From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751466AbVKORt4 (ORCPT ); Tue, 15 Nov 2005 12:49:56 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751467AbVKORt4 (ORCPT ); Tue, 15 Nov 2005 12:49:56 -0500 Received: from pentafluge.infradead.org ([213.146.154.40]:56969 "EHLO pentafluge.infradead.org") by vger.kernel.org with ESMTP id S1751466AbVKORtz (ORCPT ); Tue, 15 Nov 2005 12:49:55 -0500 Subject: Re: DMA transfer with kiobuf, kernel 2.4.21 From: Arjan van de Ven To: sej Cc: linux-kernel@vger.kernel.org In-Reply-To: <437A1D6E.4060302@aie-etudes.com> References: <437A1D6E.4060302@aie-etudes.com> Content-Type: text/plain Date: Tue, 15 Nov 2005 18:49:45 +0100 Message-Id: <1132076986.2822.34.camel@laptopd505.fenrus.org> Mime-Version: 1.0 X-Mailer: Evolution 2.2.3 (2.2.3-2.fc4) Content-Transfer-Encoding: 7bit X-Spam-Score: 1.8 (+) X-Spam-Report: SpamAssassin version 3.0.4 on pentafluge.infradead.org summary: Content analysis details: (1.8 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- 0.1 RCVD_IN_SORBS_DUL RBL: SORBS: sent directly from dynamic IP address [213.93.14.173 listed in dnsbl.sorbs.net] 1.7 RCVD_IN_NJABL_DUL RBL: NJABL: dialup sender did non-local SMTP [213.93.14.173 listed in combined.njabl.org] X-SRS-Rewrite: SMTP reverse-path rewritten from by pentafluge.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2005-11-15 at 18:39 +0100, sej wrote: > Hi, > I allocate a big chunck of memory from user space with : > > #define MEM_SIZE_DMA (128*1024*1024) > // allocate 128MB of memory > void *_pVirtualMem = memalign(sysconf(_SC_PAGESIZE), MEM_SIZE_DMA); > > // Reserve memory > memset(_pVirtualMem, 0, MEM_SIZE_DMA); > > // Lock memory > if (!mlock(_pVirtualMem, MEM_SIZE_DMA )) > { > free(_pVirtualMem); > return false; > } > > Then I call an IOCTL from my driver (DmaMapDescrpImg) to create a DMA > scatter gather list. that sounds the wrong approach.. why don't you make your device driver export an mmap function.. and let the userspace app use that ? > > transfer->Descript[i].size = PAGE_SIZE; > transfer->Descript[i].pciaddr = (ULONG) > virt_to_phys(page_address(iobuf->maplist[idxIobuf])); you really need to use the PCI DMA mapping api!