On 22/12/2015 15:13, Christoph Hellwig wrote:
On Tue, Dec 22, 2015 at 11:17:54AM +0200, Sagi Grimberg wrote:
What makes me worried here is that the IB/RoCE specification really
defines different keys for local and remote access. I'm less concerned
about our consumers but more about our providers. We keep seeing new
providers come along and its not impossible that a specific HW will
*rely* on this distinction. In such a case we'd need to revert this
patch altogether in that very moment.
I think we're better off working on proper abstractions to help ULPs
get it right (and simple!), without risking future devices support.
With the new API in the next patch ULPs simply can't request an lkey
and a rkey at the same time, so for kernel use it's not a problmblem at
all.
This is why I said that the problem here is not the ULPs. But if a new
HW comes along with distinction between rkeys and lkeys it will have a
problem. For example a HW allocates two different keys, rkey and lkey.
And, it chooses to fail SEND from a rkey, or incoming READ/WRITE to a
lkey. How can such a device be supported with an API that allows a
single key per MR?
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