RE: [PATCH V3 1/5] RDMA/core: Transport-independent access flags

["Steve Wise" <swise@opengridcomputing.com>]

> -----Original Message-----
> From: linux-rdma-owner@vger.kernel.org [mailto:linux-rdma-owner@vger.kernel.org] On Behalf Of Steve Wise
> Sent: Tuesday, July 14, 2015 3:51 PM
> To: 'Jason Gunthorpe'
> Cc: 'Christoph Hellwig'; 'Sagi Grimberg'; 'Steve Wise'; 'Tom Talpey'; 'Doug Ledford'; sagig@mellanox.com; ogerlitz@mellanox.com;
> roid@mellanox.com; linux-rdma@vger.kernel.org; eli@mellanox.com; target-devel@vger.kernel.org; linux-nfs@vger.kernel.org;
> trond.myklebust@primarydata.com; bfields@fieldses.org; 'Oren Duer'
> Subject: RE: [PATCH V3 1/5] RDMA/core: Transport-independent access flags
> 
> 
> 
> > -----Original Message-----
> > From: linux-rdma-owner@vger.kernel.org [mailto:linux-rdma-owner@vger.kernel.org] On Behalf Of Jason Gunthorpe
> > Sent: Tuesday, July 14, 2015 3:42 PM
> > To: Steve Wise
> > Cc: 'Christoph Hellwig'; 'Sagi Grimberg'; 'Steve Wise'; 'Tom Talpey'; 'Doug Ledford'; sagig@mellanox.com; ogerlitz@mellanox.com;
> > roid@mellanox.com; linux-rdma@vger.kernel.org; eli@mellanox.com; target-devel@vger.kernel.org; linux-nfs@vger.kernel.org;
> > trond.myklebust@primarydata.com; bfields@fieldses.org; 'Oren Duer'
> > Subject: Re: [PATCH V3 1/5] RDMA/core: Transport-independent access flags
> >
> > On Tue, Jul 14, 2015 at 02:58:23PM -0500, Steve Wise wrote:
> > > The local_dma_lkey can be used in any rdma sge that requires an
> > > lkey.
> >
> > No, this is where iWarp doesn't follow the generic API - a local dma
> > lkey cannot be used with iWarp's RDMA_READ WR lkey. In effect RDMA
> > READ requires an *rkey* (confusingly stuck into the lkey slot) for
> > iWarp. (Right?)
> >
> 
> Right, a local_dma_lkey is not an rkey, and iwarp requires the rkey for the read destination MR.  Further that rkey needs
> REMOTE_WRITE.
>

BTW: What use is an IB rkey with no REMOTE_ flags set?  Can it be used somehow differently than the associated lkey?