From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id A925421E87990 for ; Mon, 11 Sep 2017 07:38:22 -0700 (PDT) Date: Mon, 11 Sep 2017 10:41:11 -0400 From: Mike Snitzer Subject: Re: [PATCH v3 2/2] dm: allow device-mapper to operate without dax support Message-ID: <20170911144111.GA15556@redhat.com> References: <150169667935.39569.15808116323143633486.stgit@dwillia2-desk3.amr.corp.intel.com> <150169668989.39569.8174620146135008137.stgit@dwillia2-desk3.amr.corp.intel.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <150169668989.39569.8174620146135008137.stgit@dwillia2-desk3.amr.corp.intel.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-nvdimm-bounces@lists.01.org Sender: "Linux-nvdimm" To: Dan Williams Cc: kbuild test robot , linux-nvdimm@lists.01.org, linux-kernel@vger.kernel.org, dm-devel@redhat.com, Bart Van Assche , Alasdair Kergon List-ID: On Wed, Aug 02 2017 at 1:58pm -0400, Dan Williams wrote: > Rather than have device-mapper directly 'select DAX', let the fact that > BLK_DEV_PMEM selects dax act as a gate for the device-mapper dax > support. We arrange for all the dax core routines to compile to nops > when CONFIG_DAX=n. With that in place we can simply handle the > alloc_dax() error as expected and ifdef out the other device-mapper-dax > support code. > > Now, if dax is provided by a leaf driver that driver may only arrange to > compile the dax core as a module. Since device-mapper dax support is > consumed by the always-built-in portion of the device-mapper > implementation we need to upgrade from DAX=m to DAX=y. I applied the patches and then got nervous once I dug in.. this last paragraph makes little sense to me. "the always-built-in portion of the device-mapper implementation" is why: DM core can happily be compiled as a module (dm-mod.ko). And I'm not sure why you're referencing DAX related drivers/md/dm-builtin.c, why are you attachd DM's DAX support to that? I'm not seeing where that is actually happening. I don't see why DM's support for DAX would need to force DAX to be builtin rather than just a module. Sorry I didn't get around to looking at this until now, but it seems you went wrong along the way? Or maybe I'm just missing something? Mike _______________________________________________ Linux-nvdimm mailing list Linux-nvdimm@lists.01.org https://lists.01.org/mailman/listinfo/linux-nvdimm