arm: msm: Add System MMU support.
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From: Roedel, Joerg on 29 Jul 2010 04:40 On Thu, Jul 29, 2010 at 04:26:55AM -0400, Arnd Bergmann wrote: > On Thursday 29 July 2010 05:35:48 FUJITA Tomonori wrote: > > > > > > From what I have been able to tell, the IOMMU interface was written by > > > AMD/Intel to allow the kvm code to work with a common IOMMU interface. To > > > > Don't confuse the IOMMU interface with the DMA API that Arnd > > mentioned. > > > > They are not related at all. Thats not 100% true. They are not strictly related, but they are related as they may use the same backend kernel drivers to provide their functionality. Both APIs exist for different purposes, of course. > Exactly, thanks for the clarification. I also didn't realize that there > is now an include/linux/iommu.h file that only describes the PCI SR-IOV > interfaces, unlike the generic IOMMU support that we have in your > include/linux/dma-mapping.h file. The IOMMU-API is not about SR-IOV. It is about the capabilities of modern IOMMU hardware that we can not provide to the kernel with the DMA-API such as the ability to choose ourself at which io-virtual address a given cpu physical address should be mapped. Also I wouldn't call the DMA-API an IOMMU interface. The API does not depend on an IOMMU which is an important difference to the IOMMU-API. The IOMMU-API is probably not generic enough to handle all kinds of IOMMUs but its closer to a generic IOMMU-API than the DMA-API. Joerg -- Joerg Roedel - AMD Operating System Research Center Advanced Micro Devices GmbH Einsteinring 24 85609 Dornach General Managers: Alberto Bozzo, Andrew Bowd Registration: Dornach, Landkr. Muenchen; Registerger. Muenchen, HRB Nr. 43632 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: FUJITA Tomonori on 29 Jul 2010 04:40 On Thu, 29 Jul 2010 10:26:55 +0200 Arnd Bergmann <arnd(a)arndb.de> wrote: > On Thursday 29 July 2010 05:35:48 FUJITA Tomonori wrote: > > > > > > From what I have been able to tell, the IOMMU interface was written by > > > AMD/Intel to allow the kvm code to work with a common IOMMU interface. To > > > > Don't confuse the IOMMU interface with the DMA API that Arnd > > mentioned. > > > > They are not related at all. > > Exactly, thanks for the clarification. I also didn't realize that there > is now an include/linux/iommu.h file that only describes the PCI SR-IOV > interfaces, unlike the generic IOMMU support that we have in your > include/linux/dma-mapping.h file. > > Maybe we should rename linux/iommu.h to something more specific so we > can reduce this confusion in the future. I also said that linux/iommu.h was a bad name when it was introduced :) Well, the author disagreed. Now the name actually confuse developers. The author might rethink. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: FUJITA Tomonori on 29 Jul 2010 04:50 On Thu, 29 Jul 2010 10:40:19 +0200 "Roedel, Joerg" <Joerg.Roedel(a)amd.com> wrote: > The IOMMU-API is not about SR-IOV. That's true. However, the point is that include/iommu.h is far from the IOMMU-API. You could still insist that include/iommu.h is designed for the generic IOMMU-API. But the fact is that it's designed for very specific purposes. No intention to make it for generic purposes. Since you added it two years ago, nobody has tried to extend it. Instead, we have something like arch/arm/plat-omap/include/plat/iommu.h. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Roedel, Joerg on 29 Jul 2010 05:10 On Thu, Jul 29, 2010 at 04:46:59AM -0400, FUJITA Tomonori wrote: > On Thu, 29 Jul 2010 10:40:19 +0200 > "Roedel, Joerg" <Joerg.Roedel(a)amd.com> wrote: > > > The IOMMU-API is not about SR-IOV. > > That's true. However, the point is that include/iommu.h is far from > the IOMMU-API. > > You could still insist that include/iommu.h is designed for the > generic IOMMU-API. But the fact is that it's designed for very > specific purposes. No intention to make it for generic purposes. I have no clue about the ARM iommus on the omap-platform. From a quick look into the header file I see some similarities to the IOMMU-API. I am also very open for discussions about how the IOMMU-API could be extended to fit the needs of other platforms. Only because nobody has tried to discuss about such an effort is no reason to push the IOMMU-API back. > > Since you added it two years ago, nobody has tried to extend > it. Instead, we have something like > arch/arm/plat-omap/include/plat/iommu.h. And I think we should try to merge this platform-specific functionality into the IOMMU-API. Joerg -- Joerg Roedel - AMD Operating System Research Center Advanced Micro Devices GmbH Einsteinring 24 85609 Dornach General Managers: Alberto Bozzo, Andrew Bowd Registration: Dornach, Landkr. Muenchen; Registerger. Muenchen, HRB Nr. 43632 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: FUJITA Tomonori on 29 Jul 2010 05:20
On Thu, 29 Jul 2010 11:06:08 +0200 "Roedel, Joerg" <Joerg.Roedel(a)amd.com> wrote: > On Thu, Jul 29, 2010 at 04:46:59AM -0400, FUJITA Tomonori wrote: > > On Thu, 29 Jul 2010 10:40:19 +0200 > > "Roedel, Joerg" <Joerg.Roedel(a)amd.com> wrote: > > > > > The IOMMU-API is not about SR-IOV. > > > > That's true. However, the point is that include/iommu.h is far from > > the IOMMU-API. > > > > You could still insist that include/iommu.h is designed for the > > generic IOMMU-API. But the fact is that it's designed for very > > specific purposes. No intention to make it for generic purposes. > > I have no clue about the ARM iommus on the omap-platform. From a quick > look into the header file I see some similarities to the IOMMU-API. I am ARM's iommu stuff might be more appropriate as the IOMMU-API than include/linux/iommu.h > also very open for discussions about how the IOMMU-API could be extended > to fit the needs of other platforms. Only because nobody has tried to > discuss about such an effort is no reason to push the IOMMU-API back. Well, the reason (nobody has tried) might be that linux/iommu.h doesn't look something intended for the generic IOMMU-API. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |