Messages in this thread | | | Date | Tue, 3 Apr 2012 10:58:36 -0400 | Subject | Re: Linux 3.4-rc1 | From | Jerome Glisse <> |
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On Tue, Apr 3, 2012 at 5:07 AM, Arnd Bergmann <arnd@arndb.de> wrote: > On Tuesday 03 April 2012, Kyungmin Park wrote: >> > >> > - DMA-mapping framework. The tree now has a few more acks from >> > people, and it's largely in the same situation as HSI is: I'll >> > probably pull, but I really wanted the users who are impacted to >> > actually talk to me about it. >> > >> Hi, >> >> Now Marek and Nvidia persons are used it for DMA mapping based IOMMU. >> >> Are there other person who help to merge it? >> (+CC related persons). > > I can give a little more background information. > > We used to have separate implementations of dma_map_ops for each > architecture that had the need to abstract dma_alloc_coherent > and dma_map_* across both IOMMU and linear (virt_to_bus style) > mappings and/or swiotlb. Those dma_map_ops imlpementations were > already merged before the start of the git history and subsequently > got used on powerpc, ia64, x86_64, sparc, alpha, mips, unicore32 > and hexagon, roughly in that order. > > We are seeing lots of IOMMUs come up on ARM now, but unfortunately > the existing dma_map_ops do not cover the need on ARM to have > two different kind of coherent memory (write-combine and not > write-combine) that we have traditionally abstracted using > the dma_alloc_coherent and dma_alloc_writecombine functions on both > arm and avr32. In order to support IOMMUs on ARM using the same > API as everyone else, I've asked Marek to use dma_map_ops on > ARM, which requires slightly extending the include/linux/dma-mapping.h > interfaces so they cover this variation. > > The actually interesting work to implement a better abstraction for > IOMMUs, building the dma-mapping.h API on top of the iommu.h API > in an architecture independent way has also been implemented but > requires these changes as a prerequisite. > > Arnd
Out of curiosity where is the IOMMU abstraction work being discussed ? Worked on ? I would like similar things on x86 platform and i spend sometimes thinking on it in the past. Would like to make sure this could also fit our need.
Cheers, Jerome -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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