P1394 Mail Archive: P1394> How to Log Back in....

P1394 Mail Archive: P1394> How to Log Back in....

P1394> How to Log Back in....

Mike Fenelon (mfenelon@microsoft.com)
Mon, 4 Jan 1999 15:22:26 -0800

I had an action item from the San Diego meeting to find out if we could use
the 1212 Message Request/Message Response (MRMR) register as a way to allow
a target to inform an initiator it should Login.

Well I discussed it with our 1394/SBP-2 team here and the verdict is that it
would be workable, but it presents a set of problems. Mainly that if we used
a fixed location on the initiator (PC) then there could be a time where we
could get into a race condition if more than one target (device) asked to be
logged into at the same time. Our team just resolved a problem like this in
another area and would love to avoid a repeat if possible.

The alternate solution is that after a successful login the initiator will
send a command to the target with an address in the initiator. This address
will persist on the host after a logout. The address will be a location that
the target can write a Status Block. This status block would inform the host
to please log into the target. If a bus reset occurs, the address is not
guaranteed to still exist so a target can not send status back to an
initiator that has not reconnected. After reconnect it should send a new
address (could be the same as before). This would allow the host to assign a
new address per device and make sure the login request gets routed to the
correct driver.

Mike Fenelon
Microsoft