Reserved field validation

keiji_katata at post.pioneer.co.jp keiji_katata at post.pioneer.co.jp
Mon May 30 20:13:53 PDT 2005


* From the T10 Reflector (t10 at t10.org), posted by:
* keiji_katata at post.pioneer.co.jp
*

Hi all,

Many MMC devices intentionally ignore reserved field setting of CDB and
Mode Parameters. It is because that many people made many changes in CDB
and Mode page to add new media. They assumed that MMC device may ignore
such fields. No problem or no error should be caused, then current
application (BIOS, OS) can work with both of new MMC device and legacy MMC
device.
Of course, some changes are designed to cause an error intentionally to
help end user from incorrect application implementation. So incorrect data
writing may be rejected by legacy device.

Basically, new functions that uses reserved field of CDB/Parameter are
shown by option bit of Feature Descriptor sent by Get Configuration
Command. Therefore host application can detect such new function capability
of device & medium combination by the option bit setting. If the option bit
says that the function is not available now, host application shall not use
the function. But device may / may not report associated error.
If device shows the option bit, the device shall support the function
correctly.

I think this is the story of MMC.

Best regards,

Keiji Katata
PIONEER CORP.





Rich Ramos <t10 at RichRamos.com>@t10.org on 2005/05/26 10:02:16

$BAw?.<T(J:     owner-t10 at t10.org




$B08 at h(J:  t10 at t10.org
cc:
bcc:
$B7oL>(J:  Reserved field validation

* From the T10 Reflector (t10 at t10.org), posted by:
* Rich Ramos <t10 at RichRamos.com>
*

In SPC-3 (actually for a long time pre-SPC-3), it's been stated that:
"If a logical unit validates reserved CDB fields and receives a
reserved field within the CDB that is not zero, then the logical unit
shall terminate the command with CHECK CONDITION status..."

So what I'm wondering is... Is there a way to find out from a device
if it does said validation?  In other words is there some way to
inquire from the device to see if it does reserved field validation,
other than of course sending a CDB with non-zero values in reserved
fields and seeing if I get a check condition.  I would prefer an
non-"trial and error" method to get a affirmative confirmation/denial
of this option.

Thanks,
Rich
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