Potential XL State Machine holes

Hoglund, Tim Tim.Hoglund at lsil.com
Wed Feb 11 08:22:31 PST 2004


* From the T10 Reflector (t10 at t10.org), posted by:
* "Hoglund, Tim" <Tim.Hoglund at lsil.com>
*
See below, responses prefaced with <TEH>.
I will prepare a proposal to address the identified issues.
TimH

~~~~~~~~~~~~~~~~~~~~~~~
Tim.Hoglund at lsil.com
LSI Logic Corporation
Storage Std Products
719/533-7450 (Voice)
719/533-7480 (Fax)
~~~~~~~~~~~~~~~~~~~~~~~

-----Original Message-----
From: Fred Dutton [mailto:fred.dutton at qlogic.com]
Sent: Wednesday, January 14, 2004 5:24 PM
To: t10 at t10.org
Subject: Potential XL State Machine holes


* From the T10 Reflector (t10 at t10.org), posted by:
* Fred Dutton <fred.dutton at qlogic.com>
*

I am confused about some of the XL state machine transitions described in
SAS 1.1 Revision 2 in section 7.15.

I noticed the specification doesn't always explain what transitions have
priority when two or more events, that would result in 
different transitions, occur simultaneously. I don't know if the situations
described below are possible or if they represent real 
problems.

I would appreciate it if someone could address the following concerns and/or
questions:

Thank you!


Transitions out of XL1
----------------------
What is the correct transition when:

<TEH> XL9:Break for each of these cases.

1) An Arb Won confirmation is received at the same time as a BREAK Received
message
2) An Arb Reject confirmation is received at the same time as a BREAK
Received message
3) An Arb Lost confirmation is received at the same time as a BREAK Received
message

Should the XL1:Request_Path to XL9:Break transition have priority over all
other transitions?
<TEH> Yes.

Transitions out of XL3
----------------------
The XL2:Request_Open to XL3:Open_Confirm_Wait transition description
(7.15.5.2) states: "If a BREAK Received message is received, 
this state shall include a BREAK Received argument with the transition.".
However, there is no mention of this "argument" and its 
results once the XL3 state is entered (i.e. send a Transmit Break request to
the ECR). Perhaps some clarification text could be 
added to section 7.15.6.1 (similar to the description in 7.15.9.1)

<TEH> Agree.

Is it possible to receive a BREAK Received message at the same time as
Transmit Break indication? If so, what is the correct 
transition out of XL3?

<TEH> XL9:Break

Transitions out of XL4
----------------------
The XL4:Open_Reject state is not sensitive to BREAK Received messages. Is
this acceptable?

<TEH> Yes - the behavior in this case is the same as when OPEN_REJECT and
BREAK cross on the wire in which XL will not respond to BREAK and the
endpoint's break timeout timer will fire.

Transitions out of XL6
---------------------- 
Is it possible to receive a BREAK Received message at the same time as
Transmit Break indication? If so, what is the correct 
transition out of XL6?

<TEH> XL9:Break

Transitions out of XL7
----------------------
Is it possible to receive a BREAK Received message at the same time as
Transmit Break indication? If so, what is the correct 
transition out of XL7?

<TEH> XL9:Break

What is the correct transition if a BREAK Received message is received at
the same time as a Transmit Close indication? Should the 
state machine transition to the XL8:Close_Wait state with a BREAK Received
argument included with the transition?

<TEH> No - the transition should be to XL9:Break.  If a BREAK was received
|from an endpoint, that endpoint will be waiting for BREAK not CLOSE.

Transitions out of XL8
----------------------
Is it possible to receive a BREAK Received message at the same time as
Transmit Break indication? If so, what is the correct 
transition out of XL8?

<TEH> XL9:Break


Thanks for your help.

Fred Dutton

__________________________________________
Fred Dutton
QLogic Corporation
949.389.6340


__________________________________________
Fred Dutton
QLogic Corporation
949.389.6340

*
* For T10 Reflector information, send a message with
* 'info t10' (no quotes) in the message body to majordomo at t10.org
*
* For T10 Reflector information, send a message with
* 'info t10' (no quotes) in the message body to majordomo at t10.org




More information about the T10 mailing list