Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753631Ab2JPK2M (ORCPT ); Tue, 16 Oct 2012 06:28:12 -0400 Received: from hqemgate03.nvidia.com ([216.228.121.140]:5816 "EHLO hqemgate03.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752193Ab2JPK2K convert rfc822-to-8bit (ORCPT ); Tue, 16 Oct 2012 06:28:10 -0400 X-PGP-Universal: processed; by hqnvupgp05.nvidia.com on Tue, 16 Oct 2012 03:28:02 -0700 From: Hiroshi Doyu To: "linux@arm.linux.org.uk" CC: "m.szyprowski@samsung.com" , "inki.dae@samsung.com" , "arnd@arndb.de" , "linux-kernel@vger.kernel.org" , "linaro-mm-sig@lists.linaro.org" , "linux-mm@kvack.org" , "kyungmin.park@samsung.com" , "linux-arm-kernel@lists.infradead.org" , "linux-tegra@vger.kernel.org" Date: Tue, 16 Oct 2012 12:27:55 +0200 Subject: Re: [Linaro-mm-sig] [RFC 0/2] DMA-mapping & IOMMU - physically contiguous allocations Thread-Topic: [Linaro-mm-sig] [RFC 0/2] DMA-mapping & IOMMU - physically contiguous allocations Thread-Index: Ac2riOooZrAc82VmQtCUqeE7OlPJLQ== Message-ID: <20121016.132755.661591248175727826.hdoyu@nvidia.com> References: <20121016090434.7d5e088152a3e0b0606903c8@nvidia.com><20121016085928.GV21164@n2100.arm.linux.org.uk> In-Reply-To: <20121016085928.GV21164@n2100.arm.linux.org.uk> Accept-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-nvconfidentiality: public acceptlanguage: en-US Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1478 Lines: 33 Hi Russell, Russell King - ARM Linux wrote @ Tue, 16 Oct 2012 10:59:28 +0200: > On Tue, Oct 16, 2012 at 09:04:34AM +0300, Hiroshi Doyu wrote: > > In addition to those contiguous/discontiguous page allocation, is > > there any way to _import_ anonymous pages allocated by a process to be > > used in dma-mapping API later? > > > > I'm considering the following scenario, an user process allocates a > > buffer by malloc() in advance, and then it asks some driver to convert > > that buffer into IOMMU'able/DMA'able ones later. In this case, pages > > are discouguous and even they may not be yet allocated at > > malloc()/mmap(). > > That situation is covered. It's the streaming API you're wanting for that. > dma_map_sg() - but you may need additional cache handling via > flush_dcache_page() to ensure that your code is safe for all CPU cache > architectures. > > Remember that pages allocated into userspace will be cacheable, so a cache > flush is required before they can be DMA'd. Hence the streaming > API. Is the syscall "cacheflush()" supposed to be the knob for that? Or is there any other ones to have more precise control, "clean", "invalidate" and "flush", from userland in generic way? -- 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/