SAS letter ballot comment resolution teleconference Thursday 2pm Central

Elliott, Robert (Server Storage) Elliott at hp.com
Tue Mar 18 09:29:53 PST 2003


* From the T10 Reflector (t10 at t10.org), posted by:
* "Elliott, Robert (Server Storage)" <Elliott at hp.com>
*
SAS Letter ballot comment resolution teleconference
Thursday 20 March 2003
2:00pm Central time

- Toll Free Access Number: 866-639-4721
- Toll Access Number: 574-948-0372
- Participant PIN: 5185037

This call is to review the port layer and a few minor issues that have
cropped up since last week.

Agenda:
* Port layer
* NOTIFY (RESERVED 2)
* Wide port opening itself
* STP affiliation usage model
* SMP target ports and invalid frame lengths
* BROADCAST (CHANGE) from SL
* 03-114r2 incorporation changes



Detailed agenda:

03-024r2 Port layer rewrite  (Mark Evans)
===========================
Mark has posted a potentially final revision.


NOTIFY (RESERVED 2) encoding (Rob Elliott)
============================
This primitive is not neutral.  We need an alternative encoding.


Wide port opening itself (Rob Elliott)
========================
Options discussed:
a) Add connection rate to fairness comparison (makes it the same
   as used by expanders)

b) Add rule that SAS ports doing this shall resolve it by only
   replying to one of the crossing connection requests 
   if a) is adopted, this is needed if these match:
     AWT, source address, connection rate
   if a) is not adopted, this is needed if these match:
     AWT, source address


03-131r0 STP affiliation usage model   (Bob Sheffield)
====================================
Is this explanatory text desired in SAS-1?


SMP target port and invalid SMP frame lengths (Rob Elliott)
=============================================
SMP frame lengths < 2 dwords and > 258 dwords result in a 
BREAK from the SMP target port link layer.  

An SMP frame type other than 40h results in a BREAK from
the SMP target port transport layer.

How should lengths within the legal range be handled (e.g. a 
REPORT GENERAL function that is not exactly 32 bytes long)?

Options are
a) BREAK
b) new SMP function response of INVALID REQUEST FRAME LENGTH

Since SMP frame type errors generate BREAK, we prefer that
approach for length problems too.


BROADCAST (CHANGE) from SL (Rob Elliott)
==========================
SAS ports are allowed to generate BROADCAST (CHANGE), although
target ports are told they "should not" do so.  The SL state machine
does not mention this.  I'd like to add this statement to the
SL_CC0 description to allow this at the proper time:

This state may send a Transmit BROADCAST message to the SL transmitter.

and add it to the SL transmitter section and the figure.


03-114r2 SP_DWS receiver incorporation changes (Rob Elliott)
==============================================
The rewording of the SP_DWS receiver text loses the concept that once a
primitive is detected, the receiver assumes dword synchronization (i.e.
that every 4 characters which follows is a dword).  03-114r2's text
implies that the receiver may still search for K characters and data
dwords at random (using "anytime" is too loose).

Proposed was:
Upon receiving a Find Dword message, the SP_DWS receiver shall monitor
the input data stream and force each K28.5 character detected into the
first byte position as a possible dword. If the next three characters
are data characters, it shall send the dword as a Dword Received (Valid
Primitive) message to the SP_DWS state machine. Until it receives
another Find Dword message, it shall:

   a) send a Dword Received (Valid Primitive) message to the SP_DWS
state
      machine anytime a dword is received that contains a K28.5
character
      in the first byte position followed by three data characters;
   b) send a Dword Received (Invalid) message to the SP_DWS state
machine
      anytime an invalid dword (see 3.1.61xx) is received; or
   c) send a Dword Received (Valid Data Dword) message to the SP_DWS
state
      machine anytime a data dword is received.

Incorporating as:
Upon receiving a Find Dword message, the SP_DWS receiver shall monitor
the input data stream and force each K28.5 character detected into the
first byte position as a possible dword. If the next three characters
are data characters, it shall send the dword as a Dword Received (Valid
Primitive) message to the SP_DWS state machine. Until it receives
another Find Dword message, for every four characters it receives it
shall:

   a) send a Dword Received (Invalid) message to the SP_DWS state
machine
      if the dword is an invalid dword (see 3.1.63);
   b) send a Dword Received (Valid Primitive) message to the SP_DWS
state
      machine if the dword is a primitive (i.e., the dword contains a
K28.5
      character in the first byte position followed by three data
      characters); or
   c)  send a Dword Received (Valid Data Dword) message to the SP_DWS
state
      machine if the dword is not an invalid dword or a primitive.


03-114r2 SP_DWS0 incorporation changes  (Rob Elliott)
======================================
The new wording never sends a new Find Dword message to the receiver to
try to find a primitive again when returning to DWS0 from DWS1 or DWS2.

Also, it reinitializes the timer in DWS8 and DWS9 when transitioning to
DWS0.  This is unnecessary; DWS0 reinitializes it when it gets Start DWS
|from SP.  DWS0 won't do anything until that arrives.

Proposed was:
This is the initial state of this state machine. 

Upon entry into this state, this state shall send an Phy Layer Not Ready
confirmation to the link layer.
After receiving a Start DWS message, this state shall:
a) send a Find Dword message to the SP_DWS receiver, and wait for a
Dword Received (Valid Primitive) message; and 
b) initialize and start the DWS reset timeout timer;

If this state is entered from SP_DWS1 or SP_DWS2 the DWS reset timeout
timer shall continue running.

If this state is entered from SP_DWS1 or SP_DWS2 the DWS and the reset
timeout timer is expired then this state may send a DWS Reset message to
the SP state machine (e.g., if the phy chooses to initiate a new link
reset sequence because dword synchronization has been lost for too
long).

This state shall not send a DWS Reset message to the SP until the DWS
reset timeout timer expires. 
If the DWS reset timeout timer expires this state may send a DWS Reset
message to the SP state machine.

Incorporating as:
This is the initial state of this state machine.

After receiving a Start DWS message, this state shall:
a) send a Find Dword message to the SP_DWS receiver; and 
b) initialize and start the DWS Reset Timeout timer;

If this state is entered from SP_DWS1:Valid1 or SP_DWS2:Valid2, this
state shall send a Find Dword message to the SP_DWS receiver and the DWS
Reset Timeout timer shall continue running.

If this state is entered from SP_DWS1:Valid1 or SP_DWS2:Valid2 and the
DWS Reset Timeout timer has expired, this state may send a DWS Reset
message to the SP state machine (e.g., if the phy chooses to initiate a
new link reset sequence because dword synchronization has been lost for
too long).

This state shall not send a DWS Reset message to the SP until the DWS
Reset Timeout timer expires.

If the DWS Reset Timeout timer expires, this state may send a DWS Reset
message to the SP state machine.


--
Rob Elliott, elliott at hp.com
Hewlett-Packard Industry Standard Server Storage Advanced Technology
https://ecardfile.com/id/RobElliott



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