SPC Inquiry for Quad-Aligned Zero -- deprecated since SPC-4 maybe

Mark Evans Mark.Evans at wdc.com
Thu Jan 3 07:49:02 PST 2008


* From the T10 Reflector (t10 at t10.org), posted by:
* "Mark Evans" <Mark.Evans at wdc.com>
*
Hi Ralph,
Now what I think Pat is trying to do is to highlight that setting ALLOCATION
LENGTH to zero in an INQUIRY command is allowed, and that this setting may
be used as, "...a way of asking to test Command Out and Status In without
asking to test Data...".  However, I think this is covered.  Why the value
in the ALLOCATION LENGTH should be set to five or four is already explained
by the cross references in 6.4.1 INQUIRY command introduction, albeit not as
clearly as my suggested wording, but definitely more succinctly.  Wow.
Three "ly" adverbs in one sentence -- ha!
The qualification for the five or four in the ALLOCATION LENGTH field in an
INQUIRY command as defined in 6.4.1 is only a "should".  Based on that text,
zero is allowed as a value in the field for whatever reason.  In addition,
the second paragraph in 4.3.4.6 Allocation length reads, "An allocation
length of zero specifies that no data shall be transferred.  This condition
shall not be considered as an error."  So, 6.4.1 implicitly permits zero as
an allowed value for an INQUIRY command, and 4.3.4.6 explicity allows a
value of zero in an ALLOCATION LENGTH field for any command.
I think that there are many words that could be added to further explain the
setting of the ALLOCATION LENGTH field in an INQUIRY command.  However, "the
standard [already] says so."
Pat, if you want some more words in SPC-4, I'd suggest submitting a proposal
to T10, but based on what is already in the standard, I think you may have
tough sledding.
Regards,
Mark Evans
Western Digital Corporation
5863 Rue Ferrari
San Jose,  CA  95138
Email: mark.evans at wdc.com
Office: 408.363.5257
Fax: 408.363.5139
Cell: 408.391.7805
-----Original Message-----
From: owner-t10 at t10.org [mailto:owner-t10 at t10.org] On Behalf Of Ralph Weber
Sent: Wednesday, January 02, 2008 7:26 PM
To: T10 at t10.org
Subject: Re: SPC Inquiry for Quad-Aligned Zero -- deprecated since SPC-4
maybe
* From the T10 Reflector (t10 at t10.org), posted by:
* Ralph Weber <roweber at ieee.org>
*
Mark,
> ... The only possible clarification I can see is to explain
> a touch more about the reason for the five and four. ...
This of course assumes that some *reason* other than
"because the standard says so" is needed. :-)
All the best,
.Ralph
Mark Evans wrote:
> * From the T10 Reflector (t10 at t10.org), posted by:
> * "Mark Evans" <Mark.Evans at wdc.com>
> *
> Hi Pat,
>
> I'm not sure what you're trying to fix.  The only possible clarification I
> can see is to explain a touch more about the reason for the five and four.
> This could be done by adding a few words the paragraph you mention in
6.4.1
> INQUIRY command introduction as follows:
>
> The ALLOCATION LENGTH field is defined in 4.3.4.6.  If EVPD is set to
zero,
> then the allocation length should be at least five so that the ADDITIONAL
> LENGTH field (i.e., byte 4 in the standard INQUIRY data) is returned
> providing the application client with the length of the data available
(see
> 6.4.2).  If EVPD is set to one, then the allocation length should be
should
> be at least four so that the PAGE LENGTH field (i.e., byte 3 or bytes 2
and
> 3 in a vital product data page) is returned providing the application
client
> with the length of the data in the specified VPD page (see 7.6).
>
> The cross references are already in the paragraph, but I guess a few more
> words wouldn't hurt.	Am I missing the issue that you're trying to
resolve?
> Please let me know.
>
> Regards,
>
> Mark Evans
> Western Digital Corporation
> 5863 Rue Ferrari
> San Jose,  CA  95138
> Email: mark.evans at wdc.com
> Office: 408.363.5257
>
> -----Original Message-----
> From: owner-t10 at t10.org [mailto:owner-t10 at t10.org] On Behalf Of
> plavarre at lexar.com
> Sent: Wednesday, January 02, 2008 1:15 PM
> To: T10 at t10.org
> Subject: RE: SPC Inquiry for Quad-Aligned Zero -- deprecated since SPC-4
> maybe
>
> * From the T10 Reflector (t10 at t10.org), posted by:
> * <plavarre at lexar.com>
> *
> Here's one specific way we could correct the Spc4r11.pdf 6.4 Inquiry
> English:
>
>
> """The ALLOCATION LENGTH field is defined in 4.3.4.6. [+ The allocation
> length should be zero else at least four or five.] If EVPD is set to
> zero, the allocation length should be at least five, so that the
> ADDITIONAL LENGTH field in the parameter data (see 6.4.2) is returned.
> If EVPD is set to one, the allocation length should be [- should be] at
> least four, so that the PAGE LENGTH field in the parameter data (see
> 7.6) is returned."""
>
>
> Like it?
>
>
> The [+] change notation indicates text I think we should add. The [-]
> change notation indicates text I think we should subtract. The
> """quotes""" enclose the wrong I see in our 14 May 2007 Spc4r11.
>
>
> Right way to move forward?
>
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