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

plavarre at lexar.com plavarre at lexar.com
Wed Dec 12 09:49:49 PST 2007


* From the T10 Reflector (t10 at t10.org), posted by:
* <plavarre at lexar.com>
*
> http://t10.org/scsi-3.htm
> http://t10.org/ftp/t10/drafts/spc4/spc4r11.pdf
> 14 May 2007
> ...
> 6.4 INQUIRY command
> 6.4.1 INQUIRY command introduction
> ...
>
> The ALLOCATION LENGTH field is defined in 4.3.4.6.
>
> 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.
Whoa.
Do we actually now mean to be so explicitly deprecating the SCSI test
tradition of SPC Inquiry for zero?
"12 00 00 00 00 00" is the six byte hex CDB I mean.
The tradition I knew was: "The host may send this CDB to discover if
Command Out and Status In works without simultaneously testing Data Out,
Data In, and Sense In and without risk of popping a Unit Attention
(though with the risk of wiping out some read-and-clear Sense data)."
So in future SPC do we mean "any nonzero allocation length should be at
least four" or do we mean "every allocation length should be at least
four" or do we mean something else?
Curiously yours, thanks in advance,
P.S. And while we're here does anyone happen to know where our language
is that recommends SPC Inquiry Allocation Lengths be quad-aligned for
SCSI transports that require quad-aligned data phases?
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