
IBM2520L8767
IBM Processor for ATM Resources
atmrm.chapt05.01
08/27/99
Receive Queues (RXQUE)
Page 307 of 553
The receive queues are maintained by RXQUE with the following operations being avail to software:
dequeue
Remove the entry at the head of the queue
enqueue
Add arbitrary entry at the tail of the queue
The following figure shows how events, in a receive queue, link to other data structures including LC control
blocks, packet buffers, and cell buffers.
0x38=111000
Virtual Memory Resource Event
This event specifies that an AAL5 cell was received, but could not be
written into the buffer because a virtual memory boundary was crossed
and a buffer was not available to fill in the next segment. This can also
happen if the cell crosses a boundary that would make the buffer larger
than the virtual buffer size. The event information contains either a
pointer to the packet if receiving bad frames, or a pointer to the LCD that
on which this packet was received.
0x39=111001
Buffer Overflow Event
This event specifies that an AAL5 cell was received, but could not be
written into the buffer because it would exceed the real buffer size. The
event information contains either a pointer to the packet if receiving bad
frames, or a pointer to the LCD on which this packet was received.
0x3a=111010
No DMA Desc for AAL7 Packet Event
This event specifies that an AAL7 (AAL5 with cut-through) packet was
completed, but no DMA descriptors were available to DMA the packet
header. The event information contains either a pointer to the packet if
receiving bad frames, or a pointer to the LCD on which this packet was
received.
0x3b=111011
DMA Cancelled for AAL7 Packet Due to
Error Event
This event specifies that a DMA desc enqueued with a cut-through
operation was cancelled because an error condition was detected with
the packet (CRC, length, ...). The event information contains the system
descriptor address that was cancelled.
0x3c=111100
No Pages Available for AAL5 Scatter
Packet
This event specifies that a AAL5 packet completed with no errors, but
there was a lack of scatter buffers to complete the scatter DMA. The
user must interrogate the partial DMA list in the packet header to
recover the system pages. Once this is done, the packet should be
freed. The user can alternately treat this as a good packet and complete
the packet processing by setting up additional DMAs to move the
remaining data to system pages. The event information contains the
IBM2520L8767 buffer address.
0x3d=111101
IBM2520L8767 Counter Overflow Event
This event specifies that a counter overflow event has been raised. The
event info specifies which counter overflowed. Multiple counter over-
flows can be specified with a single event. The following is the definition
of the event information:
bit 31 Segbf Total User Cells Tx Overflow
bit 30 Segbf Total User Cells with CLP=0 Tx Overflow
bit 29 Reasm Total User Cells Rx Overflow
bit 28 Reasm Total User Cells with CLP=0 Rx Overflow
bit 27 Gpdma Write Dma Byte Count Overflow
bit 26 Gpdma Read Dma Byte Count Overflow
bit 25 Rxque Timestamp Counter Overflow
bit 24 Pcint Performance Counter 1 Overflow
bit 23 Pcint Performance Counter 2 Overflow
0x3e=111110
Pools Status Event
This event specifies that a pools status event has been raised. The
event info contains the status. See POOLS for the definition.
0x3f=111111
Timestamp Event
This event specifies that a timestamp event has been placed ahead of
next event. The event info contains the timestamp.
Bit(s)
Name
Description