99-208r1 - MRIE behavior with TEST bit asserted

Gerry_Houlder at notes.seagate.com Gerry_Houlder at notes.seagate.com
Wed Oct 20 12:27:14 PDT 1999

* From the T10 Reflector (t10 at t10.org), posted by:
* Gerry_Houlder at notes.seagate.com
I have read Rob's proposed wording a couple of times:

>The text I propose adding in several places is:
>    If TEST = 0, the status may be returned on any command
>    after the informational exception condition occurs. If
>    TEST = 1, the status shall be returned on the next
>    command that is capable of returning an informational
>    exception condition when TEST = 0.

The TEST=1 case has a "shall" in it but then has the weasel words "next comand
that is capable of returning an informational exception condition ..". The net
effect of the weasel words is to negate the shall so the initiator still can't
be sure whether the next command should return a CHECK or not, unless there is
an agreed list of commands that "shall" always return the CHECK. Is this really
an improvement over the old wording?

I would think one of the wider holes in this scheme is when tagged queuing is in
use. When the MODE SELECT command (that sets the TEST bit) completes with GOOD
status, how many of the queued commands will finish with GOOD status (meaning
they were at least partially processed before the Mode page change took effect
and could still be assuming the previous mode setting) before the target gets to
one that will report CHECK status? An initiator can control this case, of
course, by not doing the Mode Select command when there are outstanding tagged
commands. I'm not sure what case Rob is trying to describe, but this wording
doesn't add any more certainty than the old wording.

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