From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1765996AbYEUIGM (ORCPT ); Wed, 21 May 2008 04:06:12 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1763856AbYEUIFS (ORCPT ); Wed, 21 May 2008 04:05:18 -0400 Received: from mail37.messagelabs.com ([216.82.244.163]:53335 "EHLO mail37.messagelabs.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1763309AbYEUIFN (ORCPT ); Wed, 21 May 2008 04:05:13 -0400 X-VirusChecked: Checked X-Env-Sender: Uwe.Kleine-Koenig@digi.com X-Msg-Ref: server-14.tower-37.messagelabs.com!1211357111!1237924!1 X-StarScan-Version: 5.5.12.14.2; banners=-,-,- X-Originating-IP: [66.77.174.13] Date: Wed, 21 May 2008 10:05:03 +0200 From: Uwe =?iso-8859-1?Q?Kleine-K=F6nig?= To: Paul Mundt , Magnus Damm , "Hans J. Koch" , , , Subject: Re: [PATCH 00/03][RFC] Reusable UIO Platform Driver Message-ID: <20080521080503.GA28751@digi.com> References: <20080520105132.1474.73941.sendpatchset@rx1.opensource.se> <20080520210713.GE3220@local> <20080521064938.GA11580@digi.com> <20080521074950.GA27310@linux-sh.org> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20080521074950.GA27310@linux-sh.org> User-Agent: Mutt/1.5.13 (2006-08-11) X-OriginalArrivalTime: 21 May 2008 08:05:04.0193 (UTC) FILETIME=[6028EB10:01C8BB19] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Paul Mundt wrote: > On Wed, May 21, 2008 at 08:49:38AM +0200, Uwe Kleine-K?nig wrote: > > Magnus Damm wrote: > > > Extending uio_pdrv driver with a chunk of physically > > > contiguous memory isn't a big deal though. > > I wonder how you use that memory. Isn't it just some kind of shared > > memory? If so, why not use normal shared memory? Do you really need > > that? > > > Physically contiguous memory is a real requirement, especially for DMA. > I'm not sure what's confusing about that? I got that, yes. The problem is I don't see how you can use it for DMA. The physical address is stored in info->mem[$last].internal_addr and if there is a way to access that variable from user space, I don't see it and would appretiate a hint. Sorry for not expressing my concern more clear at the first go. I hope it's understandable now. @Magnus: Maybe you can provide the userspace part of the driver? How is that mapping used there? Best regards Uwe -- Uwe Kleine-König, Software Engineer Digi International GmbH Branch Breisach, Küferstrasse 8, 79206 Breisach, Germany Tax: 315/5781/0242 / VAT: DE153662976 / Reg. Amtsgericht Dortmund HRB 13962