Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751682AbdG2T5X (ORCPT ); Sat, 29 Jul 2017 15:57:23 -0400 Received: from mail-vk0-f53.google.com ([209.85.213.53]:37692 "EHLO mail-vk0-f53.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751593AbdG2T5V (ORCPT ); Sat, 29 Jul 2017 15:57:21 -0400 MIME-Version: 1.0 In-Reply-To: <1501258623.2413.3.camel@wdc.com> References: <149245612770.10206.15496018295337908594.stgit@dwillia2-desk3.amr.corp.intel.com> <149245618859.10206.13182319600260215993.stgit@dwillia2-desk3.amr.corp.intel.com> <1501258623.2413.3.camel@wdc.com> From: Dan Williams Date: Sat, 29 Jul 2017 12:57:19 -0700 Message-ID: Subject: Re: [resend PATCH v2 11/33] dm: add dax_device and dax_operations support To: Bart Van Assche Cc: "linux-nvdimm@lists.01.org" , "dm-devel@redhat.com" , "linux-kernel@vger.kernel.org" , "toshi.kani@hpe.com" , "linux-block@vger.kernel.org" , "hch@lst.de" , "snitzer@redhat.com" , "linux-fsdevel@vger.kernel.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: 1167 Lines: 28 On Fri, Jul 28, 2017 at 9:17 AM, Bart Van Assche wrote: > On Mon, 2017-04-17 at 12:09 -0700, Dan Williams wrote: >> diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig >> index b7767da50c26..1de8372d9459 100644 >> --- a/drivers/md/Kconfig >> +++ b/drivers/md/Kconfig >> @@ -200,6 +200,7 @@ config BLK_DEV_DM_BUILTIN >> config BLK_DEV_DM >> tristate "Device mapper support" >> select BLK_DEV_DM_BUILTIN >> + select DAX >> ---help--- >> Device-mapper is a low level volume manager. It works by allowing >> people to specify mappings for ranges of logical sectors. Various > > (replying to an e-mail of three months ago) > > Hello Dan, > > While building a v4.12 kernel I noticed that enabling device mapper support > now unconditionally enables DAX. I think there are plenty of systems that use > dm but do not need DAX. Have you considered to rework this such that instead > of dm selecting DAX that DAX support is only enabled in dm if CONFIG_DAX is > enabled? > I'd rather flip this around and add a CONFIG_DM_DAX that gates whether DM enables / links to the DAX core. I'll take a look at a patch.