On Thu, Dec 23, 2021 at 08:59:14PM +0800, Cheng Xu wrote: > > > On 12/23/21 6:23 PM, Leon Romanovsky wrote: > > On Wed, Dec 22, 2021 at 11:35:44AM +0800, Cheng Xu wrote: > > > > > > > <...> > > > > > > > > > > > > For the ECS instance with RDMA enabled, there are two kinds of devices > > > > > allocated, one for ERDMA, and one for the original netdev (virtio-net). > > > > > They are different PCI deivces. ERDMA driver can get the information about > > > > > which netdev attached to in its PCIe barspace (by MAC address matching). > > > > > > > > This is very questionable. The netdev part should be kept in the > > > > drivers/ethernet/... part of the kernel. > > > > > > > > Thanks > > > > > > The net device used in Alibaba ECS instance is virtio-net device, driven > > > by virtio-pci/virtio-net drivers. ERDMA device does not need its own net > > > device, and will be attached to an existed virtio-net device. The > > > relationship between ibdev and netdev in erdma is similar to siw/rxe. > > > > siw/rxe binds through RDMA_NLDEV_CMD_NEWLINK netlink command and not > > through MAC's matching. > > > > Thanks > > Both siw/rxe/erdma don't need to implement netdev part, this is what I > wanted to express when I said 'similar'. > What you mentioned (the bind mechanism) is one major difference between > erdma and siw/rxe. For siw/rxe, user can attach ibdev to every netdev if > he/she wants, but it is not true for erdma. When user buys the erdma > service, he/she must specify which ENI (elastic network interface) to be > binded, it means that the attached erdma device can only be binded to > the specific netdev. Due to the uniqueness of MAC address in our ECS > instance, we use the MAC address as the identification, then the driver > knows which netdev should be binded to. It really doesn't match our driver binding model to rely on MAC addreses. Our standard model would expect that the virtio-net driver would detect it has RDMA capability and spawn an aux device to link the two things together. Using net notifiers to try to link the lifecycles together has been a mess so far. Jason
