PQI Question

Huy Nguyen huyn at marvell.com
Fri Nov 1 14:24:05 PDT 2013

Formatted message: <a href="http://www.t10.org/cgi-bin/ac.pl?t=r&f=r1311010_f.htm">HTML-formatted message</a>

Thank you, David Geddes, Brad Besmer and Robert Elliot for your answers.
I have another question:
What is a typical use for the Vendor Specific field in the Alternative Data
Block descriptor? Can I have an example?
Thanks again,
Huy Nguyen
From: owner-t10 at t10.org [mailto:owner-t10 at t10.org] On Behalf Of Besmer, Brad
Sent: Thursday, October 31, 2013 4:30 PM
To: Paul Wassenberg; t10 at t10.org
Subject: RE: PQI Question
Your question could be interpreted 2 ways, so I will try to explain what you
would need.
A SGL needs to start with one of the SGL descriptors (Data Block, Bit Bucket,
Standard SGL Segment, Last Standard SGL Segment or Last Alternative SGL
Segment Descriptor). It cannot immediately start off with the Alternative SGL
Segment (Table A.2) itself.
So, for example, for a SOP Command IU, the Data Buffer Descriptor Area starts
at offset 64. At this location, a 16-byte Last Alternative SGL Segment
descriptor (Table A.1), which itself is effectively a pointer to the
Alternative SGL Segment (Table A.2), which is a single array of Alternative
Data Block descriptors (Table A.3).
Clear as mud?
From: owner-t10 at t10.org [mailto:owner-t10 at t10.org] On Behalf Of Paul
Sent: Thursday, October 31, 2013 4:44 PM
To: t10 at t10.org
Subject: PQI Question
Marvell has a question about PQI.
Regarding Alternative SGL Segment in the PQI Spec, Annex A - Can the very
first segment be an Alternative SGL Segment?
Paul Wassenberg

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