[openib-general] Re: RDMA memory registration

[Bill Jordan]

On 4/29/05, Greg Lindahl <lindahl at pathscale.com> wrote:
> On Fri, Apr 29, 2005 at 12:33:54PM -0700, Grant Grundler wrote:
> 
> > Being mostly clueless about Quadrics implementation, I'm probably
> > missing something that makes Quadrics a MMU but not the IB variants.
> > Can someone clue me in please?
> 
> As far as I can tell it's mostly a marketing distinction. Many
> Quadrics customers run with memory registration, and Mellanox could
> probably alter their firmware to not require registration.  Myricom
> certainly can, and in fact Patrick Geoffrey claimed they were doing so
> in their MX software. The only one I know of that isn't that flexible
> is PathScale's InfiniPath. Ours is a pure hardware mechanism, but it
> requires memory registration and is clearly not an MMU.
> 
> Confused yet?

I'm very confused at this point. Can you briefly explain how this
works, or point me to a description? I don't see how you could do user
level I/O without registering the memory with the hardware. I'm
especially confused by the comment (may not have been yours) that the
memory doesn't have to be pinned.
-- 
Bill Jordan
InfiniCon Systems