From: konrad.wilk@oracle•com (Konrad Rzeszutek Wilk)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCHv2 3/4] mm: vmalloc: add VM_DMA flag to indicate areas used by dma-mapping framework
Date: Tue, 29 May 2012 11:07:14 -0400 [thread overview]
Message-ID: <20120529150714.GA8293@phenom.dumpdata.com> (raw)
In-Reply-To: <001d01cd3caa$a05d0510$e1170f30$%szyprowski@samsung.com>
On Mon, May 28, 2012 at 10:19:39AM +0200, Marek Szyprowski wrote:
> Hello,
>
> On Sunday, May 27, 2012 2:35 PM KOSAKI Motohiro wrote:
>
> > On Thu, May 24, 2012 at 8:28 AM, Paul Mundt <lethal@linux-sh•org> wrote:
> > > On Thu, May 24, 2012 at 02:26:12PM +0200, Marek Szyprowski wrote:
> > >> On Tuesday, May 22, 2012 9:08 AM Minchan Kim wrote:
> > >> > Hmm, VM_DMA would become generic flag?
> > >> > AFAIU, maybe VM_DMA would be used only on ARM arch.
> > >>
> > >> Right now yes, it will be used only on ARM architecture, but maybe other architecture will
> > >> start using it once it is available.
> > >>
> > > There's very little about the code in question that is ARM-specific to
> > > begin with. I plan to adopt similar changes on SH once the work has
> > > settled one way or the other, so we'll probably use the VMA flag there,
> > > too.
> >
> > I don't think VM_DMA is good idea because x86_64 has two dma zones. x86 unaware
> > patches make no sense.
>
> I see no problems to add VM_DMA64 later if x86_64 starts using vmalloc areas for creating
> kernel mappings for the dma buffers (I assume that there are 2 dma zones: one 32bit and one
> 64bit). Right now x86 and x86_64 don't use vmalloc areas for dma buffers, so I hardly see
> how this patch can be considered as 'x86 unaware'.
Well they do - kind off. It is usually done by calling vmalloc_32 and then using
the DMA API on top of those pages (or sometimes the non-portable virt_to_phys macro).
Introducing this and replacing the vmalloc_32 with this seems like a nice step in making
those device drivers APIs more portable?
next prev parent reply other threads:[~2012-05-29 15:07 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-05-17 10:54 [PATCHv2 0/4] ARM: replace custom consistent dma region with vmalloc Marek Szyprowski
2012-05-17 10:54 ` [PATCHv2 1/4] mm: vmalloc: use const void * for caller argument Marek Szyprowski
2012-05-22 6:58 ` Minchan Kim
2012-05-17 10:54 ` [PATCHv2 2/4] mm: vmalloc: export find_vm_area() function Marek Szyprowski
2012-05-22 7:01 ` Minchan Kim
2012-05-17 10:54 ` [PATCHv2 3/4] mm: vmalloc: add VM_DMA flag to indicate areas used by dma-mapping framework Marek Szyprowski
2012-05-22 7:07 ` Minchan Kim
2012-05-24 12:26 ` Marek Szyprowski
2012-05-24 12:28 ` Paul Mundt
2012-05-27 12:35 ` KOSAKI Motohiro
2012-05-28 8:19 ` Marek Szyprowski
2012-05-29 15:07 ` Konrad Rzeszutek Wilk [this message]
2012-05-17 10:54 ` [PATCHv2 4/4] ARM: dma-mapping: remove custom consistent dma region Marek Szyprowski
2012-05-22 7:33 ` Minchan Kim
2012-05-22 12:50 ` Marek Szyprowski
2012-05-30 0:11 ` KOSAKI Motohiro
2012-05-30 7:15 ` Marek Szyprowski
2012-05-30 7:22 ` KOSAKI Motohiro
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