about the SAS XL state machine

Gil Romo gil.romo at qlogic.com
Tue Nov 18 13:26:05 PST 2003


* From the T10 Reflector (t10 at t10.org), posted by:
* Gil Romo <gil.romo at qlogic.com>
*
Hello Shogo and others,

> > If phy#A receives a Transmit Open indication before receiving an Arbitrating 
> > (Normal) confirmation, perhaps it should transition to XL5.

I meant to express that phy#A has entered the XL1 state when the ECR sends it a 
Transmit Open.

Did I understand your question?

Note that I have changed my wording in "phy#A receives a Transmit Open" to "when 
the ECR sends it a Transmit Open", since the XL1 state does not detect any ECR 
indications.

The XL state machine definition assumes that phy#A is in the XL0 state (Idle) 
when phy#B sends a Transmit Open request to the ECR.  If this is not the case, 
the destination phy will not receive the forwarded Transmit Open arguments and 
the source phy will not receive an ECR confirmation.

The XL state machine definition does handle the case where phy#A receives an 
OPEN address frame after already transmitting an OPEN address frame that was 
passed to it via a Transmit Open request.  This is possible because XL5 and XL6 
states detect the OPEN address received message.

I hope that I have understood your question and will continue giving this 
problem my attention.

Best regards,
Gil

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> From: "Shogo Hamasaku" <hamasaku at d1.hw.necst.nec.co.jp>
> To: <t10 at t10.org>
> Subject: Re: about the SAS XL state machine
> Date: Tue, 18 Nov 2003 10:47:34 +0900
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> * From the T10 Reflector (t10 at t10.org), posted by:
> * "Shogo Hamasaku" <hamasaku at d1.hw.necst.nec.co.jp>
> *
> Gil, thank you for your consideration.
> I agree with you in the case of your explanation.
> 
> So, what do you think in the case of that in my previous e-mail?
> That means Phy#A state machine changed to XL1 just before 
> (or simultaneously) to receive Transmit Open request from Phy#B 
> via ECR.
> 
> Thanks,
> Shogo Hamasaku
> 
> 
> > If phy#A receives a Transmit Open indication before receiving an Arbitrating 
> > (Normal) confirmation, perhaps it should transition to XL5.  The transition 
> > would have been XL0 to XL5 if the OPEN address frame had not yet been 
received. 
> > The passing requests are handled by the XL6 state.
> > 
> > > X-Authentication-Warning: t10.org: lohmeyer set sender to 
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> > > From: "Shogo Hamasaku" <hamasaku at d1.hw.necst.nec.co.jp>
> > > To: <t10 at t10.org>
> > > Subject: about the SAS XL state machine
> > > Date: Fri, 14 Nov 2003 19:29:19 +0900
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> > > * From the T10 Reflector (t10 at t10.org), posted by:
> > > * "Shogo Hamasaku" <hamasaku at d1.hw.necst.nec.co.jp>
> > > *
> > > Hi all,
> > > 
> > > I have a question about the SAS XL state machine.
> > > 
> > > What do I do with the XL state machine of Phy#A after Step:3?
> > > I could not find a description about this situation in SAS-1.1 rev.1. 
> > > I think that the XL state of Phy#A depends on the priority of both 
requests.
> > > 
> > > Step:1  Phy#A is XL0:Idle
> > > 
> > > Step:2  Phy#A receives an OPEN Address Frame.
> > >         Then, XL state machine of Phy#A changes from XL0 to 
XL1:Request_Path.
> > > 
> > > Step:3  Phy#A requests a Request Path to the ECM. 
> > >         At the same time, Phy#A recives a Transmit Open request from Phy#B 
> > >         via the ECR, because The ECM has determined to make a connection 
> > >         between Phy#B and Phy#A.
> > > 
> > > So, I thought that a new state (XL11) could be add to the XL sate machine.
> > > 
> > > Transition XL1:Idle to XL11  
> > >   - A Transmit Open request is received.
> > > 
> > > State description about XL11
> > >   - This state shall compare a Request Path request arguments and 
> > >     a Transmit Open request arguments according to the arbitration 
fairness 
> > >     comparison. 
> > >   - If a Request Path request is a higher priority, this state shall send 
a 
> > Backoff
> > >      Retry or a Backoff Reverse Path response to a opposite Phy via the 
ECR.
> > >   - If a Transmit Open request is a higher priority,  this state shall 
change 
> > to 
> > >      XL5:Forward_Open.
> > > 
> > > Thanks,
> > > Shogo Hamasaku
> > > NEC System Technologies, Ltd.
> > >   External:(+81)89-947-7901
> > > *
> > > * For T10 Reflector information, send a message with
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> > 
> > ------------
> > Gilbert Romo
> > Circuits & Integration
> > QLogic Corporation, Aliso Viejo, California
> > Office: 949-389-6266
> > E-mail: gil.romo at qlogic.com
> *
> * For T10 Reflector information, send a message with
> * 'info t10' (no quotes) in the message body to majordomo at t10.org

------------
Gilbert Romo
Circuits & Integration
QLogic Corporation, Aliso Viejo, California
Office: 949-389-6266
E-mail: gil.romo at qlogic.com

*
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