From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jiri Pirko Subject: Re: [RFC PATCH v3 0/3] Enable virtio_net to act as a backup for a passthru device Date: Fri, 23 Feb 2018 23:38:02 +0100 Message-ID: <20180223223802.GA2010@nanopsycho> References: <1518804682-16881-1-git-send-email-sridhar.samudrala@intel.com> <20180216183817.42b07af6@cakuba.netronome.com> <0d158bf6-79b3-442b-2c61-3e900ff40922@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: "Duyck, Alexander H" , virtio-dev@lists.oasis-open.org, "Michael S. Tsirkin" , Jakub Kicinski , "Samudrala, Sridhar" , Alexander Duyck , virtualization@lists.linux-foundation.org, Netdev , David Miller To: Siwei Liu Return-path: Content-Disposition: inline In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org List-Id: netdev.vger.kernel.org Fri, Feb 23, 2018 at 11:22:36PM CET, loseweigh@gmail.com wrote: [...] >>> >>> No, that's not what I was talking about of course. I thought you >>> mentioned the upgrade scenario this patch would like to address is to >>> use the bypass interface "to take the place of the original virtio, >>> and get udev to rename the bypass to what the original virtio_net >>> was". That is one of the possible upgrade paths for sure. However the >>> upgrade path I was seeking is to use the bypass interface to take the >>> place of original VF interface while retaining the name and network >>> configs, which generally can be done simply with kernel upgrade. It >>> would become limiting as this patch makes the bypass interface share >>> the same virtio pci device with virito backup. Can this bypass >>> interface be made general to take place of any pci device other than >>> virtio-net? This will be more helpful as the cloud users who has >>> existing setup on VF interface don't have to recreate it on virtio-net >>> and VF separately again. How that could work? If you have the VF netdev with all configuration including IPs and routes and whatever - now you want to do migration so you add virtio_net and do some weird in-driver bonding with it. But then, VF disappears and the VF netdev with that and also all configuration it had. I don't think this scenario is valid. >> >> >> Yes. This sounds interesting. Looks like you want an existing VM image with >> VF only configuration to get transparent live migration support by adding >> virtio_net with BACKUP feature. We may need another feature bit to switch >> between these 2 options. > >Yes, that's what I was thinking about. I have been building something >like this before, and would like to get back after merging with your >patch.