On Wed, Jun 06, 2018 at 02:24:47PM -0700, 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.
Well failover seems to maintain this invariant with the 3 dev model. > 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 feel I'm misunderstood. I was asking whether a 3-rd device can be hidden so that userspace does not know that you switched to a 3 device model. It will think there are 2 devices and will keep working. If you do that, then there won't be anything that would be perceived as breaking existing userspace, will there? > 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. That's clear enough. > Any time you introduce new UAPI behavior something breaks. Not if we do it right. > On the rename front, I really don't care if VF can be renamed. OK that's nice. > And for > netvsc want to allow the PV device to be renamed. That's because of the 2 device model, right? So that explains why even if the delayed hack is good for the goose it might not be good for the gander :) > Udev developers want that > but have not found a stable/persistent value to expose to userspace > to allow it.
