[T10] delayed review comment on 18-117r2 (Configure port mode)

Kevin.Marks at dell.com Kevin.Marks at dell.com
Thu Jan 17 08:24:14 PST 2019

Yes this needs more discussion, as even with SP=0, a change in the bit map would cause re-config effects, but only once as changes were not saved.


From: t10-bounces at t10.org <t10-bounces at t10.org> On Behalf Of Gerry Houlder
Sent: Thursday, January 17, 2019 10:03 AM
To: T10 Reflector
Subject: [T10] delayed review comment on 18-117r2 (Configure port mode)

I have observed an issue with this wording in the proposal:

For a MODE SELECT command with the PC field set to 00b (i.e, current values), if any bit in the port mode bitmap in the parameter data is set to one and is different than the current value for that bit, then upon successful completion...

First, the PC field only applies to a MODE SENSE command not MODE SELECT. This is a serious mis-statement.

Second, If a MODE SELECT command only changes the current value of a mode page bit (i.e., because SP=0), then the saved value is likely to be different. Then when a reset occurs, the current value is updated with the saved value. This will cause the port configuration to revert to the previous phy configuration. I suspect this would be bad.

The best way for an initiator to make this change is with a MODE SELECT command with SP field set to one. i request that this besubmitted in a new proposal.

This forces the current and saved value of the mode page bits to be the same. I don't know if it is reasonable to require a target to reject a MODE SELECT command that changes any of the port mode bitmap bits if SP=0 -- I wonder if we can specify that any MODE SELECT command that changes port mode bitmap shall update both current and saved bits even if SP=0. Alternatively, we can just let the phys fall where they may if the initiator does something this stupid.

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