From: Alex Williamson <alex.williamson@hp.com>
To: Paul Mundt <lethal@linux-sh.org>
Cc: dwmw2@infradead.org, iommu@lists.linux-foundation.org,
linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org
Subject: Re: [PATCH 1/5] dma: create dma_generic_alloc/free_coherent()
Date: Mon, 26 Oct 2009 20:26:39 -0600 [thread overview]
Message-ID: <1256610399.19177.3.camel@2710p.home> (raw)
In-Reply-To: <20091027005748.GB17085@linux-sh.org>
On Tue, 2009-10-27 at 09:57 +0900, Paul Mundt wrote:
> On Mon, Oct 26, 2009 at 05:24:58PM -0600, Alex Williamson wrote:
> > Move dma_generic_alloc_coherent() out of x86 code and create
> > corresponding dma_generic_free_coherent() for symmetry. These
> > can then be used by IOMMU drivers attempting to implement
> > passthrough mode.
> >
> Except that dma_generic_alloc_coherent() is only "generic" for platforms
> with consistent DMA. Everyone else will need a cacheflush and potentially
> a remap. It's not even obvious from looking at the consistent DMA
> platforms that they'll be able to use it out of the box due to expecting
> something other than page_address(), which all suggests that this is
> better off remaining an x86-only routine.
>
> This is also making changes to the DMA-API without any documentation
> updates and without consulting with any other architecture people.
Ok, thanks for the feedback. Let's forget this patch and I'll see how
amenable David is to doing something within intel-iommu since it only
supports platforms with consistent DMA. Thanks,
Alex
next prev parent reply other threads:[~2009-10-27 2:26 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-10-26 23:24 [PATCH 0/5] intel-iommu fixes Alex Williamson
2009-10-26 23:24 ` [PATCH 1/5] dma: create dma_generic_alloc/free_coherent() Alex Williamson
2009-10-27 0:57 ` Paul Mundt
2009-10-27 2:26 ` Alex Williamson [this message]
2009-10-27 1:47 ` FUJITA Tomonori
2009-10-26 23:25 ` [PATCH 2/5] intel-iommu: Use dma_generic_alloc_coherent() for passthrough mappings Alex Williamson
2009-10-27 3:24 ` [PATCH v2 2/5] intel-iommu: Obey coherent_dma_mask for alloc_coherent on passthrough Alex Williamson
2009-10-26 23:25 ` [PATCH 3/5] intel-iommu: Use max_pfn to determine whether a device can passthrough Alex Williamson
2009-10-26 23:25 ` [PATCH 4/5] intel-iommu: Reinstate RMRRs if a device is removed from passthrough domain Alex Williamson
2009-10-27 8:15 ` David Woodhouse
2009-10-27 15:50 ` Alex Williamson
2009-10-28 14:36 ` David Woodhouse
2009-10-28 16:06 ` Alex Williamson
2009-10-28 20:35 ` Alex Williamson
2009-10-26 23:25 ` [PATCH 5/5] intel-iommu: Quiet unnecessary output Alex Williamson
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