RE: [rddp] verb spec clarification

["Culley, Paul" <paul.culley at hp.com>]

I've always thought that "Inbound RDMA Write and inbound RDMA Read
Response" were the same thing (one bit) for purposes of the QP enable.
Basically an inbound RDMA Read Response IS an inbound RDMA Write (same
DDP opcode).  The idea for this enable was inherited from VI.

The sections I referenced DO address this; on page 111 for Memory Region
checks the following is stated:

"When a local or remote operation attempts to access a registered Memory
Region, the RI MUST ensure that: 
...
The Access Rights of the QP allow the type of access being performed by
the operation,"

And the zero length check (stated in thread below) over-rides this.

There is similar text under the Memory Window section.

Paul R. Culley
HP Fellow
281-514-5543
 

> -----Original Message-----
> From: pat_thaler at agilent.com [mailto:pat_thaler at agilent.com] 
> Sent: Tuesday, March 29, 2005 7:08 PM
> To: cait at asomi.com; Culley, Paul
> Cc: pkaplan at chelsio.com; rddp at ietf.org
> Subject: RE: [rddp] verb spec clarification
> 
> I think Paul missed the context of the question. Not 
> surprising because the question is a little confusing:
> "Section 9.2.5.1 states that QPs have Inbound RDMA Read 
> enable and Inbound RDMA Write and inbound RDMA Read Response enable.
>  
> Does the inbound RDMA Read Response enable check apply to a 
> zero length read response?"
> 
> The sections Paul mentioned don't address this question.
> 
> There is no RDMA Read Response enable check. Verbs seems to 
> lack any description of the effect of these enables.
> 
> RDMA Read Response enable is a feature of queue creation. 
> Presumably if RDMA Read Response handling is not enabled, 
> there will be no resources provided for initiating RDMA 
> Reads, i.e. ORD will be zero. Attempting to initiate an RDMA 
> Read will fail.
> 
> These enables are not described very much and they may seem 
> redundant with setting IRD and ORD to zero. A modify QP can 
> change IRD and ORD. Setting up the QP with Inbound RDMA Read 
> Response enabled and ORD zero would allow a later attempt to 
> modify the QP to increase ORD. My expectation is that when a 
> QP was set up with Inbound RDMA Read Response disabled, the 
> RNIC can assume that RDMA Read initiation will never be 
> allowed and any attempt to allocate ORD depth could be 
> failed. This is the way I think it should work, but the 
> reaction of an RNIC to a Create QP with Inbound RDMA write 
> and RDMA Read Response disabled and ORD non-zero or a Modify 
> QP for non-zero ORD when this is disabled are not described.
> 
> It also isn't clear why Inbound RDMA Write and inbound RDMA 
> Read response share a single enable. They require different 
> resources since the RDMA Read Response requires ORD depth. 
> They aren't always needed together. An iSCSI target will 
> receive inbound RDMA Writes and will not receive RDMA Read 
> responses. An iSCSI initiator has the reverse situation. 
> 
> Regards,
> Pat
> 
> -----Original Message-----
> From: rddp-bounces at ietf.org [mailto:rddp-bounces at ietf.org]On 
> Behalf Of Caitlin Bestler
> Sent: Tuesday, 29 March, 2005 7:41 AM
> To: Culley, Paul
> Cc: Patricio Kaplan; rddp at ietf.org
> Subject: Re: [rddp] verb spec clarification
> 
> 
> Culley, Paul wrote:
> > For Verbs, The answer is no.
> > 
> > Section 7.6.3 pg 112 near top
> > "If the length of the access is zero, the RI MUST NOT 
> perform any of 
> > the above checks on the Memory Region."
> > 
> > Section 7.10.6.2 pg 124, 2/3 down
> > "If the length of the access is zero, the RI MUST NOT 
> perform any of 
> > the above checks on the Memory Window."
> > 
> 
> Additional point: checking IRD credits is a check on the 
> connection(QP) not on the Memory Region/Memory Window.
> 
> _______________________________________________
> rddp mailing list
> rddp at ietf.org
> https://www1.ietf.org/mailman/listinfo/rddp
> 

_______________________________________________
rddp mailing list
rddp at ietf.org
https://www1.ietf.org/mailman/listinfo/rddp