SAS - PL_OC state machine - How many?

Day, Brian bday at
Wed May 14 14:47:12 PDT 2003

* From the T10 Reflector (t10 at, posted by:
* "Day, Brian" <bday at>

I believe Rob has given some good guidance.  An actual HW implementation
"could" be a single state machine that understands how to operate
across all the phys in single device, and understands how each phy of that
device ended up being configured in it's various wide/narrow port

Brian Day
LSI Logic

* From the T10 Reflector (t10 at, posted by:
* "Elliott, Robert (Server Storage)" <Elliott at>
> Does the standard expect the SAS port layer being implemented 
> in firmware?
> Otherwise, how does hardware implemented SAS port layer can 
> dynamically support various number of PL_OC state
> machines (not easy)?

The standard is not very close to actual RTL implementation in the
port and transport layers.  The transport layer describes state 
machines being created and destroyed based on frame reception and
application layer requests.  This is not how real hardware works.

One way to conceptualize an implementation is as a single
"port layer" state machine that handles up to 4 ports 
simultaneously.  Everything it deals with has a
"port number" index appended to it.

> In the SAS spec, it does not mention about this kind of 
> situation and how
> the PL_OC state machine or port layer handle this situation?  Did I
> interpert the PL_OC state machine wrong?
> Pak

* For T10 Reflector information, send a message with
* 'info t10' (no quotes) in the message body to majordomo at

More information about the T10 mailing list