Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752020AbWCBRJU (ORCPT ); Thu, 2 Mar 2006 12:09:20 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752018AbWCBRJU (ORCPT ); Thu, 2 Mar 2006 12:09:20 -0500 Received: from pentafluge.infradead.org ([213.146.154.40]:58311 "EHLO pentafluge.infradead.org") by vger.kernel.org with ESMTP id S1752017AbWCBRJT (ORCPT ); Thu, 2 Mar 2006 12:09:19 -0500 Date: Thu, 2 Mar 2006 17:09:15 +0000 From: Christoph Hellwig To: "Ju, Seokmann" Cc: "Ju, Seokmann" , linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org Subject: Re: Question: how to map SCSI data DMA address to virtual address? Message-ID: <20060302170915.GA31316@infradead.org> Mail-Followup-To: Christoph Hellwig , "Ju, Seokmann" , "Ju, Seokmann" , linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org References: <9738BCBE884FDB42801FAD8A7769C2651420C1@NAMAIL1.ad.lsil.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <9738BCBE884FDB42801FAD8A7769C2651420C1@NAMAIL1.ad.lsil.com> User-Agent: Mutt/1.4.2.1i 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 Content-Length: 900 Lines: 22 On Thu, Mar 02, 2006 at 09:53:06AM -0700, Ju, Seokmann wrote: > Hi, > > In the 'scsi_cmnd' structure, there are two entries holding address > information for data to be transferred. One is 'request_buffer' and the > other one is 'buffer'. > In case of 'use_sg' is non-zero, those entries indicates the address of > the scatter-gather table. > > Is there way to get virtual address (so that the data could be accessed > by the driver) of the actual data in the case of 'use_sg' is non-zero? For each sg list entry do something like: buffer = kmap_atomic(sg->page, KM_USER0) + sg->offset; kunmap_atomic(buffer - sg->offset, KM_USER0); - 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/