From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:46391) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bobWQ-0005Kr-MQ for qemu-devel@nongnu.org; Mon, 26 Sep 2016 15:25:03 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bobWM-0004mf-GH for qemu-devel@nongnu.org; Mon, 26 Sep 2016 15:25:01 -0400 Received: from mx1.redhat.com ([209.132.183.28]:34956) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bobWM-0004ma-A1 for qemu-devel@nongnu.org; Mon, 26 Sep 2016 15:24:58 -0400 Date: Mon, 26 Sep 2016 22:24:55 +0300 From: "Michael S. Tsirkin" Message-ID: <20160926221112-mutt-send-email-mst@kernel.org> References: <1474872056-24665-1-git-send-email-yuanhan.liu@linux.intel.com> <1474872056-24665-2-git-send-email-yuanhan.liu@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Subject: Re: [Qemu-devel] [PATCH 1/2] vhost: enable any layout feature List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Stephen Hemminger Cc: Yuanhan Liu , Maxime Coquelin , dev@dpdk.org, qemu-devel@nongnu.org On Mon, Sep 26, 2016 at 11:01:58AM -0700, Stephen Hemminger wrote: > I assume that if using Version 1 that the bit will be ignored > Therein lies a problem. If dpdk tweaks flags, updating it will break guest migration. One way is to require that users specify all flags fully when creating the virtio net device. QEMU could verify that all required flags are set, and fail init if not. This has other advantages, e.g. it adds ability to init device without waiting for dpdk to connect. However, enabling each new feature would now require management work. How about dpdk ships the list of supported features instead? Management tools could read them on source and destination and select features supported on both sides. -- MST