On Wed, Jun 6, 2018 at 2:54 PM, Samudrala, Sridhar <sridhar.samudr...@intel.com> wrote: > > > On 6/6/2018 2:24 PM, Stephen Hemminger wrote: >> >> On Wed, 6 Jun 2018 15:30:27 +0300 >> "Michael S. Tsirkin" <m...@redhat.com> wrote: >> >>> On Wed, Jun 06, 2018 at 09:25:12AM +0200, Jiri Pirko wrote: >>>> >>>> Tue, Jun 05, 2018 at 05:42:31AM CEST, step...@networkplumber.org wrote: >>>>> >>>>> The net failover should be a simple library, not a virtual >>>>> object with function callbacks (see callback hell). >>>> >>>> Why just a library? It should do a common things. I think it should be a >>>> virtual object. Looks like your patch again splits the common >>>> functionality into multiple drivers. That is kind of backwards attitude. >>>> I don't get it. We should rather focus on fixing the mess the >>>> introduction of netvsc-bonding caused and switch netvsc to 3-netdev >>>> model. >>> >>> So it seems that at least one benefit for netvsc would be better >>> handling of renames. >>> >>> Question is how can this change to 3-netdev happen? Stephen is >>> concerned about risk of breaking some userspace. >>> >>> Stephen, this seems to be the usecase that IFF_HIDDEN was trying to >>> address, and you said then "why not use existing network namespaces >>> rather than inventing a new abstraction". So how about it then? Do you >>> want to find a way to use namespaces to hide the PV device for netvsc >>> compatibility? >>> >> Netvsc can't work with 3 dev model. MS has worked with enough distro's and >> startups that all demand eth0 always be present. And VF may come and go. >> After this history, there is a strong motivation not to change how kernel >> behaves. Switching to 3 device model would be perceived as breaking >> existing userspace. > > > I think it should be possible for netvsc to work with 3 dev model if the > only > requirement is that eth0 will always be present. With net_failover, you will > see eth0 and eth0nsby OR with older distros eth0 and eth1. It may be an > issue > if somehow there is userspace requirement that there can be only 2 netdevs, > not 3 > when VF is plugged. > > eth0 will be the net_failover device and eth0nsby/eth1 will be the netvsc > device > and the IP address gets configured on eth0. Will this be an issue? > Did you realize that the eth0 name in the current 3-netdev code can't be consistently persisted across reboot, if you have more than one VFs to pair with? On one boot it got eth0/eth0nsby, on the next it may get eth1/eth1nsby on the same interface.
It won't be useable by default until you add some custom udev rules. -Siwei > > >> >> With virtio you can work it out with the distro's yourself. >> There is no pre-existing semantics to deal with. >> >> For the virtio, I don't see the need for IFF_HIDDEN. >> With 3-dev model as long as you mark the PV and VF devices >> as slaves, then userspace knows to leave them alone. Assuming userspace >> is already able to deal with team and bond devices. >> Any time you introduce new UAPI behavior something breaks. >> >> On the rename front, I really don't care if VF can be renamed. And for >> netvsc want to allow the PV device to be renamed. Udev developers want >> that >> but have not found a stable/persistent value to expose to userspace >> to allow it. > >