From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chen Gang Subject: Re: [PATCH] include/asm-generic/io.h: add 'UML' case just like 'no-MMU' Date: Wed, 26 Jun 2013 16:58:05 +0800 Message-ID: <51CAAD1D.8050801@asianux.com> 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> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: Received: from intranet.asianux.com ([58.214.24.6]:47120 "EHLO intranet.asianux.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751263Ab3FZI67 (ORCPT ); Wed, 26 Jun 2013 04:58:59 -0400 In-Reply-To: <51CAA8D6.9000505@nod.at> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Richard Weinberger Cc: Jeff Dike , Arnd Bergmann , dhsharp@google.com, Mark Brown , "sfr@canb.auug.org.au" , Steven Rostedt , Ingo Molnar , uml-devel , uml-user , "linux-kernel@vger.kernel.org" , Linux-Arch On 06/26/2013 04:39 PM, Richard Weinberger wrote: >>>>> >>>> The drivers internal code has already check the related return value, >>>>> >>>> so it is the architecture's duty to 'tell' the driver whether support >>>>> >>>> io memory (e.g. define ioremap, but return NULL). >>> >> It does so already by setting CONFIG_HAS_IOMEM=n >> > >> > Excuse me, I use "grep -rn ioremap *" under "include/" and "arch/um/" >> > directory, but can not find the related definition for 'ioremap'. >> > >> > Is there another declaration or definition way which I don't know ? >> > (maybe it is). > Both UML and s390 (in the !CONFIG_PCI) do not define ioremap() because > without io memory you cannot have a ioremap(). > I assume if ioremap() return NULL, it means "without io memory", is it correct ? If it is correct, "define a dummy ioremap(), and return NULL" is just the meaning that you mentioned above. If so, for UML, it is not requirement, but recommend to define a dummy ioremap() which return NULL, so can be generic enough to mach all cases. >> > For our case, the ".config" file does not define 'CONFIG_HAS_IOMEM', can >> > I assume it means "CONFIG_HAS_IOMEM=n" ? > If I'm not mistaken it works the other way around. > All archs except UML and s390 set CONFIG_HAS_IOMEM=y. I guess so, too. Thanks. -- Chen Gang Asianux Corporation