Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752211Ab3FZKRZ (ORCPT ); Wed, 26 Jun 2013 06:17:25 -0400 Received: from b.ns.miles-group.at ([95.130.255.144]:1661 "EHLO radon.swed.at" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751513Ab3FZKRX (ORCPT ); Wed, 26 Jun 2013 06:17:23 -0400 Message-ID: <51CABFAC.1040505@nod.at> Date: Wed, 26 Jun 2013 12:17:16 +0200 From: Richard Weinberger User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130510 Thunderbird/17.0.6 MIME-Version: 1.0 To: Chen Gang CC: Geert Uytterhoeven , Jeff Dike , Arnd Bergmann , David Sharp , "sfr@canb.auug.org.au" , Steven Rostedt , Ingo Molnar , uml-devel , uml-user , "linux-kernel@vger.kernel.org" , Linux-Arch , Mark Brown Subject: Re: [PATCH] include/asm-generic/io.h: add 'UML' case just like 'no-MMU' References: <51CA8AB8.7080504@asianux.com> <51CA900E.9020407@nod.at> <51CA9E92.4000107@asianux.com> <51CAA0C6.60007@nod.at> <51CAA78C.5040900@asianux.com> <51CAA8D6.9000505@nod.at> <51CAAD1D.8050801@asianux.com> <51CAAE7C.9090003@nod.at> <51CAB556.4070700@asianux.com> <51CAB689.70008@nod.at> <51CABBDD.403@asianux.com> In-Reply-To: <51CABBDD.403@asianux.com> X-Enigmail-Version: 1.5.1 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1764 Lines: 40 Am 26.06.2013 12:01, schrieb Chen Gang: > On 06/26/2013 05:48 PM, Geert Uytterhoeven wrote: >> On Wed, Jun 26, 2013 at 11:38 AM, Richard Weinberger wrote: >>>>>> Since the API itself already contents the meaning: "return NULL means >>>>>> the arch has no related io memory", >> No, NULL means it could not map the I/O memory. >> > > "it could not map the I/O memory" includes "has no related io memory". > So it is enough for our case. > >>>>>> Why not define a generic dummy one in "include/asm-generic/io.h" instead >>>>>> of "HAS_IOMEM" (which has already spread many various places, and also, >>>>>> most of new drivers have to know about it). >>>>>> >>>>>> e.g: in "include/asm-generic/io.h", if "CONFIG_HAS_IOMEM=n", define a >>>>>> dummy ioremap() which return NULL ... (also need consider more details). >>>> >>>> Because we don't even want to build these drivers and not make them fail while >>>> executing io memory related functions. >> Indeed, it doesn't make sense to build drivers that cannot work. >> And they may fail in a very bad way. > > That is our 'platform' guys feeling, not the 'module' guys, as > 'platform' guys, it is better to provide the choice to 'module' guys, > and let them decide by themselves, not forced by us. FYI, this is my last reply to this thread. As Geert and I said, drivers which need io memory have to depend on HAS_IOMEM=y. If an arch does not have io memory these drivers cannot work and therefore we don't want them built. Over and out, //richard -- 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/