[openib-general] Re: [Rdma-developers] Meeting (07/22) summary:OpenRDMA community development discussion

[Yaron Haviv]

> -----Original Message-----
> From: openib-general-bounces at openib.org [mailto:openib-general-
> bounces at openib.org] On Behalf Of Christoph Hellwig
> Sent: Friday, July 29, 2005 8:02 AM
> To: Tom Duffy
> Cc: Venkata Jagana; rdma-developers at lists.sourceforge.net; Christoph
> Hellwig; openib-general at openib.org
> Subject: [openib-general] Re: [Rdma-developers] Meeting (07/22)
> summary:OpenRDMA community development discussion
> 
> On Thu, Jul 28, 2005 at 02:02:08PM -0700, Tom Duffy wrote:
> > At OLS (and in previous forums), the kernel maintainers have made it
> > *very* clear that there should only be one API.
> 
> _and_ that this api is neither RNIC-PI or KDAPL.  In fact for anything
> that doesn't look very similar to the current IB midlayer you'd need
> very convincing arguments.
> 

I assume it is not as simplistic as that 
iWarp CM model is quite different than IB, and iWarp doesn't have SA/SM
and a bunch of other IB specific things 

For example: 
The correct common abstraction is one where a user can issue a
connection by using a logical end-point address (such as an IP), and
doesn't have to deal with the IB or iWarp specific CM state machine or
SA/SM. 

If you look at DAPL you can break it to simple Verbs (e.g. send, ..)
where its just a simple overlay on to of the verbs (and may be
redundant) 
However there is a second part that implements a simple connection
establishment model (much like BSD) that can be mapped to both IB (CM,
SA, ..) or iWarp (TCP Syn/SynAck, ARP, etc'), this serves couple of main
purposes:
a. make it simple for ULP developer and put the complex part in a common
place   
b. define a common model for different HW

we can spend time and discuss theories and intentions, at the end of the
day an iWarp RNIC cannot just reside under IB-Verbs without major
changes to the overall infrastructure.
Several guys spent some time looking it over and came with an
abstraction that IS possible on top of IB & iWarp & foo, that is called
DAPL (or IT as another similar alternative)

It would probably be wise to try and merge that effort with IB-verbs
etc' 
(e.g. make the verbs portion of the API closer), and on the same time
preserve the effort that was done in kDAPL to overcome the differences
(e.g. in the CM, addressing portions)

Yaron

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