> On May 5, 2023, at 4:03 PM, Chuck Lever III <chuck.lever@xxxxxxxxxx> wrote: > >> On May 5, 2023, at 3:58 PM, Jason Gunthorpe <jgg@xxxxxxxx> wrote: >> >> On Fri, May 05, 2023 at 11:43:11AM -0400, Chuck Lever wrote: >>> From: Chuck Lever <chuck.lever@xxxxxxxxxx> >>> >>> In the past, LOOPBACK and NONE (tunnel) devices had all-zero MAC >>> addresses. siw_device_create() would fall back to copying the >>> device's name in those cases, because an all-zero MAC address breaks >>> the RDMA core IP-to-device lookup mechanism. >> >> Why not just make up a dummy address in SIW? It shouldn't need to leak >> out of it.. It is just some artifact of how the iWarp stuff has been >> designed > > I've been trying that. > > Even though the siw0 device is now registered with a non-zero GID, > cma_acquire_dev_by_src_ip() still comes up with a zero GID which > matches no device. Address resolution then fails. > > I'm still looking into why. The tun0 device's flags are: UP|POINTOPOINT|NOARP|MULTICAST That flag combination turns addr_resolve_neigh() into a no-op, so that the returned GIDs and addresses are uninitialized. Cc'ing Parav because he's the last person who did significant work on this code path. I can hack this to make it work, but I have no idea what the proper solution would be. -- Chuck Lever
