On 20/08/2021 17:32, Jason Gunthorpe wrote: > On Fri, Aug 20, 2021 at 03:58:33PM +0300, Gal Pressman wrote: > >> Though it would've been nicer if we could agree on a solution that could work >> for more than 1-2 RDMA devices, using the existing tools the RDMA subsystem has. > > I don't think it can really be done, revoke is necessary, and isn't a > primitive we have today. > > Revoke is sort of like rereg MR, but with a guaranteed no-change to > the lkey/rkey > > Then there is the locking complexity of linking the mr creation and > destruction to the lifecycle of the pages, which is messy and maybe > not general. For instance mlx5 would call its revoke_mr, disconnect > the dmabuf then destroy the mkey - but this is only safe because mlx5 > HW can handle concurrent revokes. Thanks, that makes sense. >> That's why I tried to approach this by denying such attachments for non-ODP >> importers instead of exposing a "limited" dynamic importer. > > That is fine if there is no revoke - once revoke exists we must have > driver and HW support. Agree. IIUC, we're talking about three different exporter "types": - Dynamic with move_notify (requires ODP) - Dynamic with revoke_notify - Static Which changes do we need to make the third one work?
