From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755691AbeDZM1q (ORCPT ); Thu, 26 Apr 2018 08:27:46 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:48622 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754723AbeDZM1o (ORCPT ); Thu, 26 Apr 2018 08:27:44 -0400 From: Jeff Moyer To: Dan Williams Cc: Pankaj Gupta , Linux Kernel Mailing List , KVM list , Qemu Developers , linux-nvdimm , Linux MM , Jan Kara , Stefan Hajnoczi , Rik van Riel , Haozhong Zhang , Nitesh Narayan Lal , Kevin Wolf , Paolo Bonzini , "Zwisler\, Ross" , David Hildenbrand , Xiao Guangrong , Christoph Hellwig , Marcel Apfelbaum , "Michael S. Tsirkin" , niteshnarayanlal@hotmail.com, Igor Mammedov , lcapitulino@redhat.com Subject: Re: [RFC v2 1/2] virtio: add pmem driver References: <20180425112415.12327-1-pagupta@redhat.com> <20180425112415.12327-2-pagupta@redhat.com> X-PGP-KeyID: 1F78E1B4 X-PGP-CertKey: F6FE 280D 8293 F72C 65FD 5A58 1FF8 A7CA 1F78 E1B4 X-PCLoadLetter: What the f**k does that mean? Date: Thu, 26 Apr 2018 08:27:41 -0400 In-Reply-To: (Dan Williams's message of "Wed, 25 Apr 2018 07:43:52 -0700") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Dan Williams writes: > [ adding Jeff directly since he has also been looking at > infrastructure to track when MAP_SYNC should be disabled ] > > On Wed, Apr 25, 2018 at 7:21 AM, Dan Williams wrote: >> On Wed, Apr 25, 2018 at 4:24 AM, Pankaj Gupta wrote: >>> This patch adds virtio-pmem driver for KVM >>> guest. >> >> Minor nit, please expand your changelog line wrapping to 72 columns. >> >>> >>> Guest reads the persistent memory range >>> information from Qemu over VIRTIO and registers >>> it on nvdimm_bus. It also creates a nd_region >>> object with the persistent memory range >>> information so that existing 'nvdimm/pmem' >>> driver can reserve this into system memory map. >>> This way 'virtio-pmem' driver uses existing >>> functionality of pmem driver to register persistent >>> memory compatible for DAX capable filesystems. >> >> We need some additional enabling to disable MAP_SYNC for this enable to disable... I like it! ;-) >> configuration. In other words, if fsync() is required then we must >> disable the MAP_SYNC optimization. I think this should be a struct >> dax_device property looked up at mmap time in each MAP_SYNC capable >> ->mmap() file operation implementation. Ideally, qemu (seabios?) would advertise a platform capabilities sub-table that doesn't fill in the flush bits. -Jeff