 2008 17:23:05 -0700 (PDT)
Message-Id: <20080322.172305.103826809.davem@davemloft.net>
To: fujita.tomonori@lab.ntt.co.jp
Cc: linux-kernel@vger.kernel.org, linux-sparc@vger.kernel.org, tomof@acm.org,
       akpm@linux-foundation.org
Subject: Re: [PATCH -mm 1/2] SPARC64: add the segment boundary checking to
 IOMMUs while merging SG entries
From: David Miller <davem@davemloft.net>
In-Reply-To: <1205380027-28230-1-git-send-email-fujita.tomonori@lab.ntt.co.jp>
References: <1205380027-28230-1-git-send-email-fujita.tomonori@lab.ntt.co.jp>
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From: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Date: Thu, 13 Mar 2008 12:47:06 +0900

> Some IOMMUs allocate memory areas spanning LLD's segment boundary
> limit. It forces low level drivers to have a workaround to adjust
> scatter lists that the IOMMU builds. We are in the process of making
> all the IOMMUs respect the segment boundary limits to remove such work
> around in LLDs.
> 
> SPARC64 IOMMUs were rewritten to use the IOMMU helper functions and
> the commit 89c94f2f70d093f59b55d3ea8042d13889169346 made the IOMMUs
> not allocate memory areas spanning the segment boundary limit.
> 
> However, SPARC64 IOMMUs allocate memory areas first then try to merge
> them (while some IOMMUs walk through all the sg entries to see how
> they can be merged first and allocate memory areas). So SPARC64 IOMMUs
> also need the boundary limit checking when they try to merge sg
> entries.
> 
> Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>

Acked-by: David S. Miller <davem@davemloft.net>
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