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From: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
To: davem@davemloft.net
Cc: tomof@acm.org, fujita.tomonori@lab.ntt.co.jp,
	jens.axboe@oracle.com, linux-kernel@vger.kernel.org
Subject: Re: more iommu sg merging fallout
Date: Tue, 19 Feb 2008 19:57:58 +0900	[thread overview]
Message-ID: <20080219195758V.fujita.tomonori@lab.ntt.co.jp> (raw)
In-Reply-To: <20080217.234142.157527607.davem@davemloft.net>

On Sun, 17 Feb 2008 23:41:42 -0800 (PST)
David Miller <davem@davemloft.net> wrote:

> From: FUJITA Tomonori <tomof@acm.org>
> Date: Sat, 16 Feb 2008 15:03:43 +0900
> 
> > [PATCH] sparc64: make IOMMU code respect the segment boundary limits
> > 
> > Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
> 
> Looks good, but I think it will break sound for some ALI chips.
> 
> Please see arch/sparc64/kernel/pci.c:ali_sound_dma_hack()
> and it's caller pci_dma_supported().

Could you explain the problem a little more?

The shift argument is only used as an offset when iommu-helper decides
whether a memory area (index plus npages) spanning LLD's segment
boudnary size or not.

For example, if a device's segment boudary size is 64K, the helper see
the following value is larger than 64K or not:

((the offset + index of the IOMMU table) ((64K / 8K) - 1) + npages

  reply	other threads:[~2008-02-19 10:58 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-02-06  4:41 David Miller
2008-02-06 23:12 ` FUJITA Tomonori
2008-02-06 23:18   ` David Miller
2008-02-06 23:53     ` FUJITA Tomonori
2008-02-07  0:01       ` David Miller
2008-02-07  1:38         ` FUJITA Tomonori
2008-02-12  5:40           ` David Miller
2008-02-16  6:03             ` FUJITA Tomonori
2008-02-18  7:41               ` David Miller
2008-02-19 10:57                 ` FUJITA Tomonori [this message]
2008-02-21  6:56                   ` David Miller

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