On Thu, Jun 07, 2018 at 07:51:12AM -0700, Stephen Hemminger wrote: > On Thu, 7 Jun 2018 07:17:51 -0700 > Alexander Duyck <alexander.du...@gmail.com> wrote: > > > On Wed, Jun 6, 2018 at 3:25 PM, Stephen Hemminger > > <step...@networkplumber.org> wrote: > > > On Wed, 6 Jun 2018 14:54:04 -0700 > > > "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? > > > > > > DPDK drivers in 18.05 depend on 2 device model. Yes it is a bit of mess > > > but that is the way it is. > > > > Why would DPDK care what we do in the kernel? Isn't it just slapping > > vfio-pci on the netdevs it sees? > > Alex, you are correct for Intel devices; but DPDK on Azure is not Intel > based.,. > The DPDK support uses: > * Mellanox MLX5 which uses the Infinband hooks to do DMA directly to > userspace. This means VF netdev device must exist and be visible. > * Slow path using kernel netvsc device, TAP and BPF to get exception > path packets to userspace. > * A autodiscovery mechanism that to set all this up that relies on > 2 device model and sysfs.
Could you describe what does it look for exactly? What will break if instead of MLX5 being a child of the PV, it's a child of the failover device? > In this version, there is no VFIO-PCI. And also Hyper-V does not have virtual > IOMMU so VFIO will not work there at all. >
