[openib-general] ib_get_dma_mr and remote access

[Talpey, Thomas]

At 05:53 PM 8/15/2006, Louis Laborde wrote:
>Hi there,
>
>I would like to know if any application today uses ib_get_dma_mr verb with
>remote access flag(s).

The NFS/RDMA client does this, if configured to do so. Otherwise, it registers
specific byte regions when remote access is required. The client supports
numerous memory registration strategies, to suit user requirements and
HCA/RNIC limitations.

>It seems to me that such a dependency could first, create a security hole
>and second, make this verb hard to implement for some RNICs.

Yes, and yes.

>If only local access is required for this "special" memory region, can
>it be implemented with the "Reserved LKey" or "STag0", whichever way it's
>called?

Sure, and I expect many consumers would be fine with this. Note however
that iWARP RDMA Read requires remote write access to be granted on the
destination sge's, unlike IB RDMA Read, which requires only local.

Tom.