Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752359AbbG2S1U (ORCPT ); Wed, 29 Jul 2015 14:27:20 -0400 Received: from mx2.suse.de ([195.135.220.15]:52370 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750871AbbG2S1R (ORCPT ); Wed, 29 Jul 2015 14:27:17 -0400 Date: Wed, 29 Jul 2015 20:27:13 +0200 From: "Luis R. Rodriguez" To: Christoph Hellwig Cc: Dan Williams , linux-arch@vger.kernel.org, Arnd Bergmann , "linux-nvdimm@lists.01.org" , "linux-kernel@vger.kernel.org" , Ingo Molnar , "H. Peter Anvin" , Russell King , Thomas Gleixner , "linux-arm-kernel@lists.infradead.org" Subject: Re: [PATCH v2 08/25] arch: introduce memremap() Message-ID: <20150729182712.GI30479@wotan.suse.de> References: <20150725023649.8664.59145.stgit@dwillia2-desk3.amr.corp.intel.com> <20150725023842.8664.97620.stgit@dwillia2-desk3.amr.corp.intel.com> <20150726172527.GA29513@lst.de> <20150727051258.GB15836@lst.de> <20150729065004.GA17162@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150729065004.GA17162@lst.de> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1389 Lines: 29 On Wed, Jul 29, 2015 at 08:50:04AM +0200, Christoph Hellwig wrote: > On Mon, Jul 27, 2015 at 04:26:03PM -0700, Dan Williams wrote: > > Oh, because all we have at this point is ioremap_cache() which > > silently falls back. It's not until the introduction of > > arch_memremp() where we update the arch code to break that behavior. > > Ok, makes sense. Might be worth to document in the changelog. > > > That said, I think it may be beneficial to allow a fallback if the > > user cares. So maybe memremap() can call plain ioremap() if > > MEMREMAP_STRICT is not set and none of the other mapping types are > > satisfied. > > Is there a real use case for it? Fallback APIs always seem confusing > and it might make more sense to do this in the caller(s) that actually > need it. It seems semantics-wise we are trying to separate these two really, so I agree with this. Having a fallback would onloy make things more complicated for any sanitizer / checker / etc, and I don't think the practical gains of having a fallback outweight the gains of having a clear semantic separation on intended memory type and interactions with it. Luis -- 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/