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From: Zach Pfeffer <zpfeffer@codeaurora.org>
To: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: linux@arm.linux.org.uk, ebiederm@xmission.com,
	linux-arch@vger.kernel.org, dwalker@codeaurora.org,
	mel@csn.ul.ie, linux-arm-msm@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	andi@firstfloor.org, linux-omap@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [RFC 1/3 v3] mm: iommu: An API to unify IOMMU, CPU and device memory management
Date: Wed, 14 Jul 2010 13:11:49 -0700	[thread overview]
Message-ID: <20100714201149.GA14008@codeaurora.org> (raw)
In-Reply-To: <20100714104353B.fujita.tomonori@lab.ntt.co.jp>

On Wed, Jul 14, 2010 at 10:59:38AM +0900, FUJITA Tomonori wrote:
> On Tue, 13 Jul 2010 05:14:21 -0700
> Zach Pfeffer <zpfeffer@codeaurora.org> wrote:
> 
> > > You mean that you want to specify this alignment attribute every time
> > > you create an IOMMU mapping? Then you can set segment_boundary_mask
> > > every time you create an IOMMU mapping. It's odd but it should work.
> > 
> > Kinda. I want to forget about IOMMUs, devices and CPUs. I just want to
> > create a mapping that has the alignment I specify, regardless of the
> > mapper. The mapping is created on a VCM and the VCM is associated with
> > a mapper: a CPU, an IOMMU'd device or a direct mapped device.
> 
> Sounds like you can do the above with the combination of the current
> APIs, create a virtual address and then an I/O address.
> 

Yes, and that's what the implementation does - and all the other
implementations that need to do this same thing. Why not solve the
problem once?

> The above can't be a reason to add a new infrastructure includes more
> than 3,000 lines.

Right now its 3000 lines because I haven't converted to a function
pointer based implementation. Once I do that the size of the
implementation will shrink and the code will act as a lib. Users pass
buffer mappers and the lib will ease the management of of those
buffers.

>  
> 
> > > Another possible solution is extending struct dma_attrs. We could add
> > > the alignment attribute to it.
> > 
> > That may be useful, but in the current DMA-API may be seen as
> > redundant info.
> 
> If there is real requirement, we can extend the DMA-API.

If the DMA-API contained functions to allocate virtual space separate
from physical space and reworked how chained buffers functioned it
would probably work - but then things start to look like the VCM API
which does graph based map management.

> 
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  reply	other threads:[~2010-07-14 20:11 UTC|newest]

Thread overview: 53+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-07-03  5:38 [RFC 1/3 v3] mm: iommu: An API to unify IOMMU, CPU and device memory management Zach Pfeffer
2010-07-03 19:06 ` Eric W. Biederman
2010-07-07 22:44   ` Zach Pfeffer
2010-07-07 23:07     ` Russell King - ARM Linux
2010-07-08 23:59       ` Zach Pfeffer
2010-07-12  1:25         ` FUJITA Tomonori
2010-07-13  5:57           ` Zach Pfeffer
2010-07-13  6:03             ` FUJITA Tomonori
2010-07-13 12:14               ` Zach Pfeffer
2010-07-14  1:59                 ` FUJITA Tomonori
2010-07-14 20:11                   ` Zach Pfeffer [this message]
2010-07-14 22:05                     ` Russell King - ARM Linux
2010-07-15  1:29                       ` Zach Pfeffer
2010-07-15  1:47                         ` Eric W. Biederman
2010-07-15  5:40                           ` Zach Pfeffer
2010-07-15  5:35                         ` Zach Pfeffer
2010-07-15  8:55                         ` Russell King - ARM Linux
2010-07-16  0:48                           ` Tim HRM
2010-07-16  7:58                             ` Russell King - ARM Linux
2010-07-17  0:01                               ` Larry Bassel
2010-07-19  9:21                                 ` Tim HRM
2010-07-21  0:44                                   ` Zach Pfeffer
2010-07-21  1:44                                     ` Timothy Meade
2010-07-22  4:06                                       ` Zach Pfeffer
2010-07-19 17:55                               ` Michael Bohan
2010-07-19 18:40                                 ` Russell King - ARM Linux
2010-07-20 22:02                                   ` stepanm
2010-07-20 22:29                                     ` Russell King - ARM Linux
2010-07-21  5:49                                       ` Shilimkar, Santosh
2010-07-21  7:28                                         ` Russell King - ARM Linux
2010-07-21  7:45                                           ` Shilimkar, Santosh
2010-07-21 18:04                                           ` stepanm
2010-07-20 20:45                               ` Zach Pfeffer
2010-07-20 20:54                                 ` Russell King - ARM Linux
2010-07-20 21:56                                   ` Zach Pfeffer
2010-07-19  6:52                           ` Zach Pfeffer
2010-07-19  7:44                             ` Eric W. Biederman
2010-07-22  4:25                               ` Zach Pfeffer
2010-07-22  7:34                                 ` Russell King - ARM Linux
2010-07-22 16:25                                   ` Zach Pfeffer
2010-07-14 23:07                     ` FUJITA Tomonori
2010-07-15  1:41                       ` Zach Pfeffer
2010-07-19  8:22                         ` Russell King - ARM Linux
2010-07-20 10:09                           ` FUJITA Tomonori
2010-07-20 22:20                           ` Zach Pfeffer
2010-07-21  1:44                             ` FUJITA Tomonori
2010-07-22  4:30                               ` Zach Pfeffer
2010-07-22  4:43                                 ` FUJITA Tomonori
2010-07-22 16:44                                   ` Zach Pfeffer
2010-07-22  7:39                                 ` Russell King - ARM Linux
2010-07-22 16:28                                   ` Zach Pfeffer
  -- strict thread matches above, loose matches on Subject: below --
2010-07-06 15:42 Zach Pfeffer
2010-07-21  5:18 stepanm

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