From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:54499) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1e4Mpu-0003D5-PD for qemu-devel@nongnu.org; Tue, 17 Oct 2017 04:02:56 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1e4Mpq-0007BG-Kg for qemu-devel@nongnu.org; Tue, 17 Oct 2017 04:02:50 -0400 Received: from bombadil.infradead.org ([65.50.211.133]:58356) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1e4Mpq-00079y-B3 for qemu-devel@nongnu.org; Tue, 17 Oct 2017 04:02:46 -0400 Date: Tue, 17 Oct 2017 01:02:36 -0700 From: Christoph Hellwig Message-ID: <20171017080236.GA27649@infradead.org> References: <20171012155027.3277-1-pagupta@redhat.com> <20171012155027.3277-3-pagupta@redhat.com> <20171017071633.GA9207@infradead.org> <1441791227.21027037.1508226056893.JavaMail.zimbra@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1441791227.21027037.1508226056893.JavaMail.zimbra@redhat.com> Subject: Re: [Qemu-devel] [RFC 2/2] KVM: add virtio-pmem driver List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Pankaj Gupta Cc: Christoph Hellwig , kwolf@redhat.com, haozhong zhang , jack@suse.cz, xiaoguangrong eric , kvm@vger.kernel.org, david@redhat.com, linux-nvdimm@ml01.01.org, ross zwisler , linux-kernel@vger.kernel.org, qemu-devel@nongnu.org, linux-mm@kvack.org, stefanha@redhat.com, pbonzini@redhat.com, dan j williams , nilal@redhat.com On Tue, Oct 17, 2017 at 03:40:56AM -0400, Pankaj Gupta wrote: > Are you saying do it as existing i.e ACPI pmem like interface? > The reason we have created this new driver is exiting pmem driver > does not define proper semantics for guest flushing requests. At this point I'm caring about the Linux-internal interface, and for that it should be integrated into the nvdimm subsystem and not a block driver. How the host <-> guest interface looks is a different idea. > > Regarding block support of driver, we want to achieve DAX support > to bypass guest page cache. Also, we want to utilize existing DAX > capable file-system interfaces(e.g fsync) from userspace file API's > to trigger the host side flush request. Well, if you want to support XFS+DAX better don't make it a block devices, because I'll post patches soon to stop using the block device entirely for the DAX case.