Advanced Communications Controller B.03.32.00 Release Notes

Patches and Fixes for this Version

Chapter 118

• JAGad69876

Symptoms: Transmit messages stop after ACC runs out of transmit buffers.

Defect/Fix: When an ACC card is heavily using its internal buffers, the DAM can, in rare

situations, be notified that the card is out of buffers for this subchannel or port even

though the driver does not have a single pending write request on the card. This is an

issue because the write completion is what normally restarts the outbound data flow

when the driver goes into outbound flow control (e.g., the card says its out of buffers). In

this special case, the driver keeps track of the subchannel(s) which are in this state and

starts a timer to restart the outbound I/O since there are no write completions to start the

outbound I/O.

After analysis of the problem, it appears that the subchannel is not being placed back onto

the transmit linked list when the timer pops.

When the condition arises where the cards rejects an write request on a subchannel and

the driver does not have any pending write requests on that subchannel, the driver starts

a timer. When the timer pops, the driver finds all subchannels in this state and attempts

to restart any pending writes.

The problem is that the driver is not placing the subchannel back into the linked lists of

subchannels with a pending write request. Code has been added to insert the subchannel

back into the transmit linked list.

• JAGab67070

Symptoms: No automatic card restart after firmware failure.

Defect/Fix: When a Z7200 mux is crashed deliberately (using zcbug, “ru 0 off ok”), the

DAM detects the crash, but there is no automatic card restart. During ZCOM startup, if

there is a problem with the mux $RSET, the DAM issues IRR (Interface Restart Requests)

to the IRR queue and a failure result is returned to ZMON. ZMON retries the RESET for

3 times. This ends up with 3 IRRs being queued up. When ZCOM is ready (of course, with

a bad mux), ZMON receives 3 IRRs in a row and tried to restart the same mux. ZMON

forks a child to handle each IRR. So a total of 3 zmon restarting the same mux in parallel,

end up with a “DAM has too many requests” error.

The following changes have been made,

— controlled restart/shutdown to avoid concurrent control to a mux

— provide info for selective retry when necessary