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T10 Reflector Admin by way of John Lohmeyer <john.lohmeyer@lsil.com> jlohmeye at lsil.com
Mon Feb 3 07:53:17 PST 2003


* From the T10 Reflector (t10 at t10.org), posted by:
* jlohmeye at lsil.com (T10 Reflector Admin) (by way of John Lohmeyer <john.lohmeyer at lsil.com>)
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Approved: iscs2
 From: ;Packer, John; <John_Packer at adaptec.com>
 To: t10 at t10.org
 Subject: RE: SAS SSP CDB field - handling extra bytes
 Date: Mon, 3 Feb 2003 06:58:09 -0800 

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 I've always interpreted reserved to mean it must be zero, it is ignored, and
 it is not be used since the protocol has a reservation on those bits, i.e.
 it may want to use them later.  It is not safe to use them in a vendor
 unique fashion because of that.  To say they shall be ignored means just
 that and does not imply reservation.

  

 -----Original Message-----
 From: Elliott, Robert (Server Storage) [mailto:Elliott at hp.com] 
Sent: Sunday, February 02, 2003 9:30 AM
 To: t10 at t10.org
 Subject: SAS SSP CDB field - handling extra bytes

  

 Section 9.2.2.1 COMMAND information unit current includes this rule: 
;The CDB and ADDITIONAL CDB BYTES fields together contain the CDB to be
 interpreted by the addressed logical 
unit. Any bytes between the end of the CDB and the end of the two fields are
 reserved.; 

A letter ballot comment questions whether ;reserved; is the proper term: 
38. (T) Section 9.2.2.1, second paragraph after table 91. Defining fields to
 be reserved generally means they must be tested for zero. Change the second
 sentence from ;Any bytes between the end of the CDB and the end of the two
 fields are reserved; to ;Any bytes between the end of the CDB and the end of
 these two field shall be ignored;. Change the last sentence to ;...the
 remaining ten bytes shall be ignored and the...;

  

 The current wording matches that in other transport protocols, although that
 doesn't necessarily make it correct.  Does anyone want to make this change?

 FCP-2: 
Bytes between the end of a CDB and the end of the FCP_CDB field or, if
 applicable, the ADDITIONAL_FCP_CDB field 
shall be reserved. 

SRP: 
The CDB and ADDITIONAL CDB fields together contain the CDB to be interpreted
 by the addressed logical unit. Any 
bytes between the end of the CDB and the end of the two fields shall be
 reserved. 

iSCSI: 
<doesn't mention what to do with excess bytes> 

SPI-5: 
The CDB field contains the actual CDB to be interpreted by the addressed
 logical unit. The CDB field and the 
task attribute field is not valid and is ignored if the TASK MANAGEMENT
 FUNCTIONS field is not zero. Any bytes 
between the end of a 6 byte CDB, 10 byte CDB, or 12 byte CDB and the end of
 the CDB field shall be 
reserved. 

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

 

 
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 I've always interpreted reserved to mean it must be zero, it is ignored, and it is not be used since the protocol has a reservation on those bits, i.e. it may want to use them later.  It is not safe to use them in a vendor unique fashion because of that.  To say they shall be ignored means just that and does not imply reservation.

  

 -----Original Message-----
 From: Elliott, Robert (Server Storage) [mailto:Elliott at hp.com] 
Sent: Sunday, February 02, 2003 9:30 AM
 To: t10 at t10.org
 Subject: SAS SSP CDB field - handling extra bytes

  

 Section 9.2.2.1 COMMAND information unit current includes this rule: 
;The CDB and ADDITIONAL CDB BYTES fields together contain the CDB to be interpreted by the addressed logical 
unit. Any bytes between the end of the CDB and the end of the two fields are reserved.; 

A letter ballot comment questions whether ;reserved; is the proper term: 
38. (T) Section 9.2.2.1, second paragraph after table 91. Defining fields to be reserved generally means they must be tested for zero. Change the second sentence from ;Any bytes between the end of the CDB and the end of the two fields are reserved; to ;Any bytes between the end of the CDB and the end of these two field shall be ignored;. Change the last sentence to ;...the remaining ten bytes shall be ignored and the...;

  

 The current wording matches that in other transport protocols, although that doesn't necessarily make it correct.  Does anyone want to make this change?

 FCP-2: 
Bytes between the end of a CDB and the end of the FCP_CDB field or, if applicable, the ADDITIONAL_FCP_CDB field 
shall be reserved. 

SRP: 
The CDB and ADDITIONAL CDB fields together contain the CDB to be interpreted by the addressed logical unit. Any 
bytes between the end of the CDB and the end of the two fields shall be reserved. 

iSCSI: 
<doesn't mention what to do with excess bytes> 

SPI-5: 
The CDB field contains the actual CDB to be interpreted by the addressed logical unit. The CDB field and the 
task attribute field is not valid and is ignored if the TASK MANAGEMENT FUNCTIONS field is not zero. Any bytes 
between the end of a 6 byte CDB, 10 byte CDB, or 12 byte CDB and the end of the CDB field shall be 
reserved. 

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

 

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