verify32 byte-by-byte app tag mask question

scott taggart taggart at taggarts.org
Wed May 26 20:52:45 PDT 2010


* From the T10 Reflector (t10 at t10.org), posted by:
* scott taggart <taggart at taggarts.org>
*
John,
Thanks.  Yes, my mistake on which spec version I was referring to - I was 
reading 3r21 but thought I had printed 3r22.  Thanks for the quote of that 
section - it certainly seems to imply/insist that the mask does apply to 
the byte-by-byte checking!  That must be a bear to implement in h/w since 
it is such a special case of byte-by-byte comparison.
Scott
At 06:26 PM 5/26/2010, John Osterlund wrote:
>* From the T10 Reflector (t10 at t10.org), posted by:
>* "John Osterlund" <j.osterlund at sisa.samsung.com>
>*
>Scott,
>
>I think you mean Table 79 in SBC3r21.	(In SBC3r22 it is table 87)
>
>While I cannot find an explicit statement, I would say the following
>paragraph from SBC3r21 implies that the tag mask be taken into account
>since it references the table 79.
>
>===================
>If the ATO bit is set to one in the Control mode page (see SPC-4), and
>checking of the LOGICAL BLOCK APPLICATION TAG field is enabled (see
>table 76, table 77, table 78, and table 79 in 5.24), then the LOGICAL
>BLOCK APPLICATION TAG MASK field contains a value that is a bit mask for
>enabling the checking of the LOGICAL BLOCK APPLICATION TAG field in
>every instance of the protection information for each logical block
>accessed by the command. A LOGICAL BLOCK APPLICATION TAG MASK bit set to
>one enables the checking of the corresponding bit of the EXPECTED
>LOGICAL BLOCK APPLICATION TAG field with the corresponding bit of the
>LOGICAL BLOCK APPLICATION TAG field in every instance of the protection
>information.
>======================
>
>
>Others may have more definitive input.
>
>
>John Osterlund
>HDD Sr. Applications Engineer.
>Samsung Information Systems America (SISA)
>75 W. Plumeria Dr.
>San Jose, CA 95134
>Office: 408 544 5774
>
>-----Original Message-----
>From: owner-t10 at t10.org [mailto:owner-t10 at t10.org] On Behalf Of scott
>taggart
>Sent: Wednesday, May 26, 2010 9:56 AM
>To: t10 at t10.org
>Subject: verify32 byte-by-byte app tag mask question
>
>* From the T10 Reflector (t10 at t10.org), posted by:
>* scott taggart <taggart at taggarts.org>
>*
>Hi,
>
>Referring to SBC3r22, Table 79 "VRPROTECT field with byte-by-byte set to
>one":
>
>When the device is doing the byte-by-byte check of the media data
>compared
>to the data-out buffer, does the app tag mask value in the CDB get taken
>
>into account?	For example, if the app-tag mask is all zero (0x0000),
>should the device hardware NOT compare the apptag?  Or, is the
>app-tag-mask
>ignored for the byte-by-byte compare (i.e. the compare ALWAYS takes
>place).
>
>Thanks,
>
>Scott
>
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