> I had a talk with my firmware buddies, and the solution we
> eventually implemented was to ignore those LUN bits for Inquiry
> and Request
> Sense commands only, all other commands will check condition as before. I
> disagree about ignoring reserved fields, not checking reserved fields is
> definitely a bad way to go from the firmware's perspective.
[Disclaimer: The following is from a general protocol definition viewpoint.
I don't know for fact if this applies to SCSI or to this
particular field in SCSI. I could be very wrong.]
No. No. No. The whole point of reserved fields is to allow
for future expansion. Any device that sends a reserved field
should fill it with some well-defined value (almost always
zero). Any device that received a reserved field should
ignore it.
Later, if newer devices need to use this field, the sender will
fill it with a non-zero value. Older devices will still ignore
it. Newer devices will check it, see the non-zero value and
act accordingly.
> As you
> recommended, it's probably prudent to deviate from the spec in
> order to be a
> good bus device.
Does the spec actually say "the receiver should check
that reserved bits are zero?"
Later,
Kenn
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