Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755320AbbGZRtm (ORCPT ); Sun, 26 Jul 2015 13:49:42 -0400 Received: from mail-wi0-f181.google.com ([209.85.212.181]:34997 "EHLO mail-wi0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755276AbbGZRtl (ORCPT ); Sun, 26 Jul 2015 13:49:41 -0400 MIME-Version: 1.0 In-Reply-To: <20150726172527.GA29513@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> Date: Sun, 26 Jul 2015 10:49:39 -0700 Message-ID: Subject: Re: [PATCH v2 08/25] arch: introduce memremap() From: Dan Williams To: Christoph Hellwig Cc: 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" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1129 Lines: 30 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. >> +enum { >> + MEMREMAP_WB = 1 << 0, >> + MEMREMAP_WT = 1 << 1, >> + MEMREMAP_CACHE = MEMREMAP_WB, > > What's the point of having this MEMREMAP_CACHE alias? For developers that are used to seeing ioremap_cache()... > Also please document the meaning of the flags for the poor users. Will do. I'll mostly borrow from the x86 mapping type definitions, but these will also have architecture specific semantics / constraints. -- 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/