Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752171Ab3GABlT (ORCPT ); Sun, 30 Jun 2013 21:41:19 -0400 Received: from intranet.asianux.com ([58.214.24.6]:39456 "EHLO intranet.asianux.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751678Ab3GABlR (ORCPT ); Sun, 30 Jun 2013 21:41:17 -0400 X-Spam-Score: -106.8 Message-ID: <51D0DE09.4090702@asianux.com> Date: Mon, 01 Jul 2013 09:40:25 +0800 From: Chen Gang User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130110 Thunderbird/17.0.2 MIME-Version: 1.0 To: Chen Gang CC: Richard Weinberger , 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 , David Miller 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> <51CABFAC.1040505@nod.at> <51CAC0D0.60505@asianux.com> In-Reply-To: <51CAC0D0.60505@asianux.com> 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: 3714 Lines: 96 On 06/26/2013 06:22 PM, Chen Gang wrote: > On 06/26/2013 06:17 PM, Richard Weinberger wrote: >> 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. > Hmm, if the modules select 'COMPILE_TEST', it is better to let asm-generic support this features (at least, not forbid it) So how about the diff below ? ;-) ---------------------------diff begin----------------------------------- diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h index d5afe96..ede3775 100644 --- a/include/asm-generic/io.h +++ b/include/asm-generic/io.h @@ -303,13 +303,17 @@ static inline void *phys_to_virt(unsigned long address) /* * Change "struct page" to physical address. * - * This implementation is for the no-MMU case only... if you have an MMU - * you'll need to provide your own definitions. + * This for the no-MMU, or no-IOMEM but still try to COMPILE_TEST cases. + * if you have an MMU and IOMEM, you'll need to provide your own definitions. */ -#ifndef CONFIG_MMU +#if !defined(CONFIG_MMU) || \ + (!defined(CONFIG_HAS_IOMEM) && defined(COMPILE_TEST)) static inline void __iomem *ioremap(phys_addr_t offset, unsigned long size) { +#if !defined(CONFIG_MMU) return (void __iomem*) (unsigned long)offset; +#else + return NULL; } #define __ioremap(offset, size, flags) ioremap(offset, size) @@ -325,7 +329,7 @@ static inline void __iomem *ioremap(phys_addr_t offset, unsigned long size) static inline void iounmap(void __iomem *addr) { } -#endif /* CONFIG_MMU */ +#endif /* !MMU || (!HAS_IOMEM && COMPILE_TEST) */ #ifdef CONFIG_HAS_IOPORT #ifndef CONFIG_GENERIC_IOMAP ---------------------------diff end------------------------------------- > It is really the time for stopping discussion, and thank you all for > spending your time resources on this discussion. > > Next, I will send related patch for it (also cc to you all). > > > Thanks. > -- Chen Gang -- 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/