From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Wed, 1 Jul 2015 08:23:52 +0200 From: Christoph Hellwig Subject: Re: [PATCH v5 2/6] arch: unify ioremap prototypes and macro aliases Message-ID: <20150701062352.GA3739@lst.de> References: <20150622081028.35954.89885.stgit@dwillia2-desk3.jf.intel.com> <20150622082427.35954.73529.stgit@dwillia2-desk3.jf.intel.com> <20150622161002.GB8240@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org To: Dan Williams Cc: Christoph Hellwig , Arnd Bergmann , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , Thomas Gleixner , Ross Zwisler , Andrew Morton , Juergen Gross , X86 ML , "Kani, Toshimitsu" , "linux-nvdimm@lists.01.org" , Benjamin Herrenschmidt , Luis Rodriguez , Konrad Rzeszutek Wilk , "linux-kernel@vger.kernel.org" , Stefan Bader , Andy Lutomirski , linux-mm@kvack.org, Geert Uytterhoeven , Ralf Baechle , Henrique de Moraes Holschuh , mpe@ellerman.id.au, Tejun Heo , Paul Mackerras , Russell King - ARM Linux , "linux-arm-kernel@lists.infradead.org" List-ID: On Tue, Jun 30, 2015 at 03:57:16PM -0700, Dan Williams wrote: > > void __iomem *ioremap_flags(resource_size_t offset, unsigned long size, > > unsigned long prot_val, unsigned flags); > > Doesn't 'flags' imply a specific 'prot_val'? Looks like the values are arch specific. So as a first step I'd like to keep them separate. As a second step we could look into unifying the actual ioremap implementations which look mostly the same. Once that is done we could look into collapsing the flags and prot_val arguments. > One useful feature of the ifdef mess as implemented in the patch is > that you could test for whether ioremap_cache() is actually > implemented or falls back to default ioremap(). I think for > completeness archs should publish an ioremap type capabilities mask > for drivers that care... (I can imagine pmem caring), or default to > being permissive if something like IOREMAP_STRICT is not set. There's > also the wrinkle of archs that can only support certain types of > mappings at a given alignment. I think doing this at runtime might be a better idea. E.g. a ioremap_flags with the CACHED argument will return -EOPNOTSUP unless actually implemented. On various architectures different CPUs or boards will have different capabilities in this area. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752401AbbGAGYH (ORCPT ); Wed, 1 Jul 2015 02:24:07 -0400 Received: from verein.lst.de ([213.95.11.211]:46285 "EHLO newverein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750869AbbGAGYA (ORCPT ); Wed, 1 Jul 2015 02:24:00 -0400 Date: Wed, 1 Jul 2015 08:23:52 +0200 From: Christoph Hellwig To: Dan Williams Cc: Christoph Hellwig , Arnd Bergmann , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , Thomas Gleixner , Ross Zwisler , Andrew Morton , Juergen Gross , X86 ML , "Kani, Toshimitsu" , "linux-nvdimm@lists.01.org" , Benjamin Herrenschmidt , Luis Rodriguez , Konrad Rzeszutek Wilk , "linux-kernel@vger.kernel.org" , Stefan Bader , Andy Lutomirski , linux-mm@kvack.org, Geert Uytterhoeven , Ralf Baechle , Henrique de Moraes Holschuh , mpe@ellerman.id.au, Tejun Heo , Paul Mackerras , Russell King - ARM Linux , "linux-arm-kernel@lists.infradead.org" Subject: Re: [PATCH v5 2/6] arch: unify ioremap prototypes and macro aliases Message-ID: <20150701062352.GA3739@lst.de> References: <20150622081028.35954.89885.stgit@dwillia2-desk3.jf.intel.com> <20150622082427.35954.73529.stgit@dwillia2-desk3.jf.intel.com> <20150622161002.GB8240@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 30, 2015 at 03:57:16PM -0700, Dan Williams wrote: > > void __iomem *ioremap_flags(resource_size_t offset, unsigned long size, > > unsigned long prot_val, unsigned flags); > > Doesn't 'flags' imply a specific 'prot_val'? Looks like the values are arch specific. So as a first step I'd like to keep them separate. As a second step we could look into unifying the actual ioremap implementations which look mostly the same. Once that is done we could look into collapsing the flags and prot_val arguments. > One useful feature of the ifdef mess as implemented in the patch is > that you could test for whether ioremap_cache() is actually > implemented or falls back to default ioremap(). I think for > completeness archs should publish an ioremap type capabilities mask > for drivers that care... (I can imagine pmem caring), or default to > being permissive if something like IOREMAP_STRICT is not set. There's > also the wrinkle of archs that can only support certain types of > mappings at a given alignment. I think doing this at runtime might be a better idea. E.g. a ioremap_flags with the CACHED argument will return -EOPNOTSUP unless actually implemented. On various architectures different CPUs or boards will have different capabilities in this area. From mboxrd@z Thu Jan 1 00:00:00 1970 From: hch@lst.de (Christoph Hellwig) Date: Wed, 1 Jul 2015 08:23:52 +0200 Subject: [PATCH v5 2/6] arch: unify ioremap prototypes and macro aliases In-Reply-To: References: <20150622081028.35954.89885.stgit@dwillia2-desk3.jf.intel.com> <20150622082427.35954.73529.stgit@dwillia2-desk3.jf.intel.com> <20150622161002.GB8240@lst.de> Message-ID: <20150701062352.GA3739@lst.de> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Tue, Jun 30, 2015 at 03:57:16PM -0700, Dan Williams wrote: > > void __iomem *ioremap_flags(resource_size_t offset, unsigned long size, > > unsigned long prot_val, unsigned flags); > > Doesn't 'flags' imply a specific 'prot_val'? Looks like the values are arch specific. So as a first step I'd like to keep them separate. As a second step we could look into unifying the actual ioremap implementations which look mostly the same. Once that is done we could look into collapsing the flags and prot_val arguments. > One useful feature of the ifdef mess as implemented in the patch is > that you could test for whether ioremap_cache() is actually > implemented or falls back to default ioremap(). I think for > completeness archs should publish an ioremap type capabilities mask > for drivers that care... (I can imagine pmem caring), or default to > being permissive if something like IOREMAP_STRICT is not set. There's > also the wrinkle of archs that can only support certain types of > mappings at a given alignment. I think doing this at runtime might be a better idea. E.g. a ioremap_flags with the CACHED argument will return -EOPNOTSUP unless actually implemented. On various architectures different CPUs or boards will have different capabilities in this area.