[MtFuji] MMC / Mt Fuji: 8 bytes and 4 bytes flavors of 'No Event'

Mike Berhan mikeb at bustrace.com
Wed Mar 25 08:39:50 PDT 2009

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David and I discussed this privately and I thought I would bring this to the
reflectors.  It is true that busTRACE decodes bit 0 of CDB offset 1 of the
GESN CDB as the "Immed" bit and not the "POLLED" bit.  This is caused by Mt.
Fuji defining it as the "Immed" bit and MMC defining it as the "POLLED" bit.
I tend to use Mt. Fuji as my primary reference with MMC used for those
definitions that are not defined in Mt Fuji.  Where both specifications
define the same thing, they normally use the same nomenclature.  Not in this
case though.  As a point of information, MMC used to define this as the
"Immed" bit though MMC-3.  MMC-4 changed it to the "POLLED" bit.
I am posting the following information in case one of the two committees
wants to address this. 
Mt. Fuji defines this bit as the "Immed" bit and states:
If the Immed bit is set to one, and if there is no Event to report the
command shall return good status.
If the Immed bit is set to zero (and the logical unit supports tagged
command queuing) and if there is no event to report, the GET EVENT/STATUS
NOTIFICATION command shall be queued by the logical unit until there is an
Event to report.
If the Immed bit is set to zero and the logical unit does not support tagged
command queuing, the logical unit shall return CHECK CONDITION status,
MMC4/5/6 defines this bit as the "POLLED" bit and states:
The Polled bit is used to select operational mode. When Polled is set to
zero, the Host is requesting asynchronous operation. If the Drive does not
support asynchronous operation, the command shall be terminated with CHECK
CONDITION status and the values for SK/ASC/ASCQ shall be set to ILLEGAL
When Polled is set to one, the Host is requesting polled operation. The
Drive shall return event information for the highest priority requested
event. If no event has occurred, the Drive shall report the "No Change"
event for the highest priority requested event class.

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