From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [PATCH v2 08/25] arch: introduce memremap() Date: Mon, 27 Jul 2015 07:12:58 +0200 Message-ID: <20150727051258.GB15836@lst.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> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from verein.lst.de ([213.95.11.211]:35844 "EHLO newverein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750776AbbG0FNA (ORCPT ); Mon, 27 Jul 2015 01:13:00 -0400 Content-Disposition: inline In-Reply-To: Sender: linux-arch-owner@vger.kernel.org List-ID: To: Dan Williams Cc: Christoph Hellwig , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , linux-arch@vger.kernel.org, "Kani, Toshimitsu" , Arnd Bergmann , "linux-nvdimm@lists.01.org" , "linux-kernel@vger.kernel.org" , Russell King , "linux-arm-kernel@lists.infradead.org" On Sun, Jul 26, 2015 at 10:49:39AM -0700, Dan Williams wrote: > On Sun, Jul 26, 2015 at 10:25 AM, Christoph Hellwig wrote: > > On Fri, Jul 24, 2015 at 10:38:42PM -0400, Dan Williams wrote: > >> The behavior change to return NULL on an unsupported request is reserved > >> for a later patch. > > > > Why? > > This is for drivers like pmem that care about the mapping type. For > example, if pmem can't get a cache-enabled mapping it is potentially > putting the write durability of the persistent media at risk. I understand that part, but the question is why the old behavior is retained for now and only changed later.