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From: Mark Hounschell <markh-n2QNKt385d+sTnJN9+BGXg@public.gmane.org>
To: iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org
Subject: Re: [PATCH v6 1/3] iommu: Implement common IOMMU ops for DMA mapping
Date: Fri, 30 Oct 2015 14:18:27 -0400	[thread overview]
Message-ID: <5633B473.9070605@compro.net> (raw)
In-Reply-To: <20151030140923.GJ27420-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>

On 10/30/2015 10:09 AM, Joerg Roedel wrote:
> On Fri, Oct 30, 2015 at 09:17:52AM +0800, Daniel Kurtz wrote:
>> Hmm, I thought the DMA API maps a (possibly) non-contiguous set of
>> memory pages into a contiguous block in device memory address space.
>> This would allow passing a dma mapped buffer to device dma using just
>> a device address and length.
>
> If you are speaking of the dma_map_sg interface, than there is absolutly
> no guarantee from the API side that the buffers you pass in will end up
> mapped contiguously.
> IOMMU drivers handle this differently, and when there is no IOMMU at all
> there is also no way to map these buffers together.
>

That is what CMA is for ya know. It makes it physically contiguous.

Mark

  parent reply	other threads:[~2015-10-30 18:18 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-10-01 19:13 [PATCH v6 0/3] arm64: IOMMU-backed DMA mapping Robin Murphy
     [not found] ` <cover.1443718557.git.robin.murphy-5wv7dgnIgG8@public.gmane.org>
2015-10-01 19:13   ` [PATCH v6 1/3] iommu: Implement common IOMMU ops for " Robin Murphy
     [not found]     ` <ab8e1caa40d6da1afa4a49f30242ef4e6e1f17df.1443718557.git.robin.murphy-5wv7dgnIgG8@public.gmane.org>
2015-10-26 13:44       ` Yong Wu
2015-10-26 16:55         ` Robin Murphy
2015-10-30  1:17           ` Daniel Kurtz
2015-10-30 14:09             ` Joerg Roedel
     [not found]               ` <20151030140923.GJ27420-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
2015-10-30 18:18                 ` Mark Hounschell [this message]
2015-10-30 14:27             ` Robin Murphy
2015-11-02 13:11               ` Daniel Kurtz
2015-11-02 13:43                 ` Tomasz Figa
2015-11-03 17:41                   ` Robin Murphy
2015-11-03 18:40                     ` Russell King - ARM Linux
2015-11-04  5:15                       ` Tomasz Figa
     [not found]                         ` <CAAFQd5COY-dvBE73R=sUWoGfXR9CvgurGchYgXB6y9eqQ=BBUQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2015-11-04  9:10                           ` Russell King - ARM Linux
2015-11-04  5:12                     ` Tomasz Figa
     [not found]                       ` <CAAFQd5A4TcvkDMFezqEpkfWL+7yO2v=Hm=twk=p-NpADPpvqEQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2015-11-04  9:27                         ` Russell King - ARM Linux
2015-11-04  9:48                           ` Tomasz Figa
     [not found]                             ` <CAAFQd5ApSFC6Pm4tDhZbJOVZ7szCx=diKUtGXq=M9a5Y_4qzOQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2015-11-04 10:50                               ` Russell King - ARM Linux
2015-11-09 13:11                       ` Robin Murphy
2015-11-17 12:02             ` Marek Szyprowski
2015-10-01 19:13   ` [PATCH v6 2/3] arm64: Add IOMMU dma_ops Robin Murphy
2015-10-07  9:03     ` Anup Patel
     [not found]       ` <CAAhSdy2tpAfH+i=1axDkmRqZixsbVhd-_9VGvpyQ=5e06v=Kpg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2015-10-07 16:36         ` Robin Murphy
2015-10-07 17:40           ` Anup Patel
     [not found]     ` <80cb035144a2648a5d94eb1fec3336f17ad249f1.1443718557.git.robin.murphy-5wv7dgnIgG8@public.gmane.org>
2015-10-06 11:00       ` Yong Wu
2015-10-07 16:07         ` Robin Murphy
     [not found]           ` <56154349.8040101-5wv7dgnIgG8@public.gmane.org>
2015-10-09  5:44             ` Yong Wu
2015-10-14 11:47       ` Joerg Roedel
2015-10-14 13:35       ` Catalin Marinas
     [not found]         ` <20151014133538.GG4239-M2fw3Uu6cmfZROr8t4l/smS4ubULX0JqMm0uRHvK7Nw@public.gmane.org>
2015-10-14 16:34           ` Robin Murphy
2015-11-04  8:39       ` Yong Wu
2015-11-04 13:11         ` Robin Murphy
     [not found]           ` <563A0419.9070100-5wv7dgnIgG8@public.gmane.org>
2015-11-04 17:35             ` Laura Abbott
2015-10-01 19:14   ` [PATCH v6 3/3] arm64: Hook up " Robin Murphy
2015-10-13 12:12   ` [PATCH v6 0/3] arm64: IOMMU-backed DMA mapping Robin Murphy
     [not found]     ` <561CF53E.7000809-5wv7dgnIgG8@public.gmane.org>
2015-10-14 11:50       ` joro-zLv9SwRftAIdnm+yROfE0A
     [not found]         ` <20151014115013.GM27420-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
2015-10-14 18:19           ` Robin Murphy
2015-10-15 15:04   ` Joerg Roedel

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